JP2018071473A - Cylinder head of multicylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder head which can largely suppress the generation of thermal strain.SOLUTION: In an internal combustion engine having three or more cylinders, a center cooling water jacket 15, an exhaust-side upper cooling water jacket 16 and an exhaust-side lower cooling water jacket 17 are formed in a cylinder head. The center cooling water jacket 15, the exhaust-side upper cooling water jacket 16 and the exhaust-side lower cooling water jacket 17 are separated from one another. A bypass passage 29 for surrounding an exhaust port from below is formed in a point corresponding to an intermediate cylinder located between both ends of a cylinder row out of the center cooling water jacket 15. Since a peripheral part of the exhaust port corresponding to the intermediate cylinder (intermediate combustion chamber) is firmly cooled, and a rise of a temperature is suppressed, it can be largely suppressed that thermal strain is generated in the cylinder head as a whole. Since the bypass passage is formed into a tunnel shape, the lowering of rigidity does not occur compared with the case that a groove-shaped cooling water passage is formed at a lower face of the cylinder head.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a cylinder head of a multi-cylinder internal combustion engine for vehicles or the like, and is characterized by a cooling structure of the cylinder head.

  As an exhaust structure of an internal combustion engine, there is a type in which an exhaust collective space is formed inside a cylinder head, and one or a plurality of collective outlet holes are provided on the exhaust side of the cylinder head. This type has advantages such as overall compactness and effective use of heat, but there is a problem that the cylinder head is exposed to a harsh thermal environment as compared with a type in which an exhaust manifold is externally attached.

  With respect to this point, as disclosed in Patent Document 1, for example, a cooling water jacket is formed in a state of projecting toward the exhaust collecting space to cool a portion of the exhaust collecting space. The cooling water jacket is divided into an upper part and a lower part with an exhaust port and an exhaust collecting space interposed therebetween, and communicates with both front and rear ends and a middle part. Further, a main cooling water passage is provided in the upper part of the cylinder row, and an intake side cooling water passage is provided in the intake area.

JP 2012-57468 A

  The thermal damage to the cylinder head is particularly problematic because of heat distortion caused by non-uniform heating and cooling. The heat distortion causes the cylinder head to warp and deform between the cylinder head and the cylinder block. As a result, a slip phenomenon may occur, resulting in problems such as a decrease in sealing performance and leakage of cooling water and combustion gas, and an increase in camshaft rotation resistance and mechanical loss. There is a problem to do.

  In order to prevent / suppress thermal strain, it is necessary to strongly cool the portion that is heated strongly. When looking at the cylinder head of three or more cylinders, the position of the intermediate cylinder between the end cylinders at both ends (or In the intermediate combustion chamber), the heat is deeply heated and is heated to a high temperature, so that it is necessary to cool (dissipate heat) more strongly than the positions of the cylinders at both ends.

  However, in the conventional structure as in Patent Document 1, attention is not paid to the difference in temperature rise between the end cylinder portion and the intermediate cylinder portion, and therefore, thermal strain can be prevented and suppressed. It can be said that it was not enough.

  The present invention is based on such knowledge and analysis, and is intended to provide a cylinder head capable of preventing and suppressing thermal distortion.

The present invention is directed to a cylinder head of a multi-cylinder internal combustion engine having three or more cylinders. This cylinder head
An exhaust collecting passage for collecting exhaust gas discharged from each exhaust port in one or a plurality of collecting outlet holes in an exhaust side area in which a group of exhaust ports opened to each cylinder is formed, and the exhaust port and the exhaust An exhaust-side upper cooling water jacket located above the collecting passage and an exhaust-side lower cooling water jacket located below the exhaust port and the exhaust collecting passage are formed, and in an area above the cylinder row A basic cooling water jacket extending in the crank axis direction is formed.

  In the basic configuration, the center cooling water jacket, except for the exhaust ports located at both ends of the cylinder row, individually or as a group wraps downward from the side to be embraced from below. An enclosing bypass passage is formed. The intermediate exhaust port means an exhaust port located between both ends as specified in the claims, and does not mean the central portion. For example, in the case of a four-cylinder internal combustion engine, the exhaust ports corresponding to the second cylinder and the third cylinder are intermediate exhaust ports.

  In the present invention, first, the cooling water jacket of the cylinder head is separated into the center cooling water jacket, the exhaust-side upper cooling water jacket, and the exhaust-side lower cooling water jacket, so that the cooling water is directed to each cooling water jacket. Since it flows with the coolant, it is possible to distribute the cooling water evenly to each jacket and contribute to the prevention of uneven cooling of the cylinder head.

  Now, in the cylinder head with a built-in exhaust manifold targeted by the present invention, the places around the exhaust port and the places around the exhaust collecting passage are exposed to the exhaust gas and become high temperature. The entire temperature can be made uniform by cooling from above and below, but even if the upper and lower sides of the exhaust port are cooled, heat is trapped in the area between adjacent exhaust ports. Only with the exhaust side upper cooling water jacket and the exhaust side lower cooling water jacket, it is difficult to sufficiently absorb the trapped heat.

  On the other hand, in the present invention, since the exhaust port at the location of the intermediate cylinder is surrounded by the bypass passage, heat exchange can be accurately performed from the meat portion located between the adjacent exhaust ports to the cooling water in the bypass passage. Can do. As a result, it is possible to prevent an abnormal temperature rise at the intermediate cylinder and prevent a large thermal strain from occurring. Therefore, warp deformation caused by thermal strain and slipping between the cylinder block and the like can be prevented or remarkably suppressed, and high sealing performance can be secured, and mechanical loss can be reduced.

  Now, as a cooling means at the location of the exhaust port, a groove-shaped cooling water passage that opens downward may be formed in the lower portion of the lower surface of the cylinder head, but in this case, the cooling water passage Due to the opening downward, there is a problem that the rigidity of the cylinder head is lowered and thermal deformation is likely to occur.

  On the other hand, in the present invention, a bypass passage is provided in the center cooling water jacket, and heat exchange is performed with respect to the cooling water passing through the bypass passage. A tunnel-like bypass passage is formed in the flesh of the cylinder head. Therefore, even if the temperature of the cylinder head rises, stress concentration is very difficult to occur, and the rigidity of the cylinder head does not decrease. Therefore, the thermal distortion of the cylinder head can be prevented without reducing the rigidity of the cylinder head.

It is a figure which shows embodiment, (A) is a top view of a cooling water jacket, (B) is a top view of a cylinder head. (A) is the side view which looked at the cooling water jacket from the exhaust side surface direction, (B) is the side view of a cylinder head. (A) is the rear view which looked at the cooling water jacket from the crank-axis direction, (B) is the rear view of a cylinder head. It is a perspective view of a cooling water jacket. It is a rough top view of a cooling water jacket. (A) is a top view of a cooling water jacket, (B) is a bottom view of a cooling water jacket, (C) is CC sectional view side view of (A). It is a separation top view of a cooling water jacket. It is a perspective view of a center cooling water jacket. It is a bottom view of a cylinder head. (A) is AA sectional view taken on the line of FIG. 9, (B) is BB sectional drawing of FIG.

(1). Outline Next, an embodiment of the present invention will be invented based on the drawings. In the present embodiment, the crank axis direction is defined as the front-rear direction, and the direction is clearly shown in FIG. Although not shown in the figure, the front side that covers the timing chain is the front side. This embodiment is applied to a cylinder head of a three-cylinder internal combustion engine.

  As can be understood from FIGS. 1 (B) and 10 (A), the upper surface of the cylinder head 1 is formed with a space that opens upward, and therefore, an upward peripheral wall 2 is provided around the space. . In the interior surrounded by the peripheral wall 2, three spark plug holding holes 3 are arranged in the longitudinal direction (the direction of the crankshaft 4).

  A partition rib 5 constituting a bearing portion for holding the camshaft extends in the width direction in the space of the cylinder head 1, and a valve holding hole in which the valve shaft is fitted on both sides of the partition rib 5. Two pairs of 6 are formed.

  The cylinder head 1 has an intake side surface 8 in which an intake port 7 is opened. As shown in FIG. 10, the intake side surface 8 is inclined so as to go outward as it goes downward. Similarly, as shown in FIG. 10, the cylinder head 1 is formed with three combustion chambers 9 aligned in the crank axis direction. The combustion chamber 9 is formed in a trapezoidal shape that spreads downward, and of course has the same diameter and concentricity as the cylinder of the cylinder block (see FIG. 1A). A spark plug mounting hole 10 is opened in the center of the combustion chamber 9.

  The cylinder head 1 is formed with two exhaust ports 11 (see FIG. 10A) corresponding to one combustion chamber, and each exhaust port has one exhaust collecting passage 12 shown in FIGS. Are gathered. As shown in FIGS. 2 and 7, the exhaust collecting passage 12 has one collecting outlet hole 13, and the collecting outlet hole 13 opens in the exhaust side surface 14. The collecting outlet hole 13 is an oval long hole that is long in the longitudinal direction of the cylinder head 1.

(2) Cooling water jacket As can be understood from the comparison of FIGS. 1 to 3 and FIGS. 6 and 7, cooling water jackets 15, 16, and 17 through which the cooling water passes are formed inside the cylinder head 1. The center cooling water jacket 15 is formed in the upper area of the row of the combustion chambers 9 (cylinders), and the exhaust side upper cooling water jacket 16 and the exhaust side lower cooling water jacket 17 are formed in the exhaust area having the exhaust port 11. Is formed.

  The parallel diagonal lines and the dot display in FIGS. 1 to 3 are for clearly showing the outer shape of the cooling water jacket 15. The cooling water jacket shown by the solid parallel diagonal lines is the center cooling water jacket 15, the cooling water jacket shown by the dotted parallel diagonal lines is the exhaust side upper cooling water jacket 16, and the cooling water jacket shown by dots is the exhaust side lower part. This is a cooling water jacket 17. In FIG. 9, the outline of the center cooling water jacket 15 is roughly displayed.

  As can be easily understood from FIGS. 1, 4, and 6, the exhaust side upper cooling water jacket 16 and the exhaust side lower cooling water jacket 17 are located on the exhaust side surface 14 side. The center cooling water jacket 15 is formed above the cylinder row. Therefore, the center cooling water jacket 15 extends to both the left and right sides with the cylinder row center line interposed therebetween.

  For example, in FIG. 1A, the center cooling water jacket 15 has an outer portion 15a concentric with the cylinder (combustion chamber), and the intake side meat portion 18 of the cylinder head 1 is surrounded by the outer portion 15a. Yes. The intake side meat portion 18 is a support portion of the intake valve.

  Between the exhaust side upper cooling water jacket 16 and the exhaust side lower cooling water jacket 17 and the center cooling water jacket 15 is a partition wall portion 19 which is a flesh portion of the cooling water jacket group. The partition wall 19 is formed. The intake side meat portion 18 also has a reinforcing function. However, since the partition wall portion 19 and the intake side meat portion 18 are substantially symmetrical with respect to the crankshaft 4, the reinforcement function of the partition wall portion 19 and the intake side meat portion 18 is enhanced. Balance and further contribute to the suppression of heat distortion.

  As clearly shown in FIG. 10A, the exhaust side upper cooling water jacket 16 covers the exhaust collecting passage 12 from above, and the exhaust side lower cooling water jacket 17 covers the exhaust side upper cooling water jacket 16 from below. Yes. The exhaust side upper cooling water jacket 16 and the exhaust side lower cooling water jacket 17 communicate with each other at both front and rear ends. Further, the jackets 16 and 17 communicate with each other at a plurality of locations even in the inner part away from the exhaust side surface 14. Therefore, the part behind the exhaust collecting passage 12 and the part around the exhaust port are also cooled accurately. In FIG. 1, there are three island-shaped exhaust-side flesh portions 20 inside the exhaust-side upper cooling water jacket 16, which are flesh portions for forming head bolt insertion holes.

  As shown in FIGS. 4 and 5, the front junction of the exhaust side upper cooling water jacket 16 and the exhaust side lower cooling water jacket 17 and the front end of the center cooling water jacket 15 face the cylinder block. Cooling water inlets 21 and 22 are connected. The exhaust side jackets 16 and 17 have one cooling water inlet 21, and the center cooling water jacket 15 has two cooling water inlets 22 on the left and right sides. In FIG. 1, the cooling water inlets 21 and 22 show only rough positions with black circles.

  Although not shown, a block jacket surrounding the cylinder row is formed in the cylinder block. The exhaust side water supply port communicating with the cooling water inlet 21 of the exhaust side jackets 16 and 17 and the center cooling water jacket 15 are formed. A combustion chamber side water supply port communicating with the cooling water inlet 22 is formed at a portion near the front end of the cylinder block.

  Cooling water is pumped from the water pump to the jacket of the cylinder block, but low-temperature cooling water that does not pass through the jacket of the cylinder block is sent to the cooling water inlet 21 of the exhaust side jackets 16 and 17. Therefore, the exhaust-side area is accurately cooled even with a relatively small amount of cooling water. On the other hand, the coolant through the cylinder block jacket flows into the coolant inlet 22 of the center coolant jacket 15. Since the center portion of the cylinder head 1 is not higher in temperature than the exhaust side area, even if the heated cooling water flows into the center cooling water jacket 15, the temperature of the cooling water does not rise excessively. Absent.

  The exhaust collecting passage 12 is curved in a laterally convex shape in a plan view, and accordingly, the exhaust side upper cooling water jacket 16 and the exhaust side lower cooling water jacket 17 have a portion sandwiching the exhaust side meat portion 20 therebetween. Warped outwardly bowed.

  As shown in FIGS. 2A and 3B, the jackets 15 to 17 are connected to a large number of downward holes 25. This is because the jackets 15, 16, and 17 are connected to each other by a core type. In forming, it is a remnant of dummy legs provided to support the core mold. Since the downward hole 25 is closed with a gasket, it is in the same state as it does not exist.

  As can be easily understood from FIG. 1A, the rear end portion of the center cooling water jacket 15 and the rear end portion of the exhaust-side upper cooling water jacket 16 communicate with each other via a joint portion 26. Therefore, the cooling water that has cooled the exhaust-side jackets 16 and 17 flows into the end portion of the center cooling water jacket 15. And the control part 27 shown by the hatching display in FIG.1 and FIG.2 is integrally connected to the terminal end of the center cooling water jacket 15. FIG.

(3) Bypass passage As clearly shown in FIGS. 7 and 8, as shown in FIG. 1 (A) and FIGS. 6 (A) and 6 (B), the center cooling water jacket 15 and the exhaust side upper cooling water jacket 16 are connected. In between, there are two exhaust port meat portions 28 corresponding to each cylinder. An exhaust port 11 is formed in the exhaust port meat portion 28 as shown in FIG. Since the internal combustion engine is a two-valve system, two exhaust ports 11 are paired, and each exhaust port communicates with the exhaust collecting passage 12.

  Then, as shown in FIGS. 6B and 7A, two exhaust ports 11 corresponding to the second cylinder (combustion chamber 9) are formed at the front and rear intermediate portions of the center cooling water jacket 15. A bypass passage 29 is formed that surrounds the exhaust port meat portion 28 so as to surround the exhaust port meat portion 28 from the side. By exchanging heat with the cooling water flowing through the bypass passage 29, heat is prevented from being trapped in the exhaust port meat portion 28 corresponding to the intermediate cylinder (second cylinder), so that it corresponds to the intermediate cylinder. Heat can be radiated firmly from the exhaust port meat portion 28. As a result, heat distortion can be prevented, and the sealing performance can be improved and the mechanical loss can be reduced.

  Although the bypass passage 29 is bowed in plan view, an outwardly recessed recess (bottleway) 30 is formed in the front and rear intermediate portion in plan view, and the upper end is passed through the location of the recess 30. An inclined auxiliary water supply hole (drilling path) 31 communicated with the center cooling water jacket 15 is formed. The lower end of the auxiliary water supply hole 31 communicates with a cooling water jacket formed in the cylinder block.

  Therefore, cooling water with a low temperature rise can be sent from the cooling water jacket of the cylinder block to the center cooling water jacket 15 to assist cooling of the cylinder head 1. Moreover, since the auxiliary water supply hole 31 also functions as a cooling water jacket, it is possible to cool a portion of the exhaust port meat portion 28 between the two exhaust ports 11 forming a set. As shown in FIG. 9, the auxiliary water supply holes 31 are also provided at locations corresponding to the cylinders (combustion chambers) at the front and rear ends, but may be provided only at the locations of the intermediate cylinders.

  As shown in FIG. 9, the cylinder head has an oil drop hole 32 through which oil accumulated in the valve operating chamber flows down toward the oil pan, and one end portion in the front-rear direction is formed in the front-rear intermediate portion of the intermediate cylinder. positioned. Therefore, the auxiliary water supply hole 31 is shifted to the cylinder axis side so as not to interfere with the oil dropping hole 32, and as a result, a recess 30 is formed in the bypass passage 29. Therefore, when the oil drop hole 32 does not exist, it is not necessary to form the recess 30 in the bypass passage 29. Even if the depression 30 forms a bottleneck in the bypass passage 29, there is no problem with the cooling function. This point has been confirmed by experiments.

  As shown in FIG. 10, the bypass passage 29 is connected to a downward hole 33 opened on the lower surface of the cylinder head 1, and this downward hole 33 is a dummy leg formed to support the core during casting. It is a remnant of. Since the downward hole is closed with a gasket, there is no particular problem. In addition, it is also possible to supply cooling water from the cooling water jacket of the cylinder block to the bypass passage by using the downward hole 33 (in this case, the downward hole 33 is provided in the front and rear intermediate portions of the bypass passage 29). Preferably provided).

  Although the above embodiment was applied to a three-cylinder internal combustion engine, the present invention can be applied to an internal combustion engine having four or more cylinders. In the case of an internal combustion engine having four or more cylinders, a bypass passage may be formed at each location of each intermediate cylinder excluding the end cylinder, or a group of exhaust ports 11 of a plurality of intermediate cylinders may be connected to one bypass passage 29. It is also possible to enclose with.

  Alternatively, a main bypass passage that encloses the entire group of intermediate exhaust ports is formed, and a sub bypass passage that communicates with the center cooling water jacket 15 and the main bypass passage is formed at a portion located between adjacent cylinders. It is also possible. For example, in the case of a four-cylinder internal combustion engine, the exhaust ports corresponding to the first and second cylinders are collected in the first collecting outlet hole, and the exhaust ports corresponding to the third and fourth cylinders are set to the second. It is also possible to provide a plurality of collective exit holes, such as grouping into collective exit holes.

  The present invention can be embodied in a cylinder head of an internal combustion engine. Therefore, it can be used industrially.

DESCRIPTION OF SYMBOLS 1 Cylinder head 9 Combustion chamber 11 Exhaust port 12 Exhaust collecting passage 13 Collecting exit hole 14 Exhaust side 15 Center cooling water jacket 16 Exhaust side upper cooling water jacket 17 Exhaust side lower cooling water jacket 19 Partition part 28 Exhaust port meat part 29 Bypass passage 31 Auxiliary water supply hole

Claims (1)

A cylinder head of a multi-cylinder internal combustion engine having three or more cylinders,
An exhaust collecting passage for collecting exhaust gas discharged from each exhaust port in one or a plurality of collecting outlet holes in an exhaust side area in which a group of exhaust ports opened to each cylinder is formed, and the exhaust port and the exhaust An exhaust-side upper cooling water jacket located above the collecting passage, and an exhaust-side lower cooling water jacket located below the exhaust port and the exhaust collecting passage are formed,
And the center cooling water jacket extending in the crank axis direction is formed in the area above the cylinder row,
A bypass passage is formed in the center cooling water jacket so as to enclose the intermediate exhaust ports excluding the exhaust ports located at both ends of the cylinder row individually or as a group so as to be embraced from the lower side. Yes,
Cylinder head of a multi-cylinder internal combustion engine.

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