JPH0141881Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a ceramic piston constituting an adiabatic ceramic engine.

Recent advances in ceramic application technology have been remarkable, and many things, including engine combustion chambers and pistons, are now made of ceramic materials. As the main parts of internal combustion engines are made of ceramic, the need for cooling progresses, and the operating temperature level is 30% lower than when metal parts are used.
It has become possible to increase this even further. Of these, in adiabatic engines, especially those whose pistons are made of ceramic material, when the engine is operating, oil splashes may occur locally on the lower surface of the piston crown, that is, on the inner wall surface of the recessed cavity where the connecting rod is attached. Being rushed away caused them to receive a large thermal shock, which could cause cracks or damage. Moreover, damage to the piston during high-speed rotation can lead to destruction of the entire engine, which is extremely dangerous. On the other hand, even if the piston is not damaged, if oil splashes hit the high-temperature inner wall of the concave cavity of the piston, it will not only cool the piston, but also cause a carbonized layer of oil to form on the wall, further accelerating oil deterioration. There were some inconveniences such as. For this reason, pistons have been proposed in which the oil shielding plate is directly attached to the concave cavity below the piston with screws or the like. However, another problem that has been highlighted is the occurrence of cracks in screw holes and a decrease in strength that can cause damage.

The present invention has been devised in view of the above circumstances, and is an oil shielding device having a shape that almost follows the shape of the concave cavity below the piston to which the small end of the connecting rod is attached. By attaching the small end of the connecting rod, there is no need to machine any screw holes for installing oil shields on the ceramic piston body side, which eliminates the need for lubrication and reduces the strength of the piston body. small end of the connecting rod,
The cylinder liner is appropriately lubricated through the oil holes 24 and is configured to prevent oil splashes from being applied to the wall surface, thereby preventing the generation of thermal shock to the ceramic piston and reducing the cooling effect. An object of the present invention is to provide a ceramic piston designed to prevent oil deterioration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical sectional view of a piston having an oil shield according to the present invention in a recessed cavity, and FIG. 2 is a three-dimensional perspective view showing only the oil shield in FIG. 1.

The oil shielding device 100 provided in the ceramic piston 20 according to this embodiment is made of iron, aluminum,
It is made of a metal plate such as stainless steel, and its longitudinal section forms a band shape along the outer peripheral surface of the small end 11 of the connecting rod 10, and both ends 111, 112 thereof.
has a belt-shaped part 110 with bolt holes 111a and 112a bored therein, and an outer peripheral part 121 that protrudes almost horizontally and roughly follows the shape of the concave cavity 21 of the ceramic piston 20 on the outer peripheral part of the belt-shaped part 110. 13
1, which shields oil splashes from the oil hole 24 formed near the crank chamber and the piston ring 23 toward the wall surface 22 of the ceramic piston 20 during the rocking movement of the connecting rod 10, and has a concave cavity 2.
A pair of upper brim portions 120, 120 and a lower brim portion 13 that are large enough not to come into contact with the wall surface 21a of 1.
0,130.

Further, the connecting rod 10 is connected to the piston 20 by a piston pin 30 at its small end 11, and performs a rocking motion as the engine operates. Therefore, the upper collar portions 120, 120 and the lower collar portions 130, 130 are connected to the piston pin 30.
In order to perform reciprocating rotation by a slight rotation angle around It has a shape. Moreover, the upper collar portions 120, 120 are connected to the piston ring during the downward stroke of the piston 20, which reciprocates up and down within the cylinder liner 40.
3, the oil collected by the oil hole 24
When it flows into the concave cavity 21 through the piston, it provides a shielding effect to prevent it from flying onto the high-temperature lower surface 22 of the piston. On the other hand, the lower brim portion 130,1
30, the oil splashed by the crankshaft from the oil pan in the crank chamber is supplied to the piston lower surface 22.
It acts as a shield from flying into the air.

Such an oil shield 100 is difficult to machine and is highly susceptible to notch effects, and the strip 110 is not attached to a ceramic piston that is subject to significant mechanical and thermal stresses during operation.
Bolt holes 111a, 112a drilled at the ends of
Connecting rod 1 is connected by bolts 41 and 42 inserted into
It is fixed to the small end 11 of 0. Note that ribs or the like may be appropriately formed at required locations on the upper and lower brim portions 120, 120, 130, and 130 or the band portion 110 to provide reinforcement against deformation.

As described above, according to the present invention, the oil shield can be attached to the small end of the connecting rod without adding any machining to the ceramic piston so that it is located in the concave cavity below the piston. Due to this,
It is possible to shield the relatively low-temperature oil from splashing on the underside of the piston, which is at a high temperature, thereby preventing thermal shock from occurring, especially to ceramic pistons, during engine operation.
It is possible to avoid damage due to thermal shock,
Furthermore, it is possible to provide a ceramic piston that has many functions and effects, such as being able to prevent deterioration of oil without deteriorating the heat insulation properties of the piston, and as a result, a high-performance engine can be provided.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the ceramic piston according to the present invention, and FIG. 2 is a three-dimensional perspective view showing only the oil shielding device constituting the ceramic piston in FIG. 1. Explanation of symbols, 10... Connecting rod, 11... Small end, 20... Ceramic piston, 21... Concave cavity, 100... Oil shield, 110... Band-shaped part, 111, 112... End part , 120, 130...
...Brim part.

Claims (1)

[Scope of utility model registration request] In a ceramic piston in which an oil shielding device is provided in a lower concave cavity of a piston body made of a ceramic material, the oil shielding device is connected to a band-shaped portion attached to a small end of a connecting rod, and from the band-shaped portion to the concave cavity. 1. A ceramic piston comprising a plurality of flange portions that protrude substantially along the flange portion.