Steam Engine Design

Main > Energy > Steam Engine

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This page will be used to describe the OSE Open Source Steam Engine design, design issues, and completed drawings.

See bump valve prior art - http://www.rossen.ch/solar/wcengine.html

See also:

• Existing and Historic Designs
  • Steam Engine Design/Historic
  • Steam Engine Design/White Cliffs
• Other Engine Designs
  • Steam Engine Design/2009
  • Steam Engine Design/Solenoid
• Steam Generator Designs
  • Steam Engine Design/Boiler

Bump Valve Engine Design

Three points in the steam cycle are shown.

Design Updates:

• 5/2/11 - Initial bump valve design.
• 5/6/11 - Added flange on crankshaft end of cylinder and exhaust plenum.
• 5/10/11 - Improved bump valve added, cylinder liner is now thick.
• 5/11/11 - Added mount brackets, pillow block, extended piston stem.

1. Steam Fires

2. Steam Expands

3. Steam Vents

Description

This is a single-action uniflow steam engine that uses a bump valve to admit steam and an exhaust vent to emit cooled steam.

Design Features:

• Simple design with a mix of fabricated and off-the-shelf parts.
• Modular and stackable - cylinders can be ganged together to increase power.
• Easy assembly - minimal welding
• Repairable - comes apart for cleaning, maintenance, and repair.
• Easy fabrication - lathing, milling, cutting, and drilling.
• Self-lubricating - oil sprays.
• Crank shaft can be configured for multiple cylinders.

Sub-assembly Designs:

• Steam Engine Design/Bump Valve
• Steam Engine Design/Cylinder
• Steam Engine Design/Crank Shaft
• Steam Engine Design/Piston
• Steam Engine Design/Lubrication
• Steam Engine Design/Exhaust

Alternative Designs:

• Steam Engine Design/Piston Valve

Review Notes

Tom Kimmel of SACA

Some observations and recommendations from Tom:

1. Do more research.
2. Come to my shop and look at real steam engines.
3. Add teeth to the flywheel to allow an electric starter motor.
4. Cylinder liners (sleeve) should be cast iron. Look into motor rebuild kits.
5. Valves are not "chinese hat". Talk to Jay Carr about his design.
6. Open or closed crank is a choice. Not critical.
7. Lubrication is important, but had no specific recommendations.
8. Start with conservative materials (like iron) and consider advanced materials later (like nitride coatings).
9. Consider designing an exhaust manifold from the start.
10. Visit Bill Ryan north of Chicago who has experience with making bash valves.
11. Don't use stainless steel as a cylinder line.
12. Consider 12v electric system for fans, solenoids, relays, water level sensors, and starter motor.

Ken Helmick of SACA

Some observations and recommendations from Ken:

1. Initial decisions having huge influence on final design.
2. Higher operating pressures and temperatures lead to potentially higher efficiency.
3. A uniflow engine has the potential of higher efficiency.
4. A counterflow engine has the relative advantage of being more easily operated.
5. Wrapping a sleeve and welding is not likely to yield a satisfactory engine
6. To make a sleeve, consider:
   1. Cast it using a sand mold.
   2. Use off-the-shelf sleeves.
   3. Purchase already honed hydraulic cylinder tubes.
   4. Convert an existing IC engine or extensively utilize IC engine components.
7. If welding is employed, stress-relieve the assembly and then re-hone lightly in case of any slight thermal induced distortion to the bore.
8. Valve springs must be wound from superalloys and heat treated. Conventional springs will fail from the heat of the steam.
9. Bump valve engines probably are more efficient at some moderate rpm.
10. An alternative to bump valves is a smaller piston valve mounted coaxially with, and upon, the engine piston.
11. Always enclose the crankcase of any higher rpm engine.
12. There is an incredible variety of piston rings available in almost any size, configuration and material imaginable and this is about the last reason I would select a given engine diameter.
13. Electric starter motors are simple. Older General Motors alternators are widely available and they have an integral voltage regulator.
14. A uniflow exhaust manifold could be very, very simple, depending on the cylinder.
15. The crankshaft is the heart of the engine.
16. The average home machinist is typically not equipped for (nor capable of) building a multiple throw, one piece crankshaft.
17. One route to consider is the built-up crank.
18. If a one piece crank is desired, the best route to go would be to either cast a rough out of a high grade of iron.
19. The home machinist can balance a crank with a single throw but multiple pin cranks can only be balanced in a shop with a dynamic balancing machine.