CN217813674U - Double-cylinder two-stroke power variable air intake system - Google Patents

Abstract

The utility model discloses a variable air intake system of two-cylinder two-stroke power, including carburetor assembly, air intake manifold, first throttle, second throttle, air intake manifold includes main intake duct, the vice intake duct of bypass, the vice intake duct one end bypass of bypass communicates in main intake duct, and the export of carburetor assembly communicates through first throttle and main intake duct one end, and the main intake duct other end, the vice intake duct other end of bypass communicate respectively in two cylinder assemblies, and the second throttle is located in the main intake duct. The utility model discloses can satisfy the demand of the different operating condition of engine, make the operational environment in the engine cylinder very improve.

Description

Double-cylinder two-stroke power variable air intake system

Technical Field

The utility model relates to an engine air intake system field specifically is a variable air intake system of two-cylinder two-stroke power.

Background

The small gasoline engine has light weight, convenient carrying, high operation efficiency and wide application. Common are mowers, ground drills, impact picks, water pumps, lawn mowers, and the like.

After the existing gasoline engine is produced, an air inlet system of the existing gasoline engine is determined, so that the problem that the air inlet system cannot meet the requirements of different working states exists. When the engine is operating at high rotational speeds, the crankcase needs to be charged with sufficient air-fuel mixture to produce sufficient power. At the moment, the engine works at full load, the heat productivity is large, the temperature in the cylinder is high, and the mixed gas is required to be not heated outside the crankcase as much as possible so as to prevent the volume expansion density of the mixed gas from being reduced and the actual gas mixture volume entering the crankcase from being reduced; on the other hand, the low-temperature mixed gas entering the cylinder can cool high-temperature parts such as the cylinder and the piston, and at the moment, the short and thick air inlet channel of the mixed gas is expected to reduce the resistance of the mixed gas entering the crankcase and reduce the time of the mixed gas contacting the air inlet channel as much as possible. When the machine works at low speed or idling, the required air mixture amount is less, the air mixture flow speed is reduced for the same air inlet passage area, and the gasoline atomization and evaporation conditions are poor. And the short air inlet channel ensures that the passing time of the mixed air is short and the heating is insufficient. At the moment, the temperature of the piston of the cylinder is not high, so that the difficulty of gasoline atomization and evaporation is increased. If the engine is required to run normally, more gasoline is needed in the mixed gas to meet the requirement of slightly rich mixed gas, and the emission of the engine is poor. Therefore, the requirements for the intake system to operate at high and low speeds are just the opposite, and the intake system has been determined to be incapable of meeting the requirements of the engine for different operating conditions.

To solve this problem, the prior art may use a variable manifold, for example, in automobiles, and the variable manifold intake technology has been widely used. In the variable manifold technology, the length or the sectional area of the air inlet pipe is changed, so that the inflation efficiency is improved, the engine is more stable and has more sufficient torque at low rotating speed, and the engine is smoother and has more power at high speed.

The principle of the variable manifold technology is that: the intake valves are continuously opened and closed while the engine is running. When the valve is opened, the mixed gas in the intake manifold enters the cylinder through the valve at a certain speed; when the valve is closed, the flowing mixed gas is suddenly stopped, so that the gas rebounds, and the gas vibrates repeatedly along with the running of the gasoline engine. If the intake manifold is short, the wave formed by the bouncing mixture will soon encounter an obstruction, and the bouncing will occur again and return along the original path. Since the traveling speed of the wave formed by the mixed gas after bouncing is constant, if the intake manifold is shorter, the shorter the time for the wave to encounter an obstacle, the faster the bouncing will occur, and the frequency of the wave of the mixed gas vibration will be high. Conversely, if the intake manifold is longer, the time for the wave to encounter an obstacle is longer, and the distance between obstacles is longer, the frequency of the vibration of the air-fuel mixture is lower. When the vibration frequency of the mixed gas is consistent with the opening frequency of the valve, the mixed gas enters the cylinder when the valve is opened, and the energy of a vibration wave is added to a part of the mixed gas. The inflation coefficient of the cylinder is improved, and the power is further improved under the condition of not changing the displacement of the engine. Thus, the variable intake manifold provides optimal air distribution at both high and low engine speeds. When the engine is in low speed, the thin and long air inlet manifold is used to increase the air flow speed and negative pressure of air inlet, so that gasoline can be better atomized and combusted, and the torque can be increased. When the engine needs a large amount of mixed gas at high rotating speed, the air inlet manifold becomes thick and short, so that more mixed gas can be sucked, and the output power is improved.

Although the existing variable manifold technology can adapt to different working states of an engine, different valves are required to control different intake manifolds, the structure is complex, resident vibration of mixed gas is realized by continuously opening and closing the valves, the valves are required to be controlled to continuously act, and the problem of complex intake control exists.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a variable air intake system of double-cylinder two-stroke power to solve the variable manifold technique air inlet structure of prior art and control complicated problem.

In order to achieve the above purpose, the utility model discloses the technical scheme who adopts is:

a two-cylinder two-stroke power variable intake system for an engine having a two-cylinder assembly, comprising a carburetor assembly, an intake manifold, wherein: still include first throttle valve, second throttle valve, air intake manifold includes main intake duct, the vice intake duct of bypass one end bypass communicates in main intake duct, the length of main intake duct is less than the length of the vice intake duct of bypass, and the internal diameter of main intake duct is greater than the internal diameter of the vice intake duct of bypass, the export of carburetor assembly communicates through first throttle valve and main intake duct one end, the main intake duct other end communicates in one of them cylinder assembly, and the vice intake duct other end of bypass communicates in another cylinder assembly, the second throttle valve is located in the main intake duct, and the vice intake duct of bypass communicates the position and is located between second throttle valve, the first throttle valve at the bypass of main intake duct.

Furthermore, one section of the main air inlet channel communicated with the corresponding cylinder assembly is set as a reducing section, and the inner diameter of the reducing section gradually decreases in the direction gradually close to the corresponding cylinder assembly.

Further, the minimum inner diameter of the main air inlet channel is larger than the inner diameter of the bypass auxiliary air inlet channel.

Furthermore, the main air inlet channel is provided with a bending part, and the diameter-variable section is set as the main air inlet channel from the bending part to the corresponding cylinder assembly.

Furthermore, the second throttle valve is arranged in the bending position of the main air inlet channel.

Furthermore, the inner diameter of the bypass auxiliary air inlet channel is 1/5-1/3 of the inner diameter of the main air inlet channel.

Furthermore, the inner diameter of the bypass auxiliary air inlet channel is 1/5-1/3 of the minimum inner diameter of the main air inlet channel.

Furthermore, a turning section is arranged in the bypass auxiliary air inlet channel, and the turning angle is an acute angle.

Furthermore, the cylinder assembly lateral wall that the vice intake duct of bypass corresponds is equipped with the air inlet, the air inlet is established to the reducing mouth of internal diameter gradual change, and the minimum one end in the internal diameter of reducing mouth leads to in the cylinder assembly, the vice intake duct of bypass corresponds the end and communicates in the maximum one end of the internal diameter of reducing mouth, and the minimum internal diameter of reducing mouth is greater than the vice intake duct internal diameter of bypass.

Furthermore, the main air inlet channel is also communicated with and provided with an air storage tank.

The utility model discloses in essence to the improvement of current air intake manifold technique, designed an air intake manifold who comprises main intake duct, the vice intake duct of bypass. In order to ensure that the channel resistance of the mixed gas entering the cylinder is small, the main air inlet channel and the bypass auxiliary air inlet channel are smoothly connected with the air inlets in the corresponding cylinders. The utility model relates to an engine has two cylinders. The two cylinders are respectively fixed on the crankcase through cylinder sealing gaskets, and the two cylinders share one crankcase. Because of the two cylinders, the air inlet manifold behind the carburetor is divided into a main air inlet passage and a bypass auxiliary air inlet passage which are respectively connected with the air inlets of the two cylinders. In order to reduce the flow resistance of the whole inner pipeline of the intake manifold, the inner wall of the whole pipeline of the intake manifold is smooth.

The utility model discloses in, set up the second throttle as the valve through being close to intake manifold bifurcation department in main intake duct, when engine idle running or low-speed operation, the second throttle is closed main intake duct. The passage of the mixture into the engine can only enter the crankcase through the bypass auxiliary air inlet channel. The bypass auxiliary air inlet channel is longer and has smaller cross section, so that mixed gas can enter the cylinder only in a longer time when running at low speed, and sufficient time is provided for absorbing heat on the wall of the bypass auxiliary air inlet channel; further, since the flow cross-sectional area is reduced, the air flow velocity is increased and the air pressure is lowered. Both of these conditions favor the atomization of gasoline. Therefore, at low speed, the gasoline has longer atomization time and lower intake negative pressure, and the increased flow speed can also form stronger vortex in the crankcase, so that the air and the gasoline are better mixed.

When the engine runs at high speed, a large amount of mixture needs to enter the cylinder. At this time, the second throttle valve is in the main intake passage of the intake manifold, and the second throttle valve is opened. Because the main air inlet passage has a large cross-sectional area, the resistance to flowing air mixture is almost eliminated, and a large amount of air mixture quickly enters the cylinder through the main air inlet passage. Because the intake section area is big, and flow resistance is little to main intake duct is short, and the time that the mixture passes through main intake duct is short, and the mixture is inhaled the cylinder under the condition that has not been heated yet, and the mixture volume expansion is not big. Therefore, the mixed gas entering the cylinder has high density, and the inflation coefficient of the cylinder is increased; and the low-temperature mixed gas entering the cylinder is gasified to absorb a large amount of heat of the cylinder and the piston, so that the machine is not too hot.

Compared with the prior art, the utility model discloses a to the improvement of variable manifold, only need set up the second throttle at main intake duct, and first throttle is used for carburetor assembly gas, compares and need set up the throttle respectively at different pipelines in traditional variable manifold, has simplified overall structure. And in the utility model, the second air throttle does not need to be opened and closed continuously, thus simplifying the air intake control. On the basis, the utility model discloses still can satisfy the demand of the different operating condition of engine, make the operational environment in the engine cylinder very improve.

Drawings

Fig. 1 is a front sectional view of the assembled structure of the present invention and an engine.

Fig. 2 is a partially enlarged view of a position I in fig. 1.

Fig. 3 is a partial enlarged view of position II in fig. 1.

Fig. 4 is a working state diagram of the engine assembled with the engine of the present invention at high speed.

Fig. 5 is a partially enlarged view of a position III in fig. 4.

Fig. 6 is a state diagram of the air tank of fig. 5 in operation.

In the figure: 1. a spark plug; 2. a first cylinder assembly; 3. a piston assembly; 4. a crankshaft assembly; 5. an air inlet pipe sealing gasket; 6. a cylinder gasket; 7. a crankcase; 8. bypassing the secondary air intake; 9. a second throttle valve; 10. a gas storage tank; 11. a primary air intake; 12. a first throttle valve; 13. a carburetor assembly; 14. a choke valve; 15. a second cylinder assembly.

Detailed Description

The present invention will be further explained with reference to the drawings and examples.

As shown in fig. 1, 2 and 3, the present invention relates to a two-cylinder two-stroke power variable intake system for an engine comprising a crankcase 7, a first cylinder assembly 2 and a second cylinder assembly 15. The spark plugs 1 are respectively arranged on the first cylinder assembly 2 and the second cylinder assembly 15, the crankshaft assembly 4 is arranged on the crankcase 7, the crankshaft assembly 4 rotates clockwise, and the piston component 3 can slide in the first cylinder assembly 2 and the second cylinder assembly 15 under the drive of the crankshaft assembly 4. The first cylinder assembly 2, the second cylinder assembly 15 and the crankcase 7 are sealed by cylinder gaskets 6 and fixed by screws.

The utility model discloses a carburetor assembly 13, air intake manifold, first air throttle 12, the second air throttle 9 of engine, wherein air intake manifold includes main intake duct 11, the vice intake duct 8 of bypass, and the entrance point bypass of the vice intake duct 8 of bypass communicates in main intake duct 11 one side. The outlet end of the bypass auxiliary air inlet channel 8 is fixedly connected with the air inlet of the first cylinder assembly 2 through an air inlet pipe sealing gasket 5 by screws, and the outlet end of the same main air inlet channel 11 is fixedly connected with the air inlet of the second cylinder assembly 15 through the air inlet pipe sealing gasket 5 by screws. The first throttle valve 12 is installed in the outlet of the carburetor assembly 13, the outlet of the carburetor assembly 13 is communicated with the inlet end of the main intake duct 11 through the first throttle valve 12, and the inlet of the carburetor assembly 13 is communicated to the outside through the choke valve. The main air inlet 11 is provided with a second throttle valve 9 for switching between high and low speeds. The air storage tank 10 is fixed on the main air inlet 11 through screw thread communication. The inner diameter of the bypass auxiliary inlet channel 8 is about 1/4 of the inner diameter of the main inlet channel 11.

The air inlet of the first air cylinder assembly 2 is set to be a reducing opening, one end with the smallest inner diameter of the reducing opening leads to the inside of the first air cylinder assembly 2, the end with the largest inner diameter of the reducing opening is communicated and connected with the outlet end of the bypass auxiliary air inlet channel 8, and the smallest inner diameter of the air inlet of the first air cylinder assembly 2 is larger than the inner diameter of the bypass auxiliary air inlet channel 8.

The main air inlet 11 is provided with a bending part corresponding to the branch position of the air inlet manifold, a section of the main air inlet from the bending part to the second air cylinder assembly 15 is set as a reducing section, the inner diameter of the reducing section gradually decreases along the direction gradually close to the second air cylinder assembly 15, and the minimum inner diameter of the main air inlet 11 is still larger than the inner diameter of the bypass auxiliary air inlet 8. The second throttle valve 9 is arranged in a bent part of the main air inlet channel 11, and the bypass auxiliary air inlet channel 8 is positioned between the second throttle valve 9 and the first throttle valve 12 at a bypass communication position of the main air inlet channel 11.

Principle of operation

An idling state:

when the engine is operated in an idling or low-speed state, the engine operating speed is low. The two-stroke power configuration features that the phase of opening and closing the intake ports is determined by the position of the ports on the cylinder assembly and does not change once manufacture is complete. However, because the engine is designed with the maximum working speed for valve timing, the time from opening to closing of the engine air inlet is prolonged compared with the high speed. At this time, the second throttle valve 9 is in a closed state, the first throttle valve 12 is also in an idle or low speed position, and the passage of the main intake passage 11 to the second cylinder assembly 15 is closed. The mixture from the carburetor assembly 13 is throttled by the first throttle valve 12 and then enters the first cylinder assembly 2 via the bypass intake manifold 8. And the bypass auxiliary air inlet channel 8 is longer in pipeline, and although the amount of the mixed gas entering the cylinder is small, the flow speed of the mixed gas is still higher and the pressure of the mixed gas is small due to the small inner diameter of the bypass auxiliary air inlet channel 8, so that the gasoline atomization and evaporation are facilitated. And the bypass auxiliary air inlet channel 8 is longer, and the mixed gas is heated by the bypass auxiliary air inlet channel 8 for a longer time before entering the first cylinder assembly 2, so that evaporation of gasoline in the mixed gas is facilitated. Meanwhile, the sharp bend of the bypass auxiliary air inlet channel 8 enables larger unvaporized gasoline drops in the mixed gas to be stuck at the turning part due to inertia, and separation of the larger gasoline drops and the mixed gas is realized. So as to prevent the large gasoline drops from being adhered to the inner wall of the crankcase 7 and not easy to be vaporized. Therefore, the mixed gas which is well mixed and easy to burn enters the crankcase 7, which is beneficial to reducing the emission value in idling and reducing the oil consumption. The trapped gasoline is completely vaporized by the continuous impact of the subsequent mixture before entering the crankcase 7. After the mixed gas enters the crankcase 7, due to the special shape of the air inlet of the first cylinder assembly 2, the sectional area of the mixed gas entering the cylinder 2 from the bypass auxiliary air inlet passage 8 is suddenly increased, and the mixed gas sprayed into the first cylinder assembly 2 from the bypass auxiliary air inlet passage 8 generates strong vortex; and the high speed rotation of the crankshaft assembly 4 creates a large vacuum behind the bell crank. The mixed gas entering the first cylinder assembly 2 from the bypass auxiliary air inlet passage 8 is sprayed into the crankcase 7 and then is rotationally hit by the rotating crank throw, so that the mixed gas is mixed more uniformly, and the mixing of gasoline and air is promoted. Thereby the mixed gas is fully combusted, the oil consumption is low, and the harmful components in the exhaust gas are reduced.

High speed heavy load

As shown in fig. 4, 5, and 6, when the engine is operating at a high speed, more fresh air-fuel mixture is required. The second throttle valve 9 now opens the passage to the main intake duct 11, and the first throttle valve 12 of the carburettor assembly 13 is fully open, at which time the machine speed is high. The carburetor assembly 13 produces a large amount of air mixture that is regulated by the first throttle valve 12, passed through the main intake duct 11, the second throttle valve 9 and into the second cylinder assembly 15. At this time, the bypass sub-intake duct 8 may be led to the first cylinder assembly 2, but the inner diameter of the bypass sub-intake duct 8 is small and may be ignored. The path of the mixed gas from the main air inlet passage 11 to the second cylinder assembly 15 is extremely short, and the inner diameter of the main air inlet passage 11 is larger, so that the mixed gas quickly enters the second cylinder assembly 15 with small resistance and large charge coefficient, and the dynamic property of the engine is ensured. And the shape of the inner diameter of the main air inlet channel 11 from the turning part to the air inlet of the second air cylinder assembly 15 is a funnel shape with a large outer part and a small inner part, the transition is smooth, and the resistance of the mixed air entering the air cylinder 15 is reduced. Meanwhile, the funnel-shaped structure with the larger outer part and the smaller inner part increases the flow speed of the mixed gas, and the flow speed reaches the maximum when the mixed gas reaches the gas inlet of the second cylinder assembly 15, and then the mixed gas is sprayed into the second cylinder assembly 15 from the gas inlet of the second cylinder assembly 15. The cross-sectional area suddenly increases, generating a vortex. Then flows into the crankcase 7 and is further forcibly stirred by the crankshaft assembly 4 rotating at high speed, the mixed gas is uniformly mixed, the mixed gas is ignited and combusted fully and quickly, the power of the engine is improved, and the oil consumption is reduced. The reason why the second throttle valve 9 is not located close to the second cylinder assembly 15 is because the diameter of the main intake passage 11 decreases from the turn toward the second cylinder assembly 15. The installation shaft and the valve plate of the second throttle valve 9 have certain volume, and the installation of the second throttle valve can reduce the flow cross section of the main air inlet 11.

An air storage tank 10 is mounted on the main air intake duct 11 at the rear end of the carburetor assembly 13. When the engine works, the inlet valves of the first cylinder assembly 2 and the second cylinder assembly 15 are just opened, and the piston assembly 3 does not move far towards the top dead center of the first cylinder assembly 2 and the second cylinder assembly 15, so that the volume of the space in the crankcase 7 is not increased, and the negative pressure in the crankcase 7 is not large at the moment, and the suction force to the mixed gas is not large. As the piston assembly 3 is closer to the top dead center, the vacuum suction is greater and the speed of the mixture flowing into the second cylinder assembly 15 is faster and faster. As the piston assembly 3 moves past top dead center to bottom dead center, the vacuum suction within the crankcase 7 becomes less and less. The piston assembly 3 continues to travel downward and the skirt portion of the piston assembly 3 closes the intake port of the second cylinder assembly 15. The flow rate of the mixture is large due to the high speed operation of the engine. After the intake port of the second cylinder assembly 15 is suddenly closed, the mixture flow rate suddenly drops to zero. The mixed gas can only flow into the gas storage tank 10 without other paths under the inertia effect. When the piston assembly 3 moves next time to open the air inlet of the second cylinder assembly 15, the generated negative pressure sucks the mixture provided by the carburetor assembly 13; meanwhile, the air pressure of the air-fuel mixture stored in the air tank 10 last time is also higher than the pressure in the main intake duct 11, and the air tank 10 also supplies the air-fuel mixture to the main intake duct 11. This makes the pressure of the mixture gas in the main intake duct 11 large, and makes it easier to suck a large amount of mixture gas in the crankcase 7 in a short time. Due to the presence of the air reservoir 10, the air pressure in the main air intake duct 11 does not fluctuate much. The large vacuum degree in the crankcase 7, the large suction force, the high flow speed of the mixed gas, the large amount of the sucked gasoline and the heavy mixed gas do not exist; the vacuum degree is small, the suction force is small, and the mixed gas is thin. Thus, the mixture concentration does not fluctuate much. And, the intake efficiency is improved, and the air-fuel ratio is also improved, so that the performance and the fuel consumption are improved.

Therefore, the utility model discloses because the vice intake duct of bypass 8 is thin again long during well low-speed, petrol obtains fully preheating before getting into crankcase 7. And when the gasoline engine is started, the negative pressure is low, and the gasoline is easy to atomize and evaporate. The engine is easy to start, stable in idling operation and low in oil consumption.

The utility model discloses in, the gas mixture gets into through a sharp bend earlier between the cylinder 2 through the vice intake duct 8 of bypass. Can generate a large amount of vortex, and is beneficial to the atomization and evaporation of the gasoline. Meanwhile, the sharp bend can screen the mixed gas, so that large gasoline drops which are not atomized and evaporated cannot enter the crankcase 7. And gasoline oil drops caught at the sharp bend are impacted by the mixed gas all the time until the gasoline oil drops are atomized and evaporated. The cross section area of the bypass air inlet valve 8 is small, and the airflow speed is high; and the longer intake path allows the gasoline more time to absorb heat. So that fuel consumption is low at idle.

The utility model discloses when the engine is high-speed, 11 sectional areas of main intake duct are big to the sectional area changes slowly, and the main intake duct is shorter, and air resistance is little. The time for the mixed gas to enter the crankcase 7 from the carburetor assembly 13 is short, and the mixed gas is not easily heated before entering the cylinder 15; the crankcase 7 is thus highly charged and the engine power is high. The low mixed gas temperature can better cool the first cylinder assembly 2 and the second cylinder assembly 15, and the temperature of the engine is not too high in a high-power state.

The utility model discloses in, the existence of gas holder 10 lets power inflation efficiency higher. When the air flows from the main air inlet 11 to the air storage tank 10, the pressure difference is small, the air flow pressure difference passing through the carburetor assembly 13 is reduced due to the existence and filling of the container, so that the mixed air which is rich in the original engine is corrected to be the right concentration, which is the main reason of saving the oil.

The embodiments of the present invention are only descriptions of the preferred embodiments of the present invention, not right the present invention is designed and limited, without departing from the design concept of the present invention, the technical personnel in the field should fall into the protection scope of the present invention for various modifications and improvements made by the technical solution of the present invention, and the technical contents of the present invention are all recorded in the claims.

Claims (10)

1. A two-cylinder two-stroke power variable intake system for an engine having a two-cylinder assembly, comprising a carburetor assembly, an intake manifold, wherein: still include first throttle valve, second throttle valve, air intake manifold includes main intake duct, the vice intake duct of bypass one end bypass communicates in main intake duct, the length of main intake duct is less than the length of the vice intake duct of bypass, and the internal diameter of main intake duct is greater than the internal diameter of the vice intake duct of bypass, the export of carburetor assembly communicates through first throttle valve and main intake duct one end, the main intake duct other end communicates in one of them cylinder assembly, and the vice intake duct other end of bypass communicates in another cylinder assembly, the second throttle valve is located in the main intake duct, and the vice intake duct of bypass communicates the position and is located between second throttle valve, the first throttle valve at the bypass of main intake duct.

2. A dual cylinder two-stroke power variable intake system as defined in claim 1 wherein: the main air inlet channel is communicated with one section of the corresponding air cylinder assembly and is set as a reducing section, and the inner diameter of the reducing section gradually decreases along the direction gradually close to the corresponding air cylinder assembly.

3. A dual cylinder two-stroke power variable intake system as claimed in claim 2, wherein: the minimum inner diameter of the main air inlet channel is larger than the inner diameter of the bypass auxiliary air inlet channel.

4. A dual cylinder two-stroke power variable intake system as claimed in claim 2, wherein: the main air inlet channel is provided with a bending part, and the diameter-variable section is arranged from the bending part to one section of the main air inlet channel between the corresponding air cylinder assemblies.

5. The dual cylinder two-stroke power variable intake system of claim 4, wherein: the second throttle valve is arranged in the bending position of the main air inlet channel.

6. A dual cylinder two-stroke power variable intake system as claimed in claim 1, wherein: the inner diameter of the bypass auxiliary air inlet channel is 1/5-1/3 of the inner diameter of the main air inlet channel.

7. A dual cylinder two-stroke power variable intake system as claimed in claim 2 or 6, wherein: the inner diameter of the bypass auxiliary air inlet channel is 1/5-1/3 of the minimum inner diameter of the main air inlet channel.

8. A dual cylinder two-stroke power variable intake system as defined in claim 1 wherein: and a turning section is arranged in the bypass auxiliary air inlet channel, and the turning angle is an acute angle.

9. A dual cylinder two-stroke power variable intake system as claimed in claim 1, wherein: the cylinder assembly lateral wall that vice intake duct of bypass corresponds is equipped with the air inlet, the air inlet is established to the reducing mouth of internal diameter gradual change, and in the minimum one end of reducing mouth internal diameter accesss to the cylinder assembly, vice intake duct of bypass corresponds the end and communicates in the maximum one end of reducing mouth internal diameter, and the minimum internal diameter of reducing mouth is greater than the vice intake duct internal diameter of bypass.

10. A dual cylinder two-stroke power variable intake system as defined in claim 1 wherein: the main air inlet channel is also communicated with and provided with an air storage tank.

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