JPH082452Y2 - Engine cylinder head structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to an engine cylinder head structure having an improved exhaust passage cooling structure.

(Prior Art) In a valve mechanism of a 4-cycle engine, for example, a direct-acting type OHC is generally configured as shown in FIG. That is, 1 is a cylinder block, and a cylinder head 2 is provided on the upper part thereof. The cylinder head 2 is provided with two cam shafts 3, 3.
A cam 4 is provided on the cam shaft 3. Sliding holes 5 and 5 are provided in the cylinder head 2 facing the camshafts 3 and 3 so as to be inclined in a V shape, and valve tappets 6 and 6 are vertically movable in these sliding holes 5 and 5. It is provided in. Further, an intake valve 8 and an exhaust valve 9 slidably supported by valve guides 7 are provided below the sliding holes 5 and 5, and a valve stem 8a of the intake valve 8 and the exhaust valve 9 is provided. 9a is in contact with the valve tappets 6, 6. Further, valve springs 10, 10 for urging the intake valve 8 and the exhaust valve 9 in the valve closing direction are housed inside the sliding holes 5, 5.
The upper surfaces of the valve tappets 6 and 6 are in contact with the cams 4 and 4, and the rotation of the camshafts 3 and 3 pushes down the intake valve 8 and the exhaust valve 9 via the valve tappets 6 and 6, thereby reducing the intake passage. 11, the exhaust passage 12 is opened.

By the way, since the exhaust passage 12 is heated by the high temperature combustion gas exhausted from the combustion chamber 13, the exhaust passage 12
The cylinder head 2 around is heated to a high temperature. Therefore, the cylinder head 2 is provided with a water jacket 14 and an oil jacket 15 to circulate and cool water and oil.

(Problems to be Solved by the Invention) As described above, the most common method is to provide a water jacket and an oil jacket on the cylinder head to cool them, but one cylinder is provided with two intake passages and two exhaust passages. Further, in the cylinder head of the four-valve engine, the structure becomes complicated, and the layout of the water jacket and the oil jacket is difficult.

This invention was made in view of the above circumstances, and the purpose thereof is to simplify the structure of the cylinder head and reduce the weight of the engine, and to obtain the flexibility of the layout of the water jacket of the engine. It is to provide a cylinder head structure.

[Constitution of device]

(Means and Actions for Solving Problems) This invention is a cylinder of an engine in which an intake passage and an exhaust passage communicating with a combustion chamber are provided in a cylinder head body, an intake valve is provided in the intake passage, and an exhaust valve is provided in the exhaust passage. In the head structure, a ceramic liner is provided on the inner peripheral surface of the exhaust passage to eliminate the upper water jacket of the exhaust passage, an upper water jacket is provided above the combustion chamber, and communicates with the water jacket of the cylinder block. A jacket extension extending upward from the lower water jacket at the bottom of the exhaust passage along the side surface of the exhaust passage wall is provided in the cylinder head, and further passes through the vicinity of the valve stem of the exhaust valve, and the upper ends of the upper water jacket and the jacket extension are provided. It is characterized in that a communication passage communicating with the section is provided.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a 21-cylinder head main body is provided with an intake passage 23 and an exhaust passage 24 which communicate with the combustion chamber 22. An intake valve 25 is provided in the intake passage 23, and an exhaust valve 26 is provided in the exhaust passage 24 so as to be openable and closable. Further, a cylindrical partition wall 27 is provided at the center of the cylinder head body 21, and the partition wall 27
A spark plug 28 is mounted inside the. Further, a cylindrical ceramic liner 29 having excellent heat resistance is attached to the inner peripheral surface of the exhaust passage 24 to prevent overheating in the vicinity of the combustion chamber 22 of the exhaust passage 24. Further, a stem guide 30 that is slidably supported by the valve stem 26a of the exhaust valve 26 is provided integrally with the cylinder head body 21 in the upper portion of the exhaust passage 24. Further, between the stem guide 30 and the partition wall 27, that is, the partition wall 27.
An upper water jacket 31 is provided on the cylinder head body 21 located on the outer periphery of the exhaust passage 24
A lower water jacket 32 is provided on the cylinder head body 21 located at the lower part of the. The upper water jacket 31 and the lower water jacket 32 are formed with extensions 31a and 32a so as to wrap the exhaust passage 24 from above and below, and cool the periphery of the exhaust passage 24. Further, the extension 31 of the upper water jacket 31
The a and the lower water jacket 32 communicate with each other through a lower water port 33 formed of a bolt hole, and the extension 32a of the lower water jacket 32 and the upper water jacket 31 form an upper water port as a communication passage formed of a bolt hole. It communicates with 34. That is,
The upper water port 34 is provided around the stem guide 30 provided at the upper part of the exhaust passage 24, and the valve stem 26
It is designed to cool a. In addition, the intake passage 23
A water jacket 35 is provided on the cylinder head main body 21 located at the lower part of the above, and it communicates with the upper water jacket 31 through a water port 36.

By providing the ceramic liner 29 on the inner peripheral surface of the exhaust passage 24 of the cylinder head main body 21 in this manner, there is a heat insulating effect, the water jacket on the upper portion of the exhaust passage 24 can be eliminated, and the upper portion of the exhaust passage 24 and Exhaust passage by water jackets 31 and 32 provided at the bottom
24 can prevent overheating. Moreover, the valve stem 26a can be cooled by connecting the upper and lower water jackets 31, 32 with the water port 33.
The volume of the water jacket can be reduced, and the cooling water can be reduced.

[Effect of device]

As described above, according to this invention, the water jacket in the upper part of the exhaust passage can be eliminated, and the size and weight can be reduced. As a result, there is an effect that the flexibility of the layout of the oil jacket can be obtained even in the one-cylinder, four-valve engine. Furthermore, by providing a communication passage that passes around the valve stem of the exhaust valve and connects the upper water jacket and the upper end of the jacket extension of the lower water jacket, it is possible to cool the lower and lateral sides of the exhaust passage, and Since the valve stem can also be cooled by this, deformation of the valve stem due to thermal deformation of the cylinder head can be prevented, and due to the increase in the sliding resistance of the exhaust valve that would be expected if the upper water jacket of the exhaust passage were simply abolished. This has the effect of preventing uneven wear and seizure of the exhaust valve.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional front view showing a cooling water passage of a cylinder head showing an embodiment of the present invention. FIG. 2 is a vertical sectional front view of a conventional cylinder head. 21 ... Cylinder head body, 22 ... Combustion chamber, 23 ... Intake passage,
24 ... Exhaust passage, 25 ... Intake valve, 26 ... Exhaust valve, 30 ...
Stem guide, 31, 32 ... Water jacket, 33, 34 ...
Water port.

Front page continuation (72) Inventor Takashi Dogahara 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Atsushi Isomoto 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Kogyo Co., Ltd. (72) Inventor Yoshio Akishino 533-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Ren Ren Hirako 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation Stock In-house (72) Hiroshi Kamata 3-5-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Co., Ltd. (72) Shinji Asada 1 Uzumasa-cho, Ukyo-ku, Kyoto-shi, Kyoto Japan Automotive Engineering Co., Ltd. Kyoto Project In-house (56) Reference JP-A-58-190537 (JP, A) Actually opened 53-64906 (JP, U) Actually opened 60-97343 (JP, U) Actually opened 58-44455 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A cylinder head body is provided with an intake passage and an exhaust passage communicating with a combustion chamber, and an intake valve is provided in the intake passage.
In an engine cylinder head structure in which an exhaust valve is provided in an exhaust passage, a ceramic liner is provided on an inner peripheral surface of the exhaust passage to eliminate a water jacket above the exhaust passage, and an upper water jacket is provided above the combustion chamber. A jacket extension, which extends upward from the lower water jacket at the lower portion of the exhaust passage communicating with the water jacket of the cylinder block along the side surface of the exhaust passage wall, is provided in the cylinder head, and further extends around the valve stem of the exhaust valve. A cylinder head structure for an engine, comprising: a communication passage that connects the upper water jacket and an upper end of the jacket extension.