JP2015124768A - Cooling structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure of an internal combustion engine which properly adjusts amounts of a coolant distributed to water jackets of a cylinder block and a cylinder head despite a simple structure.SOLUTION: A cooling structure of an internal combustion engine includes: a first water gallery 34 which supplies a coolant from the exterior of a cylinder block 11 to a water jacket 31 in the cylinder block 11; a second water gallery 34 which is branched from the first water gallery 34 and supplies the coolant split from the first water gallery 34 to a water jacket 32 in a cylinder head; and a flow regulating valve 40 which opens and closes the first water gallery 34. The flow regulating valve 40 is disposed in a part of the first water gallery 34 which is located at the downstream side of a branch part from which the second water gallery 36 is branched. The flow regulating valve 40 is pressed by the coolant to be rotated from a closing position where the flow regulating valve 40 closes the first water gallery 34 and thereby opens the first water gallery 34.

Description

  The present invention relates to a cooling structure for an internal combustion engine capable of adjusting a distribution amount of cooling water to a cylinder block and a cylinder head.

  In the water-cooled engine, each of the cylinder block and the cylinder head is provided with a water jacket through which cooling water flows. Such a cooling structure for an internal combustion engine includes a two-system cooling system that individually cools a cylinder head that is required to be low temperature and a cylinder block that is required to be moderately high temperature. There is something.

  The internal combustion engine cooling structure equipped with a dual cooling system improves the charging efficiency by keeping the temperature of the cylinder head low, prevents knocking and pre-ignition, and maintains the cylinder block temperature at a moderately high temperature for lubrication. The oil is made to have a low viscosity to reduce flicking of each part.

  As a cooling structure of an internal combustion engine provided with this kind of two-system cooling system, there is one that adjusts the distribution amount of cooling water to a cylinder head and a cylinder block by controlling a motor and a solenoid. However, the use of a motor or solenoid causes a deterioration in fuel consumption due to power consumption.

  On the other hand, a cooling structure for an internal combustion engine is known in which the distribution amount of cooling water to the cylinder head and the cylinder block is mechanically adjusted in a thermostat (see Patent Document 1). In the device described in Patent Document 1, two valves whose flow paths are switched according to the coolant temperature are provided in the thermostat, and four pipes for the water pump, the cylinder block, the radiator, and the heater are connected to the thermostat. And, at the time of cold start of the engine, the cooling water is supplied to the cylinder head while the cooling water supply to the cylinder block is stopped, and the cooling water is supplied to the cylinder block as the cooling water temperature rises. The amount of cooling water distributed to the cylinder block and cylinder head is adjusted.

JP 2012-184893 A

  However, since the cooling structure of the conventional internal combustion engine adjusts the distribution amount of the cooling water by providing two valves in the thermostat, the structure of the thermostat and the piping of the cooling water connected to the thermostat are complicated. There was a problem of becoming.

  The present invention has been made in view of the above problems, and is a cooling system for an internal combustion engine capable of appropriately adjusting the distribution amount of cooling water to the water jacket of the cylinder block and the cylinder head while having a simple structure. The purpose is to provide a structure.

  In order to solve the above-described problems and achieve the object, a first aspect of the present invention is a cylinder block having a water jacket in a cylinder block in which cooling water flows around the cylinder, and cooling water around the combustion chamber. A cylinder head having a water jacket in the cylinder head that circulates, wherein the cooling water that has circulated through the water jacket in the cylinder block is supplied to the water jacket in the cylinder head. A first water gallery for supplying cooling water to the water jacket in the cylinder block, and a second water for branching from the first water gallery and supplying the cooling water branched from the first water gallery to the water jacket in the cylinder head. Gallery and the first wall A flow regulating valve that opens and closes a gallery, and the flow regulating valve is disposed downstream of a branch portion of the first water gallery with the second water gallery, and closes the first water gallery. The first water gallery is opened by being rotated by being pushed by the cooling water from the posture.

  As a 2nd aspect of this invention, it is preferable that the said flow regulating valve is arrange | positioned directly under the downstream of the said branch part of a said 1st water gallery.

  As a third aspect of the present invention, the flow rate adjusting valve is formed in a plate shape, and the closing posture of the flow rate adjusting valve is a posture in which the flow rate adjusting valve extends in the branch direction of the second water gallery. It is preferable.

  As a fourth aspect of the present invention, the first water gallery has a rectangular cross-sectional shape, and the flow regulating valve is formed in a rectangular shape so as to coincide with the cross-sectional shape of the first water gallery when in the closed posture. A rotation shaft that rotatably supports the flow rate adjusting valve in the first water gallery, and the rotation shaft is brought close to an inner wall surface of the first water gallery on the second water gallery side. Preferably they are arranged.

  As a 5th aspect of this invention, it is preferable that the said rotating shaft is arrange | positioned above the gravity center of the said flow regulating valve.

  As a sixth aspect of the present invention, it is preferable that the second water gallery branches vertically upward from the first water gallery.

  As a seventh aspect of the present invention, it is preferable that the first water gallery and the second water gallery are arranged inside the cylinder block.

  According to the first aspect of the present invention, when the temperature of the cooling water is low and the flow rate is low, the flow rate adjusting valve is in the closed position, so that the supply of the cooling water to the water jacket in the cylinder block is stopped. The cooling water can be supplied to the water jacket in the head, and the cooling water can be supplied also to the water jacket in the cylinder block by rotating the flow rate adjusting valve as the cooling water temperature rises. Further, since the flow rate adjusting valve is pressed by the cooling water and rotates to open the first water gallery, a driving device such as a motor or a solenoid for opening and closing is unnecessary, and the structure is simplified. be able to. As a result, the distribution amount of the cooling water to the water jacket in the cylinder block and the water jacket in the cylinder head can be appropriately adjusted with a simple structure.

  According to the second aspect of the present invention, since the flow rate adjusting valve is arranged immediately downstream of the branch portion in the first water gallery, when the flow rate adjusting valve is in the closed posture, in the upstream region of the flow rate adjusting valve. Due to the increased water pressure, the cooling water can be flowed to the second water gallery in the shortest distance from directly below the branching portion. For this reason, since the pressure loss of the cooling water is reduced, it is possible to optimize the diversion effect of the cooling water to the second water gallery side when the flow rate adjusting valve is in the closed posture.

  According to the 3rd aspect of this invention, the extension direction at the time of the obstruction | occlusion attitude | position of a flow regulating valve can be made to correspond with the branch direction of a 2nd water gallery. Therefore, the cooling water is guided to the second water gallery side by hitting the flow rate adjusting valve that is plate-shaped and matches the branch direction of the second water gallery. As a result, the flow rate adjusting valve can smoothly flow the cooling water to the second water gallery side in the closed posture.

  According to the fourth aspect of the present invention, it is possible to prevent the upper end portion of the flow rate adjusting valve from greatly projecting to the second water gallery side when the flow rate adjusting valve is rotated by the coolant pressure. Therefore, when the flow rate adjusting valve rotates, the upper end portion of the flow rate adjusting valve does not block a part of the second water gallery, so that the flow of the cooling water diverted to the second water gallery side is obstructed. It is never done.

  According to the fifth aspect of the present invention, the flow rate adjustment valve can return to the closed posture by its own weight. For this reason, a return spring for valve closing or the like is not required, and the flow rate adjusting valve can have a simple structure.

  According to the sixth aspect of the present invention, when the flow rate adjustment valve is in the closed position due to its own weight, the flow rate adjustment valve extends in the same vertical direction as the branch direction of the second water gallery. Therefore, the cooling water is guided to the second water gallery side by hitting the flow rate adjusting valve. As a result, the flow rate adjusting valve can smoothly flow the cooling water to the second water gallery side in the closed posture.

  According to the seventh aspect of the present invention, the first water gallery and the second water gallery are arranged inside the cylinder block. For this reason, since the 1st water gallery and the 2nd water gallery can be formed easily at the time of casting or post-processing of a cylinder block, the 1st water gallery and the 2nd water gallery are constituted by a separate pipe etc. Can be made unnecessary.

FIG. 1 is a side view of an engine including an internal combustion engine cooling structure according to an embodiment of the present invention. FIG. 2 is a top view of a cylinder block of an engine provided with a cooling structure for an internal combustion engine according to an embodiment of the present invention, and shows a state when the flow rate adjustment valve is closed. FIG. 3 is a top view of a cylinder block of an engine provided with a cooling structure for an internal combustion engine according to an embodiment of the present invention, and shows a state when the flow rate adjustment valve is opened. FIG. 4 is a perspective view of the internal combustion engine cooling structure according to the embodiment of the present invention when the flow rate adjustment valve is closed. FIG. 5 is a perspective view of the internal combustion engine cooling structure according to an embodiment of the present invention when the flow rate adjustment valve is opened. FIG. 6 is a side view of the internal combustion engine cooling structure according to the embodiment of the present invention when the flow rate adjustment valve is closed. FIG. 7 is a side view of the flow rate adjustment valve provided in the internal combustion engine cooling structure according to the embodiment of the present invention when the valve is opened.

  Below, the cooling structure of the internal combustion engine which concerns on embodiment of this invention is demonstrated based on drawing. First, the configuration will be described. In FIG. 1, an engine 1 as an internal combustion engine mounted on a vehicle includes a cylinder block 11, a cylinder head 12 provided on an upper portion of the cylinder block 11, a head cover 13 provided on an upper portion of the cylinder head 12, and a cylinder. And an oil pan 16 provided at a lower portion of the block 11.

  A cylinder liner 21 is provided inside the cylinder block 11. Inside the cylinder liner 21 is formed a cylinder bore 22 which is a space in which the piston reciprocates. As shown in FIGS. 2 and 3, three cylinder liners 21 are provided in the engine 1 and connected to each other, and have a configuration of a siamese cylinder (continuous integrated cylinder row).

  The cylinder block 11 is provided with a crank pulley 19 and an alternator 17, and an auxiliary machine drive belt 20 is stretched between the crank pulley 19 and the alternator 17. The alternator 17 generates alternating-current electricity by transmitting the rotation of the crankshaft to the alternator pulley 17a via the crank pulley 19 and the accessory drive belt 20.

  A cylinder block water jacket 31 is formed inside the cylinder block 11. The water jacket 31 in the cylinder block is formed so as to surround the three connected cylinder liners 21 as shown in FIGS. 2 and 3, and the cooling water is circulated around the cylinder liner 21. Yes.

  A water pump 18 is provided on the lower side surface of the cylinder block 11, and the water pump 18 pumps cooling water that has been cooled by the atmosphere through the radiator when the thermostat (not shown) is opened into the cylinder block 11. It is supposed to be. As the water pump 18, either a mechanical type driven by transmission of rotation of the crankshaft or an electric type driven by an electric motor can be used.

  As shown in FIGS. 1 to 3, a first water gallery 34 as a cooling water corridor is formed in the cylinder block 11. One end side of the first water gallery 34 opens to the lower side surface of the cylinder block 11, and the other end side communicates with the lower part of the cylinder arrangement end portion of the water jacket 31 in the cylinder block.

  The first water gallery 34 supplies cooling water pumped from the water pump 18 outside the cylinder block 11 to the water jacket 31 in the cylinder block. In the present embodiment, the first water gallery 34 has a rectangular cross-sectional shape.

  In the water jacket 31 in the cylinder block, a narrowed portion 31b having a narrower flow path than other portions is formed, and a communication passage 31a having a wider flow path than other portions is formed on the center side in the cylinder arrangement direction of the narrowed portion 31b. Is formed.

  The communication passage 31a is formed to extend in the vertical direction so that the cooling water that hits the throttle portion 31b is supplied to the water jacket 32 in the cylinder head through a communication hole 33 described later of the cylinder head 12. It has become.

  Further, a second water gallery 36 as a cooling water corridor is formed inside the cylinder block 11. The second water gallery 36 is branched from the first water gallery 34, and the cooling water branched from the first water gallery 34 is supplied to a water jacket 32 in the cylinder head described later.

  The second water gallery 36 branches from the first water gallery 34 vertically upward in the cylinder block 11. The lower end of the second water gallery 36 is connected to the first water gallery 34, and the upper end of the second water gallery 36 is connected to the cylinder head water jacket 32.

  A combustion chamber 23 is formed below the cylinder head 12, and the combustion chamber 23 communicates with the cylinder bore 22. An intake pipe 15 and an exhaust pipe 14 are connected to the cylinder head 12. The intake pipe 15 supplies outside air to the combustion chamber 23 via an intake manifold (not shown). The exhaust pipe 14 is configured to exhaust the exhaust gas generated in the combustion chamber 23.

  In the cylinder head 12, a water jacket 32 within the cylinder head is formed so as to surround the combustion chamber 23, and the water jacket 32 within the cylinder head allows cooling water to flow around the combustion chamber 23. .

  A communication hole 33 is formed in the cylinder head 12, and the communication hole 33 connects the upper end portion of the water jacket 31 in the cylinder block and the water jacket 32 in the cylinder head. The cooling water that has circulated through the water jacket 31 in the cylinder block is supplied to the water jacket 32 in the cylinder head through the communication passage 31 a and the communication hole 33.

  As shown in FIGS. 4 to 7, a rectangular plate-like flow rate adjustment valve 40 is provided inside the first water gallery 34. The flow rate adjusting valve 40 is disposed immediately downstream of the branch portion 34c of the first water gallery 34 with the second water gallery 36 (closest to the branch portion 34c of the downstream region 34b), and the water jacket in the cylinder block. 31 and the distribution amount of the cooling water to the water jacket 32 in the cylinder head are adjusted.

  A rotating shaft support portion 40c having a plate pressure thicker than other parts is formed on the upper part of the flow rate adjusting valve 40, and a rotating shaft 41 is inserted into the rotating shaft support portion 40c. The rotation shaft 41 is fixed to the side wall of the first water gallery 34, and supports the flow rate adjustment valve 40 in the first water gallery 34 so as to be rotatable. The rotating shaft 41 is fixed to a portion of the cylinder block 11 that forms the above-described throttle portion 31b.

  The flow regulating valve 40 is arranged above the center of gravity of the flow regulating valve 40 so that the flow regulating valve 40 takes a closed posture by its own weight when the cooling water pressure is not applied or is weak. ing. In order for the flow rate adjustment valve 40 to be in the closed position due to its own weight, it is desirable that the rotation shaft 41 be disposed horizontally. Here, the closed posture of the flow regulating valve 40 is a posture in which the flow regulating valve 40 extends in the branching direction of the second water gallery 36, that is, in the vertical direction.

  The flow rate adjustment valve 40 is formed in a rectangular shape that matches the cross-sectional shape of the first water gallery 34. Thereby, between the upper end part 40a of the flow regulating valve 40 of the obstruction | occlusion attitude | position, and the inner wall surface of the upper side of the 1st water gallery 34, and the lower wall part 40b of the flow regulating valve 40, and the inner wall surface of the lower side of the 1st water gallery 34 There is no gap between them.

  As shown in FIGS. 3, 5, and 7, when the amount of cooling water passing through the first water gallery 34 increases, the flow rate adjustment valve 40 is rotated from the closed posture by the water pressure, thereby causing the first water gallery. 34 is opened.

  Further, the rotation shaft 41 is arranged close to the inner wall surface of the first water gallery 34 on the second water gallery 36 side. That is, the rotating shaft 41 is disposed close to the upper inner wall surface of the first water gallery 34 in FIGS.

  Next, the operation will be described. Hereinafter, a case where the water pump 18 is a mechanical type will be described as an example.

  When the engine 1 is cold started, etc., and the cooling water is at a low temperature, the thermostat is closed, so that the cooling water flowing into the first water gallery 34 from the water pump 18 is small. In this case, as shown in FIGS. 2, 4, and 6, the flow rate adjustment valve 40 assumes a closed posture because the pressing force from the cooling water is weak.

  Since the flow rate adjustment valve 40 is disposed on the downstream side of the branch portion 34 c in the first water gallery 34, the cooling water is blocked by the flow rate adjustment valve 40 and flows to the second water gallery 36. Therefore, the amount of cooling water flowing through the water jacket 31 in the cylinder block is small, and the amount of cooling water flowing through the water jacket 32 in the cylinder head is large.

  On the other hand, when the cooling water is at a high temperature, such as when the engine 1 is operating at a high speed and a high load, the thermostat is open, so that a large amount of cooling water flows from the water pump 18 into the first water gallery 34.

  In this case, as shown in FIGS. 3, 5, and 7, the flow rate adjustment valve 40 is rotated by being pressed by the cooling water. For this reason, since the first water gallery 34 is opened, the cooling water flows to both the first water gallery 34 and the second water gallery 36 according to the opening degree of the flow rate adjusting valve 40.

  Therefore, the distribution amount of the cooling water to the water jacket 31 in the cylinder block and the water jacket 32 in the cylinder head depends on the amount of the cooling water flowing into the first water gallery 34 from the water pump 18, that is, the total amount of the cooling water. Adjusted.

  As a result, the larger the total amount of cooling water, the larger the opening of the flow rate adjustment valve 40, and the greater the amount of cooling water distributed to the cylinder jacket water jacket 31 side.

  Thus, in the cooling structure of the internal combustion engine of the present embodiment, when the engine 1 is cold started, the flow rate adjustment valve 40 is in a closed state, so the supply of the cooling water to the cylinder block 11 is stopped. Cooling water can be supplied to the head 12, and the cooling water can be supplied to the cylinder block 11 by rotating the flow rate adjusting valve 40 as the cooling water temperature rises.

  For this reason, when cooling water is low temperature, by suppressing the temperature of the cylinder head 12 to low temperature, it is possible to improve filling efficiency and prevent knocking and pre-ignition, and when the cooling water is high temperature, By maintaining the temperature of the cylinder block 11 at a moderately high temperature, the lubricating oil can be made to have a low viscosity and the flicking of each part can be reduced.

  Therefore, the distribution amount of the cooling water to the water jacket 31 in the cylinder block and the water jacket 32 in the cylinder head can be adjusted appropriately. Here, in the present embodiment, the flow rate adjustment valve 40 is pressed by the cooling water and rotates to open the first water gallery 34. Therefore, a driving device such as a motor or a solenoid for opening and closing is provided. It becomes unnecessary and can be a simple structure.

  As a result, the cooling structure of the internal combustion engine of the present embodiment is a simple structure, but can appropriately adjust the distribution amount of the cooling water to the water jacket 31 in the cylinder block and the water jacket 32 in the cylinder head.

  Further, in the present embodiment, the first water gallery 34 is opened when the flow rate adjustment valve 40 rotates. For this reason, compared with the structure which moves a valve body on a straight line and seats on a valve seat, since a valve seat becomes unnecessary, it can be set as a simple structure.

  Even if the foreign matter is sandwiched between the upper end portion 40a or the lower end portion 40b of the flow rate adjustment valve 40 and the wall surface of the first water gallery 34, the foreign matter is sheared when the flow rate adjustment valve 40 rotates. For this reason, it is possible to prevent the flow rate adjustment valve 40 from being closed due to a foreign object being caught.

  Further, in the cooling structure of the internal combustion engine of the present embodiment, since the flow rate adjustment valve 40 is disposed immediately downstream of the branch portion 34c in the first water gallery 34, the flow rate adjustment valve 40 is adjusted when the flow rate adjustment valve 40 is in the closed posture. Due to the water pressure increased in the upstream region 34 a of the valve 40, the cooling water can be flowed to the second water gallery 36 from immediately below the branch portion 34 c to the second water gallery 36.

  That is, if the flow regulating valve 40 is disposed farther from the branch portion 34 c toward the water jacket 31 in the cylinder block, a part of the cooling water goes back to the first water gallery 34 after hitting the flow regulating valve 40. As a result, the pressure loss increases because it flows into the second water gallery 36.

  On the other hand, the pressure loss of the cooling water is reduced by disposing the flow rate adjusting valve 40 immediately below the branch portion 34c. As a result, it is possible to optimize the cooling water diversion effect to the second water gallery 36 when the flow rate adjustment valve 40 is in the closed posture.

  In the cooling structure of the internal combustion engine of the present embodiment, the flow rate adjustment valve 40 is formed in a plate shape, and the closing posture of the flow rate adjustment valve 40 is a posture extending in the branch direction of the second water gallery 36.

  For this reason, the extending direction when the flow regulating valve 40 is in the closed posture can be matched with the branch direction of the second water gallery 36. Therefore, the cooling water is guided to the second water gallery 36 side by hitting the flow rate adjustment valve 40 that is plate-shaped and coincides with the branch direction of the second water gallery 36.

  As a result, the flow rate adjusting valve 40 can smoothly flow the cooling water toward the second water gallery 36 when in the closed posture.

  In the cooling structure of the internal combustion engine of the present embodiment, the cross-sectional shape of the first water gallery 34 and the shape of the flow rate adjustment valve 40 are formed in a rectangular shape, and the flow rate adjustment valve is rotatably supported in the first water gallery 34. The rotating shaft 41 is provided, and the rotating shaft 41 is disposed close to the inner wall surface of the first water gallery 34 on the second water gallery 36 side.

  For this reason, when the flow rate adjusting valve 40 is rotated by the coolant pressure, the upper end portion 40a of the flow rate adjusting valve 40 is prevented from projecting greatly toward the second water gallery 36. Therefore, when the flow rate adjustment valve 40 rotates, the upper end portion 40a of the flow rate adjustment valve 40 does not block a part of the second water gallery 36, so that the cooling is divided into the second water gallery 36 side. Water flow is not hindered.

  Further, in the internal combustion engine cooling structure of the present embodiment, since the rotation shaft 41 is disposed above the center of gravity of the flow rate adjustment valve 40, the flow rate adjustment valve 40 can return to the closed posture by its own weight. For this reason, a return spring for valve closing or the like is unnecessary, and the flow rate adjusting valve 40 can have a simple structure.

  In the internal combustion engine cooling structure of the present embodiment, the second water gallery 36 branches from the first water gallery 34 vertically upward. For this reason, when the flow regulating valve 40 is closed due to its own weight, the flow regulating valve 40 extends in the same vertical direction as the branch direction of the second water gallery 36.

  Therefore, the cooling water is guided to the second water gallery 36 side by hitting the flow rate adjustment valve 40. As a result, the flow rate adjusting valve 40 can smoothly flow the cooling water toward the second water gallery 36 when in the closed posture.

  In the internal combustion engine cooling structure of the present embodiment, the first water gallery 34 and the second water gallery 36 are arranged inside the cylinder block 11. Therefore, since the first water gallery 34 and the second water gallery 36 can be easily formed at the time of casting or post-processing of the cylinder block 11, the first water gallery 34 and the second water gallery 36 are separated from each other. It is possible to eliminate the need for the configuration.

  Although the embodiments have been described above, it is obvious that those skilled in the art can make changes without departing from the scope of the present invention. The present invention is intended to include all such modifications and equivalents.

  DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 11 ... Cylinder block, 23 ... Combustion chamber, 31 ... Water jacket in cylinder block, 32 ... Water jacket in cylinder head, 34 ... 1st water gallery, 34c ... Branch part, 36 ... 2nd Water gallery 40 ... Flow rate adjusting valve 41 ... Rotating shaft

Claims (7)

A cylinder block having a water jacket in the cylinder block through which cooling water flows around the cylinder;
A cylinder head having a water jacket in the cylinder head through which cooling water flows around the combustion chamber,
In the cooling structure of the internal combustion engine in which the cooling water flowing through the water jacket in the cylinder block is supplied to the water jacket in the cylinder head,
A first water gallery for supplying cooling water to the water jacket in the cylinder block from the outside of the cylinder block;
A second water gallery that branches off from the first water gallery and supplies cooling water branched from the first water gallery to the water jacket in the cylinder head;
A flow rate adjustment valve for opening and closing the first water gallery,
The flow regulating valve is
The first water gallery is arranged on the downstream side of the branch portion with the second water gallery, and is rotated by being pushed by the cooling water from the closed posture for closing the first water gallery. A cooling structure for an internal combustion engine, wherein the water gallery is opened.   2. The cooling structure for an internal combustion engine according to claim 1, wherein the flow rate adjusting valve is arranged immediately downstream of the branch portion of the first water gallery. The flow rate adjusting valve is formed in a plate shape,
The cooling structure for an internal combustion engine according to claim 1 or 2, wherein the closing posture of the flow rate adjusting valve is a posture in which the flow rate adjusting valve extends in a branching direction of the second water gallery. The first water gallery has a rectangular cross-sectional shape;
The flow regulating valve is formed in a rectangular shape so as to coincide with a cross-sectional shape of the first water gallery when in the closed posture,
A rotation shaft for rotatably supporting the flow rate adjusting valve in the first water gallery;
The cooling structure for an internal combustion engine according to any one of claims 1 to 3, wherein the rotation shaft is disposed close to an inner wall surface on the second water gallery side in the first water gallery. .   The cooling structure for an internal combustion engine according to any one of claims 1 to 4, wherein the rotation shaft is disposed above a center of gravity of the flow rate adjusting valve.   The cooling structure for an internal combustion engine according to claim 5, wherein the second water gallery branches vertically upward from the first water gallery.   The cooling structure for an internal combustion engine according to any one of claims 1 to 6, wherein the first water gallery and the second water gallery are arranged inside the cylinder block.

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