JP3304246B2 - Engine cooling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cooling device for an engine mounted on, for example, an automobile or a construction machine.

[0002]

2. Description of the Related Art Heretofore, for example, the following are known technologies relating to this type of engine cooling device. SUMMARY OF THE INVENTION This known technique is used in an engine cooling section of a construction machine.
The cooling air is supplied to the heat exchanger by an axial fan connected to a crankshaft of the engine via a fan belt.

[0003] Japanese Patent Application Laid-Open No. 4-269326 discloses a known technique of using a diagonal flow fan as a fan for supplying cooling air in a vehicle diesel engine cooling unit, and simultaneously sucking a fixed shroud for introducing cooling air into a suction pipe. Higher pressure and higher pressure than axial fan
The purpose is to increase the air volume.

The internal combustion engine Vol. 31, NO. 38
8, p. 9-27 (1992) This known technique is used in an engine cooling section of a construction machine.
The cooling performance is improved by using a centrifugal fan as a fan for supplying the cooling air, and the noise due to the engine noise is reduced by separating the engine room and the cooling device.

[0005] Japanese Patent Application Laid-Open No. 5-248239 discloses a known technique for improving the cooling performance of an engine cooling section of a working vehicle such as a tractor by using a centrifugal fan as a fan for supplying cooling air.

[0006] This known technique eliminates an exhaust duct required when using an axial fan by using a centrifugal fan as a fan for supplying cooling air in an engine cooling section of an automobile. Things.

[0007]

In recent years, the use of an intercooler for the engine cooling fan, and a demand for a higher airflow and a higher pressure have been required due to a demand for an improved airtightness and a more compact engine room for noise reduction. ing. However, in the related art, since an axial fan or an oblique-axis fan is used, it is difficult to sufficiently increase the air volume and pressure due to the characteristics of the fan, and the heat of a radiator, an oil cooler or the like is difficult. If an attempt is made to increase the air volume and pressure while forcing the exchanger and other cooling air passages to have the same dimensions, there has been a problem that the number of revolutions becomes extremely high and noise increases. Also, in the known art, since the flow past the axial fan flows in such a manner as to collide with the engine, the pressure loss is large, and in some cases, the backflow of the cooling air is generated around the engine oil pan, which is effective for cooling. There was also a problem in configuring a simple flow path. Furthermore, in the related arts, since the centrifugal fan is not provided with a rotating shroud that rotates together with the fan, there is a problem that the fan efficiency is deteriorated and the noise is increased. Also, in the known art, the flow path from the heat exchanger, which is a main cause of noise generation, to the fan suction port is essentially easy to cause separation of the flow and has a shape that raises the noise. There is also a problem that the suction diameter is much smaller than the height of the heat exchanger, and the pressure loss at the fan suction part from the heat exchanger increases.

SUMMARY OF THE INVENTION It is an object of the present invention to increase the air flow without reducing the fan efficiency and without increasing the noise.
An object of the present invention is to provide an engine cooling device capable of increasing pressure.

[0009]

In order to achieve the above object, according to the present invention, a radiator is provided in an engine room in which an engine is provided, and cools water of the engine. At least one heat exchanger, a fan for guiding cooling air for cooling the heat exchanger, and introducing the cooling air upstream of the fan and downstream of the heat exchanger to a suction side of the fan in the engine cooling system and a suction pipe for the fan is either one of the centrifugal fan and mixed flow fan, and with fixed the impeller to the impeller and the impeller comprising a plurality of blades A rotary shroud that rotates, wherein the suction pipe is disposed so that a downstream end thereof covers a vicinity of a suction side end of the rotary shroud, and A partition wall that forms a gap between the downstream end of the rotary shroud and the suction side end of the rotary shroud, and forms a substantially closed space inside that blocks a backflow of cooling air flowing from the outlet side of the fan toward the gap. This partition
The wall projects toward the outer wall surface of the rotating shroud
So that it is fixed to the outer wall surface of the suction pipe,
Large clearance between the partition wall and the outer wall surface of the rotary shroud.
The size Y1 is between the downstream end of the suction pipe and the rotary shroud.
The size of the gap with the end of the loud suction side must be smaller than X
An engine cooling device is provided. There
According to the second aspect of the present invention, the engine is provided internally.
In the engine room, which cools the cooling water of the engine.
At least one heat exchanger including a radiator for cooling
And a fan that guides cooling air to cool this heat exchanger.
Provided upstream of the fan and downstream of the heat exchanger.
Suction for introducing the cooling air to the suction side of the fan.
An engine cooling device having
The fan is either a centrifugal fan or a mixed flow fan.
Impeller provided with a plurality of blades, and the impeller
And the rotating shroud that rotates with the impeller
The suction pipe, the downstream end of which is
Arranged to cover near the suction side end of rotating shroud
The downstream end of the suction pipe and the rotary shroud.
A gap is formed between the suction side end of the fan and the fan.
Blocks the backflow of cooling air from the outlet of
A partition wall that forms a substantially closed space inside is provided.
The wall projects toward the outer wall surface of the suction pipe
Fixed to the outer wall surface of the rotating shroud,
The size of the gap between the partition wall and the outer wall surface of the suction pipe
Y2 is the downstream end of the suction pipe and the rotary shroud.
Must be smaller than the size X of the gap with the udo suction side end
An engine cooling device is provided. In other words, by using a centrifugal fan or a mixed flow fan as the fan, the centrifugal force acts to easily increase the air volume and pressure with the same outer diameter and the same resistance as compared with the conventional axial flow fan and the inclined flow fan. Can be achieved. Therefore, there is no need to increase the number of revolutions as in the case of increasing the air volume and increasing the pressure with an axial fan / oblique axial fan, so that noise can be reduced. In addition, the rotating shroud that rotates with the impeller is fixed to the impeller,
The fan efficiency can be improved, and the noise can be further reduced. At this time, since the pressure on the fan outlet side is higher than that on the fan inlet side, a part of the cooling air from the fan flows between the rotating shroud suction side end and the suction pipe downstream side end covering the vicinity thereof. May flow back into the suction pipe through the gap. However, in the present invention, by providing a partition wall that forms a substantially closed space inside, the partition wall and the closed space become a resistance to the cooling air flow that tends to flow backward from the fan outlet side to the gap, and the flow is reduced. Blocking and backflow can be reduced. That is, it is possible to reduce a part of the cooling air from flowing back into the suction pipe from the gap between the rotating shroud and the suction pipe. Also, the partition wall and rotating shroud
The size of the gap Y1 between the outer wall surface or the partition wall and the suction pipe
The size Y2 of the gap with the outer wall surface is on the downstream side of the suction pipe.
The size of the gap between the end and the end on the rotating shroud suction side
Because it is smaller than X, the suction pipe downstream end and rotation
Near the gap (size X) between the ends of the shroud suction side
In the direction of the fan outlet generated by the vane
Such a flow is created by the gap between the partition wall and the outer wall of the rotating shroud.
Between (size Y1), or partition wall and suction pipe outer wall surface
After being squeezed by the gap (size Y2)
Will flow. Therefore, formed inside the partition wall
Pressure inside the space can be higher than outside
So the flow is going to flow back from the fan outlet side to the inlet side
Can be completely prevented . Therefore, part of the cooling air
Is inside the suction pipe from the gap between the rotating shroud and the suction pipe
Backflow can be more reliably prevented.

[0010]

[0011]

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show an embodiment of the present invention.
This will be described below. This embodiment is an embodiment of an engine cooling device provided in an engine room of a hydraulic shovel.
FIG. 1 is a side sectional view showing a schematic structure of an engine room of a hydraulic shovel to which the present embodiment is applied. In FIG. 1, the engine cooling device according to the present embodiment is provided in an engine room 1 in which an engine 5 is installed, and supplies an intercooler 6 a for pre-cooling combustion air to the engine 5 and hydraulic oil for a hydraulic shovel. An oil cooler 6b for cooling, a radiator 6c for cooling the cooling water of the engine 5, a centrifugal fan 4 driven by a fan belt 3 to which power from the crankshaft 2 of the engine 5 is transmitted, a radiator 6c and a centrifugal fan 4 And a suction pipe 8 for introducing cooling air to the suction side of the centrifugal fan 4. The centrifugal fan 4 includes an impeller 4c having a plurality of blades, a rotating shroud 4a fixed to the impeller 4c, and rotating to suck cooling air.
c, which is fixed to the engine 5 side and guides cooling air in a substantially radial direction and a substantially circumferential direction. Further, the suction pipe 8 is supported by the engine room 1 via a shielding plate 11, and the engine 5 is fixed to the engine room 1 via anti-vibration rubber (not shown) to reduce vibration transmission. (Not shown). Cooling air from the outside of the engine room 1 enters the engine room 1 through the cooling air inlet 7, passes through the intercooler 6a, the oil cooler 6b, and the radiator 6c, is throttled by the suction pipe 8, and enters the centrifugal fan 4. Thereafter, the cooling air blown in the outer circumferential direction of the centrifugal fan 4 is supplied to the engine 5 and the oil pan 1.
0, and cool them while flowing around the cooling air outlet 9.
From the engine room 1.

FIG. 2 is an enlarged side sectional view of a main part showing a detailed structure near the suction pipe 8 and the centrifugal fan 4 shown in FIG.
FIG. 2A shows a state in which a partition wall 12 (described later) is removed from the configuration of FIG. 2 (a) and 2 (b),
The diameter of the downstream end 8A of the suction pipe 8 is larger than the suction diameter of the rotary shroud 4a of the centrifugal fan 4, and the downstream end 8A is arranged so as to cover the vicinity of the suction side end 4aA of the rotary shroud 4a. ing. That is, this makes it easy to manage the gap at the time of assembling, and can prevent an accident such as contact between the suction pipe 8 and the rotating shroud 4a at the time of assembling.

The rotary shroud 4a is provided with a plurality of vanes 13 standing near the suction side (left side in the drawing), and the suction pipe 8 has an outer wall surface of the suction pipe 8 and an outer surface of the rotary shroud 4a. A substantially annular partition wall 12 is fixed so as to cover the wall surface. The partition wall 12 is fixed to the outer wall surface of the suction pipe 8 so as to protrude toward the outer wall surface of the rotary shroud 4a, and forms an air chamber N which is a substantially closed space inside. The size X is set between the downstream end 8A of the suction pipe 8 and the suction end 4aA of the rotary shroud so that the suction pipe 8 and the rotary shroud 4a do not contact each other even when the engine 5 vibrates.
(= For example, 20 to 25 mm), the size Y ₁ of the gap 22 between the partition wall 12 and the outer wall surface of the rotary shroud 4 a is smaller than the size X of the gap 21. I have.

Next, the operation of the present embodiment will be described. As a first comparative example of the present embodiment, FIG. 3 is a side sectional view illustrating a schematic configuration of an engine room in which an engine cooling device including an axial fan is provided. Members equivalent to those in the present embodiment are denoted by the same reference numerals. In FIG. 3, the main difference from the engine cooling device of the first embodiment shown in FIG. 1 is that an axial fan 14 is employed as a fan, and the shape of the suction pipe 8 is slightly changed accordingly. And that the intercooler 6a is not provided.
Other configurations are almost the same as those of the first embodiment.

In such an engine cooling device,
Due to the nature of the axial fan 14, the number of revolutions must be increased in order to achieve a large air volume and a high pressure. In this case, noise must be increased. Therefore, the adoption of the intercooler 6a which is effective for future emission control,
There is a problem that it is difficult to apply to an engine room of a construction machine or the like in the future where a demand for a large air volume and a high pressure is increased in a form corresponding to an improvement in the degree of sealing of the engine room 1 by downsizing the whole system. . The flow past the axial fan 14 has a large pressure loss because it flows in such a manner as to collide with the engine 5.
There are also difficulties in configuring a flow path effective for cooling, such as a backflow of cooling air around the oil pan 10.

On the other hand, in the engine cooling device according to this embodiment shown in FIG. 1, the centrifugal fan 4 is used as a fan, and
With the same outer diameter, the same resistance, and the same rotational speed, it is possible to easily increase the pressure to at least twice as high as that of the axial flow fan 14, and at this time, to achieve a high air volume. That is, since it is not necessary to increase the number of revolutions as in the case of increasing the air volume and increasing the pressure with the axial fan 14, the noise can be reduced.
Therefore, even when the intercooler 6a is newly added, it is possible to secure the air volume without increasing the noise and to supply the cooling air by overcoming the pressure loss. Even if the number increases or the miniaturization progresses,
The cooling air can be supplied by overcoming an increase in pressure loss in the upstream resistor / engine room flow path. In addition, since the direction in which the cooling air is blown out is the radial direction and the circumferential direction of the centrifugal fan 4 and does not directly collide with the engine 5, for example, good cooling that flows along the surface of the engine 5 and the surface of the oil pan 10 below the engine. There is also an effect that wind can be obtained. Further, since the rotating shroud 4a that rotates together with the impeller 4c is provided, fan efficiency can be improved as compared with the case where a centrifugal fan without the rotating shroud 4a is used, and noise can be further reduced accordingly. .

As a second comparative example of this embodiment, FIG. 4 is a side sectional view showing a schematic configuration of an engine room in which an engine cooling device provided with a centrifugal fan and not provided with a backflow preventing means is provided. FIG. 5 is an enlarged side sectional view of a main part showing a detailed structure near the heat exchanger, the suction pipe, and the centrifugal fan. Members equivalent to those in the present embodiment are denoted by the same reference numerals. 4 and 5, the main difference from the engine cooling device of the first embodiment shown in FIG. 1 is that the partition wall 12 and the vane 13 as backflow preventing means are not provided. Other configurations are substantially the same as those of the first embodiment, including the point that the size of the gap 21 between the downstream end 8A of the suction pipe 8 and the suction end 4aA of the rotary shroud is X.

In this engine cooling device, an intercooler 6a, an oil cooler 6b, a radiator 6c
After passing, the cooling air squeezed by the suction pipe 8
When the centrifugal fan 4 blows out the outer peripheral direction of the centrifugal fan 4 as indicated by an arrow, the centrifugal fan outlet side M has a higher pressure than the centrifugal fan inlet side S. Thereby, as shown by the broken line in FIG.
Clearance 21 between rotary shroud 4a suction side end 4aA
There is a problem that a gap flow that flows backward in the suction pipe 8 through the air passage causes the cooling efficiency to deteriorate and the noise to increase.

On the other hand, in the engine cooling device according to the present embodiment shown in FIG. 1, the rotary shroud 4a
When the rotary shroud 4a rotates together with the impeller 4c by erecting a plurality of vanes 13 near the suction side end 4aA, a pressure barrier is formed between the vanes 13 by centrifugal force based on the difference between the inside and outside of each vane 13. Raise,
In the vicinity of the gap 21 between the downstream end portion 8A of the suction pipe 8 and the rotary shroud 4a, a flow can be formed in the vicinity of the gap 21 between the centrifugal fan outlet side M (see the broken line arrow in FIG. 2A). . Also, at this time, if only these vanes 13 are provided, it is not possible to prevent the flow which is going to flow backward toward each vane 13 at the centrifugal fan outlet side M, and the pressure in the gap 21 at most is not increased. Just block at the barrier. However, in the configuration according to the present embodiment shown in FIG. 1, in addition to the vanes 13, the partition wall 12 that covers the outer wall surface of the suction pipe 8 and the outer wall surface of the rotary shroud 4 a and forms the air chamber N inside is further provided. the magnitude Y ₁ of the gap 22 between the wall 12 and the outer wall surface of the rotary shroud 4a, by less than the size X of the gap 21 between the suction pipe 8 downstream end 8A rotating shroud 4a suction-side end 4aA After the flow generated by the vane 13 near the gap 21 is narrowed by the gap 22, it flows to the fan outlet side M. Therefore, the inside of the air chamber N formed inside the partition wall 12 can be made higher in pressure than the fan outlet side M on the outside, so that the flow that is going to flow backward from the centrifugal fan outlet side M to each vane 13 can be completely completed. Can be prevented. Therefore, backflow of a part of the cooling air into the suction pipe 8 can be more reliably prevented than when only the vane 13 is provided.
Therefore, the cooling air can be reliably sucked in to improve the cooling efficiency, and the increase in noise due to the backflow can be prevented.

In the above embodiment, the partition wall 12 is fixed to the outer wall surface of the suction pipe 8 so as to project toward the outer wall surface of the rotary shroud 4a. However, the present invention is not limited to such a structure. As shown in FIG.
The rotary shroud 4 a is fixed to the outer wall surface of the rotary shroud 4 a so as to protrude toward the outer wall surface of the suction pipe 8.
And the size Y ₂ of the gap 23 between the outer wall of the suction pipe 8 and
The size of the gap 21 may be smaller than the size X. In this case, the same effect is obtained. Further, in the above embodiment, the partition wall 12 is substantially annular, that is, the side cross-sectional shape is linear as shown in FIGS. 1 and 2, but is not limited thereto, and is shown in FIG. 7. As described above, the side sectional shape may be substantially L-shaped. In this case, partition wall 1
The gap 22 between the outer wall surface of the rotary shroud 4a and the outer wall surface of the rotary shroud 4a (or the gap 23 between the partition wall 12 and the outer wall surface of the suction pipe 8) has an effect of compensating for the restriction.
Even if the size Y ₁ (or Y ₂ ) of 3) is increased accordingly, the same backflow prevention effect as before the increase can be obtained.
Further, in the above embodiment, the gap 21 between the partition wall 12 the magnitude Y ₁ of the gap 22 between the outer wall surface of the rotary shroud 4a, and the suction pipe 8 downstream end 8A rotating shroud 4a suction-side end 4aA Is smaller than the size X, but is not limited to such a dimensional relationship. For example, Y ₁ ≧ X
Even when the partition wall 12 is configured as follows,
The flow which tends to flow backward toward the vane 13 at the outlet side M of the centrifugal fan can be sufficiently prevented. This also applies to Y ₂ of the gap 23. Further, in the above-described embodiment, the vane 13 is provided on the rotary shroud 4a, and the flow toward the centrifugal fan outlet side M is positively formed to prevent the backflow. However, the present invention is not limited to this, and the vane 13 is omitted. Is also good. In this case, the flow for preventing the backflow is not positively formed, but the partition wall 12 and the closed space formed inside the partition wall 12 are not allowed to flow back from the centrifugal fan 4 outlet side M to the inlet side S. On the other hand, since it becomes a resistor, this flow can be blocked and the backflow can be reduced. That is, a part of the cooling air is supplied to the rotary shroud 4a suction side end 4aA.
The backflow into the suction pipe 8 from the gap 21 between the downstream end 8A of the suction pipe 8 can be reduced. Also,
In the above embodiment, the centrifugal fan 4 is used as a fan, but the present invention is not limited to this, and a mixed flow fan may be used. In this case, a similar effect is obtained. Further, the above embodiment has been described by taking the engine cooling device provided in the construction machine as an example. However, the present invention is not limited to this, and may be applied to an engine cooling device mounted on an automobile, an agricultural machine, or another machine. Can be. In these cases, a similar effect is obtained.

[0022]

According to the first and second aspects of the present invention, since a centrifugal fan or a mixed flow fan is used as a fan, the same outer diameter and the same resistance are easier than conventional axial flow and oblique flow fans. Therefore, it is possible to increase the air volume and pressure. Therefore, noise can be reduced. Further, since the rotating shroud that rotates together with the impeller is fixed to the impeller, fan efficiency can be improved, and noise can be further reduced accordingly. In addition, since the partition wall is provided to form a substantially closed space inside, the flow from the fan outlet side to the backflow to the gap between the rotary shroud suction side end and the suction pipe downstream end that covers the vicinity thereof And the backflow can be reduced. Therefore, the cooling air can be reliably sucked in, and the cooling efficiency can be improved. Also, an increase in noise due to the backflow can be prevented. In addition, partition walls and
Size Y1 of the gap between the outer wall surface of the rolling shroud and the partition wall
And the size of the gap Y2 between the suction pipe and the outer wall surface of the suction pipe
Between the downstream end of the pipe and the rotary shroud suction end
Formed inside the partition wall because it is smaller than the size of the gap X
The inside of the space is made higher than the outside, and the fan exit side
To prevent the flow from going back to the inlet side completely.
Can be. Therefore, part of the cooling air is
Backflow into the suction pipe from the gap between the suction pipe
More reliably prevent, further improve cooling efficiency and increase noise
Prevention can be achieved.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a schematic structure of an engine room of a hydraulic shovel to which an embodiment of the present invention is applied.

FIG. 2 is an enlarged side sectional view of a main part showing a detailed structure in the vicinity of a suction pipe and a centrifugal fan shown in FIG. 1;

FIG. 3 is a side sectional view illustrating a schematic configuration of an engine room in which an engine cooling device including an axial fan according to a first comparative example is provided.

FIG. 4 is a side sectional view showing a schematic configuration of an engine room provided with an engine cooling device provided with a centrifugal fan according to a second comparative example and provided with no backflow prevention means.

5 is an enlarged side sectional view of a main part showing a detailed structure near a heat exchanger, a suction pipe, and a centrifugal fan in FIG. 4;

FIG. 6 is an enlarged side cross-sectional view of a main part showing a structure of a modification example regarding a partition wall.

FIG. 7 is an enlarged side cross-sectional view of a main part illustrating a structure of a modification example regarding a partition wall.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine room 2 Engine crankshaft 3 Belt 4 Centrifugal fan 4a Rotary shroud 4aA Suction side end 4b Core plate 4c Impeller 5 Engine 6 Heat exchanger 6a Intercooler 6b Oil cooler 6c Radiator 7 Cooling air intake 8 Suction pipe 8A Downstream Side end 9 Cooling air exhaust port 10 Oil pan 11 Backflow prevention plate 12 Partition wall 13 Vane 14 Axial fan 21 Gap between suction pipe downstream end and rotary shroud suction side end 22 Partition wall and outer wall of rotary shroud 23 The gap between the partition wall and the outer wall of the suction pipe

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshio Yahito 650 Kandamachi, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. (72) Inventor Toshio Takishita Toshio Takishita 650 Kandate-cho, Tsuchiura-shi, Ibaraki Pref.Hitachi Construction Machinery Co., Ltd. 56) references Patent flat 4-54998 (JP, a) JitsuHiraku Akira 64-15721 (JP, U) (58 ) investigated the field (Int.Cl. ^7, DB names) F01P 5/02 F01P 11/10 F04D 29/28 F04D 29/66 F04D 29/54 F04D 29/42

Claims (2)

(57) [Claims] An engine is provided in an engine room provided therein.
A radiator for cooling the engine cooling water.
Including at least one heat exchanger and cooling the heat exchanger
Fan that guides the cooling air
The cooling air provided downstream of the heat exchanger
Having a suction pipe introduced to the suction side of the fan
In the cooling device, the fan may be a centrifugal fan or a mixed flow fan.
Impeller and a plurality of impellers
Rotating shroud fixed to the impeller and rotating with the impeller
A suction pipe, the downstream end of which is provided with the rotary shroud.
To cover the vicinity of the suction side end of the suction
Suction of the rotating shroud and the downstream end of the weir
A gap is formed between the cooling air and the side end, and the cooling air flows backward from the outlet side of the fan toward the gap.
A partition wall that forms a substantially closed space inside
Only, the partition walls, the size of the gap between the towards the outer wall surface of the rotary shroud is fixed to the outer wall surface of the suction pipe so as to protrude, and said partition Setsukabe and the outer wall surface of the rotary shroud The engine cooling device according to claim 1, wherein Y1 is smaller than a size X of a gap between the downstream end of the suction pipe and the rotary shroud suction side end. 2. An engine room in which an engine is installed.
A radiator for cooling the engine cooling water.
Including at least one heat exchanger and cooling the heat exchanger
Fan that guides the cooling air
The cooling air provided downstream of the heat exchanger
Having a suction pipe introduced to the suction side of the fan
In the cooling device, the fan may be a centrifugal fan or a mixed flow fan.
Impeller and a plurality of impellers
Rotating shroud fixed to the impeller and rotating with the impeller
A suction pipe, the downstream end of which is provided with the rotary shroud.
To cover the vicinity of the suction side end of the suction
Suction of the rotating shroud and the downstream end of the weir
A gap is formed between the cooling air and the side end, and the cooling air flows backward from the outlet side of the fan toward the gap.
A partition wall that forms a substantially closed space inside
Only this partition wall is secured to the outer wall surface of the rotating shroud so as to protrude toward the outer wall surface of the suction tube, and the size of the gap between the outer wall surface of the partition Setsukabe and said suction tube The engine cooling device according to claim 1, wherein Y2 is smaller than a size X of a gap between a downstream end of the suction pipe and the rotary shroud suction side end.