阅读说明：本技术 多气缸发动机的气缸盖 (Cylinder head of multi-cylinder engine ) 是由 竹形徳之 山﨑信 山村聪 长仓正树 于 2021-03-16 设计创作，主要内容包括：本发明提供一种多气缸发动机的气缸盖,其能够在暖机时使油提早升温,并且能够在暖机后有效地冷却排气集合部的容易成为高温的部分,并且能够防止油的过热。气缸盖(3)具有：排气通路(24),其从与每个气缸(1)对应的燃烧室(6)延伸；排气集合部(25),其与多个排气通路(24)共同连接；油套(40),其形成为与排气通路(24)相邻；以及水套(30),其与燃烧室(6)和排气集合部(25)相邻,且形成为包围油套(40)。在暖机时,油借助于与排气通路(24)相邻地形成的油套40而提早升温。在暖机后,排气出口(8b)周围等容易成为高温的部分被水套(30)有效地冷却,水套(30)包围油套(40),因此油的过热被抑制。(The invention provides a cylinder head of a multi-cylinder engine, which can raise the temperature of oil early during warming-up, can effectively cool the part of an exhaust collecting part which is easy to be high temperature after warming-up, and can prevent the oil from overheating. The cylinder head (3) has: an exhaust passage (24) extending from the combustion chamber (6) corresponding to each cylinder (1); an exhaust collecting unit (25) connected in common to the plurality of exhaust passages (24); an oil jacket (40) formed adjacent to the exhaust passage (24); and a water jacket (30) that is adjacent to the combustion chamber (6) and the exhaust collection portion (25), and that is formed so as to surround the oil jacket (40). During warm-up, the oil is warmed up early by means of an oil jacket 40 formed adjacent to the exhaust passage (24). After warm-up, portions which are likely to become high temperature, such as the periphery of the exhaust outlet (8b), are effectively cooled by the water jacket (30), and the oil jacket (40) is surrounded by the water jacket (30), so that overheating of the oil is suppressed.)

1. A cylinder head of a multi-cylinder engine fastened to an upper portion of a cylinder block on which a plurality of cylinders are formed in a row, a combustion chamber being formed between the cylinder head and a top surface of a piston sliding in the cylinder,

the cylinder head has:

an exhaust passage provided for each of the cylinders and extending from the corresponding combustion chamber in a direction intersecting the direction of the bank;

an exhaust collecting unit connected in common to the plurality of exhaust passages;

an oil jacket formed adjacent to the exhaust passage; and

and a water jacket that is formed adjacent to the combustion chamber and the exhaust gas collecting portion so as to surround the oil jacket.

2. The cylinder head of claim 1,

the water jacket includes: a main water jacket extending in the bank direction adjacent to the combustion chamber; and a first exhaust side water jacket extending in the bank direction adjacent to the exhaust collecting portion on the same side as the oil jacket with respect to the exhaust passage and connected to one end and the other end of the main water jacket in the bank direction,

the oil jacket is surrounded by the main water jacket and the first exhaust side water jacket.

3. The cylinder head of claim 2,

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

4. The cylinder head of claim 2,

the water jacket includes a second exhaust-side water jacket that extends in the bank direction adjacent to the exhaust collecting portion on a side opposite to the oil jacket with respect to the exhaust passage,

the second exhaust-side water jacket is provided so as to cover a crotch of the cylinder head sandwiched by mutually adjacent portions of the exhaust passages that are adjacent to each other.

5. The cylinder head of claim 4,

the oil jacket is provided to cover the thigh portion.

6. The cylinder head according to claim 4 or 5,

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

7. The cylinder head of claim 1,

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.

8. The cylinder head of claim 7,

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

Technical Field

The present invention relates to a cylinder head of a multi-cylinder engine having an exhaust collecting portion formed therein.

Background

An exhaust manifold integrated cylinder head in which an exhaust manifold is integrally formed in a cylinder head is known (for example, patent document 1). In the exhaust manifold integrated cylinder head, it is necessary to appropriately cool the periphery of the combustion chamber and the periphery of the exhaust manifold. The cylinder head disclosed in patent document 1 has the following structure: the first water jacket that passes around the combustion chamber in the bank direction to reach the other end side in the bank direction and the second water jacket that passes around the exhaust manifold in the bank direction are independent of each other and do not communicate in the middle. This makes it easy to ensure the flow rate and flow velocity of the coolant in each water jacket.

In order to efficiently cool the outlet portion of the exhaust port (exhaust passage portion) of the exhaust manifold-integrated cylinder head, a structure is known in which a concave portion extending in the cylinder row direction below the exhaust port collecting portion is provided on the joint surface between the cylinder head and the cylinder block, and oil or water is made to flow through the concave portion (patent document 2). In this cylinder head, a pair of first oil passages formed so as to sandwich the exhaust port collecting portion on both sides in the cylinder row direction of the exhaust port collecting portion are connected to the recessed portion, and oil returned from the upper cover to the oil pan through the first oil passages passes through the recessed portion to cool the exhaust port outlet portion. Alternatively, the oil is supplied as cooling oil from an oil pump, passes through the recess, and is supplied to the upper cover plate.

Documents of the prior art

Patent document 1: japanese patent laid-open publication No. 2007-278065

Patent document 2: japanese patent laid-open No. 2008-267184

Disclosure of Invention

Problems to be solved by the invention

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 gas from all the cylinders flows is likely to be high. In the cylinder head described in patent document 1, the water jacket is divided into the first water jacket for the periphery of the combustion chamber and the second water jacket for the periphery of the exhaust manifold, whereby the periphery of the exhaust port and the periphery of the outlet of the exhaust collecting portion can be efficiently cooled. 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 at the time of engine start (warm-up), and it takes time until the oil temperature rises to reduce friction.

In the cylinder head disclosed in patent document 2, oil flows through the passage formed by the recess and the pair of first oil passages connected thereto, and thereby the oil temperature can be raised early by exhaust gas heat during warm-up. However, since the lubricating oil generally has a higher temperature than the cooling water after warming up, the cylinder head cannot effectively cool the periphery of the outlet of the exhaust collecting portion after warming up. In addition, the oil may overheat. Here, it is conceivable that the oil is caused to flow only through the pair of first oil passages without providing the recessed portions, but with such a configuration, the cooling effect of the oil on the periphery of the outlet of the exhaust gas collecting portion and the oil temperature increasing effect at the time of warm-up become small.

In view of the above-described background, an object of the present invention is to provide a cylinder head capable of raising the temperature of oil early at the time of warm-up, efficiently cooling a portion of an exhaust collecting portion that is likely to become high temperature after warm-up, and preventing overheating of oil.

Means for solving the problems

In order to achieve the above object, one embodiment of the present invention is a cylinder head 3 of a multi-cylinder engine E fastened to an upper portion of a cylinder block 2, the cylinder block 2 having a plurality of cylinders 1 formed in a row, a combustion chamber 6 being formed between the cylinder head 3 and a top face of a piston sliding in the cylinder, the cylinder head 3 having: an exhaust passage 24 provided for each of the cylinders and extending from the corresponding combustion chamber in a direction intersecting the direction of the bank; an exhaust collecting unit 25 connected in common to the plurality of exhaust passages; an oil jacket 40 formed adjacent to the exhaust passage; and a water jacket 30 that is formed adjacent to the combustion chamber and the exhaust gas collecting portion so as to surround the oil jacket.

According to this configuration, the oil can be warmed up early by the oil jacket formed adjacent to the exhaust passage at the time of warm-up. Further, since the water jacket is formed so as to surround the oil jacket, the portion that is likely to become high temperature, such as the periphery of the exhaust outlet of the exhaust collecting portion, can be efficiently cooled by the water jacket after warming up. Further, since the oil jacket is surrounded by the water jacket, overheating of the warmed oil can be suppressed.

Preferably, the water jacket includes: a main water jacket 31 extending in the bank direction adjacent to the combustion chamber; and a first exhaust side water jacket 32 that extends in the bank direction adjacent to the exhaust collecting portion on the same side as the oil jacket with respect to the exhaust passage and is connected to one end and the other end of the main water jacket in the bank direction, the oil jacket being surrounded by the main water jacket and the first exhaust side water jacket.

According to this configuration, the periphery of the exhaust port of the cylinder head, which constitutes the upstream end of the exhaust passage and is likely to become high temperature, can be cooled by the main water jacket, and the periphery of the exhaust outlet of the exhaust collecting portion of the cylinder head, which is likely to become high temperature, can be cooled by the first exhaust-side water jacket.

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

According to this configuration, the periphery of the exhaust port, which is likely to be locally heated to a higher temperature than the periphery of the combustion chamber, can be efficiently 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 bank direction adjacent to the exhaust collecting portion on a side opposite to the oil jacket with respect to the exhaust passage, the second exhaust-side water jacket being provided so as to cover a crotch portion 8c of the cylinder head sandwiched by mutually adjacent portions of the exhaust passages adjacent to each other.

According to this configuration, the periphery of the exhaust port or the periphery of the exhaust outlet, which is then likely to become high-temperature, can be cooled by the second exhaust-side water jacket.

Preferably, the oil jacket is arranged to cover the thigh.

According to this configuration, the oil can be warmed up early at the time of warming up by the heat around the thigh portion, which is likely to become a high temperature next, of the exhaust outlet in the exhaust collecting portion. After warm-up, the oil and the cooling water tend to be at a higher temperature than before, but since the periphery of the crotch portion is cooled by the second exhaust-side water jacket, overheating of the oil is suppressed.

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

According to this configuration, the oil jacket can be formed larger than in 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 warm-up. In addition, the cooling water can also be made to flow from the water jacket of the cylinder block into the second exhaust side water jacket.

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

According to this configuration, the oil is caused to flow through the oil jacket in the direction of the bank, whereby the flow path length of the oil jacket can be increased. This can improve the heat exchange efficiency between the oil and the exhaust gas.

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

According to this configuration, the oil can be made to flow through the oil jacket at a higher flow rate than in the case where the oil returned to the oil pan is made to flow through the oil jacket by gravity. This can improve the heat exchange efficiency between the oil and the exhaust gas. Further, since the oil flowing through the oil jacket is used for lubricating the valve train, it is not necessary to increase the flow rate of the oil required for lubrication.

Effects of the invention

As described above, according to the present invention, it is possible to provide a cylinder head capable of raising the temperature of oil early at the time of warm-up, efficiently cooling a portion of an exhaust collecting portion which is likely to become high temperature after warm-up, and preventing overheating of oil.

Drawings

Fig. 1 is a sectional view of a main portion of an engine of the embodiment in a direction perpendicular to a cylinder row direction.

Fig. 2 is a perspective view of the cylinder head as viewed from below.

Fig. 3 is a plan view of the cylinder head.

Fig. 4 is a top view of a core of the cylinder head.

Fig. 5 is a front view of a core of the cylinder head.

Fig. 6 is a side view of a core of the cylinder head.

Fig. 7 is an exploded perspective view of the core of the coolant passage.

Fig. 8 is a sectional view taken along line VIII-VIII in fig. 4.

Fig. 9 is a sectional view taken along line IX-IX in fig. 4.

Fig. 10 is a sectional view taken along line X-X in fig. 4.

Fig. 11 is a time chart showing the amount of heat received by oil from exhaust gas.

Description of the reference symbols

1: a cylinder;

2: a cylinder block;

3: a cylinder head;

6: a combustion chamber;

8: an exhaust collection passage;

8 a: an exhaust port;

8 b: an exhaust outlet;

8 c: a thigh;

12: a valve train mechanism;

24: an exhaust passage;

25: an exhaust gas collection unit;

29: a cooling fluid passage in the cylinder head;

30: a water jacket;

31: a main water jacket;

32: an upper exhaust side water jacket (first exhaust side water jacket);

33: a lower exhaust side water jacket (second exhaust side water jacket);

40: an oil jacket;

42: a cooling oil inflow passage (oil inlet);

43: a cooling oil discharge passage (oil outlet);

e: an engine.

Detailed Description

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

As shown in fig. 1 and 2, the engine E is an SOHC type 4-valve in-line 4-cylinder gasoline engine. As shown in fig. 1, the engine E includes: a cylinder block 2 in which 4 cylinders 1 that house pistons are formed in a row; a box-shaped cylinder head 3 fastened to an upper portion of the cylinder block 2; and a head cover 4 fastened to an upper portion of the cylinder head 3. The engine E is mounted on the automobile in a posture in which the cylinder head 3 is disposed on the upper side in the vertical direction. The cylinder block 2 and the cylinder head 3 are cast from an aluminum alloy.

The cylinders 1 extend substantially vertically and are formed in parallel with each other in the cylinder block 2. Hereinafter, the arrangement direction of the plurality of cylinders 1 arranged in an array is referred to as a cylinder row direction. The upper end of each cylinder 1 opens to an upper end surface 2a of the cylinder block 2, and the lower end opens to a crank chamber (not shown) formed in a lower portion of the cylinder block 2. A block inner water jacket 5 (block inner 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 block inner water jacket 5 is curved so as to follow the side peripheral portion of each cylinder 1, and the upper end of the block inner water jacket 5 opens at the upper end surface 2a of the cylinder block 2. The block inner jacket 5 is formed as a cavity by sand molding or the like at the time of molding the cylinder block 2 so as to allow cooling water (coolant) to flow therethrough.

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

Inside the cylinder head 3, 4 intake passages 7 are formed. The upstream end of each intake passage 7 opens an intake air inlet 7a on one side surface (the left side surface in fig. 1) of the cylinder head 3 in the cylinder row direction. The downstream end of each intake passage 7 branches into two branches so that 2 intake ports 7b open on the wall surface of the combustion chamber recess 3 b. The 8 intake ports 7b are arranged in the cylinder row direction. Further, 1 exhaust collecting passage 8 is formed inside the cylinder head 3. The upstream end of the exhaust collecting passage 8 has 2 exhaust ports 8a each opened in the wall surface of each combustion chamber recess 3 b. The downstream end of the exhaust collection passage 8 opens a single exhaust outlet 8b on the other side surface (the right side surface in fig. 1) of the cylinder head 3 in the cylinder row direction. The 8 exhaust ports 8a are arranged in the cylinder row direction. Hereinafter, with reference to the combustion chamber recess 3b, the side provided with the intake passage 7 is referred to as the intake side, and the side provided with the exhaust collecting passage 8 is referred to as the exhaust side.

In the cylinder head 3, 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 are slidably arranged in the cylinder row direction. A valve operating chamber 11 is defined between the cylinder head 3 and the head cover 4, and a valve operating mechanism 12 for driving the intake valve 9 and the exhaust valve 10 to open is housed in the valve operating chamber 11. The valve train 12 includes: a camshaft 13 rotatably mounted to the cylinder head 3; a rocker shaft 14 disposed above the camshaft 13; the rocker arm shaft 14 supports an intake rocker arm 15, an exhaust rocker arm 16, and the like so as to be swingable. The camshaft 13 is formed with 4 valve operating cams 13a that drive the pair of intake valves 9 and exhaust valves 10 for each cylinder 1.

As shown in fig. 2, the exhaust outlet 8b is formed at a longitudinally intermediate position of the exhaust-side surface 3c of the cylinder head 3. Further, a spark plug insertion hole 17 for inserting a spark plug (not shown) is formed in the wall surface of the combustion chamber recess 3b so as to penetrate the upper surface of the cylinder head 3 at the center of the 4 intake passages 7 and the exhaust collecting passage 8.

As shown in fig. 1 and 2, the exhaust collection passage 8 is formed to extend further to the exhaust side than the cylinder block joining surface 3a of the cylinder head 3. More specifically, the exhaust outlet 8b is defined by a tubular exhaust outlet tubular portion 18 protruding from the exhaust-side surface 3c of the cylinder head 3, and the exhaust outlet tubular portion 18 of the cylinder head 3 and the vicinity thereof constitute a bulging portion 19 bulging sideward with respect to the cylinder block 2.

The end surface of the exhaust outlet tubular portion 18 constitutes a connection surface 18a of a downstream-side exhaust passage member 20 such as a turbine of a supercharger (turbocharger), not shown, an exhaust gas purification device, and the like. Further, at the tip end of the exhaust outlet tubular portion 18, a plurality of (4 in the example of the drawing) fastening bosses 21 for fastening the downstream exhaust passage member 20 with bolts are formed so as to surround the exhaust outlet 8 b. On the other hand, 2 ribs 22 are formed on the lower surface of the bulging portion 19 so as to reach the fastening bosses 21 from the peripheral edge of the cylinder block joint surface 3 a. These ribs 22 extend in the front-rear direction, which is a direction approaching or separating from the cylinder row, and these ribs 22 are tapered in shape opening from the fastening boss 21 toward the cylinder block joint surface 3 a.

As described above, the downstream-side exhaust passage member 20 such as a supercharger or an exhaust gas purification device is disposed in front of the cylinder block 2 and the cylinder head 3, and after the engine E is started, these members reach high temperatures. Therefore, the bulging portion 19 of the cylinder head 3 bulging laterally with respect to the cylinder block 2 is likely to transmit heat from the supercharger or the exhaust gas purification apparatus by heat conduction, radiation, and convection, and particularly the lower surface thereof is likely to have a high temperature. Further, when the lower surface of the bulging portion 19 is at a high temperature, the sealing property between the cylinder head 3 and the downstream exhaust passage member 20 is likely to be lowered due to deformation caused by thermal expansion. In the present embodiment, ribs 22 extending in directions approaching and separating from the banks are formed on the lower surface of the bulging portion 19, whereby deformation of the bulging portion 19 is suppressed.

As shown in fig. 1 and 3, the exhaust collection passage 8 includes: 4 exhaust passages 24 provided for each cylinder 1; and an exhaust gas collecting portion 25 which is connected in common to the 4 exhaust passages 24 and joins the exhaust gas flowing therethrough. Each exhaust passage 24 has: 2 exhaust passage upstream portions 26 communicating with the corresponding combustion chambers 6; and an exhaust passage midstream portion 27 commonly connected to the 2 exhaust passage upstream portions 26. The exhaust collecting portion 25 constitutes an exhaust passage downstream portion commonly connected to the 4 exhaust passage midstream portions 27, and a single exhaust outlet 8b is formed in the other side surface (the connection surface 18a in fig. 1) of the cylinder head 3. All the exhaust passage upstream portions 26 have substantially the same cross-sectional area. All of the exhaust passage midstream portions 27 have a cross-sectional area of about 2 times that of the exhaust passage upstream portion 26. The exhaust collecting portion 25 has a height equal to the exhaust passage midstream portion 27 and a width and a cross-sectional area larger than the exhaust passage midstream portion 27, and the width and the cross-sectional area are gradually reduced toward the downstream.

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 periphery of the exhaust outlet 8b, which is the downstream end of the exhaust collecting portion 25 where the exhaust gases from the cylinders 1 are collected, receives heat from the exhaust gases around the exhaust outlet 8a close to the combustion chamber 6, and is liable to overheat. Next to these portions, the crotch portion 8c (the connection portion immediately before the exhaust collecting portion 25) sandwiched by the portions adjacent to each other immediately before the junction of the adjacent 2 exhaust passages 24 is easily overheated by heat from the exhaust gas.

As shown in fig. 4 to 7, a cylinder head internal cooling liquid passage 29 is formed in the cylinder head 3 to suppress a temperature increase caused by heat propagation of the combustion gas from the combustion chamber 6 or the exhaust collecting passage 8. The in-head cooling liquid passage 29 is also formed as a cavity by sand molding or the like at the time of molding of the cylinder head 3. On the other hand, the in-cylinder-head cooling liquid passage 29 includes: water jackets 30(31 to 36) through which cooling water (coolant) common to the cylinder block inner water jacket 5 flows; and an oil jacket 40 through which cooling oil flows. In fig. 4 to 7, a cylinder head internal cooling liquid passage 29 as a cavity portion is shown in solid in a perspective view of the cylinder head 3. In addition, the necessary wall portion of the fastening boss 21 is shown in a form 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 disposed above the plurality of combustion chamber recesses 3b so as to be 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 disposed adjacent to the exhaust collecting passage 8 so as to sandwich the exhaust collecting passage 8 from above and below, and the upper exhaust side water jacket 32 and the lower exhaust side water jacket 33 extend in the longitudinal direction of the cylinder head 3, respectively.

As shown in fig. 4 and 7, the upper exhaust side water jacket 32 is narrower than the lower exhaust side water jacket 33, and is curved along the bulging portion 19, and both ends in the longitudinal direction of the upper exhaust side water jacket 32 are connected to one end and the other end in the longitudinal direction of the main water jacket 31. The lower exhaust side water jacket 33 is formed in a shape of approximately half an ellipse that matches the planar shape of the exhaust collection passage 8, and is connected to the main water jacket 31 over the entire length 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, the flow path sectional area is set to: when a predetermined flow rate of cooling water flows through the water jacket 30, the flow velocities of the cooling water in the respective flow paths are different from each other. Specifically, the flow passage cross-sectional area of each flow passage is set so that the flow velocity of the cooling water is increased 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 shown in fig. 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 contour of the upper 2 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 contour of the lower 2 fastening bosses 21.

The broken line in fig. 2 indicates a portion of the upper end of the cylinder block water jacket 5 that faces the cylinder block joint surface 3a of the cylinder head 3 when the cylinder head 3 is fastened to the cylinder block 2. As indicated by hollow arrows, cooling water flows through the cylinder block inner water jacket 5. At one end in the cylinder row direction, 2 cooling water inflow passages 34 extending upward in the cylinder head 3 from the opposing block-engaging surface 3a and communicating with the water jacket 30 are formed in a portion of the upper end surface of the cylinder block inner water jacket 5 that faces the opposing block-engaging surface 3 a. The 2 cooling water inflow passages 34 communicate with one end side of the main water jacket 31 in the bank direction, respectively, and cooling water flows in from the cylinder block inner water jacket 5.

Further, a bypass passage 35 extending upward in the cylinder head 3 from the cylinder block joining surface 3a and communicating with the water jacket 30 is formed at an appropriate position on the other end side in the cylinder row direction than the cooling water inflow passage 34 in the broken line portion of the cylinder block joining surface 3a at the upper end of the cylinder block inner water jacket 5. The bypass passage 35 communicates with the main water jacket 31. Each bypass passage 35 is formed to have a smaller flow path cross-sectional area than the cooling water inflow passage 34.

A cooling water outflow passage 36 for discharging cooling water from the water jacket 30 is formed at the other end (end different from the side where the cooling water inflow passage 34 is provided) of the upper exhaust side water jacket 32 in the cylinder row direction. 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 in the cylinder row direction from the cooling water inflow passage 34 toward the cooling water outflow passage 36.

As shown in fig. 4 and 7, the oil jacket 40 is disposed between the main water jacket 31 and the upper exhaust side water jacket 32, adjacent to and apart from them. A cooling oil inflow passage 42 constituting an oil inlet and a cooling oil discharge passage 43 constituting an oil outlet are connected to the oil jacket 40. The oil jacket 40 is disposed 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 disposed so as to cover the 4 exhaust passages 24 and the upstream portion of the exhaust collecting portion 25 from above.

The cooling oil inflow passage 42 includes a first passage hole 42a that is provided to penetrate obliquely downward from the outer surface of the cylinder block 2 on the bulge 19 side and passes above the upper exhaust side water jacket 32 to reach one end portion in the longitudinal direction of the oil jacket 40. The first passage hole 42a is connected to a second passage hole 42b extending in the cylinder row direction and reaching a longitudinal end surface of the cylinder head 3.

The cooling oil discharge passage 43 extends upward from the other end portion in the longitudinal direction of the oil jacket 40 to reach the cam carrier. The oil jacket 40 is configured such that lubricating oil for lubricating the valve train 12 flows as cooling oil, and cools 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 a core, and are shown by imaginary lines in fig. 4, 5, and 7.

Fig. 8 to 10 are sectional views taken along line VIII-VIII, line IX-IX, and line X-X in fig. 4. In the cross sections shown in fig. 8 and 10, the oil jacket 40 is divided into left and right sides (in a direction perpendicular to the cylinder banks) of the paper surface by bolt insertion holes 45 for fastening the cylinder head 3 to the cylinder block 2. On the other hand, in these cross sections, the oil jacket 40 protrudes toward the cylinder 1 side beyond the bolt insertion hole 45, 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 through the crotch portion 8c sandwiched between the 2 exhaust passages 24, the oil jacket 40 covers not only the crotch portion 8c from above, but also extends downward so as to cover the crotch portion 8c also from the cylinder 1 side. In addition, the lower exhaust side water jacket 33 extends not only from below to cover the crotch portion 8c but also upward to cover the crotch portion 8c from the cylinder 1 side as well.

The cylinder head 3 is configured as described above. The operational effects of the cylinder head 3 configured as described above will be described below. In the cylinder head 3, the oil jacket 40 is formed adjacent to the exhaust passage 24, so that the oil is warmed up early by the heat of the exhaust gas at the time of warming up.

Fig. 11 is a time chart showing the amount of heat received by oil from exhaust gas. In the time chart, a case where the oil jacket 40 is not provided is shown as comparative example 1, and a case where the oil jacket 40 is provided as a simple vertical hole penetrating in the vertical direction between the exhaust passages 24 like the through hole 45 for the bolt is shown as comparative example 2. As shown in fig. 11, in the cylinder head 3 of the present invention, the temperature of the oil increases earlier after the engine E is started than in comparative examples 1 and 2. Further, since the oil jacket 40 is surrounded by the water jacket 30, overheating of the oil after warming up can be suppressed.

Further, the water jacket 30 is formed so as to surround the oil jacket 40, so that a portion which tends to become high in temperature, such as around the exhaust outlet 8b of the post-warming exhaust collecting portion 25, is efficiently cooled by the water jacket 30.

As shown in fig. 4 and 7, the water jacket 30 includes a main water jacket 31 extending in the cylinder row direction adjacent to the combustion chambers 6, and therefore the periphery of the exhaust ports 8a of the cylinder head 3, which are likely to become high in temperature, is cooled by the main water jacket 31. Further, since the water jacket 30 includes the upper exhaust side water jacket 32 extending in the cylinder row direction adjacent to the exhaust collecting portion 25, the periphery of the exhaust outlet 8b of the cylinder head 3, which is likely to become high in temperature, is cooled by the upper exhaust side water jacket 32.

Further, the oil jacket 40 is surrounded by the main water jacket 31 and the upper exhaust side water jacket 32, and after warming up, the oil jacket 40 is cooled by them, whereby overheating of the oil is suppressed.

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. This makes it easier for the periphery of the exhaust port 8a, which is locally at a high temperature, to be efficiently cooled by the high-flow-rate cooling water than the periphery of the combustion chamber 6.

As shown in fig. 3 and 4, the water jacket 30 includes a lower exhaust side water jacket 33 that is adjacent to the exhaust collecting portion 25 and extends in the cylinder row direction so as to cover the femoral portion 8c of the cylinder head 3. Therefore, the periphery of the exhaust port 8a and the periphery of the femoral portion 8c of the cylinder head 3, which is next likely to become high temperature, around the exhaust outlet 8b are cooled by the under-exhaust-side water jacket 33.

Further, since the oil jacket 40 is provided so as to cover the crotch portion 8c, the oil is warmed up early by the heat around the crotch portion 8c at the time of warming up. On the other hand, after warm-up, the oil and the cooling water tend to be at a higher temperature than before, but since the periphery of the crotch portion 8c is cooled by the lower exhaust side water jacket 33, 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 in the case where the oil jacket 40 is provided below the narrower exhaust collecting portion 25. This makes it possible to raise the temperature of the oil earlier during warm-up. Further, the structure in which the cooling water is caused to flow from the cylinder block inner water jacket 5 into the lower exhaust side water jacket 33 is simple, and by this structure, the periphery of the exhaust collecting passage 8 is efficiently cooled.

As shown in fig. 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 bank direction, and oil flows through the oil jacket 40 in the bank direction. This increases the flow path length of the oil jacket 40, thereby improving the heat exchange efficiency between the oil and the exhaust gas.

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

The description of the specific embodiments is completed above, but the present invention is not limited to the above embodiments, and can be widely modified and implemented. For example, in the above embodiment, the present invention is applied to a 4-cylinder gasoline engine as an example, but the present invention may be applied to a multi-cylinder engine, and may be applied to a 2-cylinder, 3-cylinder, or 5-cylinder or more engine E, or a diesel engine. In the above embodiment, the oil jacket 40 is disposed above the exhaust passage 24, but the oil jacket 40 may be disposed below the exhaust passage 24. In this case, the oil jacket 40 is preferably 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. The specific configuration, arrangement, number, angle, and the like of each member and part can be appropriately changed without departing from the scope of the present invention. On the other hand, all of the components shown in the above embodiments are not necessarily required, and can be appropriately selected.