JP2007321692A - Cooling structure for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple and light weight cooling structure for an internal combustion engine provided with a crank case, a cylinder block, and a cylinder head, and also provided with a lubricating oil passage supplying lubricating oil from an oil pump in the crank case to a structure in the cylinder head. <P>SOLUTION: A cooling oil passage groove for cooling the cylinder head is formed on a mating surface of the cylinder block and the cylinder head with passing through neighborhood of an exhaust port and a mounting hole of a spark plug and with changing section area. A start end thereof is connected to the lubricating oil passage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  As a conventional technique, an oil jacket for cooling is formed around the spark plug mounting portion, a lubricating oil passage is connected to the oil jacket, and a part of the lubricating oil is supplied. Has been disclosed (for example, see Patent Document 1).

Japanese Utility Model Publication No. 61-32512.

  In the conventional technology, the oil passage for cooling is formed by machining, and it is difficult to form an oil passage of an arbitrary shape. Therefore, the temperature of the cylinder head is made uniform by devising the shape of the oil passage. I couldn't hope to plan. Further, since the structure portion must be formed for forming the cooling oil passage, the manufacturing cost is increased, and the weight is increased by forming the structure portion, which is not preferable. The present invention seeks to provide a simple and lightweight cooling structure.

  The present invention solves the above-mentioned problems, and the invention according to claim 1 includes a crankcase, a cylinder block, and a cylinder head, and lubricates the oil from the oil pump in the crankcase to the structure in the cylinder head. In the cooling structure of the internal combustion engine provided with the lubricating oil passage for supplying the cooling oil, a cooling oil passage groove for cooling the cylinder head is formed on the mating surface of the cylinder block and the cylinder head with a change in cross-sectional area, The present invention relates to a cooling structure for an internal combustion engine, wherein the cooling oil passage groove is connected to the lubricating oil passage to allow a part of the oil to flow therethrough.

  According to a second aspect of the present invention, in the internal combustion engine cooling structure according to the first aspect, the internal combustion engine is a four-cycle internal combustion engine, an intake port and an exhaust port are formed in a cylinder head, and the cooling oil passage is formed. The groove is formed on the mating surface on the exhaust port side.

  According to a third aspect of the present invention, in the cooling structure for an internal combustion engine according to the first aspect, the cylinder head is provided with a spark plug, and the mounting hole of the spark plug is located on the circumferential side away from the cylinder center line. The cooling oil passage groove formed on the mating surface is formed so as to pass in the vicinity of the mounting hole of the spark plug.

  According to a fourth aspect of the present invention, in the internal combustion engine cooling structure according to the second or third aspect, the cross-sectional area of the cooling oil passage groove is in the vicinity of the exhaust port and / or the spark plug. It is formed so that it may increase.

  According to a fifth aspect of the present invention, in the internal combustion engine cooling structure according to the first aspect, the internal combustion engine transmits a driving force of a crankshaft to a valve operating system disposed in a cylinder head. And a valve train drive mechanism chamber that houses the valve train drive mechanism, and the downstream end of the cooling oil passage groove opens into the valve train drive mechanism chamber. It is.

  The cooling oil passage of claim 1 is connected to the lubricating oil passage, and a part of the lubricating oil is used as the cooling oil. Therefore, it is necessary to form a dedicated passage only for guiding the oil from the oil pump to the cooling portion. There is no. In addition, since the cooling oil passage is formed on the mating surface of the cylinder block and the cylinder head, the cooling oil passage can be formed by casting when casting the cylinder block or the cylinder head. The area can be changed in a complicated manner.

  According to the second aspect of the present invention, since the cooling oil passage is formed on the exhaust port side, cooling on the exhaust port side, which becomes a high temperature, is promoted, and the temperature distribution of the entire cylinder head is balanced.

  According to the invention of claim 3, by forming a cooling oil passage in the vicinity of the spark plug, the thermal load on the spark plug and its periphery can be reduced.

  According to the fourth aspect of the present invention, the oil passage cross-sectional area is increased at a place where the heat load is high, so that the amount of heat received by the oil can be increased and the cooling effect is further enhanced.

  According to the invention of claim 5, a dedicated oil return passage is not required, and at the same time, the valve drive mechanism can be lubricated.

  FIG. 1 is a bottom view of a cylinder head 1 of an air-cooled four-cycle one-cylinder internal combustion engine for a motorcycle according to a first embodiment of a cylinder head cooling structure of the present invention. This internal combustion engine is mounted on a vehicle in a slightly upward upward posture with the cylinder axis substantially horizontal, and the vertical direction is indicated by arrows in the figure. The cylinder head 1 is provided with cooling fins 2 around it. A combustion chamber 3 is provided in the center, and an intake port 4 and an exhaust port 5 are opened. A spark plug mounting hole 6 is opened on the right side of both ports. A cam chain chamber is provided on the left side of the combustion chamber 3. Stud bolt insertion holes 8 </ b> A to 8 </ b> F are provided at four locations around the combustion chamber and on the left side of the cam chain chamber 7. The stud bolts inserted through these insertion holes are bolts that connect the crankcase, the cylinder block, the cylinder head, and the head cover.

  Of the stud bolt insertion holes 8 </ b> A to 8 </ b> F, the insertion hole 8 </ b> A also serves as a lubricating oil passage for lubricating a bearing of a cam shaft provided in the cylinder head 1. Oil sent out from an oil pump provided in the crankcase is supplied to a camshaft bearing or the like through a gap between the inner surface of the stud bolt insertion hole 8A and the outer surface of the stud bolt.

  In the figure, one end is connected to the stud bolt insertion hole 8A on the bottom surface of the cylinder head, that is, the cylinder head side of the mating surface of the cylinder block and the cylinder head, passes through the vicinity of the spark plug mounting hole 6 and the exhaust port opening 5, A cooling oil passage groove 9 having a terminal end 10 opened to the cam chain chamber 7 is formed so as to substantially circulate around the combustion chamber.

  2 is a developed sectional view taken along the line II-II in FIG. The front-rear direction of this section is indicated by arrows. The figure shows that the oil passage groove is deep in the vicinity of the spark plug mounting hole 6 and the exhaust port 5.

  In the cooling structure of the first embodiment, when the four-cycle internal combustion engine is started, the lubricating oil in the oil pan is sucked by the oil pump and pumped to the cylinder head 1 via the stud bolt insertion hole / lubricating oil passage 8A. Is done. Since the oil passage groove 9 communicates with the stud bolt insertion hole 8A at the bottom surface of the cylinder head 1, a part of the lubricating oil flows through the cooling oil passage groove 9 along the arrow. In the course of this flow, the heat in the vicinity of the spark plug mounting hole 6 and the vicinity of the exhaust port 5 is absorbed and discharged to the cam chain chamber 7. The oil used for cooling is supplied to the cam chain chamber 7 for lubrication of the cam chain and a sprocket with which the cam chain is engaged, and returns to the oil pan along the inclination of the wall of the cam chain chamber. Since the vicinity of the spark plug mounting hole 6 and the vicinity of the exhaust port 5 are particularly high-temperature portions, the oil passage groove 9 in the vicinity thereof is formed deeper than the other portions. In this vicinity, heat is effectively absorbed by the large surface area of the oil passage groove 9 and the large amount of oil in the oil passage groove 9. The end 10 of the oil passage groove 9 connected to the cam chain chamber 7 is formed at a position lower than the starting end of the oil passage groove 9 (the position of the stud bolt insertion hole 8A) in the vertical position when the vehicle is mounted. Flows smoothly in the oil passage groove 9.

  FIG. 3 is a bottom view of a cylinder head 20 of an air-cooled four-cycle four-cylinder internal combustion engine for a motorcycle according to a second embodiment of the cylinder head cooling structure of the present invention. This internal combustion engine is mounted on a vehicle in a slightly forward tilted posture with the cylinder axis substantially vertical, and the front-rear direction is indicated by arrows in the figure. The cylinder head 20 is provided with cooling fins 21 around it. A total of four combustion chambers 22 are provided, two on the left and right of the bottom surface of the cylinder head, and a cam chain chamber 23 is provided in the center. Each combustion chamber 22 has two intake ports 24 and two exhaust ports 25. A spark plug mounting hole 26 is opened at the center of each combustion chamber 22. The cylinder head 20 is provided with twelve stud bolt insertion holes 27. In addition to the stud bolt insertion hole 27, two lubricating oil passage holes 28 on the left and right sides are provided in order to pressure-feed lubricating oil from the oil pump to a cam shaft bearing in the cylinder head.

  In the figure, one end of the cylinder head 20 is connected to the lubricating oil passage hole on the bottom surface of the cylinder head 20, that is, the cylinder head side of the mating surface of the cylinder block and the cylinder head, passes through the vicinity of the exhaust port 25, and the end is the cam chain chamber 23. Cooling oil passage grooves 29 are formed on the left and right sides, respectively.

  4 is a developed sectional view taken along the line IV-IV in FIG. The vertical direction of this section is indicated by arrows. The figure shows that the cooling oil passage groove 29 is deep in the vicinity of the exhaust port 25.

  In the cooling structure of the second embodiment, when the four-cycle internal combustion engine is started, the lubricating oil in the oil pan is sucked by the oil pump and sent to the cylinder head via the lubricating oil passage hole 28. Since the cooling oil passage groove 29 communicates with the lubricating oil passage hole 28 on the bottom surface of the cylinder head 20, a part of the lubricating oil flows in the cooling oil passage groove 29 along the arrow. In the process of this flow, the heat in the vicinity of the exhaust port is absorbed and then discharged to the cam chain chamber 23. After being used for lubrication of the cam chain and the sprocket with which the cam chain is engaged, Return to the oil pan along the wall. The vicinity of the exhaust port 25 is a particularly high temperature portion, and the cooling oil passage groove 29 in the vicinity thereof is formed deep. In this vicinity, heat is effectively absorbed by the large surface area of the cooling oil passage groove 29 and the large amount of oil in the cooling oil passage groove.

As described in detail above, the following effects are brought about in the above embodiment.
(1) Since the cooling oil passage is connected to the lubricating oil passage and a part of the lubricating oil is used as the cooling oil, it is necessary to form a dedicated passage only for guiding the oil from the oil pump to the cooling point. There is no. In addition, since the cooling oil passage is formed on the mating surface of the cylinder block and the cylinder head, the cooling oil passage can be formed by casting when casting the cylinder block or the cylinder head. The area can be changed in a complicated manner.
(2) Since the cooling oil passage is formed on the exhaust port side, cooling on the exhaust port side, which becomes a high temperature, is promoted, and the temperature distribution of the entire cylinder head is balanced.
(3) In the first embodiment, since the cooling oil passage is formed in the vicinity of the spark plug, the thermal load on the spark plug and its periphery can be reduced.
(4) Since the oil passage cross-sectional area is increased at a place with a high heat load, the amount of heat received by the oil can be increased, and the cooling effect is further enhanced.
(5) Since the oil is returned to the oil pan using the cam chain chamber, a dedicated oil return passage is not required, and at the same time, the valve drive mechanism can be lubricated.

1 is a bottom view of a cylinder head of an internal combustion engine according to a first embodiment of the present invention. FIG. 2 is a developed sectional view taken along the line II-II in FIG. 1. It is a bottom view of the cylinder head of the internal combustion engine which concerns on 2nd Embodiment of this invention. FIG. 4 is a developed sectional view taken along the line IV-IV in FIG. 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cylinder head, 3 ... Combustion chamber, 4 ... Intake port, 5 ... Exhaust port, 6 ... Spark plug mounting hole, 7 ... Cam chain chamber, 8A-8F ... Stud bolt insertion hole, 8A ... Stud bolt insertion hole Oil passage for lubrication, 9 ... Oil passage groove for cooling, 10 ... Terminal end of oil passage groove for cooling, 20 ... Cylinder head, 22 ... Combustion chamber, 23 ... Cam chain chamber, 24 ... Intake port, 25 ... Exhaust port, 26 ... Spark plug mounting hole, 27 ... Stud bolt insertion hole, 28 ... Lubrication oil passage hole, 29 ... Cooling oil passage groove

Claims (5)

A crankcase, a cylinder block and a cylinder head;
In the internal combustion engine cooling structure provided with a lubricating oil passage for supplying lubricating oil from the oil pump in the crankcase to the structure in the cylinder head,
A cooling oil passage groove for cooling the cylinder head is formed on the mating surface of the cylinder block and the cylinder head with a change in cross-sectional area, and the cooling oil passage groove is connected to the lubricating oil passage so A cooling structure for an internal combustion engine, characterized by circulating a part.   2. The internal combustion engine according to claim 1, wherein the internal combustion engine is a four-cycle internal combustion engine, an intake port and an exhaust port are formed in a cylinder head, and the cooling oil passage groove is formed on a mating surface on the exhaust port side. The cooling structure of the internal combustion engine as described.   The cylinder head is provided with a spark plug, the mounting hole of the spark plug is located on the circumferential side away from the cylinder center line, and the cooling oil passage groove formed in the mating surface is formed on the spark plug. 2. The cooling structure for an internal combustion engine according to claim 1, wherein the cooling structure is formed so as to pass through the vicinity of the mounting hole.   4. The internal combustion engine according to claim 2, wherein a cross-sectional area of the cooling oil passage groove is formed to increase in the vicinity of the exhaust port and / or in the vicinity of the spark plug. 5. Cooling structure. The internal combustion engine includes a valve train drive mechanism that transmits a drive force of a crankshaft to a valve train disposed in a cylinder head, and a valve train drive mechanism chamber that houses the valve train drive mechanism, 2. The cooling structure for an internal combustion engine according to claim 1, wherein a downstream end of the cooling oil passage groove opens into the valve train drive mechanism chamber.

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