JP7065901B2 - Cylinder head of multi-cylinder engine - Google Patents

Description

The present disclosure relates to a cylinder head of a multi-cylinder engine in which an exhaust collecting portion is formed inside.

An exhaust manifold integrated cylinder head in which an exhaust manifold is integrally formed in the cylinder head is known (for example, Patent Document 1). In the exhaust manifold integrated cylinder head, it is necessary to appropriately cool the area around the combustion chamber and the area around the exhaust manifold. In the cylinder head described in Patent Document 1, a first water jacket that passes around the combustion chamber in the cylinder row direction and reaches the other end side in the cylinder row direction and a second water jacket that passes around the exhaust manifold in the cylinder row direction are mutually present. It is independent and has a structure that does not communicate on the way. This makes it easy to secure the cooling water flow rate and flow velocity of each water jacket.

Further, in order to effectively cool the outlet portion of the exhaust port (exhaust passage portion) of the cylinder head integrated with the exhaust manifold, the lower part of the exhaust port assembly portion is placed in the cylinder row direction on the joint surface between the cylinder head and the cylinder block. It is known that an extending recess is provided so that oil or water can flow through the recess (Patent Document 2). In this cylinder head, a pair of first oil passages formed so as to sandwich the exhaust port assembly on both sides of the exhaust port assembly in the cylinder row direction are connected to the recess, and pass through the first oil passage from the upper deck. Oil returning to the oil pan passes through the recess and cools the exhaust port outlet. Alternatively, oil is supplied as cooling oil from the oil pump and supplied onto the upper deck through the recess.

Japanese Unexamined Patent Publication No. 2007-278065 Japanese Unexamined Patent Publication No. 2008-267184

In the cylinder head integrated with the exhaust collecting portion, the temperature around the exhaust port (upstream end of the exhaust passage) communicating with the combustion chamber and around the outlet of the exhaust collecting portion through which the exhaust from all the cylinders flows tends to be high. In the cylinder head described in Patent Document 1, the water jacket is divided into a first water jacket around the combustion chamber and a second water jacket around the exhaust manifold, so that the water jacket is around the exhaust port and around the outlet of the exhaust collecting portion. And can be cooled effectively. On the other hand, in an internal combustion engine, it is generally difficult for the temperature of the lubricating oil to be higher than the temperature of the cooling water when the engine is started (during warm-up), and it takes time for the oil temperature to rise and the friction to be reduced.

In the cylinder head described in Patent Document 2, oil flows through a passage provided by a recess and a pair of first oil passages connected to the passage, so that the oil temperature can be raised at an early stage by exhaust heat during warm-up. .. However, since the lubricating oil generally has a higher temperature than the cooling water after warming up, this cylinder head cannot effectively cool around the outlet of the exhaust collecting portion after warming up. In addition, the oil may overheat. Here, it is conceivable that the oil is circulated only in the pair of first oil passages without providing the recesses, but with such a configuration, the cooling effect around the outlet of the exhaust collecting portion by the oil and the warm-up time are considered. The effect of raising the temperature of the oil is reduced.

In view of such a background, the present invention can raise the temperature of the oil at an early stage during warm-up, effectively cool the portion of the exhaust assembly portion where the temperature tends to be high after warm-up, and prevent the oil from overheating. It is an object of the present invention to provide a capable cylinder head.

In order to achieve such an object, one embodiment of the present invention is a piston in which a plurality of cylinders (1) are fastened to an upper portion of a cylinder block (2) formed in a row and slides in the cylinder. A cylinder head (3) of a multi-cylinder engine (E) that forms a combustion chamber (6) between the top surface and the cylinder head (3), which is provided for each cylinder and intersects the corresponding combustion chamber in the cylinder row direction. An exhaust passage (24) extending to, an exhaust collecting portion (25) commonly connected to the plurality of the exhaust passages, an oil jacket (40) formed adjacent to the exhaust passages, the combustion chamber and the said. It has a water jacket (30) formed so as to surround the oil jacket adjacent to the exhaust collecting portion.

According to this configuration, the oil can be heated at an early stage by the oil jacket formed adjacent to the exhaust passage during warm-up. Further, since the water jacket is formed so as to surround the oil jacket, it is possible to effectively cool the portion where the temperature tends to be high, such as around the exhaust outlet of the exhaust collecting portion, by the water jacket after warming up. Further, since the oil jacket is surrounded by the water jacket, overheating of the oil after warming up can be suppressed.

Preferably, the water jacket is adjacent to the main water jacket (31) adjacent to the combustion chamber and extending in the cylinder row direction, and to the exhaust collecting portion on the same side as the oil jacket with respect to the exhaust passage. Includes a first exhaust side water jacket (32) that extends in the cylinder row direction and connects to one end and the other end of the main water jacket in the cylinder row direction, the oil jacket being the main water jacket and the first. It should be surrounded by a water jacket on the exhaust side.

According to this configuration, the main water jacket cools the area around the exhaust port forming the upstream end of the exhaust passage, which tends to cause the cylinder head to become hot, and the first exhaust side water jacket tends to cause the cylinder head to become hot. The area around the exhaust outlet can be cooled.

Preferably, the flow velocity in the first exhaust side water jacket is higher than the flow velocity in the main water jacket.

According to this configuration, the area around the exhaust port, which tends to be locally hotter than the area around the combustion chamber, can be effectively cooled by the cooling water having a high flow velocity.

Preferably, the water jacket includes a second exhaust side water jacket (33) extending in the cylinder row direction adjacent to the exhaust collecting portion on the side opposite to the oil jacket with respect to the exhaust passage, and mutually. It is preferable that the second exhaust side water jacket is provided so as to cover the crotch portion (8c) of the cylinder head sandwiched between the adjacent portions of the exhaust passages close to each other.

According to this configuration, the area around the crotch portion of the cylinder head, which tends to be hot next to the area around the exhaust port and the area around the exhaust outlet, can be cooled by the second exhaust side water jacket.

Preferably, the oil jacket is provided so as to cover the crotch portion.

According to this configuration, it is possible to raise the temperature of the oil at an early stage during warming up by the heat around the crotch portion, which tends to have a high temperature next to the exhaust outlet in the exhaust collecting portion. After warming up, the temperature of the oil tends to be higher than that of the cooling water, but since the area around the crotch is cooled by the second exhaust side water jacket, overheating of the oil is suppressed.

Preferably, the first exhaust side water jacket and the oil jacket are provided on the upper side with respect to the exhaust collecting portion, and the second exhaust side water jacket is provided on the lower side with respect to the exhaust collecting portion. good.

According to this configuration, the oil jacket can be formed larger than the case where the oil jacket is provided on the lower side with respect to the exhaust collecting portion, and the temperature of the oil can be raised earlier at the time of warming up. It is also possible to allow cooling water to flow from the water jacket of the cylinder block to the water jacket on the second exhaust side.

Preferably, the oil jacket has an oil inlet (42) provided at one end in the cylinder row direction and an oil outlet (43) provided at the other end in the cylinder row direction.

According to this configuration, the flow path length of the oil jacket can be lengthened by circulating the oil in the cylinder row direction through the oil jacket. This makes it possible to improve the heat exchange efficiency between the oil and the exhaust gas.

Preferably, the oil is supplied from the oil pump to the oil inlet, and the oil is sent out from the oil outlet toward the valve mechanism.

According to this configuration, the oil can be circulated to the oil jacket at a higher flow velocity than in the case where the oil returning to the oil pan by gravity is circulated to the oil jacket. This makes it possible to improve the heat exchange efficiency between the oil and the exhaust gas. Further, since the oil distributed in the oil jacket is used for lubrication of the valve mechanism, it is not necessary to increase the flow rate of the oil required for lubrication.

As described above, according to the present invention, the cylinder can raise the temperature of the oil at an early stage during warm-up, effectively cool the portion of the exhaust collecting portion where the temperature tends to be high after warm-up, and prevent the oil from overheating. Heads can be provided.

Sectional drawing of the main part of the engine which concerns on embodiment in the direction orthogonal to the cylinder row direction Perspective view of the cylinder head from below Sectional drawing of the cylinder head shown along the line III-III in FIG. Plan view of the core of the cylinder head Front view of the core of the cylinder head Side view of the core of the cylinder head An exploded perspective view of the core of the coolant passage VIII-VIII sectional view in FIG. IX-IX sectional view in FIG. XX sectional view in FIG. Time chart showing the amount of heat received from the exhaust of oil

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, the invention is applied to an internal combustion engine for automobiles (hereinafter, simply referred to as engine E). Hereinafter, the description will be given according to the vertical direction shown in FIG. 1 with reference to the state in which the engine E is mounted on the automobile.

As shown in FIGS. 1 and 2, the engine E is a SOHC 4-valve in-line 4-cylinder gasoline engine. As shown in FIG. 1, the engine E includes a cylinder block 2 in which four cylinders 1 in which pistons are housed are formed in a row, a box-shaped cylinder head 3 fastened to the upper portion of the cylinder block 2, and a cylinder head. It is provided with a head cover 4 fastened to the upper part of the cylinder 3. The engine E is mounted on the automobile in a posture in which the cylinder head 3 is arranged on the upper side in the vertical direction. The cylinder block 2 and the cylinder head 3 are cast from an aluminum alloy.

Each of the cylinders 1 extends substantially in the vertical direction and is formed in the cylinder block 2 in parallel with each other. Hereinafter, the arrangement direction of the plurality of cylinders 1 arranged in a row is referred to as a cylinder row direction. The upper end of each cylinder 1 is open to the upper end surface 2a of the cylinder block 2, and the lower end is open to a crank chamber (not shown) formed in the lower portion of the cylinder block 2. An in-block water jacket 5 (in-block cooling water passage) is formed on the side portion of the cylinder 1 of the cylinder block 2 so as to integrally surround the side peripheral portion of each cylinder 1. The water jacket 5 in the block is curved along the side peripheral portion of each cylinder 1, and the upper end of the water jacket 5 in the block is open to the upper end surface 2a of the cylinder block 2. The water jacket 5 in the block is formed as a cavity by a sand mold or the like when the cylinder block 2 is molded so that cooling water (coolant) can flow.

A combustion chamber recess 3b, which is a curved recess, is formed in a portion of the joint surface of the cylinder head 3 with the cylinder block 2 (hereinafter, referred to as a pair block joint surface 3a) facing each cylinder 1. Each combustion chamber recess 3b defines the combustion chamber 6 together with a portion above the piston of each cylinder 1. That is, the cylinder head 3 defines the upper edge of the combustion chamber 6.

Four intake passages 7 are formed inside the cylinder head 3. The upstream end of each intake passage 7 has an intake inlet 7a opened on one side surface (the left side surface in FIG. 1) of the cylinder head 3 along the cylinder row direction. The downstream end of each intake passage 7 is bifurcated so as to open two intake ports 7b on the wall surface of the combustion chamber recess 3b. The eight intake ports 7b are arranged so as to be aligned in the cylinder row direction. Further, one exhaust collecting passage 8 is formed inside the cylinder head 3. At the upstream end of the exhaust collecting passage 8, two exhaust ports 8a are opened on the wall surface of each combustion chamber recess 3b. The downstream end of the exhaust collecting passage 8 has a single exhaust outlet 8b opened on the other side surface (the right side surface in FIG. 1) along the cylinder row direction of the cylinder head 3. The eight exhaust ports 8a are arranged so as to be aligned in the cylinder row direction. Hereinafter, the side provided with the intake passage 7 is referred to as an intake side, and the side provided with the exhaust collecting passage 8 is referred to as an exhaust side with reference to the combustion chamber recess 3b.

The cylinder head 3 is provided with an intake valve 9 for opening and closing the intake port 7b and an exhaust valve 10 for opening and closing the exhaust port 8a, respectively, aligned in the cylinder row direction and slidably provided. A valve operating chamber 11 is defined between the cylinder head 3 and the head cover 4, and the valve operating chamber 11 accommodates a valve operating mechanism 12 for opening and driving the intake valve 9 and the exhaust valve 10. .. The valve mechanism 12 includes a camshaft 13 rotatably attached to the cylinder head 3, a rocker shaft 14 arranged above the camshaft 13, an intake rocker arm 15 rotatably supported by the rocker shaft 14, and an exhaust rocker arm 16. Etc. The camshaft 13 is formed with four valve drive cams 13a for driving a pair of intake valves 9 and an exhaust valve 10 for each cylinder 1.

As shown in FIG. 2, the exhaust outlet 8b is formed at an intermediate position in the longitudinal direction on the exhaust side side surface 3c of the cylinder head 3. Further, in the center of the four intake passages 7 and the exhaust collecting passage 8 on the wall surface of the combustion chamber recess 3b, a spark plug insertion hole 17 for inserting an ignition plug (not shown) penetrates the upper surface of the cylinder head 3. Is formed in.

As shown in FIGS. 1 and 2, the exhaust collecting passage 8 is formed so as to extend toward the exhaust side from the joint surface with the block 3a of the cylinder head 3. More specifically, the exhaust outlet 8b is defined by a tubular exhaust outlet tubular portion 18 projecting on the exhaust side side surface 3c of the cylinder head 3, and the exhaust outlet tubular portion 18 of the cylinder head 3 and its vicinity are connected to the cylinder block 2. On the other hand, it forms a bulging portion 19 that bulges sideways.

The tip surface of the exhaust outlet tubular portion 18 forms a connecting surface 18a of a downstream exhaust passage member 20 such as a turbine of a supercharger (turbocharger) or an exhaust purification device (not shown). At the tip of the exhaust outlet tubular portion 18, a plurality of fastening bosses 21 for fastening the downstream exhaust passage member 20 with bolts are formed so as to surround the exhaust outlet 8b (four in the illustrated example). On the other hand, on the lower surface of the bulging portion 19, two ribs 22 are formed so as to reach the fastening boss 21 from the peripheral edge of the anti-block joint surface 3a. These ribs 22 extend in the front-rear direction, which is a direction in which they are close to each other and separate from the cylinder row, and have a C-shape that opens from the fastening boss 21 toward the joint surface with the block 3a.

As described above, downstream exhaust passage members 20 such as a supercharger and an exhaust purification device are arranged in front of the cylinder block 2 and the cylinder head 3, and these become high temperatures after the engine E is started. Therefore, the bulging portion 19 of the cylinder head 3 that bulges sideways with respect to the cylinder block 2 tends to transfer heat from the turbocharger or the exhaust purification device by heat conduction, radiation, and convection, and the lower surface thereof becomes particularly high temperature. Prone. When the lower surface of the bulging portion 19 becomes hot, the sealing property between the cylinder head 3 and the downstream exhaust passage member 20 tends to deteriorate due to deformation due to thermal expansion. In the present embodiment, the deformation of the bulging portion 19 is suppressed by forming the rib 22 extending in the direction away from the cylinder row on the lower surface of the bulging portion 19.

As shown in FIGS. 1 and 3, the exhaust collecting passage 8 is commonly connected to the four exhaust passages 24 provided for each cylinder 1 and the four exhaust passages 24, and the exhaust collecting passages 8 are combined with each other. It has a portion 25. Each exhaust passage 24 has two exhaust passage upstream portions 26 communicating with the corresponding combustion chamber 6 and an exhaust passage middle flow portion 27 commonly connected to the two exhaust passage upstream portions 26. The exhaust collecting portion 25 forms a downstream portion of the exhaust passage that is commonly connected to the middle flow portion 27 of the four exhaust passages, and forms a single exhaust outlet 8b on the other side surface (connection surface 18a in FIG. 1) of the cylinder head 3. are doing. All the exhaust passage upstream portions 26 have substantially the same cross-sectional area. All the exhaust passage middle flow portions 27 have a cross-sectional area about twice that of the exhaust passage upstream portion 26. The exhaust collecting portion 25 has a height equivalent to that of the exhaust passage midstream portion 27 and a width and a cross-sectional area larger than that of the exhaust passage midstream portion 27, and the width and the cross-sectional area are gradually reduced toward the downstream side.

The upstream end of the exhaust passage upstream portion 26 forms an exhaust port 8a communicating with the combustion chamber 6. In the exhaust collecting passage 8, the area around the exhaust port 8a near the combustion chamber 6 and the area around the exhaust outlet 8b at the downstream end of the exhaust collecting portion 25 where the exhaust from each cylinder 1 collects are likely to receive heat from the exhaust and overheat. Next to these parts, the crotch part 8c (the connection part in front of the exhaust collecting part 25) sandwiched by the parts adjacent to each other in front of the confluence of the two exhaust passages 24 adjacent to each other dissipates heat from the exhaust. It is easy to receive and overheat.

As shown in FIGS. 4 to 7, inside the cylinder head 3, in order to suppress a temperature rise due to heat propagation from the combustion gas in the combustion chamber 6 and the exhaust collecting passage 8, the in-head coolant passage 29 Is formed. The coolant passage 29 in the head is also formed as a cavity by a sand mold or the like when the cylinder head 3 is molded. On the other hand, the coolant passage 29 in the head includes a water jacket 30 (31 to 36) for circulating cooling water (coolant) common to the water jacket 5 in the block, and an oil jacket 40 for circulating cooling oil. In FIGS. 4 to 7, the in-head coolant passage 29, which is a space portion, is substantially shown as seen through the cylinder head 3. Further, the required meat portion of the fastening boss 21 is shown in the form of being extracted from the cylinder head 3.

The water jacket 30 has a main water jacket 31, an upper exhaust side water jacket 32, a lower exhaust side water jacket 33, and the like as main elements. The main water jacket 31 is arranged above the plurality of combustion chamber recesses 3b adjacent to the combustion chamber recesses 3b, and extends in the cylinder row direction (longitudinal direction) of the cylinder head 3. The upper exhaust side water jacket 32 and the lower exhaust side water jacket 33 are arranged adjacent to the exhaust collecting passage 8 so as to sandwich the exhaust collecting passage 8 from above and below, and extend in the longitudinal direction of the cylinder head 3, respectively.

As is well shown in FIGS. 4 and 7, the upper exhaust side water jacket 32 is thinner than the lower exhaust side water jacket 33, is curved along the bulging portion 19, and is the main water at both ends in the longitudinal direction. It is connected to one end and the other end of the jacket 31 in the longitudinal direction. The lower exhaust side water jacket 33 has a substantially elliptical half shape that fits the planar shape of the exhaust collecting passage 8, and is connected to the main water jacket 31 over the entire longitudinal direction.

In the water jacket 30, the flow velocity of the cooling water flowing through each flow path is set by setting the cross-sectional area of each flow path. That is, when the cooling water of a predetermined flow rate flows through the water jacket 30, the flow path cross-sectional area is set so that the flow rates of the cooling water in each flow path are different from each other. Specifically, the flow path cross-sectional area of each flow path is set so that the flow velocity of the cooling water increases in the order of the upper exhaust side water jacket 32, the lower exhaust side water jacket 33, and the main water jacket 31.

As is well shown in FIGS. 5 and 6, the upper exhaust side water jacket 32 is formed between the upper fastening boss 21 and the exhaust collecting portion 25 so as to follow the contours of the upper two fastening bosses 21. .. The lower exhaust side water jacket 33 is formed between the lower fastening boss 21 and the exhaust collecting portion 25 so as to follow the contours of the two lower fastening bosses 21.

The broken line in FIG. 2 indicates a portion where the upper end of the water jacket 5 in the block contacts when the cylinder block 2 and the cylinder head 3 are fastened. In the water jacket 5 in the block, cooling water flows as shown by the white arrow. At one end in the cylinder row direction, the upper end of the water jacket 5 in the block contacts the joint surface with the block 3a, and the cooling water flows upward from the joint surface 3a with the block in the cylinder head 3 and communicates with the water jacket 30. Two passages 34 are formed. The cooling water inflow passage 34 communicates with one end side of the main water jacket 31 in the cylinder row direction, and the cooling water flows in from the water jacket 5 in the block.

Further, in the broken line portion where the upper end of the water jacket 5 in the block is in contact with the joint surface with the block 3a, on the other end side in the cylinder row direction from the cooling water inflow passage 34, the inside of the cylinder head 3 is formed from the joint surface with the block 3a. A bypass passage 35 extending upward and communicating with the water jacket 30 is formed in place. The bypass passage 35 communicates with the main water jacket 31. Each bypass passage 35 is formed to have a smaller cross-sectional area than the cooling water inflow passage 34.

At the other end of the upper exhaust side water jacket 32 in the cylinder row direction (the end different from the side where the cooling water inflow passage 34 is provided), a cooling water outflow passage 36 for discharging the cooling water from the water jacket 30 is formed. Has been done. The outer end of the cooling water outflow passage 36 communicates with a radiator (not shown) via a pipe, a hose, or the like. In the main water jacket 31, the upper exhaust side water jacket 32, and the lower exhaust side water jacket 33, the cooling water flows from the cooling water inflow passage 34 toward the cooling water outflow passage 36 in the cylinder row direction.

As is well shown in FIGS. 4 and 7, the oil jacket 40 is arranged between the main water jacket 31 and the upper exhaust side water jacket 32 adjacent to and separated from the main water jacket 31. A cooling oil inflow passage 42 forming an oil inlet and a cooling oil discharge passage 43 forming an oil outlet are connected to the oil jacket 40. The oil jacket 40 is arranged adjacent to the exhaust collecting passage 8 so as to sandwich the exhaust collecting passage 8 from above and below in cooperation with the lower exhaust side water jacket 33, and extends in the longitudinal direction of the cylinder head 3. As will be understood with reference to FIG. 3, the oil jacket 40 is arranged so as to cover the four exhaust passages 24 and the upstream portion of the exhaust collecting portion 25 from above.

The cooling oil inflow passage 42 is bored diagonally downward from the outer surface of the cylinder block 2 on the bulging portion 19 side, passes above the upper exhaust side water jacket 32, and reaches one end in the longitudinal direction of the oil jacket 40. It includes a first passage hole 42a leading to it. The first passage hole 42a is connected to the second passage hole 42b extending in the cylinder row direction and reaching the end face in the longitudinal direction of the cylinder head 3.

The cooling oil discharge passage 43 extends upward from the other end of the oil jacket 40 in the longitudinal direction and reaches the cam holder. In the oil jacket 40, lubricating oil for lubricating the valve mechanism 12 flows as cooling oil to cool the cylinder head 3 heated by the exhaust gas. The cooling oil inflow passage 42 and the cooling oil discharge passage 43 are not formed by the core, and are shown by imaginary lines in FIGS. 4, 5 and 7.

8 to 10 are cross-sectional views taken along the lines VIII-VIII, IX-IX, and XX in FIG. In the cross section shown in FIGS. 8 and 10, the oil jacket 40 is divided into left and right sides (direction orthogonal to the cylinder row) of the paper surface by a bolt insertion hole 45 for fastening the cylinder head 3 to the cylinder block 2. There is. On the other hand, in these cross sections, the oil jacket 40 extends beyond the bolt insertion hole 45 toward the cylinder 1 side as compared with the cross section shown in FIG. 9 passing through the axis of the cylinder 1. In the cross section of FIG. 10 passing through the crotch portion 8c sandwiched between the two exhaust passages 24, the oil jacket 40 extends downward so as to cover the crotch portion 8c not only from above but also from the cylinder 1 side. Further, the lower exhaust side water jacket 33 extends upward so as to cover the crotch portion 8c not only from below but also from the cylinder 1 side.

The cylinder head 3 is configured as described above. Hereinafter, the action and effect of the cylinder head 3 configured in this way will be described. In the cylinder head 3, since the oil jacket 40 is formed adjacent to the exhaust passage 24, the oil is heated at an early stage by the heat of the exhaust during warming up.

FIG. 11 is a time chart showing the amount of heat received from the exhaust gas of oil. In the time chart, the case where the oil jacket 40 is not provided is taken as Comparative Example 1, and the oil jacket 40 is in the form of a simple vertical hole that penetrates between the exhaust passages 24 in the vertical direction like an insertion hole 45 for a bolt. The case where it is provided is also shown as Comparative Example 2. As shown in FIG. 11, in the cylinder head 3 according to the present invention, it can be seen that the temperature of the oil in the cylinder head 3 according to the present invention rises earlier than that in Comparative Example 1 and Comparative Example 2 after the engine E is started. Further, since the oil jacket 40 is surrounded by the water jacket 30, overheating of the oil after warming up is suppressed.

Further, since the water jacket 30 is formed so as to surround the oil jacket 40, the portion where the temperature tends to be high, such as around the exhaust outlet 8b of the exhaust collecting portion 25, is effectively cooled by the water jacket 30 after warming up. ..

As is well shown in FIGS. 4 and 7, since the water jacket 30 includes a main water jacket 31 adjacent to the combustion chamber 6 and extending in the cylinder row direction, it is mainly around the exhaust port 8a of the cylinder head 3 where the temperature tends to be high. It is cooled by the water jacket 31. Further, since the water jacket 30 includes the upper exhaust side water jacket 32 adjacent to the exhaust collecting portion 25 and extending in the cylinder row direction, the area around the exhaust outlet 8b where the temperature of the cylinder head 3 tends to be high is cooled by the upper exhaust side water jacket 32. Will be done.

The oil jacket 40 is surrounded by a main water jacket 31 and an upper exhaust side water jacket 32, and after warming up, the oil jacket 40 is cooled by these to suppress overheating of the oil.

As described above, the flow velocity in the upper exhaust side water jacket 32 is set higher than the flow velocity in the main water jacket 31. As a result, the area around the exhaust port 8a, which tends to be locally hotter than the area around the combustion chamber 6, is effectively cooled by the cooling water having a high flow velocity.

As is well shown in FIGS. 3 and 4, the water jacket 30 includes a lower exhaust side water jacket 33 extending in the cylinder row direction adjacent to the exhaust collecting portion 25 and covering the crotch portion 8c of the cylinder head 3. There is. Therefore, the area around the crotch portion 8c of the cylinder head 3, which tends to have a high temperature next to the area around the exhaust port 8a and the area around the exhaust outlet 8b, is cooled by the lower exhaust side water jacket 33.

Further, since the oil jacket 40 is provided so as to cover the crotch portion 8c, the oil is heated at an early stage by the heat around the crotch portion 8c at the time of warming up. On the other hand, after warming up, the oil tends to have a higher temperature than the cooling water, but the crotch portion 8c is cooled by the lower exhaust side water jacket 33, so that overheating of the oil is suppressed.

In the present embodiment, the upper exhaust side water jacket 32 and the oil jacket 40 are provided on the upper side with respect to the exhaust collecting portion 25, and the lower exhaust side water jacket 33 is provided on the lower side with respect to the exhaust collecting portion 25. Therefore, the oil jacket 40 can be formed larger than the case where the oil jacket 40 is provided under the narrower exhaust collecting portion 25. This makes it possible to raise the temperature of the oil earlier during warm-up. Further, the configuration in which the cooling water flows from the water jacket 5 in the block to the water jacket 33 on the lower exhaust side is simple, and this configuration efficiently cools the area around the exhaust collecting passage 8.

As is well shown in FIGS. 4 and 7, the oil jacket 40 has a cooling oil inflow passage 42 and a cooling oil discharge passage 43 at one end and the other end in the cylinder row direction, and the oil has the oil jacket 40 in the cylinder row. Distribute in the direction. As a result, the flow path length of the oil jacket 40 becomes long, and the heat exchange efficiency between the oil and the exhaust is improved.

Then, oil is supplied from the oil pump to the cooling oil inflow passage 42, the oil flows through the oil jacket 40 at a high flow velocity, and then is sent out from the cooling oil discharge passage 43 toward the valve mechanism 12. Therefore, the oil circulates in the oil jacket 40 at a higher flow velocity than in the case where the oil returning to the oil pan by gravity is circulated in the oil jacket 40. This improves the efficiency of heat exchange between the oil and the exhaust. Further, since the oil flowing through the oil jacket 40 is used for lubrication of the valve operating mechanism 12, it is not necessary to increase the flow rate of the oil required for lubrication, and the load of the engine E does not increase.

Although the description of the specific embodiment is completed above, the present invention can be widely modified without being limited to the above embodiment. For example, in the above embodiment, the present invention is applied to a 4-cylinder gasoline engine as an example, but the subject of the invention may be a multi-cylinder engine, such as a 2-cylinder, 3-cylinder, 5-cylinder or more engine E, or It may be a diesel engine. Further, although the oil jacket 40 is arranged on the upper side with respect to the exhaust passage 24 in the above embodiment, the oil jacket 40 may be arranged on the lower side with respect to the exhaust passage 24. In this case, the oil jacket 40 may be surrounded by the lower exhaust side water jacket 33 and the main water jacket 31 having the same configuration as the upper exhaust side water jacket 32. In addition, the specific configuration, arrangement, quantity, angle, and the like of each member and portion can be appropriately changed as long as they do not deviate from the gist of the present invention. On the other hand, not all of the components shown in the above embodiments are indispensable, and they can be appropriately selected.

1 Cylinder 2 Cylinder block 3 Cylinder head 6 Combustion chamber 8 Exhaust collecting passage 8a Exhaust port 8b Exhaust outlet 8e Crotch part 12 Valve mechanism 24 Exhaust passage 25 Exhaust collecting part 29 In-head coolant passage 30 Water jacket 31 Main water jacket 32 Top Exhaust side water jacket (1st exhaust side water jacket)
33 Lower exhaust side water jacket (second exhaust side water jacket)
40 Oil jacket 42 Cooling oil inflow passage (oil inlet)
43 Cooling oil discharge passage (oil outlet)
E engine

Claims (6)

A cylinder head of a multi-cylinder engine in which a plurality of cylinders are fastened to the upper part of a cylinder block formed in a row to form a combustion chamber between the cylinder and the top surface of a piston sliding in the cylinder.
An exhaust passage provided for each cylinder and extending from the corresponding combustion chamber in a direction intersecting the cylinder row direction,
Exhaust collecting parts commonly connected to the plurality of exhaust passages,
An oil jacket formed adjacent to the exhaust passage and
It has a water jacket formed so as to surround the oil jacket adjacent to the combustion chamber and the exhaust collecting portion.
The water jacket is adjacent to the combustion chamber and extends in the cylinder row direction, and is adjacent to the exhaust collecting portion on the same side as the oil jacket with respect to the exhaust passage in the cylinder row direction. Includes a first exhaust side water jacket that extends and connects to one end and the other end of the main water jacket in the cylinder row direction.
The oil jacket is surrounded by the main water jacket and the first exhaust side water jacket.
A cylinder head characterized in that the flow velocity in the first exhaust side water jacket is higher than the flow velocity in the main water jacket . The water jacket includes a second exhaust side water jacket extending in the cylinder row direction adjacent to the exhaust collecting portion on the side opposite to the oil jacket with respect to the exhaust passage.
The cylinder head according to claim 1 , wherein the second exhaust side water jacket is provided so as to cover the crotch portion of the cylinder head sandwiched by portions of the exhaust passages adjacent to each other and adjacent to each other. The cylinder head according to claim 2 , wherein the oil jacket is provided so as to cover the crotch portion. The first exhaust side water jacket and the oil jacket are provided on the upper side with respect to the exhaust collecting portion, and the second exhaust side water jacket is provided on the lower side with respect to the exhaust collecting portion. The cylinder head according to claim 2 or 3 . One of claims 1 to 4 , wherein the oil jacket has an oil inlet provided at one end in the cylinder row direction and an oil outlet provided at the other end in the cylinder row direction. Cylinder head described in. The cylinder head according to claim 5 , wherein oil is supplied to the oil inlet from an oil pump, and the oil is sent out from the oil outlet toward a valve operating mechanism.

Images