MXPA97006439A - Ring for low fricc piston - Google Patents

Abstract

A piston ring characterized in that it has a groove that has a depth and a height, notches on both sides of the ring, and in the groove has a layer of molybdenum in which the molybdenum does not cover the entire face of the ring, but rather the groove is used to support the molybdenum

Description

RING FOR LOW FRICTION PISTON Antecedents of the Invention This invention relates to a piston ring for reciprocating internal combustion engines, whose purpose is to provide a sliding seal between the piston and the wall of the cylinder, to prevent the loss by leakage of the combustion gases, overcoming the rings of the prior art that have a conventional chromium coating applied by electroplating.

It is known that in order to ensure this seal, the design of the piston rings has required that the rings have a high value of resistance to closing (tension), which causes two undesired effects, the first of which is that part of the energy generated by the operation of the motor is wasted when it is used to overcome the resistance caused by the high tension of the rings to the reciprocating movement of the piston, the second undesired effect represents the premature wear of the parts that are in contact, that is, the cylinder and piston rings.

The present invention significantly reduces the aforementioned effects by achieving that the contact surface of the piston ring (periphery) with the cylinder is made of a material of high hardness and with antifriction properties, situation that allows the designer to substantially reduce the closing force or tension required by the ring to ensure the sealing between the piston and the cylinder, which allows to improve the working efficiency of the engine by increasing the net output power and also increases the durability of the engine by reducing the wear of the cylinders and piston rings.

Objective of the Invention The purpose of the present invention is to provide a particular type of piston rings of reciprocating type, in particular it relates to a piston ring design which receives on the contact surface with the cylinder the application of a metallic product resistant to wear by abrasion that, without detracting from its ability to ensure the sealing of its entire periphery and to resist the high temperatures of the combustion gases, may offer a lower resistance to sliding than that of its counterparts that have conventional chromium coating applied by electroplating.

This metallic coating will allow to reduce the radial load that the ring applies to the cylinder to assure to adjust to the variations of dimension and contour of the cylinders during the function of the sealing of the combustion chamber.

This type of rings does not increase the costs of the assembly process in the engine, in high production lines or with workshop type users.

The ring referred to in this document has as its main features being made of ferrous material, being circular, being tangentially compressible and therefore when compressed it presents a controlled value charge towards the cylinders of the engine, which generates a uniform radial load of the contact face, that is to say, on the entire periphery of the ring, is through this load as the sealing of the ring is ensured.

The described objectives are carried out in accordance with the present invention by providing a piston ring which is manufactured seeking to generate a spring that transmits its load radially towards the walls of the cylinders, as shown in figures 1, 2, 3 and 4 Brief Description of the Drawings Figure 1 is a front view of the ring.

Figure 2 is a top view of the ring of figure 1 Figure 3 is a top view of the ring of figure 1 Figure 4 is a sectional view taken on line A and A 'of Figure 2.

Detailed description of the invention Figures 1, 2 and 3 show the front and top views of the ring "A", whose design for this type of rings begins defining what will be the nominal working diameter 2, the load or tension 4 to ensure the sealing and the height and depth of the piston groove (not shown) that will contain it. Depending on these requirements, they define the dimensions of height 1, radial thickness 5, working opening 3, and free opening 6.Invariably, the dimension of the latter will be much greater than the working opening 3, because the characteristic of the load or tension 4 that the ring "A" will transmit radially towards the walls of the cylinder is generated by the compression of the ring until its confinement in the working diameter 2 during the assembly process, once the ring has been confined, the magnitude of the separation of the tips between the ends is called work opening 3, this should be the minimum necessary to avoid as much as possible Leakage of combustion gases, usually its value is between 0.1 mm and 0.5 mm.

The base material for manufacturing this type of rings is a ferrous material that can be gray or nodular iron or a steel strip, depending on the mechanical and dimensional characteristics that the product demands for specific engines, this base material is applied to Molybdenum based coating.

In figure 4 it is observed that the molybdenum coating 9 must be contained in a groove 13 previously manufactured in the base material, the dimensions of this groove 13 are defined by its depth 7 and by the height 1 minus the dimension of the grooves 8 , this groove is present in all the periphery of the ring. Proper centering must be ensured between the grooves 8 located on both sides of the ring, since the main function of this groove is to support the workloads and increase the contact surface between the molybdenum and the ring.

It is necessary that the slot shows an angle 10 of between 10 and 20 degrees and internal radius 11 of between 0.05 to 0.1 mm, in such a way as to ensure the elimination of interior corners that could represent areas of stress concentration. It is necessary to manufacture chamfers 12 in the inner diameter to ensure the elimination of burrs, so they have dimensions of maximum 0.1 mm.

The molybdenum layer 9 is applied to the "A" ring by means of a process known as metallization, of which there are at least two commercially available variants, the first known as flame metallization, in which the molybdenum is molten by means of a flame caused by the controlled combustion of gases of high calorific power, the second process is known as plasma metallized, in the latter the molybdenum is melted by means of the heat generated by the excitation of the electrons of a gas heated by an electric maple .

Ring "A" is called low friction, because due to the use of a molybdenum coating it is possible to significantly reduce the load or tension 4 of the "A" ring between 20 to 35% comparatively against its similar that use chromed coatings.

Claims (4)

R E I V I ND I C A C I O N S

1. A piston ring characterized in that it has a groove that has a depth and a height, notches on both sides of the ring, and in the groove has a layer of molybdenum in which the molybdenum does not cover the entire face of the ring, but rather The groove is used to support molybdenum.

2. A piston ring, as claimed in clause 1, characterized in that the groove has an angle of between 10 and 20 degrees and internal radius of between 0.05 to 0.1 mm to eliminate interior corners that could represent areas of stress concentration.

3. A piston ring, as claimed in clause 1, characterized in that it has chamfers in the inner diameter to ensure the elimination of burrs and that they have dimensions of a maximum of 0.1 mm.

4. A piston ring, as claimed in clause 1, characterized in that due to the use of the molybdenum coating it is possible to design it with a load or tension significantly less than that of an equivalent ring with chrome plating. SUMMARIZES A piston ring characterized in that it has a groove that has a depth and a height, notches on both sides of the ring, and in the groove has a layer of molybdenum in which the molybdenum does not cover the entire face of the ring, but rather The groove is used to support molybdenum.