JPH0231558Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) This invention relates to a cooling device for an engine of an automobile or the like, and particularly relates to a cooling device in which a notch groove is formed at the top of a piston.

(Prior Art) Some reciprocating engines have a narrower gap between the piston top and the cylinder head when the piston reaches top dead center in order to create a squishing effect at the end of the compression stroke. In this engine, if the peripheral part of the piston top is simply formed flat, the overlap timing of the opening of the intake and exhaust valves when moving from the exhaust stroke to the intake stroke will be affected by the arrangement of the intake and exhaust valves. In some cases, the intake valve or the exhaust valve comes into contact with the vicinity of the top of the piston that has reached the top dead center.

For this reason, conventionally, the "Bongo Parts Catalog"
As shown in the figure on page 28 of ``Piston Piston'' (issued by the applicant in September 1980), it is known that a piston is provided with a cutout groove on the top of the piston to prevent the intake valve or exhaust valve from coming into contact with the piston.

However, in an engine with this structure, the air-fuel mixture accumulates in the notched groove, and combustion is inherently difficult to occur in the quench zone that includes the notched groove.
It is difficult to propagate and burn the fire normally in this area. Particularly during high-load operation where the temperature of the combustion chamber is high, the air-fuel mixture in the notch groove spontaneously ignites when the piston passes slightly past top dead center after ignition, and this area becomes a heat point.
There was a problem that abnormal combustion (notsking) occurred.

(Purpose of the invention) The purpose of the invention is to eliminate the above-mentioned conventional drawbacks, prevent the notched groove forming portion at the top of the piston from becoming a heat point, and prevent abnormal combustion.

(Structure of the invention) The present invention is an engine in which a notch groove is formed in the quench zone at the top of the piston to prevent the intake valve or exhaust valve from coming into contact with the engine. A lubricating oil supply portion is formed on the back surface of the top of the piston corresponding to the notched groove.

(Example) The figure shows an example of the device of the present invention, and in the figure,
1 is the cylinder block, 2 is the cylinder head, 3
is a piston. A cylinder hole 4 is formed in the cylinder block 1, and a piston 3 is fitted into the cylinder hole 4. Further, the cylinder head 2 is formed with a recess that becomes a combustion chamber 5, and an intake port 6 and an exhaust port 7 that communicate with the combustion chamber 5. An intake valve 8 and an exhaust valve 9 are provided at the openings of the ports 6 and 7 into the combustion chamber 5, respectively.

The intake valve 8 is arranged so that its lowermost end is located near the lower surface of the cylinder head 2 around the combustion chamber 5 in the closed state. Further, the piston 3
is constructed so that the peripheral portion of the top approaches the lower surface of the cylinder head 2 around the combustion chamber 5 almost when it reaches the top dead center. Generally, when transitioning from the exhaust stroke to the intake stroke, the intake valve 8 has already begun to open when the piston 3 reaches the top dead center, so the intake valve 8 is prevented from coming into contact with the piston 3 at this time. In addition, a cutout groove 1 for preventing contact is provided at a predetermined location around the top of the piston 3 corresponding to the lowest end of the intake valve 8.
1 is provided.

In this structure, a lubricating oil supply section 17 is formed at a predetermined position of the piston 3 close to the notched groove 11 to cool the notched groove 11 with lubricating oil. This lubricating oil supply section 17 is formed in the shape of a notched groove that opens downward, and introduces the lubricating oil supplied to the piston 3 by splashing or the like to a position close to the notched groove 11. .

According to the cooling device having such a structure, the notched groove 11 formed at the top of the piston 3 to prevent the intake valve from coming into contact with the piston 3 is cooled by the lubricating oil supplied to the lubricating oil supply section 17, and this groove is cooled during combustion. This prevents the area from becoming a heat point. In other words, as mentioned above, the air-fuel mixture accumulates in the notched groove 11 formed at the top of the piston 3, and this notched groove 11 is a so-called quench zone, making it difficult to normally burn the air-fuel mixture in this area. In addition, especially during high-load operation where the temperature of the combustion chamber becomes high, there is an inherent tendency that this part becomes a heat point and tends to cause knocking. Therefore, by actively cooling this notched groove 11 by the lubricating oil supply section 17, abnormal combustion of the air-fuel mixture accumulated in this portion is prevented.

In the above embodiment, the notched groove 11 for preventing contact with the intake valve 8 is formed at the top of the piston 3, but the exhaust valve 9 is arranged at a position closer to the piston 3 than the intake valve 8. If so, a cutout groove for preventing contact with the exhaust valve is formed at the top of the piston. In this case as well, the lubricating oil supply section may be provided in the same manner close to the notched groove.

(Effects of the invention) As described above, the present invention has a lubricating oil that is formed on the back surface of the top of the piston to correspond to the notched groove for preventing contact between the intake valve or the exhaust valve provided in the quench zone at the top of the piston. Since it is cooled by the supply section, the notched groove does not become a heat point even during high-load operation, preventing knocking and maintaining good operating conditions.

[Brief explanation of the drawing]

The figure is a sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Cylinder block, 2... Cylinder head, 3... Piston, 8... Intake valve, 9... Exhaust valve, 11... Notch groove, 17... Lubricating oil supply section.

Claims (1)

[Scope of utility model registration request] In an engine in which a notched groove is formed in the quench zone at the top of the piston to prevent the intake valve or the exhaust valve from coming into contact with each other, a lubricating oil supply part is formed to supply lubricating oil to the back surface of the top of the piston in correspondence with the notched groove. An engine cooling device characterized by: