Piston ring

Patent metadata

Field	Value
Publication number	US-11242929-B2
Application number	US-201917254546-A
Country	US
Kind code	B2
Filing date	Jun 13, 2019
Priority date	Jun 29, 2018
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

The present invention addresses the problem of providing a piston ring covered with a DLC coating that has excellent wear resistance and shows a low attacking property on a cylinder bore sliding surface. The problem is solved by a piston ring which is used in the presence of an engine lubricating oil and includes a DLC coating on an outer peripheral sliding surface. The DLC coating has an sp 2 component ratio of 0.5 to 0.85 as determined from a TEM-EELS spectrum obtained by a combination of a transmission electron microscope (TEM) and electron energy loss spectroscopy (EELS), as well as a coating hardness of 12 GPa to 26 GPa and a Young's modulus of 250 GPa or less as measured by a nanoindentation method.

First claim

The invention claimed is:

1. A piston ring used in the presence of an engine lubricating oil, the piston ring comprising a DLC coating on an outer peripheral sliding surface, wherein an amount of hydrogen contained in the DLC coating is 5% by atom or less, and wherein the DLC coating has an sp 2 component ratio of 0.5 to 0.85 as measured by TEM-EELS using a transmission electron microscope (TEM) in combination with electron energy loss spectroscopy (EELS), as well as a coating hardness of 12 GPa to 26 GPa, a Young's modulus of 250 GPa or less as measured by a nanoindentation method, and a refractive index of 2.3 to 2.6 at a wavelength of 550 nm as measured by a spectroscopic ellipsometer.

2. The piston ring according to claim 1 , wherein the DLC coating has a Young's modulus of 200 GPa or less.

3. The piston ring according to claim 1 , wherein the number of macroparticles in the DLC coating, which is observed in a ×10,000 image of a cross-section of the DLC coating that is taken along a thickness direction under a scanning electron microscope (SEM), is 2 or less per 10 μm 2 .

4. The piston ring according to claim 1 , wherein the DLC coating has a coating hardness of 20 GPa or less.

5. The piston ring according to claim 1 , wherein the DLC coating comprises an underlayer containing Ti, Cr, or Si.

6. The piston ring according to claim 1 , wherein the DLC coating has a film thickness of 1 μm or greater.

7. A piston ring used in the presence of an engine lubricating oil, the piston ring comprising a DLC coating on an outer peripheral sliding surface, wherein a number of macroparticles in the DLC coating, which is observed in a ×10,000 image of a cross-section of the DLC coating that is taken along a thickness direction under a scanning electron microscope (SEM), is 2 or less per 10 μm 2 , and the DLC coating has a Vickers hardness of 1,000 HV to 1,500 HV and a refractive index of 2.3 to 2.6 at a wavelength of 550 nm as measured by a spectroscopic ellipsometer.

Assignees

• Tpr Co Ltd

Inventors

• Sato Tomoyuki
• Kitazume Yutaka
• Iwashita Takatsugu

Classifications

• F16J9/26 Primary

  characterised by the use of particular materials · CPC title

• C23C28/44

  characterized by a measurable physical property of the alternating layer or system, e.g. thickness, density, hardness · CPC title

• C23C14/06

  characterised by the coating material ({C23C14/0021} , C23C14/04 take precedence) · CPC title

• F02F5/00

  Piston rings, e.g. associated with piston crown · CPC title

• C23C28/044

  coatings specially adapted for cutting tools or wear applications · CPC title