Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Wear of piston rings in hydrostatic transmissions
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This study focuses on the wear of piston rings in a hydraulic radial piston motor. The piston ring has to satisfy increasing demands for reliability and longer service life. It has two contacting surfaces, the face and the flank, and operates under a boundary lubrication state.

This first part of the project aimed to detect and characterise piston ring wear. Measurement by weighing gives an overall value for wear defined as loss of mass. Two-dimensional form and surface roughness measurements show the distribution of wear on the piston ring face in contact with the cylinder bore and the piston ring flank in contact with the piston groove. Three-dimensional analyses, both quantitative and qualitative, allow the wear mechanisms to be identified.

The wear of piston rings from an actual hydraulic motor was characterised. As well, rig testing was performed in two different test rig set-ups, one simulating the sliding movement of the piston ring and the other the tilting movement at the end of the strokes. Wear during the running-in period was investigated, and the findings indicate that the period when this takes place is of short duration. In the long term, mild wear makes the surfaces smoother than they were when new, resulting in a very low wear coefficient. Significant levels of wear were measured on both contacting surfaces of the piston ring. In cases in which the flank exhibits more wear than the face, the wear on the flank can be reduced by proper design of the piston groove.

The second part of the project aimed to evaluate use of a textured surface for the cylinder bore counter surface and a coated surface for the piston ring. Three modelling experiments were performed to characterise the friction and wear properties under lean boundary lubrication conditions. Under such conditions, textured surfaces have the advantage of retaining more lubricant and supplying it over a longer time. Stable friction was also a distinctive feature of the textured surface. Use of a coating could also possibly reduce the amount of wear. Though a smooth surface, like a polished one, is hard to beat for a working texture, a coated surface is far ahead of a smooth uncoated one. Different manufactured and commonly used cylinder bore surfaces, including textured ones, were evaluated in the sliding movement test rig. That allowed favourable wear properties, such as lowest wear coefficient, to be determined with the use of a roller burnished surface.

A final part of the research involved simulating wear on the piston ring face throughout the entire service life of a hydraulic motor. This allowed us to determine the roles of surface roughness and coating in prolonging service life and achieving acceptable and secure piston ring operation. The model is simple and realistic, but still needs to be refined so as to correspond even better to reality.

Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , 55 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2005:18
Keyword [en]
piston ring, surface roughness, texture, coating, wear, hydraulic motor
National Category
Reliability and Maintenance
Identifiers
URN: urn:nbn:se:kth:diva-432ISBN: 91-7178-148-X (print)OAI: oai:DiVA.org:kth-432DiVA: diva2:11786
Public defence
2005-10-07, Sal M3, Brinellvägen 64, Stockholm, 10:15
Opponent
Supervisors
Note
QC 20101007Available from: 2005-09-27 Created: 2005-09-27 Last updated: 2010-10-07Bibliographically approved
List of papers
1. Evaluation of an ultrasonic method for measurement of oil film thickness in a hydraulic motor piston ring
Open this publication in new window or tab >>Evaluation of an ultrasonic method for measurement of oil film thickness in a hydraulic motor piston ring
2005 (English)In: Life Cycle Tribology, Elsevier, 2005, 305-312 p.Chapter in book (Refereed)
Abstract [en]

The efficiency of a hydraulic motor depends on the lubrication performance of the piston ring. If the film is too thin then wear occurs quickly, if it is too thick then oil is lost into the cylinder and efficiency is reduced. In this paper a technique for oil film measurement based on ultrasonic reflection is investigated. This has the potential to be used non-invasively on real components. An ultrasonic pulse will reflect from a thin film interposed between two solids. The proportion of the pulse that is reflected depends on the stiffness of the intermediate layer. If the acoustic properties of the film material are known, then the stiffness can readily be used to determine the film thickness. This principle has been employed for the piston ring lubrication case. A piston/cylinder test bench has been used to evaluate the ultrasonic method. A focusing piezo-electric transducer is mounted outside the cylinder and ultrasonic pulses reflected back from the inner bore. The variation of these pulses as the piston ring passes underneath is investigated and used to determine oil film thickness. Films in the range 0.7 to 1.3 μm were measured; the thickness did not depend strongly on either ring speed or sealed pressure. Several practical aspects were investigated such as, attenuation in the cylinder material, response time, and transducer resolution. Whilst this study demonstrated that film thickness measurement is feasible, there are a number of practical considerations that require further work, principally the focusing and coupling of the ultrasonic transducer and the response time.

Place, publisher, year, edition, pages
Elsevier, 2005
Series
Tribology and Interface Engineering Series, ISSN 1572-3364 ; 48
National Category
Reliability and Maintenance
Identifiers
urn:nbn:se:kth:diva-25063 (URN)10.1016/S0167-8922(05)80032-X (DOI)2-s2.0-33745113012 (Scopus ID)0-444-51687-5 (ISBN)
Conference
Leeds, 7/9-10/9 2004
Note

QC 20101007

Available from: 2010-10-07 Created: 2010-10-07 Last updated: 2014-12-02Bibliographically approved
2. Characterisation of wear on piston rings in a radial piston hydraulic motor
Open this publication in new window or tab >>Characterisation of wear on piston rings in a radial piston hydraulic motor
2002 (English)In: New horizons for tribology and lubricants: scientific achievements - industrial applications - future challenges. / [ed] Bartz, Wilfred J., Renningen-Malmsheim: Expert Verlag , 2002Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Renningen-Malmsheim: Expert Verlag, 2002
National Category
Reliability and Maintenance
Identifiers
urn:nbn:se:kth:diva-25060 (URN)3-8169-2107-8 (ISBN)
Conference
2nd World Tribology Congress, Vienna, 3-7 september 2001
Note
QC 20101007Available from: 2010-10-07 Created: 2010-10-07 Last updated: 2010-10-08Bibliographically approved
3. Initial sliding wear on piston rings in a radial piston hydraulic motor
Open this publication in new window or tab >>Initial sliding wear on piston rings in a radial piston hydraulic motor
2003 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 254, no 11, 1208-1215 p.Article in journal (Refereed) Published
Abstract [en]

The initial sliding wear of boundary lubricated piston rings used in a hydraulic motor is studied in terms of the changes in mass, form and surface toughness. The piston ring in a hydraulic motor makes an important contribution to high volumetric efficiency by properly sealing the cylinder bore and piston. The results show that the wear on the piston ring in this particular test rig takes place at the top of the asymmetric crowning at the outer surface contacting the cylinder bore. Initially, the roughness amplitude decreased rapidly, and had decreased by one-third after sliding 10 m. The dominant wear mechanism was mild wear. Abrasive wear also clearly influences the amount of wear.

Keyword
piston ring, wear, boundary lubrication, surface roughness, running-in
National Category
Reliability and Maintenance
Identifiers
urn:nbn:se:kth:diva-22829 (URN)10.1016/S0043-1648(03)00337-5 (DOI)000185448900021 ()
Note
QC 20100525Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2017-12-12Bibliographically approved
4. Experimental study of wear interaction between piston ring and piston groove in a radial piston hydraulic motor
Open this publication in new window or tab >>Experimental study of wear interaction between piston ring and piston groove in a radial piston hydraulic motor
2004 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 257, no 12, 1281-1287 p.Article in journal (Refereed) Published
Abstract [en]

The wear interaction between piston ring and piston groove in a radial piston hydraulic motor was studied in regard to mass loss and changes in form and surface roughness. A specially developed test rig that simulates the tilting movements of pistons at the end of strokes was used in the test. The results show that wear on the piston ring groove can be up to 10 times greater than the wear on the piston ring. For both interacting surfaces, the dominant wear mechanism was mild wear. The results from a factorial design show that the form of the piston groove significantly influences the amount of wear.

Keyword
piston ring, surface roughness, running in, wear, tribology, hydraulic motor
National Category
Reliability and Maintenance
Identifiers
urn:nbn:se:kth:diva-23959 (URN)10.1016/j.wear.2004.05.020 (DOI)000225750700015 ()2-s2.0-10144261310 (Scopus ID)
Note
QC 20100525 QC 20111018. 9th International Conference on Metrology and Properties of Engineering Surfaces. Halmstad, SWEDEN. SEP 10-11, 2003 Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2017-12-12Bibliographically approved
5. Influence of surface texture on friction and wear
Open this publication in new window or tab >>Influence of surface texture on friction and wear
(English)Manuscript (preprint) (Other academic)
National Category
Reliability and Maintenance
Identifiers
urn:nbn:se:kth:diva-25062 (URN)
Note
QC 20101007Available from: 2010-10-07 Created: 2010-10-07 Last updated: 2010-10-07Bibliographically approved
6. Influence Of Coating And Additive And Surface Roughness On Friction And Wear – A Pin-On-Disc Simulation
Open this publication in new window or tab >>Influence Of Coating And Additive And Surface Roughness On Friction And Wear – A Pin-On-Disc Simulation
(English)Manuscript (preprint) (Other academic)
National Category
Reliability and Maintenance
Identifiers
urn:nbn:se:kth:diva-25066 (URN)
Note
QC 20101007Available from: 2010-10-07 Created: 2010-10-07 Last updated: 2010-10-07Bibliographically approved
7. Experimental Study Of Piston Ring Wear In A Radial Piston Hydraulic Motor Influenced By Properties Of The Cylinder Bore
Open this publication in new window or tab >>Experimental Study Of Piston Ring Wear In A Radial Piston Hydraulic Motor Influenced By Properties Of The Cylinder Bore
(English)Manuscript (preprint) (Other academic)
National Category
Reliability and Maintenance
Identifiers
urn:nbn:se:kth:diva-25067 (URN)
Note
QC 20101007Available from: 2010-10-07 Created: 2010-10-07 Last updated: 2010-10-07Bibliographically approved

Open Access in DiVA

fulltext(3959 kB)17027 downloads
File information
File name FULLTEXT01.pdfFile size 3959 kBChecksum MD5
57022a6e1b5f9260d49d486fbd59edb65c030bbefa8b2117a00582bdcf9798a17d91e7b1
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Skytte af Sätra, Ulf
By organisation
Machine Design (Div.)
Reliability and Maintenance

Search outside of DiVA

GoogleGoogle Scholar
Total: 17027 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1342 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf