Expansible chamber devices – With lubricating means – Piston has lubricant retaining or conducting means
Patent
1997-02-03
1998-11-24
Nguyen, Hoang
Expansible chamber devices
With lubricating means
Piston has lubricant retaining or conducting means
92236, 1231936, F01B 3110
Patent
active
058393510
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a piston having a piston body comprising an integral combination of a crown portion and a skirt portion, and outer members fitted around the skirt portion.
BACKGROUND ART
The noise occurring due to the driving of an internal combustion engine includes slapping sounds. The slapping sounds occur due to a collision of a skirt portion of a piston with a wall surface of a cylinder liner when the piston is moved reciprocatingly in a cylinder. In order that a piston can be moved reciprocatingly in a cylinder, clearances are formed between the piston and a wall surface of a cylinder liner, and in order to prevent a blow down from a combustion chamber, piston rings are fitted in piston ring grooves formed in the piston. Therefore, when the piston is moved reciprocatingly in the cylinder, the piston collides with the portion of the inner surface of the cylinder which is in a direction perpendicular to the axis of a piston pin, i.e., in a thrust direction to cause slapping sounds to occur.
In order to reduce such slapping sounds, various types of pistons have been developed. For example, there is a piston as a slapping sound reducing piston which is disclosed in Japanese Patent Application No. 194570/1994 filed previously by the applicant of the present invention. This piston has as shown in FIG. 7 a piston body 1 comprising a crown portion 2 provided with piston ring grooves 12, and a skirt portion 3 provided with bosses 13 in which pin bores 4, through which a piston pin 22 is inserted, are formed, outer members 7 fitted around the skirt portion 3, and outer member support members 10 interposed between the bosses 13 and outer members 7 and supporting the outer members 7 so that the outer members can be moved relatively in the thrust direction, clearances between the outer members 7 and skirt portion 3 being formed so that the clearances are wider at the intermediate portions of the outer members 7 and narrower at the peripheral portions thereof, a hydraulic pressure being supplied to this clearance.
In this piston, the outer members 7 are supported so that they can be moved relatively in the thrust direction by the outer member support members 10, and, moreover, a hydraulic pressure is supplied to the clearance between the outer members 7 and skirt portion 3. Therefore, when the piston is installed in a cylinder bore with a hydraulic pressure then supplied to the clearance, the outer members 7 are pressed against a cylinder liner and closely contact the wall surface thereof.
When this piston is moved reciprocatingly, the piston body 1 is turned, i.e., moved pivotally around the axis of a piston pin 22. In accordance with this pivotal movement, the piston body 1 is moved relatively to the outer members 7. When the piston body 1 is moved toward an outer member 7, i.e., when the piston body 1 is going to collide with an outer member 7, the pressure oil in the mentioned relative clearance is forced out from the peripheral portions thereof. Since the clearance is formed so that it is wider at the intermediate portion of the relative outer member 7 and narrower at the peripheral portions thereof, the clearance becomes smaller as the piston body 1 comes closer to the outer member 7, and the peripheral portions of the outer member display the function of restrictions. Therefore, the piston body 1 receives the resistance of the hydraulic pressure, and becomes difficult to approach the outer member 7. When the piston body 1 is thus moved around the axis of the piston pin 22, the piston body 1 receives a cushioning effect of the hydraulic pressure, and the occurrence of slapping sounds is prevented, so that the slapping sound reducing performance can be maintained for a long period of time.
Although the piston disclosed in Japanese Patent Application No. 194570/1994 is formed so that a hydraulic pressure is supplied to the clearances between the outer members 7 and skirt portion 3, the parts of the skirt portion 3 to which the hydraulic pressure should be supplied are not referred
REFERENCES:
patent: 2190207 (1940-02-01), Dillon
patent: 2194247 (1940-03-01), Russel
patent: 2217542 (1940-10-01), Flammang et al.
patent: 2416487 (1947-02-01), Leupe
patent: 2464554 (1949-03-01), Bushby
patent: 4987866 (1991-01-01), Mielke et al.
Isuzu Motors Limited
Nguyen Hoang
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