CN111156075A

CN111156075A - Air guide structure of engine

Info

Publication number: CN111156075A
Application number: CN202010061184.8A
Authority: CN
Inventors: 林树军; 周大权; 龚建平; 吴兵勇; 梁浩
Original assignee: Zhejiang Qianjiang Motorcycle Co Ltd
Current assignee: Zhejiang Qianjiang Motorcycle Co Ltd
Priority date: 2020-01-19
Filing date: 2020-01-19
Publication date: 2020-05-15

Abstract

The invention provides an air guide structure of an engine, and belongs to the technical field of machinery. It has solved the inhomogeneous problem of current engine cooling, and the cooling effect is poor. This wind-guiding structure of engine of improvement structure, engine include the cylinder, and wind-guiding structure establishes the wind scooper outside the cylinder including covering, the wind scooper is including relative air intake curb plate and the exhaust curb plate that sets up, the air outlet has been seted up on the exhaust curb plate, the wind scooper is still including connecting exhaust curb plate and air intake curb plate and being used for the aviation baffle of wind-guiding, its characterized in that, the aviation baffle internal surface is provided with bellied main drainage plate and main drainage plate along protruding direction slope towards the exhaust curb plate gradually, form main drainage wind channel between main drainage plate and the exhaust curb plate, be provided with the deep bead that is used for hindering gaseous flow direction cylinder on the main drainage wind channel. The engine with the improved structure has uniform cooling and good cooling effect.

Description

Air guide structure of engine

Technical Field

The invention belongs to the technical field of machinery, and relates to an air guide structure, in particular to an air guide structure of an engine.

Background

Good cooling is of great importance to motorcycle engines, motorcycle engines generally have two cooling modes of water cooling and air cooling, air cooling is different from forced air cooling and natural air cooling, and forced air cooling motorcycle engines are widely concerned in recent years due to the characteristics of simple maintenance and small influence of the cooling effect of the engines on the speed of the whole motorcycle. The cooling is mainly carried out on a cylinder and a combustion chamber thereof in the motorcycle engine, and the cooling performance of the whole forced air-cooling motorcycle engine is directly influenced by the design quality of the air guide cover.

The patent No. 201410255072.0 discloses an engine air guide structure of a motorcycle, wherein a cooling fan is arranged on one side of a crankshaft of the engine, a spark plug mounting seat is arranged on one side of a cylinder head of the engine, the spark plug mounting seat can be used for inserting a spark plug, an air guide cover is covered on the periphery of the engine, the air guide cover comprises an upper cover cap, a lower cover cap and a fan cover, respective flanges of the upper cover cap and the lower cover cap are connected to form an air guide plate which is obliquely arranged, the air guide plate is arranged opposite to the fan, and the air guide plate can gradually guide the air at the fan into the air guide cover along the length direction of the air guide plate. According to the invention, a part of the external cooling air entering the air guide cover is guided to flow to the spark plug mounting seat of the engine by the air guide piece, so that the spark plug mounting seat of the engine is effectively cooled, and the service life and the effect of the engine are improved.

Although above-mentioned structure can be with the heat effluvium of cylinder to a certain extent, because the air outlet of wind scooper is seted up on the exhaust curb plate that has the exhaust perforation, be provided with the cylinder subassembly in the inside of wind scooper, and set up and have the perforated air intake curb plate of admitting air and then far away from the air outlet with the exhaust curb plate is relative, under the blocking effect of cylinder, most cooling air can directly get into and directly discharge towards the air outlet direction along the exhaust curb plate from the income wind gap department of wind scooper, and can not wind to air intake curb plate one side and wind the cylinder round and discharge again, only the minority can flow through air intake curb plate one side. This results in the cylinder or combustion chamber being adequately cooled on the side closer to the exhaust side plate, but not being adequately cooled on the side closer to the intake side plate, which results in uneven final cooling and poor cooling.

The conventional conceivable solution is to introduce the wind introduced from the fan into the wind scooper at a position closer to the intake side plate, so that the cylinder, the combustion chamber, or the like can be sufficiently cooled at a position closer to the intake side plate. Or it is conceivable to add a small blower or the like near the air intake side plate to introduce air into or change the position of the air outlet.

Disclosure of Invention

The invention aims to solve the problems of uneven cooling and poor cooling effect of an engine.

The purpose of the invention can be realized by the following technical scheme:

the air guide structure of the engine comprises an air cylinder, the air guide structure comprises an air guide cover which is covered outside the air cylinder, the air guide cover comprises an air inlet side plate and an air outlet side plate which are arranged oppositely, an air outlet is formed in the air outlet side plate, the air guide cover further comprises an air guide plate which is used for connecting the air outlet side plate and the air inlet side plate and guiding air, the air guide structure is characterized in that a main guide plate is arranged on the inner surface of the air guide plate, is protruded and inclines towards the air outlet side plate along the protruding direction, a main guide air channel is formed between the main guide plate and the air outlet side plate, and a wind shield used for blocking air from flowing to the air cylinder is.

The air deflector is used for guiding air, namely guiding cooling air into the air guiding cover, so that air generated from the outside of the air guiding cover flows along the direction of the air deflector after entering the air guiding cover through the air deflector. Because main drainage plate is along protruding direction slope towards the exhaust curb plate gradually, so be located the cooling air in main drainage wind channel and have the trend towards exhaust curb plate direction even air outlet direction flow. And be provided with the deep bead that is used for hindering gas flow direction cylinder again on the main drainage wind channel, then the partial wind that lies in main drainage wind channel this moment can take place the striking with the deep bead under the effect of this deep bead, can not directly flow to exhaust curb plate and direct outflow air outlet along this direction smoothly, but speed reduces suddenly and causes slow or pile up, only can stretch from the peripheral other wind channels of main drainage wind channel speed reduction or pass through from the other spaces of main drainage wind channel speed reduction, consequently, the possibility of the direct exhaust air outlet of cooling air in this department has been reduced, make it flow to other directions as far as possible and make other positions of keeping away from the air outlet all have the cooling air to pass through as far as possible.

The cooling air flowing in from the rest of the channels on the periphery of the main drainage air channel, namely from the rest of the positions of the air deflector, still has a higher flow speed, the wind energy with at least two high and low speeds enables the wind flowing in from different channels to have a speed difference, and the cooling air in the air channel adjacent to the main drainage air channel can obliquely flow by the inclined arrangement, but not directly impact the cylinder in the front direction, and flows along the tangential direction similar to the cylinder as far as possible, and the wind speed difference and the inclined flow enable the wind in the air guide cover to form a vortex around the circumferential direction of the cylinder, so that more wind can be driven to pass through one side of the air inlet side plate, the cylinder close to one side of the air inlet side plate and even the combustion chamber can be further cooled, uneven cooling is avoided, and the cooling effect can.

The conventionality is difficult to think of being provided with convex and gradually towards the main drainage plate of exhaust curb plate slope at the aviation baffle internal surface, this because the air outlet has just set up on the exhaust curb plate originally, if incline main drainage plate towards exhaust curb plate direction again, so can make more wind directly discharge toward air outlet department and can not flow toward the curb plate direction of admitting air, can cause the cooling of the different positions of whole cylinder more inhomogeneous like this, and the cooling effect is poor.

In the air guide structure of the engine, the air baffle is positioned on the air guide plate and protrudes downwards, and the air baffle is connected with the main drainage plate. Because the wind scooper has the trend of guiding wind, the wind shield can be arranged in the wind inlet direction of the wind guide cover to enable cooling wind flowing along the surface of the wind guide plate to be blocked more fully, so that great speed reduction is realized, the wind speed in the main drainage wind channel and the wind speeds at other positions are ensured to form a great speed difference, a vortex is formed better, and more wind flows to the direction of the air inlet side plate and other directions to realize more uniform and effective cooling. The wind shield and the main drainage plate are connected to be arranged so that the wind shield and the main drainage plate can be attached to each other as much as possible without gaps or the gaps are as small as possible, the wind shield and the main drainage plate can be integrally manufactured or can be connected in a split mode, and therefore cooling wind flowing towards the direction of the air outlet and attached to the surface of the main drainage plate can be blocked by most of the cooling wind so as to ensure the final cooling effect. The top-bottom direction in this case is actually for the placement direction shown in the figures.

In the air guide structure of the engine, the air deflector is arranged substantially vertically, and the lower edge of the air deflector is higher than the lower edge of the main drainage plate. The wind shield which is approximately vertically arranged can be basically parallel to the air inlet direction, so that the wind can rapidly reduce the speed after striking the wind shield, and finally the formation of vortex is ensured to realize more uniform cooling. The lower edge of the wind shield is higher than that of the main drainage plate, so that at least a small part of cooling air can still normally flow to the direction of the exhaust side plate, and the situation that the space from the wind shield to the air outlet is not cooled by enough cooling air is avoided, so that the cooling effect is ensured. Of course, the lower edge, substantially vertical in this case is actually with respect to the placement direction shown in the figures.

In the air guide structure of the engine, the air baffle is arranged in the middle of the main air guide channel. The wind shield is arranged at one part of the middle part of the main drainage air channel, so that cooling air flowing in from the outside of the wind guide cover has at least certain collection length and impact accommodation space, and meanwhile, the rear side of the wind shield and the air cylinder can also keep a certain space, so that the situation that due to too tight fit, enough space is not provided for accommodating rear vortex gas and the like is avoided, and insufficient heat dissipation is caused.

In the air guide structure of the engine, the inner surface of the air guide plate is also provided with a raised auxiliary drainage plate, the auxiliary drainage plate gradually inclines towards the exhaust side plate along the raised direction, and the auxiliary drainage plate is positioned between the main drainage plate and the air inlet side plate and forms an auxiliary drainage air channel with the air inlet side plate. The auxiliary drainage plate can divide the space at the air deflector into more flow channels, so that cooling air of each part can flow according to a specified route to form flow speed difference in order, and the problem that the cooling air is dispersed and disordered due to too small number of the flow channels and too large space of the independent flow channels, the flow speed is not obvious, and the obvious speed difference is difficult to form with the cooling air in the main drainage air channel is avoided. And the auxiliary drainage plate is also arranged towards the exhaust side plate, so that cooling air coming out from the auxiliary drainage air channel can be driven along the same rotating direction to form a vortex, and the problem that the vortex in the same direction is difficult to form due to the fact that the cooling air in different flow channels is opposite in flow direction and mutually impacted is avoided. This setting can guarantee to form effectively circling round, guarantees that the cooling is even, improves the cooling effect.

In the air guide structure of the engine, the included angle between the main drainage plate and the exhaust side plate is larger than the included angle between the auxiliary drainage plate and the exhaust side plate. Because the auxiliary drainage plate is closer to one side of the air inlet side plate relative to the main drainage plate, the inclination angle of the auxiliary drainage plate is slightly smaller, so that more air can flow out of the auxiliary drainage air channel to cool a heat source close to one side of the air inlet side plate, and the two sides of the air guide cover can be cooled uniformly.

In the air guide structure of the engine, the protrusion height of the main drainage plate is greater than that of the auxiliary drainage plate, and the main drainage plate and the auxiliary drainage plate are in smooth transition with the air guide plate. Because be provided with the deep bead on the main drainage wind channel, though still leave some clearances and supply some cooling air to follow the deep bead below the flow direction exhaust curb plate direction and flow, but because the effect of top deep bead has some cooling air deceleration and also has the influence to the velocity of flow of below, consequently with the more arch of main drainage plate setting, just that is relatively speaking main drainage wind channel's length is some longer more, can make the direct flow direction exhaust curb plate's the fractional cooling air can keep the certain speed to send out, guarantee the cooling effect. Can strengthen the structural strength of main drainage plate and supplementary drainage plate on the one hand through smooth transition's design, another part can increase the smooth and easy nature of flow of cooling air.

In the above air guide structure of the engine, the air guide structure further includes a fan disposed below the air guide cover, and the fan and the air guide plate are disposed adjacent to each other. The fan can accelerate cooling air to enter the air guide cover so as to form better cooling.

In the air guide structure of the engine, an intermediate air duct is formed between the main drainage plate and the auxiliary drainage plate, and the flow area of the intermediate air duct is larger than that of the main drainage air duct and larger than that of the auxiliary drainage air duct. The middle air duct is designed to be larger, and the air ducts on the other two sides are designed to be smaller, so that cooling air from the outside of the air guide cover can directly carry out primary cooling on most area in the middle, the cooling time is shortened, and the cooling efficiency is improved.

In the above air guide structure of the engine, the air intake side plate includes a main body portion provided with an air intake pipe interface and a straight air intake portion disposed opposite to the auxiliary drainage plate, a guide portion gradually inclining toward the exhaust side plate from the air intake portion to the main body portion is disposed between the main body portion and the air intake portion, and the main body portion is connected to the air intake portion through the guide portion. The guide portion can realize assisting drainage plate looks similar function for the cooling air that comes out from assisting the drainage wind channel also can drive along same direction of rotation and form the vortex, avoids forming the vortex of same direction from the opposite vortex that is difficult to of the cooling air flow direction in the different runners. This setting can guarantee to form effectively circling round, guarantees that the cooling is even, improves the cooling effect.

Compared with the prior art, the invention has the following technical effects:

1. the combined action of the main drainage plate and the wind shield can enable partial wind in the main drainage air channel to impact the wind shield positively under the action of the wind shield, so that the speed is reduced rapidly, and the possibility that most of cooling wind is directly discharged out of the air outlet is reduced. The cooling wind flowing from the rest channels on the periphery of the main drainage air channel, namely from the rest positions of the air deflector still has a higher flow speed, and the wind energy with at least two high and low speeds enables the wind flowing from different channels to have a speed difference so that the wind in the air deflector forms a vortex around the circumferential direction of the cylinder, thus further cooling the cylinder close to one side of the air inlet side plate and even the combustion chamber, and further improving the cooling effect.

2. The auxiliary flow guide plate can divide the space at the air guide plate into more flow channels, so that cooling air of each part can flow according to a specified route to form flow speed difference in order. And the auxiliary drainage plate is also arranged towards the exhaust side plate, so that cooling air coming out of the auxiliary drainage air channel can be driven along the same rotating direction to form a vortex, effective convolution is guaranteed to be formed, uniform cooling is guaranteed, and the cooling effect is improved.

Drawings

Fig. 1 is a schematic sectional structure diagram of an engine.

Fig. 2 is a schematic perspective view of the wind scooper.

Fig. 3 is a perspective view of another view of the wind scooper.

Fig. 4 is a plan view of the wind scooper.

Fig. 5 is a sectional view of the wind scooper.

In the figure, 1, cylinder; 2. a wind guide structure; 3. a wind scooper; 31. an air intake side plate; 311. an air inlet pipe interface; 312. a main body portion; 313. an air intake portion; 314. a guide section; 32. an exhaust side plate; 321. an air outlet; 322. an exhaust pipe interface; 33. an air deflector; 34. a main drainage plate; 35. a main drainage air duct; 36. a wind deflector; 37. an auxiliary drainage plate; 38. an auxiliary drainage air duct; 39. a middle air duct; 4. a fan.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

As shown in fig. 1, the engine includes a cylinder 1 and a crankcase located below the cylinder 1, the crankcase is connected with a crankshaft, the cylinder 1 includes a main body and a cylinder head (the cylinder head is not shown in the figure, and only the main body located below is shown in the figure) located above the main body, a combustion chamber is provided in the cylinder 1, and combustion in the combustion chamber generates a large amount of heat, so that heat dissipation needs to be performed on the structures of the cylinder 1 and the like. In this embodiment, the heat dissipation effect is enhanced mainly by the design of the wind guiding structure 2.

As shown in fig. 1, specifically, the air guiding structure 2 includes a fan 4 and an air guiding cover 3 covering the cylinder 1, the fan 4 is connected to the crankshaft, when the engine operates, the crankshaft rotates to drive the fan 4 to rotate to drive the external cooling air to enter and flow to the air guiding cover 3, as shown in fig. 2 and 5, the air guiding cover 3 includes an air inlet side plate 31 and an air outlet side plate 32 which are oppositely arranged, the air outlet side plate 32 is provided with an air outlet pipe interface 322 and a plurality of air outlets 321, and the air inlet side plate 31 is provided with an air inlet pipe interface 311. The wind scooper 3 further includes a wind scooper 33 that is located above the fan 4 and connects the exhaust side plate 32 and the intake side plate 31 for guiding wind, and the wind scooper 33 is used for guiding wind, that is, for guiding cooling wind into the wind scooper 3, so that wind generated from outside the wind scooper 3 flows in the direction of the main wind guide duct 35 after entering the main wind guide duct 35 through the wind scooper 33.

As shown in fig. 3 and 4, a convex main flow guide plate 34 is arranged on the inner surface of the air guide plate 33, the main flow guide plate 34 gradually inclines towards the exhaust side plate 32 along the convex direction, a main flow guide air duct 35 is formed between the main flow guide plate 34 and the exhaust side plate 32, and a wind shield 36 for blocking air from flowing to the air cylinder 1 is arranged on the main flow guide air duct 35. In the present embodiment, the wind deflector 36 is located on the wind deflector 33 and protrudes toward the wind inlet direction of the wind guide housing 3, specifically, the wind deflector 36 is disposed substantially vertically, and the lower edge of the wind deflector 36 is higher than the lower edge of the main drainage plate 34. The lower edge, substantially vertical in this case, is actually with respect to the placement direction shown in the figures. And the wind shield 36 is connected with the main drainage plate 34 and the wind shield 36 is arranged in the middle of the main drainage duct 35. The wind shield 36 is arranged in the middle of the main drainage air duct 35, so that cooling air flowing in from the outside of the wind guide cover 3 has at least certain collection length and impact accommodation space, meanwhile, the space of a certain degree can be kept between the rear side of the wind shield 36 and the air cylinder 1, and insufficient heat dissipation caused by insufficient space for accommodating rear vortex gas due to too tight fit is avoided.

In addition, as shown in fig. 3 and 4, the inner surface of the air guide plate 33 is further provided with a raised auxiliary drainage plate 37, the auxiliary drainage plate 37 gradually inclines towards the exhaust side plate 32 along the raised direction, the auxiliary drainage plate 37 is located between the main drainage plate 34 and the air inlet side plate 31, and an auxiliary drainage air duct 38 is formed between the auxiliary drainage plate 37 and the air inlet side plate 31. The auxiliary flow guide plate 37 can divide the space at the air guide plate 33 into more flow passages, so that the cooling air of each part can flow according to a specified route to form flow speed difference in order. And the auxiliary drainage plate 37 is also arranged towards the exhaust side plate 32, so that the cooling air coming out of the auxiliary drainage air duct 38 can be driven along the same rotating direction to form a vortex.

In this embodiment, the angle between the main flow-guide plate 34 and the exhaust side plate 32 is greater than the angle between the auxiliary flow-guide plate 37 and the exhaust side plate 32. So that more wind can be directly branched off to cool the heat source near the side of the air intake side plate 31 when flowing out of the auxiliary air guide duct 38. And the protruding height of main drainage plate 34 is greater than the protruding height of assisting drainage plate 37, and the length of main drainage wind channel 35 is more a little more relatively, can make the direct little part cooling air that flows to exhaust curb plate 32 can keep the certain speed to send out, guarantees the cooling effect. In addition, the main drainage plate 34 and the auxiliary drainage plate 37 are in smooth transition with the air guide plate 33, so that the structural strength of the main drainage plate 34 and the auxiliary drainage plate 37 can be enhanced, and the flowing smoothness of cooling air can be improved.

As shown in fig. 3, an intermediate air duct 39 is formed between the main flow guide plate 34 and the auxiliary flow guide plate 37, and the flow area of the intermediate air duct 39 is larger than the flow area of the main flow guide air duct 35 and larger than the flow area of the auxiliary flow guide air duct 38. The wind from the outside of the wind scooper 3 can firstly directly carry out primary cooling on most area in the middle, the cooling time is shortened, and the cooling efficiency is improved.

As shown in fig. 2 and 4, the air intake side plate 31 includes a main body 312 having an air intake pipe connection opening 311 and a straight air intake portion 313 disposed opposite to the auxiliary drainage plate 37, a guide portion 314 disposed between the main body 312 and the air intake portion 313 and gradually inclined toward the exhaust side plate 32 from the air intake portion 313 to the main body 312, and the main body 312 and the air intake portion 313 are connected by the guide portion 314. The guide portion 314 can perform a function similar to that of the auxiliary air guide plate 37, so that the cooling air coming out from the auxiliary air guide duct 38 can be driven in the same rotation direction to form a vortex.

When the engine works, the crankshaft rotates to drive the fan 4 to work, external cooling air can be sucked into the engine, the cooling air is guided into the wind scooper 3 through the guiding effect of the arc-shaped wind deflector 33, the air entering the wind scooper 3 is correspondingly divided by the main diversion plate 34 and the auxiliary diversion plate 37 and flows into corresponding flow channels, the cooling air flowing into the main diversion air channel 35 flows along the length direction of the wind deflector 33 and is blocked by the wind blocking plate 36, so that the air speed of part of the air is reduced, the air speed of the rest part of the air is influenced, only a small part of the air normally flows to the direction of the exhaust side plate 32 through the lower gap and flows out from the air outlet 321, the air speed of the air flowing out from the middle air channel 39 and the auxiliary diversion air channel 38 is higher, the air speed is different from the air speed of the main diversion air channel 35 and forms a vortex, and the cooling air positioned in the wind scooper 3 can form, the cooling air can flow to the direction of the air inlet side plate 31 more fully, heat dissipation is more uniform, and the cooling effect is further improved.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Although terms such as the cylinder 1, the air guide structure 2, the air guide cover 3, the air inlet side plate 31, the air inlet pipe interface 311, the main body 312, the air inlet portion 313, the guide portion 314, the air outlet side plate 32, the air outlet 321, the air outlet pipe interface 322, the air guide plate 33, the main flow guide plate 34, the main flow guide air duct 35, the air deflector 36, the auxiliary flow guide plate 37, the auxiliary flow guide air duct 38, the intermediate air duct 39, and the fan 4 are used more frequently, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention.

Claims

1. An air guide structure of an engine, the engine comprises an air cylinder (1), the air guide structure (2) comprises an air guide cover (3) covered outside the air cylinder (1), the wind scooper (3) comprises an air inlet side plate (31) and an air outlet side plate (32) which are oppositely arranged, the exhaust side plate (32) is provided with an air outlet (321), the wind scooper (3) also comprises a wind deflector (33) which is used for connecting the exhaust side plate (32) and the air inlet side plate (31) and guiding wind, it is characterized in that the inner surface of the air deflector (33) is provided with a convex main drainage plate (34), the main drainage plate (34) gradually inclines towards the exhaust side plate (32) along the convex direction, a main drainage air duct (35) is formed between the main drainage plate (34) and the exhaust side plate (32), and a wind shield (36) for blocking the gas from flowing to the cylinder (1) is arranged on the main drainage air duct (35).

2. The air guide structure of the engine according to claim 1, wherein the wind deflector (36) is located on the air deflector (33) and protrudes downward, and the wind deflector (36) is connected with the main flow guide plate (34).

3. The air guide structure of the engine according to claim 2, wherein the air deflector (36) is arranged substantially vertically, and a lower edge of the air deflector (36) is higher than a lower edge of the main flow guide plate (34).

4. The air guide structure of an engine according to claim 3, wherein the wind deflector (36) is provided in a middle portion of the main air guide duct (35).

5. The air guide structure of the engine according to claim 3 or 4, wherein a raised auxiliary flow guide plate (37) is further arranged on the inner surface of the air guide plate (33), the auxiliary flow guide plate (37) is gradually inclined towards the exhaust side plate (32) along the raised direction, the auxiliary flow guide plate (37) is located between the main flow guide plate (34) and the air inlet side plate (31), and an auxiliary flow guide air duct (38) is formed between the auxiliary flow guide plate (37) and the air inlet side plate (31).

6. The air guide structure of the engine as claimed in claim 5, wherein the included angle between the main flow guide plate (34) and the exhaust side plate (32) is larger than the included angle between the auxiliary flow guide plate (37) and the exhaust side plate (32).

7. The air guide structure of the engine as recited in claim 6, wherein the height of the protrusion of the main flow guide plate (34) is greater than that of the protrusion of the auxiliary flow guide plate (37), and the main flow guide plate (34) and the auxiliary flow guide plate (37) are in smooth transition with the air guide plate (33).

8. The air guide structure of the engine according to claim 5, wherein an intermediate air duct (39) is formed between the main flow guide plate (34) and the auxiliary flow guide plate (37), and a flow area of the intermediate air duct (39) is larger than a flow area of the main flow guide air duct (35) and larger than a flow area of the auxiliary flow guide air duct (38).

9. The air guide structure of an engine according to any one of claims 1 to 4, wherein the air guide structure (2) further comprises a fan (4) disposed below the air guide cover (3), and the fan (4) is disposed adjacent to the air guide plate (33).

10. The air guide structure of the engine according to claim 5, wherein the air intake side plate (31) includes a main body portion (312) having an air intake pipe joint (311) and a straight air intake portion (313) disposed opposite to the auxiliary drainage plate (37), a guide portion (314) that gradually inclines from the air intake portion (313) to the main body portion (312) toward the exhaust side plate (32) is disposed between the main body portion (312) and the air intake portion (313), and the main body portion (312) and the air intake portion (313) are connected by the guide portion (314).