CN117072340A - Engine cooling structure and motorcycle - Google Patents

Abstract

The application relates to an engine cooling structure and a motorcycle, which comprises a water jacket water inlet pipe, wherein the water jacket water inlet pipe comprises a water inlet main pipe, a first water inlet branch pipe and a second water inlet branch pipe, the first water inlet branch pipe and the second water inlet branch pipe are respectively communicated with the water inlet main pipe, and a flow guiding structure is arranged in a pipe cavity of the first water inlet branch pipe; the water jacket inlet of the rear cylinder is communicated with the first water inlet branch pipe; and the water jacket inlet of the front cylinder is communicated with the second water inlet branch pipe. Under the condition that the water jacket structures of the rear cylinder and the front cylinder are completely unchanged, the water guide structure can lead the cooling liquid flowing into the water jacket of the rear cylinder to be distributed again, thereby compensating the flow field difference of the water jacket inlets of the rear cylinder and the front cylinder caused by the structural arrangement problem, enhancing the cooling effect of the spark plug side of the cylinder head of the rear cylinder, leading the cooling effect of the rear cylinder and the front cylinder to be consistent, well solving the problem of local abnormal temperature rise of the engine and ensuring the safe and reliable operation of the engine.

Description

Engine cooling structure and motorcycle

Technical Field

The application relates to the technical field of vehicle cooling, in particular to an engine cooling structure and a motorcycle.

Background

When the motorcycle engine works, a great amount of heat is released due to the combustion of the mixture gas in the cylinder, wherein about one third of the heat is transferred to the cooling system through the parts contacted by the high-temperature fuel gas. According to the heat distribution of the thermal equilibrium, the heat dissipated into the cooling system must be dissipated through the cooling medium. However, as the instantaneous maximum temperature in the cylinder of the motorcycle engine can reach 2000-2500 ℃, besides the stress generated by mechanical load, the thermal load can also cause thermal stress in parts, so that the parts of the piston, the valve, the cylinder wall, the cylinder head and the like contacted with high-temperature fuel gas bear great mechanical load and thermal load. While overheating of parts can present a series of safety issues: if the temperature of the parts is increased due to strong heating, the engine can be overheated if heat is not dissipated in time. Overheating can cause damage to the normal fit clearances of the parts, deterioration and coking of the lubricating oil between the moving parts, exacerbation of friction and wear of the moving parts, severe or even damage due to seizing deformation, etc., and therefore proper cooling of the engine is necessary.

For a motorcycle engine, 50% to 65% of the total heat transferred to the cooling water is transferred through the cylinder head. Thus, the temperature level of the cylinder head is high. The design principle of the cylinder head water jacket on the structure is as follows: the high temperature area is cooled by adopting proper method, and the area between the inlet valve and the exhaust valve seat and the high temperature parts such as the spark plug seat are cooled intensively on the water-cooled engine. Therefore, when designing the structure of the cooling water jacket, water channels and tissue cooling water flows are reasonably arranged, and measures are taken to strengthen the cooling of the local high-temperature area. For a V-shaped double-cylinder engine of a motorcycle, the cooling of a local high-temperature area of each cylinder head is ensured.

Under the conventional design structure, due to the characteristic of the structural arrangement of the V-shaped double cylinders, the difference of the inlet flow fields of the front cylinder water jacket and the rear cylinder water jacket is easy to cause, so that the flow direction of the inner flow of the front cylinder water jacket and the rear cylinder water jacket is obviously different, the flow distribution difference of the cooling liquid in the cylinder head after flowing through the water passing holes is directly influenced, and finally, the difference of the flow fields of the front cylinder water jacket and the rear cylinder head and the difference of the temperature field of the front cylinder head and the rear cylinder head are caused, if the local temperature of the spark plug side of the rear cylinder is abnormally increased, and the operation safety and the reliability of an engine are influenced.

Disclosure of Invention

Based on the above, it is necessary to provide an engine cooling structure and a motorcycle aiming at the problem that the safety and reliability of the operation of the engine are affected by the too high local temperature rise of the rear cylinder caused by the difference of the flow field and the flow direction of the cooling liquid.

In one aspect, the present application provides an engine cooling structure comprising:

the water jacket water inlet pipe comprises a water inlet main pipe, a first water inlet branch pipe and a second water inlet branch pipe, wherein the first water inlet branch pipe and the second water inlet branch pipe are respectively communicated with the water inlet main pipe, and a flow guide structure is arranged in a pipe cavity of the first water inlet branch pipe;

the water jacket inlet of the rear cylinder is communicated with the first water inlet branch pipe; and

and the water jacket inlet of the front cylinder is communicated with the second water inlet branch pipe.

The engine cooling structure of the scheme is applied to an engine, can be particularly applied to a V-shaped double-cylinder engine with a front cylinder and a rear cylinder, and can be used for solving the problem of high temperature overheat caused by a large amount of heat generated by the front cylinder and the rear cylinder of the engine when the engine is in operation, at the moment, cooling liquid can flow into a first water inlet branch pipe and a second water inlet branch pipe respectively through a water inlet main pipe of a water jacket water inlet pipe and then flow into the rear cylinder and the front cylinder respectively through the first water inlet branch pipe and the second water inlet branch pipe, and the cooling liquid absorbs heat and takes away the heat, so that the effect of cooling the rear cylinder and the front cylinder can be achieved. However, in view of the structural arrangement characteristics of the rear cylinder and the front cylinder, the difference of the water jacket inlets of the front cylinder and the rear cylinder is easy to cause, so that the flow directions of the inner flows of the water jackets of the cylinder bodies of the front cylinder and the rear cylinder are obviously different, and the water guide structure is arranged in the first water inlet branch pipe, so that the cooling liquid flowing into the water jackets of the rear cylinder can be distributed in a reflow manner under the condition of ensuring that the structures of the water jackets of the rear cylinder and the front cylinder are completely unchanged, thereby compensating the flow field difference of the water jacket inlets of the rear cylinder and the front cylinder caused by the structural arrangement problem, enhancing the cooling effect of the spark plug side of the front cylinder head of the rear cylinder, enabling the cooling effect of the rear cylinder and the cooling effect of the front cylinder to be consistent, well solving the problem of local abnormal temperature rise of an engine, and ensuring the safe and reliable operation of the engine.

The technical scheme of the application is further described as follows:

in one embodiment, the flow guiding structure is configured as a flow guiding plate, and the extending direction of the flow guiding plate is consistent with the flowing direction of the cooling liquid in the first water inlet branch pipe, so that the flow guiding plate and the inner pipe wall of the first water inlet branch pipe form a water flow passage at intervals.

In one embodiment, the inner pipe wall of the first water inlet branch pipe is provided with a first pipe wall part and a second pipe wall part which are opposite to each other and are positioned on the guide plate, the guide plate is separated from the first pipe wall part to form a first water flow passage, and the guide plate is separated from the second pipe wall part to form a second water flow passage.

In one embodiment, the flow guide plate comprises a flow guide part, the flow guide part is obliquely arranged, an included angle between the flow guide part and the opposite direction of the flow path of the cooling liquid in the water inlet main pipe is set to be theta, and the range of theta is 0-90 degrees.

In one embodiment, the guide part has a start end side, the inner pipe diameter of the first water inlet branch pipe is set to be L, and the start end side is positioned in a downstream L/2 section on a flow path of the cooling liquid in the water inlet main pipe.

In one embodiment, the guide plate further includes an introduction portion, one side of the introduction portion is connected to one side of the guide portion away from the start end side, and the introduction portion is disposed in parallel with a flow direction of the cooling liquid flowing in the first water inlet branch pipe.

In one embodiment, the first and second inlet branches are at axially different positions of the inlet main pipe.

In one embodiment, the tube center line of the first water inlet branch tube and the tube center line of the second water inlet branch tube form an included angle.

In one embodiment, the number of the flow guiding structures is at least two, and the at least two flow guiding structures are arranged at intervals along the direction perpendicular to the flow path of the cooling liquid in the first water inlet branch pipe.

In another aspect, the present application also provides a motorcycle comprising the engine cooling structure as described above.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application.

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic view of an engine cooling structure according to an embodiment of the present application.

Fig. 2 is a partial sectional view of the first water inlet branch pipe of fig. 1.

Fig. 3 is a partially enlarged structural view at a in fig. 2.

Fig. 4 is a schematic structural view of a water jacket inlet pipe according to an embodiment.

Fig. 5 is a schematic diagram of the principle and structure of the water inlet pipe of the water jacket.

Reference numerals illustrate:

10. a water jacket inlet pipe; 11. a water inlet main pipe; 12. a first water inlet branch pipe; 121. a first tube wall portion; 122. a second tube wall portion; 13. a second water inlet branch pipe; 14. a deflector; 141. a flow guiding part; 142. an introduction unit; 20. a rear cylinder; 30. a front cylinder; 40. a first water flow passage; 50. and a second water flow passage.

Detailed Description

In order that the above objects, features and advantages of the application will be readily understood, a more particular description of the application will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the application, whereby the application is not limited to the specific embodiments disclosed below.

In the description of the present application, it should be understood that, if any, these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., are used herein with respect to the orientation or positional relationship shown in the drawings, these terms refer to the orientation or positional relationship for convenience of description and simplicity of description only, and do not indicate or imply that the apparatus or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application.

Furthermore, the terms "first," "second," and the like, if any, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the terms "plurality" and "a plurality" if any, mean at least two, such as two, three, etc., unless specifically defined otherwise.

In the present application, unless explicitly stated and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly. For example, the two parts can be fixedly connected, detachably connected or integrated; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present application, unless expressly stated or limited otherwise, the meaning of a first feature being "on" or "off" a second feature, and the like, is that the first and second features are either in direct contact or in indirect contact through an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that if an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. If an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein, if any, are for descriptive purposes only and do not represent a unique embodiment.

Referring to fig. 1 to 5, an engine cooling structure according to an embodiment of the present application is shown, which includes a water jacket intake pipe 10, a rear cylinder 20, and a front cylinder 30. The water jacket water inlet pipe 10 comprises a water inlet main pipe 11, a first water inlet branch pipe 12 and a second water inlet branch pipe 13, and the first water inlet branch pipe 12 and the second water inlet branch pipe 13 are respectively communicated and arranged on the water inlet main pipe 11.

The water jacket inlet of the rear cylinder 20 communicates with the first water inlet branch pipe 12, and the water jacket inlet of the front cylinder 30 communicates with the second water inlet branch pipe 13.

It is to be readily understood that the engine cooling structure should further include a coolant supply device for connection with the water inlet port of the water inlet main pipe 11 for delivering coolant into the water inlet main pipe 11 so that the coolant can flow into the rear cylinder 20 and the front cylinder 30 through the first water inlet branch pipe 12 and the second water inlet branch pipe 13, respectively, to effect cooling of the rear cylinder 20 and the front cylinder 30.

Optionally, the cooling liquid can be cooling water, cooling oil or other cooling media, and the cooling liquid can be flexibly selected according to actual needs.

In this embodiment, in order to reduce the cooling cost, cooling water is used for the cooling liquid. The water is adopted as the cooling medium, so that the use cost is low and the water is easy to obtain.

The main water inlet pipe 11, the first water inlet branch pipe 12 and the second water inlet branch pipe 13 can be integrally formed or detachably assembled. In order to ensure the connection strength and the tightness, the present embodiment preferably adopts an integral structure of the main water inlet pipe 11, the first water inlet branch pipe 12 and the second water inlet branch pipe 13.

Naturally, the main water inlet pipe 11 and the first water inlet branch pipe 12, and the main water inlet pipe 11 and the second water inlet branch pipe 13 may be assembled and fixed by flange screwing, snap-fit connection, or the like, and the sealing ring is provided on the assembly surface to perform the leakage prevention treatment.

With continued reference to fig. 4 and 5, further, the first water inlet branch pipe 12 and the second water inlet branch pipe 13 are located at different positions in the axial direction of the main water inlet pipe 11. The pipe center line of the first water inlet branch pipe 12 and the pipe center line of the second water inlet branch pipe 13 are arranged at an included angle.

The structure is equivalent to enabling the first water inlet branch pipe 12 and the second water inlet branch pipe 13 to be arranged in double dislocation in the axial direction and the peripheral direction on the water inlet main pipe 11, so that the first water inlet branch pipe 12 and the second water inlet branch pipe 13 are more beneficial to being assembled and connected with the rear cylinder 20 and the front cylinder 30 respectively, the rear cylinder 20 and the front cylinder 30 are ensured to form V-shaped structural arrangement under the condition of not interfering, and the structural arrangement requirement of the V-shaped double-cylinder engine is met.

In this embodiment, the water jacket inlet of the rear cylinder 20 is specifically a first water jacket, and the first water jacket is nested and inserted with the first water inlet branch pipe 12 to achieve the connection purpose. For example, the outer diameter of the first water jacket pipe may be smaller than the inner diameter of the first water inlet branch pipe 12, so that the end of the first water jacket pipe is inserted into the lumen of the first water inlet branch pipe 12 to achieve the plug-in fixation, or the inner diameter of the first water jacket pipe may be larger than the outer diameter of the first water inlet branch pipe 12, so that the end of the first water jacket pipe is sleeved outside the pipe end of the first water inlet branch pipe 12 to achieve the plug-in fixation. The specific installation mode is selected according to actual needs.

The water jacket inlet of the front cylinder 30 is the same as the above-described structure, and can be understood with reference to the water jacket inlet of the rear cylinder 20, and thus, a detailed description thereof will be omitted.

The first water inlet branch pipe 12 and the second water inlet branch pipe 13 may be circular pipes, square pipes, or the like. For example, the first water inlet branch pipe 12 and the second water inlet branch pipe 13 in this embodiment are square pipes.

In addition, a flow guiding structure is arranged in the pipe cavity of the first water inlet branch pipe 12. The flow guiding structure is used for improving the flow field and the flow direction condition of the cooling liquid flowing into the first water inlet branch pipe 12 from the water inlet main pipe 11, so that more cooling liquid can flow into the position (such as the spark plug side) where the rear cylinder 20 has abnormal high temperature.

In summary, implementing the technical scheme of the embodiment has the following beneficial effects: the engine cooling structure of the scheme is applied to an engine, and particularly can be applied to a V-shaped double-cylinder engine with a front cylinder 30 and a rear cylinder 20, when the engine is in operation, a large amount of heat is generated by the front cylinder 30 and the rear cylinder 20 of the engine, so that the problem of high temperature overheat occurs, at the moment, cooling liquid can flow into a first water inlet branch pipe 12 and a second water inlet branch pipe 13 respectively through a water inlet main pipe 11 of a water jacket water inlet pipe 10, then flow into the rear cylinder 20 and the front cylinder 30 respectively through the first water inlet branch pipe 12 and the second water inlet branch pipe 13, the cooling liquid absorbs the heat and takes away the heat, and the effect of cooling the rear cylinder 20 and the front cylinder 30 can be achieved.

However, in view of the characteristics of the structural arrangement of the rear cylinder 20 and the front cylinder 30, the difference of the water jacket inlet flow fields of the front cylinder and the rear cylinder is easy to cause, so that the flow direction of the inner flow of the water jackets of the cylinder bodies of the front cylinder and the rear cylinder is obviously different, and the water guide structure is arranged in the first water inlet branch pipe 12, so that the cooling liquid flowing into the water jackets of the rear cylinder 20 can be distributed again by the water guide structure under the condition of ensuring that the water jacket structures of the rear cylinder 20 and the front cylinder 30 are completely unchanged, thereby compensating the flow field difference of the water jacket inlets of the rear cylinder 20 and the front cylinder 30 caused by the structural arrangement problem, enhancing the cooling effect of the spark plug side of the cylinder head of the rear cylinder 20, enabling the cooling effect of the rear cylinder 20 and the front cylinder 30 to be consistent, well solving the problem of local abnormal temperature rise of an engine, and ensuring the safe and reliable operation of the engine.

With continued reference to fig. 2 to 5, in some embodiments, the flow guiding structure is configured as a flow guiding plate 14, and the extending direction of the flow guiding plate 14 is consistent with the flowing direction of the cooling liquid in the first water inlet branch pipe 12, so that the flow guiding plate 14 and the inner pipe wall of the first water inlet branch pipe 12 form a water flow passage at intervals.

The flow guide structure is set as the flow guide plate 14, and the flow guide plate 14 has the advantages of simple structure, convenient manufacture and reliable use. For example, the baffle 14 is integrally formed on the inner wall of the first water inlet branch pipe 12 by adopting a casting process, so that the manufacturing difficulty of the baffle 14 is reduced, and the connection strength of the baffle 14 is improved. And because the length extending direction of the guide plate 14 is consistent with the flowing direction of the cooling liquid in the first water inlet branch pipe 12, the guide plate 14 and the inner pipe wall of the first water inlet branch pipe 12 can form a water flow passage, and the water flow passage is used for enabling the cooling liquid in the water inlet main pipe 11 to smoothly flow into the first water inlet branch pipe 12 and further flow into the rear cylinder 20 so as to ensure that the rear cylinder 20 is cooled.

Further, the inner pipe wall of the first water inlet branch pipe 12 is provided with a first pipe wall portion 121 and a second pipe wall portion 122 which are opposite to each other and are positioned on the guide plate 14, the guide plate 14 is spaced from the first pipe wall portion 121 to form a first water flow passage 40, and the guide plate 14 is spaced from the second pipe wall portion 122 to form a second water flow passage 50.

For example, the width direction of the baffle 14 is consistent with the width direction of the first water inlet branch pipe 12, that is, opposite sides of the width direction of the baffle 14 are respectively and hermetically connected with inner pipe walls at two sides of the width direction of the first water inlet branch pipe 12, so that the first water flow channel 40 and the second water flow channel 50 can be formed in the section length direction of the inner pipe cavity of the first water inlet branch pipe 12, and the cooling liquid in the water inlet main pipe 11 can flow into the first water inlet branch pipe 12 twice successively, thereby realizing redistribution of the flowing cooling liquid.

As shown in fig. 5, specifically, on the basis of any of the above embodiments, the baffle 14 includes the baffle portion 141, the baffle portion 141 is disposed in an inclined shape, and the angle between the baffle portion 141 and the opposite direction of the flow path of the coolant in the main water inlet pipe 11 is set to θ, and the range of θ is 0 ° to 90 °.

Because the flow guiding part 141 is inclined, the opening area of the first water passing flow passage 40 formed by the matching of the flow guiding part 141 and the first pipe wall part 121 is larger than the opening area of the second water passing flow passage 50 formed by the matching of the flow guiding part 141 and the second pipe wall part 122, so that the flow of the cooling liquid flowing into the first water passing flow passage 40 and the second water passing flow passage 50 is different, the redistribution of the cooling liquid flowing into the cylinder head water jacket of the rear cylinder 20 can be realized, the flow of the cooling liquid flowing into the spark plug side of the rear cylinder 20 is ensured to be relatively more, the cooling effect on the spark plug side is enhanced, and the cooling effect of the rear cylinder 20 and the cooling effect of the front cylinder 30 are ensured to be basically equivalent.

For example, in the present embodiment, the installation position of the guide portion 141 is specifically limited, for example, the guide portion 141 has a start end side, and the inner pipe diameter of the first water intake branch pipe 12 is set to L, and the start end side is located in the L/2 section downstream on the flow path where the coolant is located in the water intake main pipe 11.

Of course, in other embodiments, the end side may be defined by other positions, and may be specifically selected according to actual needs, which is not described herein.

In addition, in the above embodiment, the baffle 14 further includes the introduction portion 142, one side of the introduction portion 142 is connected to one side of the introduction portion 141 away from the start end side, and the introduction portion 142 is disposed in parallel with the flow direction of the coolant flowing in the first intake branch pipe 12. Therefore, the flow guide plate 14 has small resistance to the cooling liquid flowing into the water jacket of the cylinder head of the rear cylinder 20 at the first water inlet branch pipe 12, so that the cooling liquid flows more smoothly and effectively, thereby being beneficial to enhancing the cooling effect of the cooling liquid on the rear cylinder 20.

On the basis of any of the above embodiments, at least two flow guiding structures are provided, and the at least two flow guiding structures are arranged at intervals in a direction perpendicular to the flow path of the cooling liquid in the first water inlet branch pipe 12. The provision of at least two flow guiding structures can further satisfy the technical requirements of redistributing and guiding the cooling liquid, so that the targeted key cooling treatment can be performed on different parts of the rear cylinder 20, and the cooling effect of the rear cylinder 20 and the front cylinder 30 is more consistent.

In addition, the application also provides a motorcycle which comprises the engine cooling structure according to any embodiment.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims (10)

1. An engine cooling structure, characterized by comprising:

the water jacket water inlet pipe comprises a water inlet main pipe, a first water inlet branch pipe and a second water inlet branch pipe, wherein the first water inlet branch pipe and the second water inlet branch pipe are respectively communicated with the water inlet main pipe, and a flow guide structure is arranged in a pipe cavity of the first water inlet branch pipe;

the water jacket inlet of the rear cylinder is communicated with the first water inlet branch pipe; and

and the water jacket inlet of the front cylinder is communicated with the second water inlet branch pipe.

2. The engine cooling structure according to claim 1, wherein the flow guiding structure is provided as a flow guiding plate, and an extending direction of the flow guiding plate is kept consistent with a flowing direction of the cooling liquid in the first water inlet branch pipe, so that the flow guiding plate and an inner pipe wall of the first water inlet branch pipe form a water flow passage at intervals.

3. The engine cooling structure of claim 2, wherein the inner tube wall of the first water intake manifold has opposed first and second tube wall portions located at the baffle, the baffle being spaced from the first tube wall portion to form a first water flow passage, the baffle being spaced from the second tube wall portion to form a second water flow passage.

4. The engine cooling structure according to claim 2, wherein the deflector includes a deflector portion which is provided in an inclined shape, and an angle of θ between the deflector portion and a direction opposite to a flow path of the coolant in the water intake main pipe is set to be θ, and the range of θ is 0 ° to 90 °.

5. The engine cooling structure according to claim 4, wherein the flow guiding portion has a start end side, an inner pipe diameter of the first water intake branch pipe is set to L, and the start end side is located in a downstream L/2 section on a flow path where the cooling liquid is located in the water intake main pipe.

6. The engine cooling structure according to claim 5, wherein the baffle further includes an introduction portion, one side of which is connected to a side of the guide portion remote from the start end side, the introduction portion being disposed in parallel with a flow direction of the coolant flowing in the first intake branch pipe.

7. The engine cooling structure according to any one of claims 1 to 6, characterized in that the first intake branch pipe and the second intake branch pipe are at different positions in an axial direction of the intake main pipe.

8. The engine cooling structure according to any one of claims 1 to 6, characterized in that a pipe center line of the first intake branch pipe is disposed at an angle to a pipe center line of the second intake branch pipe.

9. The engine cooling structure according to any one of claims 1 to 6, wherein at least two of the flow guiding structures are provided, the at least two of the flow guiding structures being arranged at intervals in a direction perpendicular to a flow path of the coolant in the first water intake branch pipe.

10. A motorcycle comprising the engine cooling structure according to any one of claims 1 to 9.