for Maintenance Filling of Balancing Gas Springs

Construction of a

Micro Compressor

for Maintenance Filling of Balancing Gas Springs

-

from Idea to Prototype

Master Thesis at

Division of Fluid and Mechanical Engineering Systems Department of Management and Engineering

Linköping University

in co-operation with Strömsholmen AB by

Björn Limber & Johannes Samuelsson

Examiner

Karl-Erik Rydberg, IEI, LiTH

Supervisors

Johan Runesson, Strömsholmen AB

Karl-Erik Rydberg, IEI, LiTH

iii

Abstract

At the gas spring manufacturing company Strömsholmen AB there is the need for a way to make the load alleviating gas springs more robust, endurable and maintenance free. A small high pressure compressor with a control system should solve these problems. The system would have to raise the pressure in the gas spring if it were to drop under a level and let some pressure out if it were to increase over a certain level. The construction of this Micro Compressor system is presented in this master's thesis.

At first, a deeper understanding of the task at hand was gathered resulting in a design specification, followed by a concept study generated by the systematic design method. The evaluation of the concept study resulted in a chosen concept for prototype production. This prototype system consists of a control system with a pressure switch, a pressure reducing valve and a Micro Compressor that raises the pressure when needed. An electric system was also designed to work with the pressure switch, actuating the compressor when needed. Thoughts of converting the Micro Compressor system to pneumatic drive were also considered to increase the scope of use.

The prototype system was tested to see that the requirements in the design specification were met and then the project was handed back to Strömsholmen AB for future development together with a list of suggestions of things that need improvement.

v

Sammanfattning

Hos Strömsholmen AB, som tillverkar gasfjädrar, finns ett behov för att få deras balanseringsgasfjädrar mer robusta, uthålliga och underhållsfria. Detta skulle kunna lösas med en liten högtryckskompressor och ett reglersystem. Kompressorsystemet måste kunna höja trycket i gasfjädern om det skulle sjunka under en viss nivå och sänka trycket om det skulle gå över en viss nivå. Konstruktionen av detta Mikrokompressorsystem är vad som kommer att presenteras i detta examensarbete.

Först gjordes en noggrann genomgång av uppgiften som resulterade i en designspecifikation. Det följdes av en konceptstudie baserad på en metod som kallas systematisk design vilket resulterade i ett koncept som togs vidare till produktion av ett prototypsystem. Prototypsystemet består av ett reglersystem bestående av en tryckvakt, en tryckbegränsningsventil och en mikrokompressor som kan höja trycket i gasfjädern då det behövs. En elektrisk styrning konstruerades också som samarbetar med tryckvakten för att aktivera kompressorn när trycket sjunker under den specificerade nivån. Ett förslag över hur man kan införa pneumatisk drivning istället för elektrisk gjordes även för att utöka användningsområdet för Mikrokompressorn.

Prototypsystemet testades för att se att kraven i designspecifikationen uppfylldes och sedan lämnades projektet tillbaka till Strömsholmen AB för vidareutveckling tillsammans med en lista på förbättringar som kan göras.

vii

Acknowledgements

There are several people who have, in one way or another, made this thesis possible and to whom we wish to express our gratitude. At first, we would like to thank our unofficial supervisor and mentor, Fredrik Ekman at Strömsholmen, for his support, supervision and his way of making our life a little bit easier. Also we would like to express our deepest gratitude to the people working at the construction and production department at Strömsholmen for their encouragement and commitment in helping us develop the Micro Compressor prototype. Thanks also to the examiner, Karl-Erik Rydberg and our supervisor Johan Runesson, for helping us complete the final step of our education at LiTH.

There is also one person without whom we would not have been able to pull this off, Göran Nilsson, research engineer at IEI, LiTH, who helped us enormously while constructing the electrics controlling the Micro Compressor.

Thanks above all to our families and girlfriends for being there for us with support in good times and in bad.

Tranås in November 2008