JP4070376B2 - Engine cooling system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine cooling apparatus in which a joint surface of a head cover is joined to a joint surface formed at an upper end of a cylinder head.
[0002]
[Prior art]
The cooling water jacket in the cylinder head is formed so as to mainly cool the combustion chamber ceiling wall and the exhaust passage and the surroundings of the air supply (intake) passage, and the lower end inlet of the cooling water jacket is a cylinder block. The cooling water jacket communicates with the top outlet. At the upper end of the cooling water jacket of the cylinder head, an air vent hole is formed at an appropriate position so that air in the cooling water jacket is extracted while preventing leakage of the cooling water.
[0003]
[Problems to be solved by the invention]
In the conventional cooling water jacket in the cylinder head, the joint between the cylinder head and the head cover (bonnet) is not sufficiently cooled, and much heat is transferred from the cylinder head to the head cover through the joint, which increases the temperature of the head cover. It is the cause. Moreover, when the said junction part is heated, the cover seal arrange | positioned at a junction part will be heated, and deterioration of a cover seal will be accelerated.
[0004]
OBJECT OF THE INVENTION
The object of the present invention is to effectively utilize the inside of the cylinder head joining surface forming wall, while keeping the height of the cylinder head low, promoting the cooling of the joint between the cylinder head and the head cover, and smoothly It is an object of the present invention to provide an engine cooling device that allows air to escape.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is directed to an engine cooling device in which a head cover is joined and fastened to a joining surface formed at an upper end of a cylinder head. An air vent passage that communicates with the upper end of the cooling water jacket in the cylinder head and reaches the cooling water outlet is formed in the joining surface forming wall located at one side end of the intake port side. .
[0006]
According to a second aspect of the present invention, in the engine cooling apparatus according to the first aspect of the present invention, the air vent passage is disposed at a position near a lower portion of a cover seal sandwiched between both joint surfaces.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a three-cylinder four-valve diesel engine to which the inventions according to claims 1 and 2 are applied. In FIG. 1 showing a plan view of a cylinder head alone, fuel injection valve mounting holes 3 are formed at positions corresponding to the cylinder centers C1, C2, and C3 of the cylinders of the cylinder head 1, respectively. A pair of exhaust valve holes 5 and a pair of air supply valve holes (intake valve holes) 6 are formed around the mounting hole 3. An exhaust manifold (not shown) is attached to one side wall surface 1a of the left and right side wall surfaces 1a and 1b substantially parallel to the crankshaft center line O1, and an exhaust port 7 for each cylinder is opened to the other side. An air supply manifold (not shown) is attached to the wall surface 1b, and an air supply port (intake port) 8 for each cylinder is opened.
[0008]
Exhaust passages 10 communicating with the exhaust valve holes 5 are merged for each cylinder, leading to the corresponding exhaust ports 7, and supply passages (intake passages) 11 communicating with the respective intake valve holes 6 are provided for each cylinder. Merge and reach the corresponding supply port 8.
[0009]
In the cylinder head 1, a cooling water jacket 9 (see FIG. 2) is shown around the exhaust passage 10, in the vicinity of the exhaust valve hole 5, around the air supply passage 11, and in the vicinity of the air supply valve hole 6. The lower end inlet of the cooling water jacket communicates with the upper end outlet of the cooling water jacket of the cylinder block 22 through the communication hole 23 or the communication hole 24.
[0010]
A joint surface 26 is formed around the upper end of the cylinder head 1, and a plurality of holes 28 for inserting fastening bolts, a valve rod actuating push rod insertion hole 29, and a valve arm holder mounting hole are formed on the joint surface 26. Etc., and a cover seal 27 is provided in pressure contact with the valve arm chamber so as to surround and seal the valve arm chamber as indicated by a thick dashed line.
[0011]
Of the joint surface 26, an air vent extending over substantially the entire length of the cylinder head 1 is provided below the joint surface portion 26 a formed along the side wall surface 1 a on the exhaust port 7 side in parallel with the crankshaft center line O 1. A passage (indicated by cross-hatching) 15 is formed, one end in the length direction of the air vent passage 15 is closed by a plug 34, the other end opens as a cooling water outlet 15a, and the cooling water outlet 15a A thermostat 17 is arranged. The outlet of the thermostat 17 communicates with the radiator 20, the outlet of the radiator 20 is connected to the water pump 21, and the discharge port of the water pump 21 is connected to the cooling water inlet of the cylinder block 22.
[0012]
In FIG. 2 showing an enlarged view of the II-II cross section of FIG. 1, the cover seal 27 is mounted in a seal mounting groove 33 formed in the lower end joint surface 31 of the head cover 2, and the cylinder head 1 is tightened by a tightening bolt or the like. By fastening the head cover 2, the cover seal 27 is compressed and the valve arm chamber R is sealed.
[0013]
The joint surface 26 of the cylinder head 1 is formed at a position higher than the upper bottom surface F of the cylinder head in the valve arm chamber R by being formed at the upper end of the joint surface forming wall 32 protruding upward. As described above, the air vent passage 15 is formed in the joint surface forming wall 32 located on the exhaust port 7 side, and is located in a position immediately below the cover seal 27. The cooling water jacket 9 surrounding each exhaust passage 10 is formed so as to become higher toward the exhaust port 7 side, and the uppermost end portion on the exhaust port 7 side communicates with the air vent passage 15.
[0014]
[Action]
In FIG. 1, the cooling water discharged from the water pump 21 is supplied from the lower part of the cylinder block 22 to the cooling water jacket in the cylinder block 22, and after cooling the periphery of the cylinder liner and the like, the communication hole 23 (or 24) is passed through. It passes through the cooling water jacket 9 in the cylinder head 1 shown in FIG. In the cylinder head 1, after cooling various parts in the cylinder head such as around the exhaust passage 10, it passes through the uppermost end of the cooling water jacket 9 and the air vent passage 15 to the cooling water outlet 15 a, and passes through the thermostat 17 in FIG. 1. After being supplied to the radiator 20 and cooled, it is circulated again by the water pump. In such circulation of the cooling water, the air in the cooling water jacket that is generated when the engine is started or during operation gathers in the air vent passage 15 located at the uppermost end of the cooling water jacket 9 and becomes bubbles in the cooling water. In a mixed state, the water is discharged from the cooling water outlet 15a to the radiator 20, and is removed from a hole or the like of the cap of the radiator 20.
[0015]
The air vent passage 15 circulates the cooling water mixed with bubbles as described above by using the discharge pressure of the water pump 21. Therefore, the air vent passage 15 also basically has a function as a cooling water passage. In FIG. 2, the exhaust heat is effectively suppressed from being transmitted to the joint surfaces 26a and 31 and the cover seal 27, and the joint surface forming wall 32, the joint surfaces 26a and 31 and the cover seal 27 are cooled.
[0016]
Another embodiment of the invention
(1) It is possible to form an air vent passage on the air supply port side of the cylinder head 1.
[0017]
(2) The present invention can also be applied to a single cylinder engine or a multi-cylinder engine other than three cylinders.
[0018]
【The invention's effect】
As explained above, according to the present invention,
(1) Since the air vent passage 15 is formed in the joining surface forming wall 32 positioned at the upper end of the cylinder head 1 and communicates with the upper end of the cooling water jacket 9 so as to reach the cooling water outlet 15a. The joint between the cylinder head 1 and the head cover 2 can be efficiently cooled while keeping the height of 1 low. In addition, heat transfer to the head cover 2 can be suppressed.
[0019]
(2) The air vent passage 15 is formed so as to communicate with the upper end of the cooling water jacket 9 so as to reach the cooling water outlet 15a, and is formed in the joining surface forming wall 32 positioned at the upper end of the cylinder head 1. Therefore, no special air venting mechanism is provided in the cylinder head 1, and the air in the cooling water jacket can be reliably discharged to the outside.
[0020]
(3) If the air vent passage 15 is formed in the vicinity of the lower part of the cover seal 27 sandwiched between the joint between the cylinder head 1 and the head cover 2, the cover seal 27 can be efficiently cooled together with the joint. Deterioration of the cover seal 27 can be suppressed. In particular, if the air vent passage 15 is formed in the vicinity of the lower portion of the joint surface on the exhaust port side where the heat is extremely high, deterioration of the cover seal 27 can be more effectively suppressed.
[Brief description of the drawings]
FIG. 1 is a plan view of a single cylinder head of an engine to which the inventions according to claims 1 and 2 of the present application are applied.
FIG. 2 is an enlarged cross-sectional view taken along the line II-II in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder head 1a Side end surface by the side of an exhaust port of a cylinder head 2 Head cover 5 Exhaust valve hole 6 Supply valve hole (intake valve hole)
7 Exhaust port 8 Air supply port (intake port)
9 Cylinder head cooling water jacket 10 Exhaust passage 11 Supply passage (intake passage)
15 Air vent passage 15a Cooling water outlet 26 Cylinder head joint surface 27 Cover seal 31 Head cover joint surface 32 Joint surface forming wall

Claims (2)

In a cooling device for an engine in which the joint surface of the head cover is joined to the joint surface formed at the upper end of the cylinder head, the inside of the joint surface forming wall located at one side end of the exhaust port side or the intake port side of the cylinder head And an air vent passage communicating with the upper end of the cooling water jacket in the cylinder head to reach the cooling water outlet. 2. The engine cooling apparatus according to claim 1, wherein the air vent passage is disposed at a position near a lower portion of a cover seal sandwiched between both joint surfaces.

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