CN101031742A

CN101031742A - Piston having centered pin hole and skirt profile

Info

Publication number: CN101031742A
Application number: CN 200580033174
Authority: CN
Inventors: 安德鲁·约翰·米勒
Original assignee: Federal Mogul LLC
Current assignee: Federal Mogul LLC
Priority date: 2004-08-02
Filing date: 2005-08-02
Publication date: 2007-09-05

Abstract

The present invention provides a piston which includes a piston body having a longitudinal central axis. A piston head is formed with a plurality of ring grooves and a pair of pin bosses depend from the head and are formed with a pair of pin bores that are centered on a common pin bore axis that intersects the longitudinal axis of the piston. Skirt Portions have outer surfaces with a longitudinal profile that is convexly shaped. A major diameter of the profile lies within +-2 mm of the pin bore axis in both a cold and hot condition.

Description

Piston with kingpin hole and skirt wing

The application requires the preference of No. the 60/598th, 009, the U. S. Patent provisional application submitted on August 2nd, 2004.

1. technical field

The present invention relates to be used for the piston of internal-combustion engine.

2. correlation technique

When using the taper skirt, adopt pin offset to guarantee that soft following skirt contacted the cylinder thorax before skirt on the rigidity traditionally usually, but also further propose the major diameter of this skirt is positioned to combine with offset pins on the center line of wrist pin.But pin offset can make the piston of operation produce bad secondary motion, causes the too early wearing and tearing of piston, ring and lining.

Summary of the invention

The method that the present invention adopts centrepin and central skirt to combine forms the plunger designs of symmetry.Use this structure, inertia and gas load make piston produce secondary motion never again.

The effect that centrepin and central skirt combine is: 1) reduce hot-tempered sound; 2) reduce the stress of piston opening end, thereby can reduce quality; 3) can make the land of assembling tighter, reduce blowby; 4) can reduce the skirt contact area, make contact be positioned at the skirt soft area, and then reduce friction; 5) make the easier manufacturing of centrepin; 6) can transmit piston and reduce the PCS assembling of centrepin; 7) can more easily correctly design piston first; 8) when top dead center is lighted a fire, can reduce motion change significantly, can reduce the land gap, reduce the ring lateral wearing and reduce the miniature welding that encircles.

Description of drawings

In conjunction with following detailed description and accompanying drawing, can understand these and other feature and advantage of the present invention more easily, wherein:

Fig. 1 is the front view of piston; With

Fig. 2 is the bottom view of piston shown in Figure 1.

Embodiment

Referring to Fig. 1 and Fig. 2, shown in piston 10 have a piston head 12 that constitutes by a plurality of annular grooves 14, annular groove 14 is used for ccontaining a plurality of piston ring (figure do not show).Land 16 is arranged between the annular groove.Pair of pin bosses 18 is stretched out below piston head 12, and come in the space in the horizontal.Pin have on the hub 18 axially align be used for holding the knuckle-pin pin-and-hole 20 of (figure does not show), in the mode of routine piston is connected with connecting rod (not drawing among the figure).Piston 10 has the longitudinal midline or the axle 22 that pass pin-and-hole 20 axis, so relative piston center line 22, and pin-and-hole axis 24 does not just have lateral offset.

Piston 10 comprises the skirt 26 of piston 10 relative both sides between pin hub 18, each skirt 26 all has an outer surface 28 that has the skirt wing 30, the skirt wing 30 forms at piston and the vertical convex of skirt, has a major diameter (promptly from piston center line point radially outward distance farthest), when piston during cold conditions (i.e. operation before ambient temperature) and hot (promptly being heated to running temperature), this major diameter be positioned at pin-and-hole center line 22 ± 2mm between.This kingpin hole has the advantage that known piston formerly never has with combining of the center skirt wing, comprises reducing secondary motion and wearing and tearing.

This skirt wing guarantees that soft central skirt becomes the skirt of unique contact hole.The design of this skirt wing makes the major diameter of skirt be positioned on the center line height of pin.The difference of this design is that the skirt wing and centrepin combine, and the skirt wing descends gradually in large diameter both sides.The skirt wing descends gradually in large diameter both sides and can guarantee that major diameter under various piston temperature conditions, comprises under cooling start temperature and the hot running state, all is positioned on the center line of pin.

Traditionally, piston ring top land is all wanted brachymemma, and when guaranteeing the piston operation, particularly land can not contact when starting.The piston ring top land contact will produce hot-tempered sound, causes the wearing and tearing and the distortion in hole.Use the skirt wing of the present invention, pin offset and skirt offset make piston produce tangible secondary motion never again, and the unique power that causes secondary motion is skirt friction and pin friction.Therefore, there is no need to go the brachymemma piston ring top land, the temperature the when diameter of centrepin and center skirt wing upper piston ring piston ring land only need be considered to move on the land raises and just can determine again.Land becomes just in time can avoid land to block boring ratio more favourable to the gap design in hole.If land can touch the hole really, just do not have the energy that produces hot-tempered sound or cause distortion in the land, because piston is in state of equilibrium, does not have secondary motion yet and generate and the relevant power of piston formerly with biasing pin-and-hole.So land can be preferably with helping stable plunger.

Therefore, piston of the present invention, its wrist pin has zero offset with respect to the longitudinal axis or the center line of piston, and the piston skirt wing of piston and protrusion combines, no matter piston is in cold conditions or hot, the major diameter of the skirt wing all be positioned at piston vertically go up the pin-and-hole center line ± 2mm between.

Clearly, according to above introduction, the present invention may also exist many other modifications and variations.So people must recognize, as long as within the scope of appended subsequently claim, the present invention can also adopt and be different from here specially appointed mode and implement.

Claims

1. piston, it comprises:

Piston body with center longitudinal axis;

The piston crown that constitutes by a plurality of annular grooves;

The pin hub portion, described pin hub portion is formed with a pair of pin-and-hole according to described piston crown, and described pin-and-hole is centered on the common pin-and-hole axis that the longitudinal axis with described piston body intersects; With

A pair of skirt, described skirt and described pin hub portion constitute an integral body, each described skirt all has an outer surface that has the skirt wing, the described skirt wing becomes convex in the vertical, has a major diameter, when the cold conditions of piston before operation with when being heated to running temperature hot, described major diameter be positioned at described pin-and-hole axis ± 2mm between.

2. piston according to claim 1, the described outer surface that it is characterized in that described skirt diminishes gradually on vertically and becomes little size at described large diameter two.

3. piston according to claim 1 is characterized in that the run duration after described piston is installed, and described diminishing can enough get rid of described skirt and contact in other zone that exceeds described ± 2mm and piston hole that piston moves therein.