JP5278299B2 - Cylinder head cooling structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide cooling structure of a cylinder head, capable of favorably cooling the circumference of an exhaust port. <P>SOLUTION: On an exhaust port side of a cylinder head 30 used for an internal combustion engine 10, a first water jacket 50 is provided to extend from one end side to the other end side in a cylinder row direction. A cooling water inlet port 57 leading cooling water into the first water jacket 50 is disposed on one end side in the cylinder row direction, and one side in a forming region which is divided by a straight line L1 connecting the centers of valve stems 36a of a plurality of exhaust valves 36 positioned inside the forming region of the first water jacket 50 of the cylinder head 30. Further, a cooling water discharge port 58 discharging the cooling water from the first water jacket 50 is disposed on the other end side in the cylinder row direction, and on the other side in the forming region divided by the straight line L1. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a cooling structure for a cylinder head used in a multi-cylinder internal combustion engine.

  In a water-cooled internal combustion engine, a water jacket is provided in a cylinder head and a cylinder block, and the water jacket and the radiator are connected via a cooling water circulation passage. The cooling water is circulated between the water jacket and the radiator by the water pump to uniformly cool the cylinder head and the cylinder block, while the cooling water whose temperature has been increased is cooled by the radiator.

  The cooling structure of the cylinder head of the multi-cylinder internal combustion engine includes a configuration in which cooling water flows in a direction parallel to the cylinder row direction (also referred to as a longitudinal direction) in the cylinder head, and the cooling water crosses the cylinder row direction in the cylinder head. There is a configuration in which it flows in a direction (also referred to as a horizontal direction). For example, in Patent Document 1, after introducing cooling water from a cooling water inlet provided in a cylinder block, supplying cooling water to a water jacket provided around the cylinder bore of the cylinder block, the cooling water is provided in the cylinder head. It is shown that the water is introduced into a water jacket and the cooling water flows laterally in the cylinder head.

JP 2009-002265 A

  As the water jacket for the cylinder head, a configuration in which cooling water is introduced from a water jacket around the cylinder bore of the cylinder block is often employed. However, when this configuration is applied to a water jacket for flowing cooling water in the cylinder head in the lateral direction, the pressure loss of cooling water can be reduced, but the following points are concerned. If the cooling water introduction port is provided on the exhaust side and the cooling water discharge port is provided on the intake side, the cooling water may stay around the exhaust port and stagnate, resulting in insufficient cooling around the exhaust port. There is a possibility. For this reason, the cooling performance of the exhaust gas is deteriorated. As a result, for example, there is a possibility that the heat damage of the catalyst provided in the exhaust system or the size of the EGR cooler provided in the EGR device may be increased.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a cooling structure capable of cooling the periphery of an exhaust port satisfactorily in a cylinder head used in a multi-cylinder internal combustion engine. And

In the present invention, means for solving the above-described problems are configured as follows. That is, the present invention is a cylinder head cooling structure in which an exhaust port side water jacket extending from one end side to the other end side in the cylinder row direction is provided on the exhaust port side of a cylinder head used in a multi-cylinder internal combustion engine. A cooling water inlet for introducing cooling water into the exhaust port side water jacket is provided at one end side in the cylinder row direction and at the combustion chamber side end portion in a direction orthogonal to the cylinder row direction in plan view ; cooling water discharge port for discharging the cooling water from the exhaust port side water jacket is, in plan view, in cylinder row direction of the other end, and, provided in the exhaust side end portion in the direction orthogonal to the cylinder row direction, the The exhaust port side water jacket is provided in parallel with the combustion chamber side water jacket provided around the combustion chamber .

  According to the above configuration, in the cylinder head, the cooling water introduction port and the cooling water discharge port of the exhaust port side water jacket are arranged at diagonal positions across the straight line. Water can be distributed evenly. Thereby, it is possible to prevent the cooling water from staying around the exhaust port of the cylinder head and to cool the periphery of the exhaust port satisfactorily. And the cooling property of the exhaust gas discharged | emitted via an exhaust port can be improved, and exhaust gas temperature can be made low. As a result, for example, the heat damage of the catalyst provided in the exhaust system of the internal combustion engine can be suppressed, and the cost can be reduced. In addition, when the internal combustion engine is operated at high speed, it is not necessary to cool the exhaust gas with fuel, which can contribute to an improvement in fuel consumption. Further, the temperature of the EGR gas sent to the EGR device installed in the internal combustion engine can be lowered, which can contribute to the downsizing and cost reduction of the EGR cooler.

  According to the above configuration, the amount of cooling water supplied to the exhaust port side water jacket can be easily secured without increasing the pressure loss of the entire cooling water of the exhaust port side water jacket and the combustion chamber side water jacket provided in the cylinder head. can do. Thereby, sufficient cooling performance of the exhaust gas as described above can be easily ensured.

Further, in the present invention, the exhaust port side water jacket is formed in a substantially rectangular in plan view, the cooling water inlet and cooling water outlet is preferably are found provided one each.

  According to the above configuration, in the exhaust port side water jacket, a flow of cooling water parallel to the cylinder row direction is generated at the combustion chamber side end, and a flow of cooling water parallel to the cylinder row direction is generated at the exhaust side end. Occur. The two cooling water flows as described above can suppress the retention of cooling water around the exhaust port of the cylinder head, and sufficiently cool the periphery of the exhaust port from the end on the combustion chamber side to the end on the outlet side. can do. Thereby, the cooling property of the exhaust gas discharged through the exhaust port can be improved, and the exhaust gas temperature can be lowered.

  In the present invention, the exhaust port side water jacket includes a first passage extending from one end side toward the other end side in the cylinder row direction at the combustion chamber side end portion, and a cylinder row direction at the exhaust side end portion. It is preferable to include a second passage extending from one end side to the other end side, and a third passage extending in a direction crossing the cylinder row direction and connecting the first passage and the second passage.

  According to the above configuration, in the exhaust port side water jacket, a flow of cooling water parallel to the cylinder row direction (cooling water flow in the first passage) is generated at the combustion chamber side end, and at the exhaust side end. A flow of cooling water parallel to the cylinder row direction (cooling water flow in the second passage) is generated. By such two cooling water flows, it is possible to suppress the retention of cooling water around the exhaust port of the cylinder head, and the periphery of the exhaust port extends from the end on the combustion chamber side (inlet side) to the end on the outlet side. Can be cooled sufficiently. Thereby, the cooling property of the exhaust gas discharged through the exhaust port can be improved, and the exhaust gas temperature can be lowered.

  In the present invention, the third passage is preferably provided between adjacent exhaust valves.

  According to the above configuration, the cooling water is sent from the first passage of the exhaust port side water jacket to the second passage through the third passage. For this reason, it becomes possible to cool reliably between the exhaust valves which adjoin a cylinder head with the cooling water which flows through a 3rd channel | path. That is, in the cylinder head, it is possible to improve the cooling performance between the exhaust valves, which is particularly concerned about high temperatures. As a result, the reliability of the cylinder head can be improved.

  In the present invention, it is preferable that the exhaust port side water jacket is provided so as to cover the upper side of the exhaust port.

  According to the said structure, the distribution area of the cooling water in the exhaust port side water jacket can be ensured largely. Thereby, sufficient cooling performance of the exhaust gas as described above can be easily ensured.

  According to the present invention, in the cylinder head, the cooling water introduction port and the cooling water discharge port of the exhaust port side water jacket are arranged at diagonal positions, so that the cooling water is evenly distributed in the exhaust port side water jacket. It becomes possible. Thereby, it is possible to prevent the cooling water from staying around the exhaust port of the cylinder head and to cool the periphery of the exhaust port satisfactorily. And the cooling property of the exhaust gas discharged | emitted via an exhaust port can be improved, and exhaust gas temperature can be made low.

It is sectional drawing which shows schematic structure of the principal part of the internal combustion engine to which the cooling structure of the cylinder head which concerns on embodiment of this invention is applied. It is a top view which shows typically the water jacket provided in the cylinder block of the internal combustion engine of FIG. It is a top view which shows typically the water jacket provided in the cylinder head of the internal combustion engine of FIG. It is side surface sectional drawing which shows typically the exhaust port side water jacket of the water jacket of the cylinder head of FIG. It is a top view which shows typically the combustion chamber side water jacket of the water jacket of the cylinder head of FIG. It is a front view which shows typically the flow of the cooling water in a cylinder head and a cylinder block.

  Embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a sectional view showing a schematic configuration of a main part of an internal combustion engine to which a cooling structure for a cylinder head according to an embodiment of the present invention is applied. FIG. 2 is a plan view schematically showing a water jacket provided in a cylinder block of the internal combustion engine of FIG. In FIG. 2, the water jacket of the cylinder block is mainly shown, and the detailed configuration is not shown.

  In this embodiment, as an example of a cylinder head used in a multi-cylinder internal combustion engine, a cylinder head 30 used in an in-line four-cylinder DOHC type internal combustion engine 10 is cited. However, the type of the multi-cylinder internal combustion engine is not particularly limited.

  As shown in FIG. 1, the internal combustion engine 10 is a gasoline engine, for example, and includes a cylinder block 20 and a cylinder head 30. The cylinder block 20 and the cylinder head 30 are fastened by a head bolt via a head gasket. The internal combustion engine 10 may be a diesel engine or the like.

  The cylinder block 20 is provided with a plurality of cylinder bores 21 arranged in a line in the longitudinal direction. A piston 22 is inserted into each cylinder bore 21. The cylinder block 20 is provided with a water jacket 23 through which cooling water flows. As shown in FIG. 2, the water jacket 23 is provided so as to surround the plurality of cylinder bores 21. The water jacket 23 is connected to a radiator (not shown) via a cooling water circulation passage.

  As shown in FIG. 1, the cylinder head 30 is provided with a combustion chamber 31 corresponding to each cylinder bore 21 of the cylinder block 20. A spark plug 32 is attached to the center of the top of each combustion chamber 31. Further, the cylinder head 30 is formed with an intake port 33 and an exhaust port 34 communicating with each combustion chamber 31. Two intake ports 33 and two exhaust ports 34 are provided for each combustion chamber 31. The intake port 33 is opened and closed with respect to the combustion chamber 31 by an intake valve 35 driven by an intake camshaft (not shown). The exhaust port 34 is opened and closed with respect to the combustion chamber 31 by an exhaust valve 36 driven by an exhaust camshaft (not shown).

  Cylindrical valve guides 37 and 38 that guide the opening and closing operations of the intake valve 35 and the exhaust valve 36 are attached to the cylinder head 30. A valve stem 35a of the intake valve 35 and a valve stem 36a of the exhaust valve 36 are slidably inserted in the valve guides 37 and 38.

  A water jacket 40 is provided around the combustion chamber 31 of the cylinder head 30, around the intake port 33, around the exhaust port 34, and the like. The water jacket 40 is connected to the radiator via a cooling water circulation passage.

  In the internal combustion engine 10, the coolant is circulated between the water jacket 23 of the cylinder block 20 and the water jacket 40 of the cylinder head 30 and the radiator by a water pump (W / P), whereby the cylinder head 30 and the cylinder block 20. The cooling water whose temperature has risen is cooled with a radiator.

  Here, as shown in FIG. 2, the water jacket 23 of the cylinder block 20 is divided into an intake side passage 23a and an exhaust side passage 23b. Then, the cooling water from the water pump is introduced into the exhaust side passage 23b through the cooling water introduction port 27 provided on one end side (front side in FIG. 2) of the exhaust side passage 23b in the cylinder row direction. It is like that. Then, the cooling water flows out from the exhaust side passage 23b to the water jacket 40 of the cylinder head 30, and the cooling water flows from the water jacket 40 into the intake side passage 23a. Further, the cooling water is discharged from the intake side passage 23a through the cooling water discharge port 28 provided on the other end side (rear side in FIG. 2) of the intake side passage 23a in the cylinder row direction. ing.

  Next, the water jacket 40 provided in the cylinder head 30 will be described with reference to FIGS. 3 to 6 mainly show the water jacket of the cylinder head, and the detailed configuration is not shown.

  In this embodiment, the water jacket 40 of the cylinder head 30 includes a first water jacket (exhaust port side water jacket) 50 that mainly flows cooling water in a direction (longitudinal direction) parallel to the cylinder row direction, and cooling water. It is divided into a second water jacket (combustion chamber side water jacket) 60 that flows mainly in a direction (lateral direction) intersecting the cylinder row direction. The cooling water discharged from the water pump is supplied in parallel to the first water jacket 50 and the second water jacket 60. In other words, the first water jacket 50 and the second water jacket 60 are provided independently, and the cooling water directly circulates between the first water jacket 50 and the second water jacket 60. It has a configuration that does not.

  As shown in FIG. 3, the first water jacket 50 is formed in a substantially rectangular shape in plan view, and from the one end side in the cylinder row direction (front side in FIG. 3) to the exhaust port 34 side of the cylinder head 30. It extends to the other end side (the rear side in FIG. 3). Further, the first water jacket 50 is provided from the center portion 30c of the cylinder head 30 to the exhaust side end portion 30b in a direction orthogonal to the cylinder row direction of the cylinder head 30.

  The first water jacket 50 is provided so as to cover most of the exhaust port 34 from the upper side except for the tip end portion (exit side portion) of the exhaust port 34. The first water jacket 50 has a vertically long shape in which the length in the vertical direction is longer than the length in the horizontal direction. Moreover, the 1st water jacket 50 is made into the flat shape by a front view, as shown in FIG. The first water jacket 50 is provided mainly for cooling the periphery of the exhaust port 34 of the cylinder head 30.

  As shown in FIG. 3, the cylinder head 30 is provided with a plurality of attachment regions 54 for the exhaust valve 36 inside the formation region of the first water jacket 50. The attachment region 54 is a region where the first water jacket 50 is not formed in the cylinder head 30. In this embodiment, eight attachment regions 54 are provided in a line in the cylinder row direction. The cross-sectional shape of the attachment region 54 is, for example, a circle. The attachment region 54 is a region to which the valve guide 38 of the exhaust valve 36 is attached, and includes a predetermined range from the center of the exhaust valve 36 (center of the valve stem 36a). In each attachment region 54, one exhaust valve 36 and one valve guide 38 are arranged. The cylinder head 30 is also provided with a plurality of head bolt attachment regions 55 inside the region where the first water jacket 50 is formed.

  More specifically, as shown in FIG. 3, the first water jacket 50 includes a first passage 51 extending from one end side to the other end side in the cylinder row direction in the center portion 30c of the cylinder head 30, and an exhaust gas. At the side end 30b, the second passage 52 extending from one end side toward the other end side in the cylinder row direction is connected to the first passage 51 and the second passage 52 extending in a direction crossing the cylinder row direction. The third passage 53 is included. An end 52 a on the exhaust side of the second passage 52 reaches the vicinity of the outlet of the exhaust port 34. The third passage 53 is provided between both ends in the cylinder row direction and between the adjacent exhaust valves 36. A space surrounded by the first to third passages 51 to 53 serves as an attachment region 54 for the exhaust valve 36 described above.

  In the middle of the first water jacket 50 in the cylinder row direction, as shown in FIG. The cross-sectional shape of the recess 56 is, for example, a trapezoid. The recess 56 is provided between adjacent cylinders, and is provided across the third passage 53 from the end of the first passage 51. In this way, by forming the first water jacket 50 along the shape of the exhaust port 34, the first water jacket 50 is disposed close to the exhaust port 34, so that the cooling efficiency of the exhaust gas is improved. Can be improved. Note that the first water jacket 50 may be flattened in a side view without providing the recess 56.

  As shown in FIG. 3, one cooling water inlet 57 for introducing cooling water into the first water jacket 50 and one cooling water outlet 58 for discharging cooling water from the first water jacket 50 are provided. ing. The cooling water introduction port 57 is connected to a cooling water introduction passage from the water pump. In this embodiment, the cooling water introduction passage from the water pump is connected to the exhaust-side passage 23b of the water jacket 23 of the cylinder block 20, and as shown in FIG. An extending cooling water inlet 57 is connected. The cooling water inlet 57 is arranged at a position upstream of the cooling water outlet 24 provided in the exhaust-side passage 23b, that is, at a position close to the cooling water inlet 27 (see FIG. 2). The cooling water discharge port 58 is connected to a cooling water circulation passage to the radiator. For this reason, the cooling water flows into the first water jacket 50 only through the cooling water inlet 57. Further, the cooling water flows out from the first water jacket 50 only through the cooling water discharge port 58. The cooling water from the water pump may be directly introduced into the first water jacket 50 without passing through the water jacket 23 of the cylinder block 20.

  In this embodiment, the coolant introduction port 57 is provided at one end in the cylinder row direction and on one side in the direction orthogonal to the cylinder row direction, and the coolant discharge port 58 is provided at the other end in the cylinder row direction at the cylinder row. It is provided on the other side in the direction orthogonal to the direction. Specifically, the coolant introduction port 57 is provided at the front end in the cylinder row direction and at the combustion chamber side end in the direction orthogonal to the cylinder row direction. Further, the cooling water discharge port 58 is provided at the exhaust-side end portion 30b in the direction orthogonal to the cylinder row direction at the rear end in the cylinder row direction.

  More specifically, the cooling water inlet 57 is provided on one side of the formation region of the first water jacket 50, which is divided by a straight line L1 connecting the centers of the attachment regions 54 of the plurality of exhaust valves 36 and parallel to the cylinder row direction. A cooling water discharge port 58 is provided on the other side of the region where the first water jacket 50 is formed and is divided by the straight line L1. More specifically, the straight line L1 is a line connecting the centers of the valve stems 36a of the exhaust valves 36 located in the respective attachment regions 54.

  A discharge passage 59 is integrally provided at the other end of the first water jacket 50 in the cylinder row direction. The discharge passage 59 is a passage for sending the cooling water discharged from the water jacket 23 (intake side passage 23 a) of the cylinder block 20 to the cooling water discharge port 58. That is, the cooling water discharged from the first water jacket 50 and the cooling water discharged from the water jacket 23 of the cylinder block 20 merge at the cooling water discharge port 58 and are discharged to the cooling water circulation passage. It has become. The discharge passage 59 may be provided separately from the first water jacket 50.

  In the internal combustion engine 10, as a cooling water path (first path) including the first water jacket 50, the water pump → the passage 23 b on the exhaust side of the water jacket 23 of the cylinder block 20 → the cooling water inlet 57 → the first. The water jacket 50 → cooling water discharge port 58 → radiator is provided. In the first water jacket 50, as will be described later, the cooling water mainly flows in a direction parallel to the cylinder row direction.

  As shown in FIG. 5, the second water jacket 60 includes a first passage 61 provided for each cylinder. In this embodiment, four first passages 61 are provided in a line in the cylinder row direction, and adjacent first passages 61 are connected by a second passage 62. The second water jacket 60 is provided mainly for cooling the periphery of the combustion chamber 31 of the cylinder head 30.

  The first passage 61 is provided so as to cover the combustion chamber 31 from above. The first passage 61 is provided from the intake side end 30 a of the cylinder head 30 to the exhaust side in a direction orthogonal to the cylinder row direction of the cylinder head 30. A portion on the exhaust side of the first passage 61 is branched into a plurality (three in FIG. 5) of connection passages 61a. The connection passage 61a is a passage for supplying cooling water to the periphery of the combustion chamber 31, and extends from the periphery of the combustion chamber 31 toward the exhaust side end 30b. A cooling water inlet 67, which will be described later, is disposed at the front end (exhaust end) of each connection passage 61a.

  The cylinder head 30 is provided with a plurality of attachment regions 63 for the spark plug 32 inside the formation region of the second water jacket 60. The attachment region 63 is a region where the second water jacket 60 is not formed in the cylinder head 30. In this case, four attachment regions 63 are provided in a line in the cylinder row direction. The cross-sectional shape of the attachment region 63 is, for example, a circle. The attachment region 63 is a region including a predetermined range from the center of the spark plug 32.

  The cylinder head 30 is provided with a plurality of attachment areas 64 for the intake valves 35 inside the formation area of the second water jacket 60. The attachment region 64 is a region where the second water jacket 60 is not formed in the cylinder head 30. In this case, four attachment regions 64 are provided in a line in the cylinder row direction. The cross-sectional shape of the attachment region 64 is, for example, an oval shape. The attachment region 64 is a region where the valve guide 37 of the intake valve 35 is attached, and is a region including a predetermined range from the center of the intake valve 35 (center of the valve stem 35a). In each attachment region 64, two intake valves 35 and two valve guides 37 are arranged.

  In this embodiment, as shown in FIG. 6, the cooling water of the water jacket 23 of the cylinder block 20 is introduced into the second water jacket 60. Further, the cooling water of the second water jacket 60 is discharged to the water jacket 23 of the cylinder block 20.

  Specifically, as shown in FIG. 2, the cylinder block 20 is provided with a cooling water outlet 24 through which cooling water flows out to the cylinder head 30 side. In this case, the cooling water outlet 24 is disposed in the passage 23b on the exhaust side of the water jacket 23, and three cooling water outlets 24 are provided for each cylinder. As shown in FIG. 5, the cylinder head 30 is provided with a cooling water inlet 67 for introducing cooling water into the second water jacket 60. In this case, the cooling water introduction port 67 is arranged at the tip of each connection passage 61 a of the first passage 61 of the second water jacket 60, and the cooling water introduction port 67 is provided for each first passage 61. There are three each. The cooling water outlet 24 on the cylinder block 20 side and the cooling water inlet 67 on the cylinder head 30 side are arranged and connected at positions corresponding to each other. Then, the cooling water in the water jacket 23 that has flowed out from the cooling water outlet 24 is introduced into the first passage 61 of the second water jacket 60 through the cooling water inlet 67.

  Further, as shown in FIG. 2, the cylinder block 20 is provided with a cooling water inlet 25 through which cooling water flows from the cylinder head 30 side. In this case, the cooling water inlet 25 is provided in the passage 23a on the intake side of the water jacket 23, and two cooling water inlets 25 are provided for each cylinder. As shown in FIG. 5, the cylinder head 30 is provided with a cooling water discharge port 68 for discharging cooling water from the second water jacket 60. In this case, the cooling water discharge port 68 is disposed at the end portion on the intake side of the first passage 61 of the second water jacket 60, and there are two cooling water discharge ports 68 for each first passage 61. It is provided one by one. The cooling water inlet 25 on the cylinder block 20 side and the cooling water discharge port 68 on the cylinder head 30 side are arranged and connected at positions corresponding to each other. Then, the cooling water in the first passage 61 of the second water jacket 60 discharged from the cooling water discharge port 68 flows into the water jacket 23 through the cooling water inlet 25.

  In the internal combustion engine 10, as the cooling water path (second path) including the second water jacket 60, the water pump → the passage 23 b on the exhaust side of the water jacket 23 → the cooling water outlet 24 → the cooling water inlet 67 → 2 water jacket 60 → cooling water outlet 68 → cooling water inlet 25 → passage 23a on the intake side of water jacket 23 → cooling water outlet 28 → discharge passage 59 → cooling water outlet 58 → radiator. ing. And in the 2nd water jacket 60, as shown by the arrow of FIG. 5, a cooling water flows mainly in the direction which cross | intersects a cylinder row direction. In the second water jacket 60, the pressure loss of the cooling water can be kept small, so that the cooling efficiency around the combustion chamber 31 of the cylinder head 30 can be improved.

  In this embodiment, as described above, the first water jacket 50 in which the cooling water inlet 57 for introducing the cooling water into the first water jacket 50 is divided by the straight line L1 on one end side in the cylinder row direction. The first water jacket is provided on one side of the region where the cooling water discharge port 58 for discharging cooling water from the first water jacket 50 is divided by the straight line L1 on the other end side in the cylinder row direction. 50 on the other side of the formation region. That is, in the cylinder head 30, the cooling water introduction port 57 and the cooling water discharge port 58 of the first water jacket 50 are arranged at diagonal positions, so that the cooling water is evenly distributed in the first water jacket 50. It becomes possible to make it. Thereby, it is possible to prevent the cooling water from staying around the exhaust port 34 of the cylinder head 30 and to cool the periphery of the exhaust port 34 satisfactorily.

  Specifically, as shown in FIG. 3, in the first water jacket 50, a coolant flow X1 parallel to the cylinder row direction is generated in the central portion 30c of the cylinder head 30, and the cylinder is formed in the exhaust side end 30b. A cooling water flow X2 parallel to the column direction is generated. That is, the coolant flow X1 in the first passage 51 of the first water jacket 50 and the coolant flow X2 in the second passage 52 are generated. Such two cooling water flows X1 and X2 can prevent the cooling water from staying around the exhaust port 34 of the cylinder head 30, and the exhaust port 34 is surrounded by the end of the combustion chamber 31 (inlet side). It is possible to sufficiently cool from the part to the end part on the outlet side. Thereby, the cooling performance of the exhaust gas discharged through the exhaust port 34 can be improved, and the exhaust gas temperature can be lowered. As a result, the heat damage of the catalyst provided in the exhaust system of the internal combustion engine 10 can be suppressed, and the cost can be reduced. Further, when the internal combustion engine 10 is operated at high speed, it is not necessary to cool the exhaust gas with fuel, which can contribute to improvement of fuel consumption. Furthermore, the temperature of the EGR gas sent to the EGR device installed in the internal combustion engine 10 can be lowered, which can contribute to the downsizing and cost reduction of the EGR cooler.

  In this embodiment, the first water jacket 50 and the second water jacket 60 of the cylinder head 30 are provided in parallel to the water pump. For this reason, the first water jacket 50 is provided as a dedicated water jacket for cooling the periphery of the exhaust port 34. Therefore, the amount of cooling water supplied to the first water jacket 50 can be easily ensured without increasing the pressure loss of the cooling water in the entire water jacket 40 of the cylinder head 30. In this case, since the first water jacket 50 is provided so as to cover the upper side of the exhaust port 34, a large circulation area of the cooling water in the first water jacket 50 can be secured. Thereby, sufficient cooling performance of the exhaust gas as described above can be easily ensured.

  In addition, in this embodiment, the cooling water is sent from the first passage 51 of the first water jacket 50 to the second passage 52 via the third passage 53. For this reason, the cooling water flowing through the third passage 53 can reliably cool the adjacent exhaust valves 36 of the cylinder head 30. That is, in the cylinder head 30, it is possible to improve the cooling performance between the exhaust valves 36, which is particularly concerned about high temperatures. Thereby, the reliability of the cylinder head 30 can be improved.

  In the above embodiment, the cooling water inlet 57 of the first water jacket 50 is provided in the central portion 30c of the cylinder head 30 in the direction orthogonal to the cylinder row direction, and the cooling water discharge port 58 is orthogonal to the cylinder row direction. Although the example provided in the exhaust side end 30b of the cylinder head 30 in the direction is given, the positional relationship between the cooling water inlet 57 and the cooling water outlet 58 may be reversed. That is, there is no particular limitation as long as the cooling water introduction port 57 and the cooling water discharge port 58 are disposed in a diagonal position.

  Further, the first water jacket 50 may be configured to cover not only the upper side of the exhaust port 34 but also the upper side of the combustion chamber 31.

  The present invention can also be applied to a cylinder head integrated with an exhaust manifold. For example, as disclosed in Patent Document 1, an exhaust manifold integrated cylinder head has a configuration in which the exhaust ports of the cylinders are gathered in a common exhaust collecting portion in the cylinder head.

  INDUSTRIAL APPLICABILITY The present invention can be used for a cylinder head provided with a water jacket extending from one end side to the other end side in the cylinder row direction on the exhaust port side in a multi-cylinder internal combustion engine.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 30 Cylinder head 31 Combustion chamber 34 Exhaust port 36 Exhaust valve 36a Valve stem 40 Water jacket 50 1st water jacket (exhaust port side water jacket)
51 First passage 52 Second passage 53 Third passage 57 Cooling water inlet 58 Cooling water outlet 60 Second water jacket (combustion chamber side water jacket)

Claims (5)

A cylinder head cooling structure in which an exhaust port side water jacket extending from one end side to the other end side in the cylinder row direction is provided on the exhaust port side of a cylinder head used in a multi-cylinder internal combustion engine,
A cooling water inlet for introducing cooling water into the exhaust port side water jacket is provided at one end side in the cylinder row direction and at the combustion chamber side end portion in a direction orthogonal to the cylinder row direction in plan view ,
A cooling water discharge port for discharging cooling water from the exhaust port side water jacket is provided at the other end side in the cylinder row direction and at the exhaust side end portion in a direction orthogonal to the cylinder row direction in plan view ,
The cooling structure for a cylinder head, wherein the exhaust port side water jacket is provided in parallel with a combustion chamber side water jacket provided around the combustion chamber . In the cooling structure of the cylinder head according to claim 1 ,
The exhaust port side water jacket is formed in a substantially rectangular shape in plan view,
The cooling water inlet and cooling water outlet, a cooling structure of a cylinder head, characterized by being et provided one each. In the cooling structure of the cylinder head according to claim 2 ,
The exhaust port side water jacket includes a first passage extending from one end side in the cylinder row direction toward the other end side at the end portion on the combustion chamber side, and another end from one end side in the cylinder row direction at the exhaust side end portion. A cooling structure for a cylinder head, comprising: a second passage extending toward the side; and a third passage extending in a direction intersecting the cylinder row direction and connecting the first passage and the second passage. . In the cooling structure of the cylinder head according to claim 3 ,
The cylinder head cooling structure, wherein the third passage is provided between adjacent exhaust valves. In the cooling structure of the cylinder head according to any one of claims 2 to 4 ,
The cooling structure for a cylinder head, wherein the exhaust port side water jacket is provided so as to cover an upper side of the exhaust port.

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