JP5637964B2 - Internal combustion engine cooling structure - Google Patents

Description

  The present invention relates to a cooling structure for an internal combustion engine.

  Conventionally, so-called EGR (Exhaust Gas Recirculation) in which a part of exhaust gas is recirculated to an intake side in an engine such as a vehicle is known. This EGR is used for the purpose of lowering the combustion temperature and reducing nitrogen oxides (NOx) in the exhaust gas.

  By the way, the exhaust gas exhausted from the engine is very high temperature, and if this exhaust gas is recirculated to the intake side as it is, the charging efficiency of intake air is reduced, so that the recirculated exhaust gas (EGR gas) is cooled as much as possible. It is desirable. Therefore, conventionally, cooling of EGR gas has been performed using engine cooling water.

  For example, in Patent Document 1, a water jacket (cooling water passage) is defined, and a part of the EGR passage is formed in a vertical wall portion which is one end portion in the cylinder row direction of the cylinder head. Has been disclosed that extends in the width direction of the cylinder head along the water jacket. That is, Patent Document 1 discloses an invention in which EGR gas is cooled by cooling water flowing through a water jacket.

  Patent Document 2 discloses a pipe connection member that is attached to a cylinder head and that is connected to a supply pipe that supplies cooling water to other components such as a radiator to form a cooling water circulation passage from the cylinder head to the supply pipe. An invention is disclosed in which a groove (a part of the EGR passage) surrounding the cooling water circulation passage is formed on at least one of the mating surfaces of the cylinder head and the pipe connecting member. That is, Patent Document 2 discloses an invention in which EGR gas is allowed to flow through the groove and the EGR gas is cooled by cooling water flowing through the cooling water circulation passage.

  In general, a supply pipe for supplying cooling water to other parts and a return pipe for returning the cooling water supplied to other parts are connected to one side wall in the cylinder row direction of the cylinder head, and the one side wall (See, for example, Patent Document 3). Specifically, a cooling water outlet chamber and a cooling water inlet chamber are arranged in parallel along the width direction of one side wall at one end of the cylinder head in the cylinder row direction, and a supply pipe is connected to the cooling water outlet chamber. On the other hand, a return pipe is connected to the cooling water inlet chamber, and the supply pipe and the return pipe are arranged on the same plane.

JP 2008-45498 A JP 2010-84581 A Japanese Patent No. 3485158

  By the way, in order to increase the cooling effect of the engine, it is desirable to increase the volume of the cooling water passage as much as possible. On the other hand, in order to improve the exhaust purification efficiency, it is desirable to increase the volume of the EGR passage as much as possible. However, when the cooling water passage and the EGR passage are formed in the cylinder head as in the invention described in Patent Document 1, if the volume of the cooling water passage is increased due to the space in the cylinder head, the volume of the EGR passage is increased. Inevitably decreases, and the flow rate of EGR gas decreases and exhaust purification efficiency decreases. Therefore, it is necessary to increase the volume of the EGR passage, but there has been a problem that the cylinder head inevitably increases in size.

On the other hand, in the invention described in Patent Document 1, when the volume of the EGR passage is increased, the volume of the cooling water passage is inevitably reduced, and the flow rate of the cooling water is reduced and the cooling efficiency for the EGR gas is increased. Will be reduced.
In the invention described in Patent Document 2, since the EGR passage is formed by a groove surrounding one end of the cooling water circulation passage, the heat transfer area between the EGR passage and the cooling water circulation passage is reduced. Therefore, since the heat exchange efficiency between the EGR passage and the cooling water circulation passage is poor, the cooling efficiency for the EGR gas is poor.

  Therefore, in the invention described in Patent Document 1-2, since the cooling efficiency for the EGR gas is poor, the intake charging efficiency is reduced and the combustion efficiency is deteriorated. Therefore, for example, it is necessary to separately take measures such as increasing the size of the EGR cooler that cools the EGR gas and sufficiently cool the EGR gas, resulting in a problem that the internal combustion engine is increased in size and fuel consumption is deteriorated. there were.

  Further, in the invention described in Patent Document 2, the connection portion between the supply pipe and the pipe connection member is disposed at the center in the width direction of one side wall of the cylinder head. The layout became longer and the supply piping was longer.

  Further, in the invention described in Patent Document 3, the cooling water outlet chamber and the cooling water inlet chamber are arranged in parallel along the width direction of one side wall of the cylinder head, and the supply pipe and the return pipe are arranged on the same plane. Therefore, the work of determining the piping layout so that they do not interfere with each other becomes complicated, and in order to prevent the interference between the two, it is necessary to largely bypass one of the pipings, resulting in a complicated piping layout.

The present invention was devised from such a viewpoint. Even when the volume of the cooling water passage is increased, the volume of the EGR passage can be increased to improve the exhaust gas purification efficiency. Providing a cooling structure is a first problem.
It is a second object to provide a cooling structure for an internal combustion engine that improves the cooling efficiency for EGR gas and increases the combustion efficiency.
It is a third object to provide a cooling structure for an internal combustion engine that can realize a compact and simple piping layout.

  In order to solve the above-mentioned problems, the present invention includes a cylinder head having therein a cooling water passage through which cooling water flows, and having a downstream end of the cooling water passage open on one side wall in the cylinder row direction, and the cylinder head And a pipe connection member connected to the one side wall, wherein the pipe connection member is connected to the downstream end of the cooling water passage, and A cooling water outlet to which a supply pipe for supplying the cooling water to other parts is connected, a cooling water inlet to which a return pipe to which the cooling water supplied to the other parts returns is connected, and one end on the exhaust side A passage portion forming at least a part of an EGR passage connected at the other end to the intake side, and the cooling water outlet and the cooling water inlet extend along the width direction of the one side wall. Or The passage section is formed along the extending direction of the cooling water outlet, and the supply pipe and the return pipe connected to at least one of the other parts are arranged in the cylinder axis direction. In the width direction of the side wall, the pipe connection member is connected at a position deviated to the other component side.

According to the present invention, the cylinder head has the cooling water passage inside, and the pipe connection member formed separately from the cylinder head has at least a part (passage portion) of the EGR passage, whereby the cooling water passage Since the EGR passage and the EGR passage are formed as separate members, the volume of the EGR passage can be freely set without considering the volume of the cooling water passage.
Therefore, even when the volume of the cooling water passage is increased, the volume of the EGR passage can be increased and the flow rate of the EGR gas can be increased, so that the exhaust purification efficiency can be improved. Further, since the EGR passage is formed in the pipe connecting member, it is possible to avoid an increase in the size of the cylinder head even when the volume of the EGR passage is increased.

Further, according to the present invention, since the cooling water passage and the EGR passage are formed as separate members, the volume of the cooling water passage can be freely set without considering the volume of the EGR passage. Therefore, even when the volume of the EGR passage is increased, the volume of the cooling water passage can be increased and the flow rate of the cooling water can be increased, so that the cooling efficiency for the EGR gas can be improved.
Moreover, according to the present invention, the cooling water outlet and the cooling water inlet extend along the width direction of the one side wall and are arranged vertically in the cylinder axis direction, so that the substantially width direction of the one side wall is obtained. Since the cooling water outlet can be provided over the entire length and the capacity of the cooling water outlet can be increased, the flow rate of the cooling water from the cylinder head to the cooling water outlet can be sufficiently secured.
Moreover, since the passage portion is formed along the extending direction of the cooling water outlet, the passage portion can be provided substantially parallel to the cooling water outlet and over the entire length in the width direction of one side wall. Therefore, the heat transfer area between the passage portion and the coolant outlet becomes larger than when the passage portion is formed by a groove surrounding one end of the coolant circulation passage (for example, the invention described in Patent Document 2). .

Accordingly, the flow rate of the cooling water to the cooling water outlet increases and the heat transfer area between the passage portion and the cooling water outlet increases, so that heat exchange between the passage portion and the cooling water outlet is efficiently performed. Therefore, the cooling efficiency for the EGR gas can be improved.
That is, according to the present invention, the cooling efficiency for the EGR gas is improved, the intake charging efficiency is increased, and the combustion efficiency is improved. Therefore, it is not necessary to separately take measures such as increasing the size of the EGR cooler. Increase in size and fuel consumption can be avoided.

Furthermore, according to the present invention, the supply pipe and the return pipe connected to at least one other part are connected to the pipe connection member at a position deviated toward the other part in the width direction of the one side wall. Compared to the case where the connecting portion is arranged at the center in the width direction of the cylinder head (for example, the invention described in Patent Document 2), the distance between the supply pipe and the return pipe and other parts can be reduced, so that the supply pipe In addition, the return piping can be shortened to realize a compact piping layout.
In addition, since the cooling water outlet and the cooling water inlet are arranged vertically in the cylinder axial direction, the supply piping and the return piping are positioned up and down. It becomes easy.
And since supply piping and return piping are located up and down, it is not necessary to largely bypass one piping, and a simple piping layout is realizable, preventing both interference.

  The cooling water outlet is provided above and adjacent to the cooling water inlet in the cylinder axial direction, and the passage portion is above and adjacent to the cooling water outlet in the cylinder axial direction. The supply pipe has a radiator supply pipe for supplying the cooling water to a radiator, and a connection portion of the cooling water outlet to the radiator supply pipe is connected to the cooling water passage. It is preferable to form an obtuse angle with respect to the flow direction.

According to such a configuration, the cooling water outlet connection to the radiator supply pipe forms an obtuse angle with respect to the flow direction of the cooling water flowing through the cooling water passage, so that the cooling water flowing out from the cylinder head is used for the radiator. Since it becomes easy to flow into the supply pipe, the flow rate of the cooling water flowing into the supply pipe for the radiator can be increased, so that the supply amount of the cooling water to the radiator can be sufficiently secured.
In addition, the passage portion is provided above the cooling water outlet and the cooling water inlet in the cylinder axial direction, so that it is difficult to be restricted by the cooling water outlet and the cooling water inlet when setting the volume of the passage portion. .
Furthermore, the passage portion is provided adjacent to the cooling water outlet so that heat exchange can be efficiently performed between the EGR gas flowing through the passage portion and the cooling water flowing through the cooling water outlet. This makes it possible to improve the cooling efficiency for the EGR gas, thereby contributing to the downsizing of the EGR cooler.

  In addition, the supply pipe has a plurality of supply pipes including the radiator supply pipe, the cooling water outlet has a plurality of connection parts to which the supply pipes are connected, and the plurality of the connection parts The connecting portion of the cooling water outlet to the radiator supply pipe is preferably formed so as to protrude in a direction away from the one side wall so as to have a maximum inflow cross-sectional area.

  According to this configuration, the connection portion of the cooling water outlet to the radiator supply pipe is formed so as to protrude in a direction away from the one side wall so as to have the maximum inflow cross-sectional area, whereby the cooling water to the radiator supply pipe is formed. The flow rate can be increased.

  The width direction of the one side wall of the cylinder head coincides with the longitudinal direction of the vehicle, and the supply pipe supplies an EGR cooler supply pipe for supplying the cooling water to the EGR cooler, and the heater supplies the cooling water to the heater. A heater supply pipe to be supplied, and the connection portion of the cooling water outlet to the radiator supply pipe and the EGR cooler supply pipe is arranged eccentrically in front of the vehicle, and is connected to the heater supply pipe. The connecting portion of the cooling water outlet is eccentrically arranged at the rear of the vehicle, and the connecting portion of the cooling water outlet to the supply pipe for the radiator, the supply pipe for the EGR cooler, and the supply pipe for the heater It is preferable to constitute so that it is arrange | positioned on a straight line along.

  According to this configuration, the connection portion of the cooling water outlet to the radiator supply pipe and the EGR cooler supply pipe is eccentrically arranged in front of the vehicle, while the connection portion of the cooling water outlet to the heater supply pipe is Positions (arrangements) of radiators, EGR coolers, heaters, and the like are arranged rearward and are arranged in a straight line along the vehicle front-rear direction, so that the coolant outlets connected to the supply pipes are arranged in a straight line. Therefore, the plurality of supply pipes can be distributed and arranged before and after the vehicle, so that the pipe layout of the supply pipes can be made compact and simple.

  The return pipe has an EGR cooler return pipe to which the cooling water supplied to the EGR cooler returns, and a heater return pipe to which the cooling water supplied to the heater returns. The cooling water inlet has a plurality of connection parts to which the return pipe is connected, and the connection part of the cooling water inlet with respect to the return pipe for the EGR cooler is arranged eccentrically in front of the vehicle. The connecting portion of the cooling water inlet with respect to the return pipe is eccentrically arranged at the rear of the vehicle, and the connecting portion of the cooling water inlet with respect to the return pipe for the EGR cooler and the return pipe for the heater is straight along the vehicle front-rear direction. It is preferable to be arranged as above.

According to this configuration, the connection portion of the cooling water inlet with respect to the return pipe for the EGR cooler is arranged eccentrically in front of the vehicle, while the connection portion of the cooling water inlet with respect to the return pipe for heater is unevenly arranged in the rear of the vehicle. The connecting portion of the cooling water inlet with respect to each return pipe is arranged in a straight line along the vehicle front-rear direction, so that a plurality of return pipes are arranged in the front and rear of the vehicle in accordance with the positions of the EGR cooler, the heater, etc. Since it can be distributed and arranged, the piping layout of the return piping can be made compact and simple.
In addition, as described above, the cooling water outlet and the cooling water inlet are provided adjacent to each other in the cylinder axis direction, so that the distance between the upper and lower sides of the supply pipe and the return pipe can be made closer. The entire piping layout including the return piping can be made compact and simple, and the workability during assembly is improved.

  Moreover, it is preferable that the said channel | path part is comprised so that it may protrude in the direction spaced apart from the said one side wall.

  According to such a configuration, the passage portion is formed so as to protrude away from the one side wall, so that the volume of the passage portion can be increased by adjusting the protrusion amount, and the flow rate of EGR gas can be easily increased.

  Moreover, it is preferable to comprise so that the connection part of the said cooling water outlet with respect to the said supply pipe for radiators may be provided with the water temperature sensor which detects the temperature of the said cooling water.

  As described above, the cooling water flowing out from the cylinder head easily flows into the radiator supply pipe. According to such a configuration, the water temperature sensor is provided at the connection portion of the cooling water outlet to the radiator supply pipe. The temperature of the cooling water can be detected with high accuracy.

  Further, the cooling water passage has a main flow part for allowing the cooling water to flow along the cylinder row direction above the combustion chamber, and the connection part of the cooling water outlet to the heater supply pipe is the main flow part. It is preferable to configure so as to be provided on the downstream side.

  According to such a configuration, the connecting portion of the cooling water outlet to the heater supply pipe is provided on the downstream side of the main flow portion through which the cooling water flows along the cylinder row direction above the combustion chamber. Cooling water flowing out from the head can easily flow into the heater supply passage. As a result, the flow rate of the cooling water flowing into the heater supply pipe is increased, and as a result, a sufficient supply amount of the cooling water to the heater can be secured.

  The pipe connection member and the cam angle sensor for detecting a rotation angle of a camshaft rotatably supported by the cylinder head are preferably configured to be fastened together with a bolt on the one side wall. .

According to such a configuration, during operation of the internal combustion engine, the pipe connection member is a member that is difficult to vibrate because the cooling water flows therethrough and has a relatively large weight. Since the cam angle sensor is less susceptible to vibrations by being fastened to one side wall of the cylinder head, the detection accuracy of the rotation angle of the camshaft can be improved.
In addition, since the pipe connection member and the cam angle sensor are fastened together with a bolt on one side wall of the cylinder head, the pipe connection member and the cam angle sensor can be fixed to the cylinder head at the same time, so that workability during assembly is improved.

ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the volume of a cooling water channel | path is increased, the cooling structure of the internal combustion engine which can increase the volume of an EGR channel | path and can improve exhaust gas purification efficiency can be provided.
Further, according to the present invention, it is possible to provide a cooling structure for an internal combustion engine that improves the cooling efficiency for EGR gas and increases the combustion efficiency.
Furthermore, according to the present invention, it is possible to provide a cooling structure for an internal combustion engine that can realize a compact and simple piping layout.

It is a schematic diagram which shows the cooling system of an engine. It is a schematic diagram which shows an EGR gas recirculation system. It is a left view which shows the state which assembled | attached the pipe connection member to the cylinder head. FIG. 4 is a plan view of FIG. 3. It is the II sectional view taken on the line of FIG. It is the II-II sectional view taken on the line of FIG. It is a left view which shows the exit of the water jacket of a cylinder head. (A) is a front view which shows the state which looked at the pipe connection member from the front side, (b) is a rear view which shows the state which looked at the pipe connection member from the opposite side to (a). (A) is the III-III sectional view taken on the line of FIG. 3 which shows the state which looked up the water temperature sensor periphery from the downward direction, (b) is the IV-IV sectional view taken on the line of (a). It is the VV sectional view taken on the line of FIG.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description is omitted.

Prior to the description of the engine cooling structure 100 according to the embodiment of the present invention, the cooling system S1 will be described with reference to FIG. FIG. 1 is a schematic diagram showing the cooling system S1. In addition, the solid line arrow in FIG. 1 shows the flow of cooling water.
As shown in FIG. 1, the cooling system S1 circulates cooling water so as to flow through the water jackets 12a and 14a of the cylinder block 12 and the cylinder head 14, and cools the cylinder block 12 and the like (engine 10). It is.
The cylinder block 12 and the cylinder head 14 constitute an engine main body 11 of the engine 10, and the engine main body 11 of the present embodiment is an in-line four-cylinder engine in which four cylinders # 1- # 4 are arranged in a row. It is mounted horizontally in an engine room (not shown).

  A cooling water pump 30 is disposed on one end side of the engine body 11. The cooling water pump 30 is driven by power transmitted from a crankshaft (not shown) via a belt transmission mechanism (not shown), and supplies cooling water to the cylinder block 12. An inlet 12 a 1 of the water jacket 12 a of the cylinder block 12 is connected to the downstream side of the cooling water pump 30.

  The water jacket 12a is formed so as to surround the substantially outer periphery of the cylinders # 1- # 4. The water jackets 12a and 14a communicate with each other via communication portions 18 and 18 provided on the exhaust side and the intake side. An outlet (downstream end) 14a1 of the water jacket 14a serving as a cooling water passage is open to one side wall 14b in the cylinder row direction.

In this case, the cooling water flows through the water jacket 12a on the intake side along the cylinder row direction, and then makes a U-turn to flow the water jacket 12a on the exhaust side along the cylinder row direction. The cooling water is supplied from the water jacket 12a to the water jacket 14a via the communication portions 18 and 18, and flows through the water jacket 14a along the cylinder row direction.
In the present embodiment, the cylinder row direction coincides with the vehicle width direction (left-right direction), and the width direction of the one side wall 14b coincides with the vehicle front-rear direction.

  A pipe connecting member 20 having a cooling water outlet 21 and a cooling water inlet 22 is disposed on one side wall 14 b of the cylinder head 14. The cooling water outlet 21 connects the water jacket 14a, the radiator 32, and the like via pipes P1-P4. Further, the coolant outlet 21 communicates with a flow path 12 b provided in the cylinder block 12 via a bypass passage 34 and a thermostat 36.

  The cooling water inlet 22 is connected to the heater 46 and the like via pipes P6 to P8 and communicates with the flow path 12b. In addition, the downstream end of the flow path 12b is connected to the upstream side of the cooling water pump 30 via the piping P9.

  The radiator 32 is disposed in front of the engine body 11, and a pipe P <b> 1 for supplying cooling water to the radiator 32 is disposed between the cooling water outlet 21 and the radiator 32. Between the radiator 32 and the thermo housing 40 that houses the thermostat 36, a pipe P5 through which the cooling water supplied to the radiator 32 is discharged is disposed. The thermostat 36 can be switched to a state that allows communication between the pipe P5 and the flow path 12b and a state that blocks it.

  Between the cooling water outlet 21 and the EGR cooler 42, a pipe P2 for supplying cooling water to the EGR cooler 42 is disposed. Between the cooling water inlet 22 and the EGR cooler 42, a pipe P6 for returning the cooling water supplied to the EGR cooler 42 is disposed.

  Between the coolant outlet 21 and the throttle body 44, a pipe P3 for supplying coolant to the throttle body 44 is disposed. Between the cooling water inlet 22 and the throttle body 44, a pipe P7 through which the cooling water supplied to the throttle body 44 returns is disposed.

  The heater 46 is disposed behind the engine body 11, and a pipe P <b> 4 for supplying cooling water to the heater 46 is disposed between the cooling water outlet 21 and the heater 46. Between the cooling water inlet 22 and the heater 46, a pipe P8 for returning the cooling water supplied to the heater 46 is disposed. A branch pipe P11 that branches from the middle of the pipe P4 and communicates with the downstream side of the pipe P8 is disposed between the pipe P4 and the pipe P8. In the pipe P4, a three-way valve 48 is disposed at a branch portion with the branch pipe P11. The three-way valve 48 allows the cooling water to flow to the heater 46 and the cooling pipe to the branch pipe P11. It is possible to switch to and. In addition, a cooling water pump 50 is disposed in the pipe P4.

  In this case, before the warm-up operation of the engine 10 is completed (at a low temperature), the communication state between the radiator 32 and the flow path 12b is blocked by the thermostat 36, while the communication state between the bypass path 34 and the flow path 12b is changed. The cooling water is supplied from the cooling water outlet 21 to the flow path 12b via the bypass passage 34. As a result, the cooling water is supplied from the cooling water pump 30 → the water jacket 12a of the cylinder block 12 → the water jacket 14a of the cylinder head 14 → the cooling water outlet 21 → the bypass passage 34 → the thermostat 36 → the flow path 12b → the piping P9 → the cooling water pump. It flows in order of 30. Therefore, since the cooling water does not flow through the radiator 32, the temperature of the cooling water can be quickly raised and the engine 10 can be warmed up smoothly.

  After the warm-up operation of the engine 10 is completed (at a high temperature), the thermostat 36 allows the communication state between the radiator 32 and the flow path 12b, while blocking the communication state between the bypass passage 34 and the flow path 12b. Cooling water is supplied from the radiator 32 to the flow path 12b via the pipe P5. As a result, the cooling water is supplied from the cooling water pump 30 → the water jacket 12a of the cylinder block 12 → the water jacket 14a of the cylinder head 14 → the cooling water outlet 21 → the piping P1 → the radiator 32 → the piping P5 → the thermostat 36 → the flow path 12b → the piping. It flows in order of P9-> cooling water pump 30. Therefore, since the cooling water flows through the radiator 32, the temperature of the cooling water can be reduced by heat exchange with the atmosphere, and overheating of the engine 10 can be suppressed.

  Further, before the warm-up operation of the engine 10 is completed, the communication state between the cooling water outlet 21 and the heater 46 is blocked by the three-way valve 48, and the cooling water is supplied to the branch pipe P11. As a result, the cooling water is the cooling water pump 30 → the water jacket 12a of the cylinder block 12 → the water jacket 14a of the cylinder head 14 → the cooling water outlet 21 → the pipe P4 → the branch pipe P11 → the pipe P8 → the cooling water inlet 22 → the flow path. It flows in order of 12b-> piping P9-> cooling water pump 30. Therefore, since the cooling water does not flow through the heater 46, the temperature of the cooling water can be quickly raised and the engine 10 can be warmed up smoothly.

  After the warm-up operation of the engine 10 is completed, the communication state between the cooling water outlet 21 and the heater 46 is permitted by the three-way valve 48, and the cooling water is supplied to the heater 46. As a result, the cooling water is supplied from the cooling water pump 30 → the water jacket 12a of the cylinder block 12 → the water jacket 14a of the cylinder head 14 → the cooling water outlet 21 → the piping P4 → the heater 46 → the piping P8 → the cooling water inlet 22 → the flow path 12b. → Pipe P9 → Cooling water pump 30 is passed in this order. Therefore, since the cooling water flows through the heater 46, the heater 46 can be heated.

  Further, the cooling water that has flowed into the cooling water outlet 21 is pipe P2 → EGR cooler 42 → pipe P6 → cooling water inlet 22 → flow path 12b → pipe P9 → cooling water pump 30 → water jacket 12a of the cylinder block 12 → cylinder head. 14 water jackets 14 a → cooling water outlet 21. Therefore, since the cooling water flows through the EGR cooler 42, the EGR gas can be cooled.

  Further, the cooling water flowing into the cooling water outlet 21 is pipe P3 → throttle body 44 → pipe P7 → cooling water inlet 22 → flow path 12b → pipe P9 → cooling water pump 30 → water jacket 12a of the cylinder block 12 → cylinder head. 14 water jackets 14 a → cooling water outlet 21. Therefore, since the coolant flows through the throttle body 44, the throttle body 44 can be warmed up.

  Next, the EGR gas recirculation system S2 will be described with reference to FIG. FIG. 2 is a schematic diagram showing the EGR gas recirculation system S2. In addition, the solid line arrow in FIG. 2 shows the flow of cooling water, and the dotted line arrow shows the flow of EGR gas.

The EGR gas recirculation system S2 is a system that recirculates a part of the exhaust gas to the intake side.
The cylinder head 14 includes a combustion chamber 14c, an intake port 14d that supplies air to the combustion chamber 14c, an exhaust port 14e that exhausts exhaust from the combustion chamber 14c, and a valve 14f that opens and closes the intake port 14d and the exhaust port 14e. And a passage 14g constituting a part of the EGR passage. An intake manifold 52 for introducing air into the intake port 14d is installed on the side of the cylinder head 14, while an exhaust for leading the exhaust from the exhaust port 14e to the outside on the opposite side. A manifold (not shown) is installed.

  The upstream end of the passage 14g communicates with the exhaust port 14e near the one side wall 14b of the cylinder head 14. The downstream end 14g1 of the passage 14g communicates with a passage portion 23 of the pipe connection member 20 described later. An EGR control valve 54 is attached to the upstream end of the passage portion 23. The EGR control valve 54 is connected to the EGR cooler 42 via the pipe P12, and the EGR cooler 42 is connected to the intake manifold 52 via the pipe P13.

  In this case, the EGR gas flows in the order of the exhaust port 14e → the passage 14g → the passage portion 23 of the pipe connecting member 20 → the EGR control valve 54 → the pipe P12 → the EGR cooler 42 → the pipe P13 → the intake manifold 52. It is introduced into the intake port 14d. Further, when the EGR gas passes through the passage portion 23, the EGR gas is cooled by exchanging heat with the cooling water in the cooling water outlet 21.

  Next, an embodiment of the engine cooling structure 100 will be described in detail with reference to FIGS.

3 is a left side view showing a state where the pipe connecting member 20 is assembled to the cylinder head 14, and FIG. 4 is a plan view of FIG.
The engine cooling structure 100 is a structure for cooling the engine 10 and the EGR gas. As shown in FIGS. 3 and 4, the cylinder head 14, the pipe connecting member 20, and a plurality of pipes P <b> 1-P <b> 4. P6-P8 is mainly provided.
In addition, the code | symbol 16 in FIG.3 and FIG.4 shows a cylinder head cover.

5 is a cross-sectional view taken along line II in FIG. 3, FIG. 6 is a cross-sectional view taken along line II-II in FIG. 3, and FIG. 7 is a left side view showing an outlet 14a1 of the water jacket 14a of the cylinder head 14. FIG. In FIG. 5, the piping is omitted for convenience of explanation.
As shown in FIGS. 5 and 6, the one side wall 14 b of the cylinder head 14 constitutes a mounting surface to which the pipe connecting member 20 is fixed. As shown in FIG. 7, a plurality of bolt insertion holes 14h and 14h are formed in the one side wall 14b, and an outlet 14a1 of the water jacket 14a and a downstream end 14g1 of the passage 14g are opened.

  The outlet 14a1 of the water jacket 14a is divided forward and backward by ribs 14i extending vertically, and has a first outlet 14a2 at the front and a second outlet 14a3 at the rear. The first outlet 14a2 has a larger opening area than the second outlet 14a3. By providing the ribs 14i, even when the opening area of the outlet 14a1 of the water jacket 14a is ensured to be large, a decrease in rigidity of the cylinder head 14 can be reduced. Moreover, since the cooling water is diverted back and forth with the rib 14i as a boundary, the rib 14i also functions as a guide portion for guiding the cooling water.

  The downstream end 14g1 of the passage 14g is partitioned from the outlet 14a1 of the water jacket 14a by a partition wall 14j. The downstream end 14g1 of the passage 14g is provided behind the outlet 14a1 of the water jacket 14a by a predetermined distance.

Fig.8 (a) is a front view which shows the state which looked at the pipe connection member 20 from the front side, (b) is a rear view which shows the state which looked at the pipe connection member 20 from the opposite side to (a). . The hatched portion in FIG. 8B shows a contact surface with the cylinder head 14.
The pipe connecting member 20 is a metal member configured separately from the cylinder head 14, and as shown in FIGS. 5 and 8A, the cooling water outlet 21, the cooling water inlet 22, and the passage portion 23. And a plurality of fastening portions 24, 24.

  As shown in FIGS. 5 and 8A and 8B, the cooling water outlet 21 includes an outlet chamber 21a connected to the outlet 14a1 of the water jacket 14a and a connection portion 21b to which the pipes P1-P4 are connected. -21e.

  The outlet chamber 21a is a portion that extends along the width direction of the one side wall 14b. The outlet chamber 21a is formed to project in a direction away from the one side wall 14b, and has a predetermined volume of space. As shown in FIG. 8B, an opening 21a1 is formed on the back surface of the outlet chamber 21a, and this opening 21a1 corresponds to the opening shape of the outlet 14a1 of the water jacket 14a.

  As shown in FIG. 8A, the connecting portion 21b-21e is a cylindrical portion that communicates with the outlet chamber 21a. The connection portion 21b-21e is formed to protrude outward from the outer wall of the outlet chamber 21a. In the present embodiment, from the front of the vehicle, the connecting portion 21b connected to the piping P1, the connecting portion 21c connected to the piping P2, the connecting portion 21d connected to the piping P3, and the connecting portion 21e connected to the piping P4. Arranged in order. Specifically, the connecting portions 21b and 21c are arranged eccentrically in front of the vehicle, while the connecting portions 21d and 21e are arranged eccentrically in the rear of the vehicle. The connection part 21b-21e is arrange | positioned on the straight line along the vehicle front-back direction. The connection part 21b will be described in detail later.

The cooling water inlet 22 is a part provided below and adjacent to the cooling water outlet 21 in the cylinder axial direction as shown in FIGS. 5 and 8A and 8B.
The cooling water inlet 22 has an inlet chamber 22a and connecting portions 22b-22d to which pipes P6-P8 are connected.

  The inlet chamber 22a is a portion that extends along the width direction of the one side wall 14b. The inlet chamber 22a is formed to protrude in a direction away from the one side wall 14b, and has a predetermined volume of space.

  As shown in FIG. 8A, the connecting portions 22b-22d are cylindrical portions that communicate with the inlet chamber 22a. The connecting portions 22b-22d are formed to protrude outward from the outer wall of the inlet chamber 22a. In the present embodiment, the connecting portion 22b to which the pipe P6 is connected, the connecting portion 22c to which the pipe P7 is connected, and the connecting portion 22d to which the pipe P8 is connected are arranged in this order from the front of the vehicle. Specifically, the connecting portion 22b is eccentrically arranged in front of the vehicle, and the connecting portions 22c and 22d are eccentrically arranged in the rear of the vehicle. The connecting portions 22b-22d are arranged on a straight line along the vehicle longitudinal direction.

  As shown in FIGS. 5, 8 </ b> A, and 8 </ b> B, the passage portion 23 is provided above and adjacent to the cooling water outlet 21 in the cylinder axial direction and along the extending direction of the cooling water outlet 21. It is the part that was made. The passage portion 23 constitutes a part of the EGR gas recirculation system S2 and functions as an EGR passage through which the EGR gas flows. The passage portion 23 is formed to project in a direction away from the one side wall 14b, and has a space of a predetermined volume. As shown in FIG. 8B, an opening 23a is formed on the back surface of the passage 23, and this opening 23a corresponds to the opening shape of the downstream end 14g1 of the passage 14g.

  As shown in FIG. 8A, the plurality of fastening portions 24, 24 are provided at appropriate positions of the pipe connection member 20, and have bolt insertion holes 24a, 24a. As shown in FIG. 3, the pipe connecting member 20 is fixed to the one side wall 14 b with a bolt via a fastening portion 24. Further, the pipe connecting member 20 is fastened together with one of the cam angle sensors 56a and 56b and the one side wall 14b with a bolt B via the fastening portion 24. The cam angle sensors 56a and 56b have a function of detecting the rotation angle of a cam shaft (not shown) that is rotatably supported by the cylinder head 14.

  As shown in FIGS. 1 and 3, the pipes P <b> 1 to P <b> 4 are supply pipes that connect the cooling water outlet 21 and the radiator 32 and supply cooling water from the cooling water outlet 21 to the radiator 32 and the like. As shown in FIG. 3, one end of the pipe P1 is connected to the connecting portion 21b, and is a radiator supply pipe that supplies cooling water to the radiator 32. One end of the pipe P2 is connected to the connecting portion 21c, and the EGR cooler 42 is an EGR cooler supply pipe for supplying cooling water to 42. One end of the pipe P3 is connected to the connecting portion 21d, and is a throttle body supply pipe for supplying cooling water to the throttle body 44. One end of the pipe P4 is connected to the connecting portion 21e, and the cooling water is supplied to the heater 46. It is the supply piping for heaters which supplies. The connecting portion of the piping P1-P2 with respect to the cooling water outlet 21 is eccentrically arranged in front of the vehicle, while the connecting portion of the piping P3-P4 with respect to the cooling water outlet 21 is eccentrically arranged in the rear of the vehicle. The connection part with respect to the cooling water outlet 21 of piping P1-P4 is arrange | positioned on the straight line along the vehicle front-back direction.

  As shown in FIGS. 1 and 3, the pipes P <b> 6 to P <b> 8 are return pipes that connect the cooling water inlet 22 and the EGR cooler 42 and return the cooling water from the EGR cooler 42 and the like to the cooling water inlet 22. As shown in FIG. 3, the pipe P6 is an EGR cooler return pipe whose one end is connected to the connection portion 22b and the cooling water supplied to the EGR cooler 42 returns, and one end of the pipe P7 is connected to the connection portion 22c. This is a return pipe for the throttle body to which the cooling water supplied to the throttle body 44 returns, and the pipe P8 is a return pipe for the heater to which one end is connected to the connecting portion 22d and the cooling water supplied to the heater 46 returns. . The connecting portion of the piping P6 with respect to the cooling water inlet 22 is eccentrically arranged in front of the vehicle, while the connecting portions of the piping P7 and P8 with respect to the cooling water inlet 22 are eccentrically arranged in the rear of the vehicle. The connection part with respect to the cooling water inlet 22 of piping P6-P8 is arrange | positioned on the straight line along the vehicle front-back direction.

Subsequently, the connecting portion 21b will be described in detail with reference to FIGS. 3, 4, and 6 as appropriate.
As shown in FIGS. 3 and 4, the connection portion 21 b is formed so that the outflow cross-sectional area is larger than that of the other connection portions 21 c-21 e. As shown in FIG. 6, the connecting portion 21b is disposed closer to the first outlet 14a2 having a relatively large opening area. The protruding direction X of the connecting portion 21b forms an obtuse angle with respect to the flow direction Y of the cooling water flowing through the water jacket 14a. That is, the angle θ formed by the protruding direction X of the connecting portion 21b and the cooling water flow direction Y forms an obtuse angle larger than 90 degrees. As a result, the pressure loss of the cooling water can be reduced compared to the case where the angle θ formed by the protruding direction X of the connecting portion 21b and the flowing direction Y of the cooling water is 90 degrees or less. The flow rate of water can be increased, and as a result, a sufficient amount of cooling water supplied to the radiator 32 can be secured.

  On the other hand, the connecting portion 21e is provided on the downstream side of the main flow portion T through which the cooling water flows along the cylinder row direction. Thereby, since it becomes easy to flow into the connection part 21b, the supply amount of the cooling water to the heater 46 can be sufficiently secured. The mainstream portion T is a portion of the water jacket 14a that is located above the combustion chamber 14c (see FIG. 2). In this case, the cooling water in the main flow portion T passes above the combustion chamber 14 c and flows into the cooling water outlet 21.

9A is a cross-sectional view taken along line III-III in FIG. 3 and shows a state where the periphery of the water temperature sensor 58 is viewed from below, and FIG. 9B is a cross-sectional view taken along line IV-IV in FIG.
As shown in FIG. 9A, the connecting portion 21b communicates with a bypass portion 21f that forms a part of the bypass passage 34, and in the vicinity of the bypass portion 21f, a hole portion in which the water temperature sensor 58 is mounted. 21 g is formed through. The bypass passage 34 is formed by the bypass portion 21 f and the bypass portion 14 k of the cylinder head 14.

  As shown in FIG. 9B, the water temperature sensor 58 is a sensor for detecting the temperature of the cooling water, and is inserted into the hole portion 21g and the main body portion 58a exposed to the outside of the hole portion 21g. Sensor portion 58b protruding into 21b. As described above, the water temperature sensor 58 is provided in the connection portion 21b and the water temperature sensor 58 is provided in a portion where the cooling water always flows by communicating the bypass portion 21f. However, the temperature of the cooling water can be accurately and reliably detected (regardless of whether the thermostat 36 is opened or closed).

10 is a cross-sectional view taken along line VV in FIG. In addition, the solid line arrow in FIG. 10 shows the flow of cooling water, and the dotted line arrow shows the flow of air.
Here, as shown in FIG. 10, an air vent hole 60 is provided between the water jacket 14a and the connecting portion 21b for venting air (bubbles) in the water jacket 14a. The air vent hole 60 branches off from the middle of the water jacket 14a and communicates with the connecting portion 21b. In the vicinity of the upstream end of the air vent hole 60, an air vent hole 40a for venting air in the thermo housing 40 is provided, and the air vent hole 40a communicates with the water jacket 14a. Thereby, the air in the water jacket 14a and the thermo housing 40 can be extracted to the connecting portion 21b through the air vent holes 40a and 60. Moreover, the burr | flash removal operation | work can be performed using the air vent hole 60 at the time of manufacture, confirming the burrs in the water jacket 14a.

  The engine cooling structure 100 according to the embodiment of the present invention is basically configured as described above. Next, the function and effect will be described.

  According to the present embodiment, the cylinder head 14 has the water jacket 14a therein, and the pipe connecting member 20 configured separately from the cylinder head 14 has the passage portion 23, so that the water jacket 14a and the passage portion are provided. 23 are formed as separate members, the volume of the passage portion 23 can be freely set without considering the volume of the water jacket 14a. Therefore, even when the volume of the water jacket 14a is increased, the volume of the passage portion 23 can be increased and the flow rate of the EGR gas can be increased, so that the exhaust gas purification efficiency can be improved. Further, since the passage portion 23 is formed in the pipe connection member 20, it is possible to avoid an increase in the size of the cylinder head 14 even when the volume of the passage portion 23 is increased.

  Further, according to the present embodiment, the passage portion 23 is provided above the cooling water outlet 21 and the cooling water inlet 22 in the cylinder axial direction, so that the cooling water is set when the volume of the passage portion 23 is set. It becomes difficult to be restricted by the outlet 21 and the cooling water inlet 22.

  Further, according to the present embodiment, the passage portion 23 is formed so as to protrude in the direction away from the one side wall 14b, so that the volume of the passage portion 23 is increased by adjusting the protrusion amount, and the flow rate of EGR gas is increased. Can be increased easily.

  Moreover, according to this embodiment, since the water jacket 14a and the channel | path part 23 are each formed in a separate member, the volume of the water jacket 14a can be set freely, without considering the volume of the channel | path part 23. FIG. Therefore, even when the volume of the passage portion 23 is increased, the volume of the water jacket 14a can be increased and the flow rate of the cooling water can be increased, so that the cooling efficiency for the EGR gas can be improved.

  Moreover, according to the present embodiment, the cooling water outlet 21 and the cooling water inlet 22 extend along the width direction of the one side wall 14b and are arranged vertically in the cylinder axial direction, so that one side wall Since the cooling water outlet 21 is provided over substantially the entire length of the width direction 14b and the capacity of the cooling water outlet 21 can be increased, a sufficient flow rate of the cooling water from the cylinder head 14 to the cooling water outlet 21 can be secured.

  Further, according to the present embodiment, the passage portion 23 is adjacent to the cooling water outlet 21 and is formed along the extending direction of the cooling water outlet 21, so that one end of the cooling water circulation passage is formed. The heat transfer area between the passage portion 23 and the cooling water outlet 21 is larger than when the passage portion is formed by the enclosing groove (for example, the invention described in Patent Document 2).

Accordingly, the flow rate of the cooling water to the cooling water outlet 21 is increased and the heat transfer area between the passage portion 23 and the cooling water outlet 21 is increased, so that the heat between the passage portion 23 and the cooling water outlet 21 is increased. The exchange can be performed efficiently, and the cooling efficiency for the EGR gas can be improved.
That is, according to the present embodiment, the cooling efficiency for the EGR gas is improved, the intake charge efficiency is increased, and the combustion efficiency is improved. Therefore, it is not necessary to separately take measures such as increasing the size of the EGR cooler 42, and the engine. 10 increase in size and fuel consumption can be avoided.

  Further, according to the present embodiment, the pipe P2 and the pipe P6 connected to the EGR cooler 42 are connected to the pipe connecting member 20 at a position deviated forward of the vehicle, and the pipe P4 and the pipe P8 connected to the heater 46 are connected to the vehicle. Since it is connected to the pipe connecting member 20 at a position that is eccentric to the rear, the pipe P2 and the pipe P6 and EGR are compared with the case where the cylinder head 14 is connected to the center in the width direction (for example, the invention described in Patent Document 2). Since the distance between the cooler 42 and the distance between the pipe P4 and the pipe P8 and the heater 46 can be reduced, the pipes P2, P4, P6 and P8 can be shortened to realize a compact pipe layout.

Further, according to the present embodiment, a plurality of pipes P1-P4, P6-P8 are distributed to the front and rear of the vehicle in accordance with the positions (arrangements) of the radiator 32, the EGR cooler 42, the throttle body 44, the heater 46, etc. Therefore, the piping layout can be made compact and simple.
Moreover, according to the present embodiment, the cooling water outlet 21 and the cooling water inlet 22 are provided vertically adjacent to each other in the cylinder axis direction, so that the supply pipe P2-P4 and the return pipe P6-8 are provided. As a result, the overall piping layout can be made compact and simple, and the workability during assembly is improved.

Further, according to the present embodiment, the cooling water outlet 21 and the cooling water inlet 22 are arranged vertically in the cylinder axial direction, so that the supply pipes P1-P4 and the return pipes P6-P8 Is positioned above and below, the work of determining the piping layout so that they do not interfere with each other becomes easy.
Since the supply pipe P1-P4 and the return pipe P6-P8 are positioned above and below, one of the supply pipe P1-P4 and the return pipe P6-P8 is largely bypassed. This eliminates the need for a simple piping layout while preventing interference between the two.

  Further, according to the present embodiment, the protruding direction X of the connecting portion 21b connected to the pipe P1 for the radiator 32 forms an obtuse angle with respect to the flow direction Y of the cooling water flowing through the water jacket 14a. Since the cooling water that has flowed out of the cylinder head 14 easily flows into the connecting portion 21b, the flow rate of the cooling water that flows into the pipe P1 can be increased, and as a result, a sufficient supply amount of the cooling water to the radiator 32 can be secured.

  Moreover, according to this embodiment, since the connection part 21b is formed so that it may become the largest inflow cross-sectional area with respect to the other connection part 21c-21e, it can increase the flow volume of the cooling water which flows in into the piping P1. .

  Further, according to the present embodiment, the connecting portion 21e of the cooling water outlet 21 is provided on the downstream side of the main flow portion T through which the cooling water flows along the cylinder row direction above the combustion chamber 14c. The cooling water easily flows into the pipe P4 for the heater 46. As a result, the flow rate of the cooling water flowing into the pipe P4 is increased, and as a result, a sufficient supply amount of the cooling water to the heater 46 can be secured.

  In addition, according to the present embodiment, the cooling water easily flows into the connection portion 21b of the cooling water outlet 21, but the water temperature sensor 58 is provided in the connection portion 21b where the cooling water easily flows. it can.

  Further, according to the present embodiment, when the engine 10 is in operation, the pipe connecting member 20 is a member that is difficult to vibrate because the cooling water flows therethrough and has a relatively large weight. 20 and the cam angle sensor 56a are fastened together with the one side wall 14b of the cylinder head 14, so that the cam angle sensor 56a is less susceptible to vibrations, so that the detection accuracy of the rotation angle of the camshaft can be improved. .

  Further, according to the present embodiment, the pipe connection member 20 and the cam angle sensor 56a are fastened together with the bolt B to the one side wall 14b of the cylinder head 14, whereby the pipe connection member 20 and the cam angle sensor 56a are connected to the cylinder head 14. Since it can be fixed at the same time, workability during assembly is improved.

  As mentioned above, although embodiment of this invention was described in detail with reference to drawings, this invention is not limited to this, In the range which does not deviate from the main point of invention, it can change suitably.

  In this embodiment, the case where the engine cooling structure of the present invention is applied to an in-line four-cylinder engine has been described. However, the present invention is not limited to this, and may be applied to an engine having a different number of cylinders or different cylinder arrangements. It may be applied to a gasoline engine or diesel.

  Although the thermostat 36 of this embodiment is provided in the location which connects the inlet of the engine main body 11 and the outlet of the radiator 32, this invention is not limited to this, The outlet of the engine main body 11 and the radiator 32 of the radiator 32 are provided. You may provide in the location which connects an entrance.

S1 Cooling system S2 EGR gas recirculation system 100 Cooling structure 10 Engine 14 Cylinder head 14a Water jacket (cooling water passage)
14a1 outlet (downstream end)
T main flow part 14b one side wall 14c combustion chamber 14d intake port (intake side)
14e Exhaust port (exhaust side)
14h Bolt insertion hole 20 Pipe connection member 21 Cooling water outlet 21a Outlet chamber 21b-21e Connection part 22 Cooling water inlet 22a Inlet chamber 22b-22d Connection part 23 Passage part 24 Fastening part 24a Bolt insertion hole 32 Radiator (other parts)
42 EGR cooler (other parts)
44 Throttle body (other parts)
46 Heater (other parts)
52 Intake manifold (intake side)
56a, 56b Cam angle sensor 58 Water temperature sensor 58a Body part 58b Sensor part P1 Piping (Supplying pipe for radiator)
P2 piping (EGR cooler supply piping)
P4 piping (heater supply piping)
P6 piping (return piping for EGR cooler)
P8 piping (return piping for heater)
B bolt

Claims (9)

A cylinder head having therein a cooling water passage through which the cooling water flows, and having a downstream end of the cooling water passage open on one side wall in the cylinder row direction;
A pipe connection member configured separately from the cylinder head and connected to the one side wall;
An internal combustion engine cooling structure comprising:
The pipe connecting member is
A coolant outlet connected to a downstream end of the coolant passage and connected to a supply pipe for supplying the coolant to other components;
A cooling water inlet to which a return pipe to which the cooling water supplied to the other parts returns is connected;
A passage portion forming at least a part of an EGR passage, one end of which is connected to the exhaust side and the other end is connected to the intake side;
Have
The cooling water outlet and the cooling water inlet are extended along the width direction of the one side wall, and arranged vertically in the cylinder axis direction,
The passage portion is formed along the extending direction of the cooling water outlet,
The supply pipe and the return pipe connected to at least one of the other parts are connected to the pipe connecting member at a position deviated toward the other part in the width direction of the one side wall. Internal combustion engine cooling structure. The cooling water outlet is provided above and adjacent to the cooling water inlet in the cylinder axial direction,
The passage portion is provided above and adjacent to the cooling water outlet in the cylinder axial direction,
The supply pipe has a radiator supply pipe for supplying the cooling water to the radiator,
2. The cooling of the internal combustion engine according to claim 1, wherein a connection portion of the cooling water outlet with respect to the radiator supply pipe forms an obtuse angle with respect to a flow direction of the cooling water flowing through the cooling water passage. Construction. The supply pipe has a plurality of supply pipes including the radiator supply pipe,
The cooling water outlet has a plurality of connecting portions to which the supply pipe is connected,
The connection portion of the cooling water outlet to the radiator supply pipe among the plurality of connection portions is formed to protrude in a direction away from the one side wall so as to have a maximum inflow cross-sectional area. Item 3. A cooling structure for an internal combustion engine according to Item 2. The width direction of the one side wall of the cylinder head coincides with the vehicle longitudinal direction,
The supply pipe further includes an EGR cooler supply pipe for supplying the cooling water to an EGR cooler, and a heater supply pipe for supplying the cooling water to a heater,
A connection portion of the cooling water outlet to the radiator supply pipe and the EGR cooler supply pipe is eccentrically arranged in front of the vehicle,
The connection portion of the cooling water outlet to the heater supply pipe is arranged eccentrically at the rear of the vehicle,
The connecting portion of the cooling water outlet to the radiator supply pipe, the EGR cooler supply pipe, and the heater supply pipe is arranged in a straight line along the vehicle front-rear direction. Or the cooling structure of the internal combustion engine of Claim 3. The return pipe has an EGR cooler return pipe to which the cooling water supplied to the EGR cooler returns, and a heater return pipe to which the cooling water supplied to the heater returns.
The cooling water inlet has a plurality of connecting portions to which the return pipe is connected,
A connection portion of the cooling water inlet with respect to the return pipe for the EGR cooler is eccentrically arranged in front of the vehicle,
The connection portion of the cooling water inlet with respect to the heater return pipe is eccentrically arranged at the rear of the vehicle,
5. The cooling of the internal combustion engine according to claim 4, wherein a connection portion of the cooling water inlet with respect to the return pipe for the EGR cooler and the return pipe for the heater is arranged on a straight line along the vehicle front-rear direction. Construction.   The cooling structure for an internal combustion engine according to any one of claims 1 to 5, wherein the passage portion is formed to protrude in a direction away from the one side wall.   The water temperature sensor which detects the temperature of the said cooling water is provided in the connection part of the said cooling water outlet with respect to the said supply pipe for radiators, The Claim 1 thru | or 5 characterized by the above-mentioned. The internal combustion engine cooling structure. The cooling water passage has a main flow portion for allowing the cooling water to flow along the cylinder row direction above the combustion chamber,
The cooling structure for an internal combustion engine according to claim 4 or 5, wherein a connection portion of the cooling water outlet to the heater supply pipe is provided on the downstream side of the main flow portion.   2. The pipe connecting member and a cam angle sensor for detecting a rotation angle of a cam shaft rotatably supported by the cylinder head are fastened together with bolts on the one side wall. The cooling structure for an internal combustion engine according to claim 8.

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