Internal-combustion engines – Cooling – With jacketed head and/or cylinder
Reexamination Certificate
2002-05-16
2004-05-04
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Cooling
With jacketed head and/or cylinder
C123S041790
Reexamination Certificate
active
06729272
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the construction of a cooling water or coolant jacket formed in a cylinder head of a water-cooled internal combustion engine.
2. Description of the Related Art
Conventionally, known as a cylinder head of a water-cooled internal combustion engine of this type is a cylinder head construction of an internal combustion engine disclosed by JP-A-11-117803. In this cylinder head construction, a rib is provided between adjacent cylinders which connects a circumferential edge portion of an intake valve port of one of the cylinders and a circumferential edge portion of an exhaust valve port of the other cylinder. The rib, which is formed on an upper surface of a lower deck which constitutes a bottom of a coolant jacket in such a manner as to have an angle section, connects to the circumferential edge portion of the inlet valve port on an upstream side of the flow direction of coolant flowing between the cylinders and the circumferential edge portion of the exhaust valve port on a downstream side thereof. Then, the rib so formed deflects the flow direction of the coolant to guide the coolant between circumferential edge portions of a pair of exhaust valve ports so as to attain the cooling of vicinities of the same portions.
Incidentally, in the related art, since the rib formed in such a manner as to protrude from the upper surface of the lower deck connects the circumferential edge portion of the inlet valve port and the circumferential edge portion of the exhaust valve port, there occurs on the back of the rib stagnation in the flow of coolant relative to the flow direction of coolant which flows against the rib on the upper surface of the lower deck and the surface of the circumferential portion of the exhaust valve port, whereby there is caused a problem that the cooling effect becomes deteriorated on the lower deck and the circumferential edge portion of the exhaust valve port which are particularly heated to high temperatures due to the exposure to combustion gases.
SUMMARY OF THE INVENTION
The invention was made in view of these situations, and a common object of first to fourth aspects of the invention is to improve the cooling effect of a coolant jacket of an internal combustion engine which has deflecting ribs for directing coolant to exhaust-valve-port side port wall portions whose heat load is high by reducing areas where the stagnation of coolant occurs by the deflecting ribs. Then, an object of the second and fourth aspects of the invention is to improve the cooling effect by preventing the occurrence of the stagnation at the port wall portion on the exhaust-valve-port side. Furthermore, an object of the third aspect of the invention is to improve the rigidity of the cylinder head.
According to the first aspect of the invention, there is provided a cylinder head cooling construction for an internal combustion engine with cylinders and a crankshaft in which a coolant jacket through which coolant is allowed to flow is formed by cylinder walls including bottom walls forming chamber walls of combustion chambers, intake port walls forming intake ports having intake valve ports which are opened and closed by intake valves and exhaust port walls forming exhaust ports having exhaust valve ports which are opened and closed by exhaust valves, and in which deflecting ribs are formed in the coolant jacket between intake-valve-port side port wall portions and exhaust-valve-port side port wall portions which are situated downstream of the intake-valve-port side port wall portions in a flow direction of the coolant in such a manner as to protrude upwardly from the bottom walls for directing the flow of coolant toward the exhaust-valve-port side port wall portions, the cylinder head cooling construction being characterized in that the deflecting ribs for deflecting part of the flow of coolant which flows in a cylinder head center line direction toward the exhaust-valve-port side port wall portions between the intake-valve-port side port wall portions and the exhaust-valve-port side port wall portions are formed such that the deflecting ribs leave gaps between at least either the intake-valve-port side port wall portions or the exhaust-valve-port side port wall portions and the deflecting ribs or that the deflecting ribs extend from the intake-valve-port side port wall portions and the exhaust-valve-port side port wall portions to leave gaps at intermediate positions thereof for allowing the coolant to flow wall surfaces of the bottom walls, wall surfaces of the intake-valve-port side port wall portions, or wall surfaces of the exhaust-valve-port side port wall portions.
According to the construction of the first aspect of the invention, since the deflecting ribs which protrude upwardly from the bottom walls are formed such that the deflecting ribs leave gaps between at least either the intake-valve-port side port wall portions or the exhaust-valve-port side port wall portions and the deflecting ribs or that the deflecting ribs extend from the intake-valve-port side port wall portions and the exhaust-valve-port side port wall portions to leave gaps at intermediate positions thereof for allowing the coolant to flow wall surfaces of the bottom walls, wall surfaces of the intake-valve-port side port wall portions, or wall surfaces of the exhaust-valve-port side port wall portions, the gaps eliminate any risk that the coolant stagnates on the wall surfaces of the bottom walls forming the chamber walls of the combustion chambers, the wall surfaces of the intake-valve-port side port wall portions or the wall surfaces of the exhaust-valve-port side port wall portions. As a result, the following advantage is provided. Namely, since part of the coolant is deflected to flow toward the exhaust-valve-port side port wall portions which have the highest heat load among the walls of the cylinder head which constitute the coolant jacket, the cooling effect on the exhaust-valve-port side port wall portions is improved. Moreover, being different from the continuous ribs according to the prior art, the coolant flowing through the gaps eliminates the occurrence of stagnation of coolant on the wall surfaces of the bottom walls, the wall surfaces of the intake-valve-port side port wall portions and the wall surfaces of the exhaust-valve-port side port wall portions at the portions where the gaps are formed. Furthermore, part of the coolant flowing in from the gaps flows around to the back of the deflecting ribs, and this reduces further areas where the stagnation in the flow of coolant is generate, whereby the areas where the coolant stagnates due to the deflecting ribs are reduced, the cooling effect on the bottom walls, the intake-valve-port side port wall portions or the exhaust-valve-port side port wall portion being thereby improved.
According to the second aspect of the invention, there is provided a cylinder head cooling construction for an internal combustion engine as set forth in the first aspect of the invention, wherein the deflecting ribs are formed to extend from the intake-valve-port side port wall portions, and wherein the gaps are designed to allow the coolant to flow on the wall surfaces of the exhaust-valve-port side port wall portions between the exhaust-valve-port side port wall portions and the deflecting ribs.
According to the construction of the second aspect of the invention, the following advantage is provided. Namely, since the gaps are formed between the exhaust-valve-port side port wall portions and the deflecting ribs, part of the coolant is deflected to flow toward the exhaust-valve-port side port wall portions which have the highest heat load among the walls of the cylinder head which constitute the coolant jacket, whereby the cooling effect on the exhaust-valve-port side port wall portions is improved. Moreover, being different from the continuous ribs according to the prior art, the coolant flowing through the gaps eliminates the occurrence of stagnation of coolant on the wall surfaces of the
Iizuka Yoshiaki
Suzuki Makoto
Takagi Kiyoshi
Arent Fox Kintner Plotkin & Kahn
Benton J.
Honda Giken Kogyo Kabushiki Kaisha
Yuen Henry C.
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