JPH0324856Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a piston for an internal combustion engine, and particularly to a piston structure using a ceramic piston ring.

(Prior art) In recent years, in internal combustion engines such as automobiles, in order to increase combustion efficiency, some or all of the pistons have been replaced with ceramic materials to insulate them and make it possible to raise the temperature of the combustion chamber. was developed and put into practical use. Engines using such pistons can maintain a high combustion chamber temperature, resulting in good combustion efficiency and high output, as well as low concentrations of hydrocarbons and low fuel consumption, which contributes to exhaust gas regulations and resource conservation. It is extremely significant these days, and its necessity is bound to increase even more in the future. However, it cannot be denied that there are still some points that need to be improved, such as the following.

(Problem to be solved by the invention) That is, since the piston ring attached to the piston is generally made of metal, high temperature creep occurs as the temperature of the combustion chamber increases, which is an important function of the piston ring. The tension for sealing is thereby degraded and the sealing function is reduced. In addition, in the case of ceramic piston cylinders,
Since the coefficients of thermal expansion are different, setting an appropriate gap at high temperatures will increase the gap at low temperatures, and setting an appropriate gap at low temperatures will eliminate the gap, and in the former case, the amount of blow-by gas will increase. This causes the oil around the ring to stick, causing a so-called ring stick, and causing the temperature of the oil in the oil pan to rise and deteriorate through the crankcase.On the other hand, in the latter case, the piston ring and cylinder are pressed together and may break during operation. etc. will occur...
etc.

In order to solve these problems, it is effective to manufacture piston rings from ceramics, but since the abutment of the ring is widened when attaching the ring to the piston, metal Ceramic piston rings, which have a Young's modulus 2 to 3 times higher than those of conventional piston rings, have a high stress during installation and have a high probability of breakage, so it has been difficult to use ceramic piston rings.

(Means for solving the problem) The present invention was made in view of the above, and the piston is divided into three parts: the main body, the piston ring, and the skirt member.
By constructing the piston ring as a split body, it is possible to install the ceramic piston ring without widening the abutment, thereby eliminating the above-mentioned problems.

(Example) The present invention will be described in detail based on the accompanying drawings. Fig. 1 is a partially cutaway perspective view showing an example of the structure of the piston of the present invention, and shows a piston head 11 and a piston concentrically attached to the head 11. Piston body 1 made of ceramic or metal, including a continuous body 12
and a holder ring 3 on the outer periphery of the piston body 1.
A ceramic piston ring 2 is surrounded from the body 12 side through a piston ring 2, a piston skirt member 4 is connected to the surrounding part of the piston ring 2 and is fitted onto the body 12 of the piston body 1, and the skirt member 4
and a piston pin 5 which is integrally connected to the body 12 of the piston body 1.
2, a holder ring 3 assembled with the plurality of piston rings 2 and holding the rings 2 at a predetermined interval is externally fitted adjacent to the piston head 11, and the piston skirt member 4 is also fitted onto the body 12. , is connected to and fitted on the holder ring 3,
Moreover, there is a piston for an internal combustion engine in which these components are mutually integrated. The piston body 1 includes, in addition to the piston head 11 and the cylindrical body 12, a combustion chamber 13 recessed in the top surface and a heat insulating chamber 14 dug in the body 12, and is made of a sintered mold made of ceramic material. It is integrally manufactured by.
In addition, the piston rings 2 are also made of ceramics, and in the illustrated example, two piston rings 2 are mounted at a predetermined distance by a holder ring 3. As mentioned above, this holder ring 3 is for maintaining the piston rings 2, 2 at a predetermined distance, and as shown in the figure, there are small diameter parts 3 into which the piston rings 2, 2 can be fitted on the upper and lower sides.
1, 31, and the piston rings 2, 2 are fitted into the small diameter portions 31, 31, and the structure is such that the piston rings 2, 2 can be fitted onto the body 12 of the main body 1. As shown in Figure 2 (an enlarged view of another embodiment corresponding to the lined portion in Figure 1), the piston ring 2 , 2 is not excluded, and the material thereof may be either metal or ceramics. however,
Since the ring 3' shown in FIG. 2 is fitted into the circumferential groove 121, it is natural that it should be made of expandable metal. Further, the piston skirt member 4 is formed into a cylindrical shape from metal such as iron, aluminum, or ceramics, and an oil scraper ring 41 is attached to the upper part of the piston skirt member 4.

(Function) To briefly describe the procedure for assembling one piston P using each of the above-mentioned members, first, the piston rings 2, 2 are fitted into the small diameter parts 31, 31 of the holder ring 3, and the 12 and adjacent to the piston head 11. At this time, it is preferable that the holder ring 3 and the body part 12 be bonded to each other using a ceramic adhesive or the like. Next, the piston skirt member 4 is fitted onto the body 12 so that its upper end is connected to the holder ring 3, and the skirt member 4 and the body 12 of the main body 1 are joined together by the piston pin 5. As a result, one piston P in which each of the above-mentioned members is fixed at a predetermined position is assembled.

In addition, reference numerals 51 and 51 in the figure are piston pin clips for holding the piston pin 5 in a predetermined position, and 6 is a connecting rod connected to a crank (not shown), and these structures are different from the conventional one. It is no different from a type of piston.

(Effect of the invention) As described above, in the piston P, the piston rings 2, 2 are made of ceramics with excellent heat resistance and heat insulation, so there is no concern that high temperature creep will occur even if the combustion chamber temperature is maintained high. The sealing function of the piston ring is fully demonstrated. Furthermore, even if this is applied to a ceramic piston cylinder, since the cylinder and piston ring are made of the same ceramic, it is easy to make the thermal expansion coefficients of both the same, and therefore the gap between the two can be adjusted correctly. By setting this, the abutment gap can be maintained properly during operation, effectively preventing the above-mentioned troubles caused by blow-by gas and breakage due to pressure contact between the piston ring and cylinder. Moreover, since the piston rings 2, 2 are installed without expanding, no stress is applied during installation, and the installation is extremely simple without causing troubles such as breakage. , reduction of blow-by gas amount,
The characteristics of preventing ring stick, preventing oil deterioration, and reducing oil consumption are fully exhibited in the piston P. Further, since the piston skirt member 4 is fitted into the body 12 of the piston body 1 and is integrally connected to the body 12 by the piston pin 5, the piston P can be assembled without expanding the piston ring 2. This is done reliably and extremely easily.

Such a piston structure is extremely effective in increasing combustion efficiency and output, and reducing hydrocarbon concentration and fuel consumption, and its practical benefits are enormous.

It should be noted that the illustrated piston P is merely an example of the present invention, and it goes without saying that other embodiments may be included as long as they do not depart from the scope of the present invention. For example, although two piston rings 2 are used, it is also possible to have three or more rings depending on the size of the piston. In this case, the holder ring 3 shown in the illustration can be divided into two or three parts. It is easy to understand what should be used. In addition, the heat insulation chamber 14 provided in the body 12 of the main body 1 literally guarantees effective heat insulation, and may be a continuous ring-shaped cavity around the axis of the body 12 or a discontinuous independent cavity. It is constructed with a plurality of cavities and is excavated according to the required insulation properties.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of the structure of the piston of the present invention, and FIG. 2 is an enlarged view of another embodiment corresponding to the line in FIG. 1. Explanation of symbols: 1... Piston body, 11... Piston head, 12... Body, 2... Ceramic piston ring, 3... Holder ring, 4...
...Piston skirt member.

Claims (1)

[Scope of utility model registration request] A ceramic piston ring is encircled from the body side via a holder ring around the outer periphery of the piston body, which includes a piston head and a body concentrically connected to the head, and the piston ring is connected to the surrounding part of the piston ring. A piston for an internal combustion engine, characterized in that a skirt member fitted onto the body of the main body and the body of the piston body are integrally connected by a piston pin.