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Engine valves

Eaton is the leading global supplier of engine valves with total production of more than one million engine valves per day, supplying nearly all vehicle and engine manufacturers worldwide.

Solutions such as hollow valve manufacturing, seat welding, salt bath nitriding, and continuous materials development overcome the issues of increased temperatures, combustion pressures, corrosion and seat wear.

For more than 85 years, Eaton has been designing and developing engine valve technologies for manufacturers that require high quality valves for gasoline, diesel and alternative fuel engines.

Eaton engine valves in a group

High performance designs and materials

Eaton hollow head engine valve cutaway

Eaton hollow head engine valve

Eaton differentiates itself by using innovative technology to produce engine valves.

Engine downsizing coupled with increased power density requires valves with higher strength and temperature resistance. This challenge can be addressed with high performance materials, special seat and stem coatings, lightweight and hollow valves, which enable internal cooling.

Eaton hollow valves ensure engine knocking reduction enabling fuel economy, catalitic converter efficiency and specific power increase

Improved wear resistance

  • Martensitic, Austenitic and Ni-base alloys ensure proper temperature/oxidation resistance for specific applications
  • CrutoniteTM  base material enables seat wear resistance without the need for facing
  • Iron, nickel and cobalt base seat facing materials improve wear resistance high temperature, dry fuel condition and severe performance applications
  • Stem coatings enable appropriate valve stem wear resistance
  • Thermal barrier coatings minimize gas enthalpy loss
  • PVD coatings improve gas flow and reduce carbon deposits

Proven reliability for increased power

  • Lightweight solutions for intake valves
  • Hollow sodium-cooled exhaust valves increase reliability and reduce knocking tendance on downsized engines with high specific power
  • Hollow head valves for top rated engines enable further mass reduction and specific power increase

What is Crutonite?

Crutonite (EMS 200) is Eaton's Automotive News PACE Award-winning, proprietary high-temperature exhaust valve alloy with reduced nickel content. It can be used in internal combustion exhaust valves or spark ignition intake or exhaust valves.

Key features and benefits:

  • Mechanical and physical properties better than conventional iron-based austenitic stainless steel alloys and comparable to nickel-based superalloys
  • Better seat wear resistance than conventional alloys without adding seat weldments
  • Adequate acid corrosion resistance at lower cost than nickel-based superalloys for EGR-type diesel engines
  • 30-50% lower nickel content compared to nickel-based superalloys
  • Lower strategic alloy content reduces impact of market price volatility

Engineering capabilities

Recognized as a pioneer in engine valve design, our failure analysis capabilities have been proven time and time again. Our proprietary instrumentation and analysis software is peerless in gathering information. This acquired knowledge influences prototyping efforts. We emphasize system optimization and component standardization to ensure that our partners receive the preeminent valve design in the world.

Valve design features and considerations

valve design features and impacts

Hollow valves

Today's engines deliver higher specific power than ever before.  This power increase leads to higher exhaust gas temperatures. Several factors lead to this temperature increase:

  • Lean burn combustion process for greenhouse gas (GHG) reduction and combustion efficiency increase
  • Increased compression ratios and combustion pressure which lead to higher combustion efficiency
  • Integrated exhaust manifolds for higher turbocharger turbine efficiency

Solid valves simply cannot perform under these conditions, so hollow valves are needed.  And while hollow valves initially cost more than solid valves, the alternative materials like TiAl, titanium, or ceramics used for solid valves are more expensive than any hollow valve.

solid valve versus hollow valve heat flow from combustion chamber to valve

Hollow valve basics

Hollow valves transfer more heat through the stem than solid valves. Martensitic stem material is a better conductor than austenitic head material. Valves with more stem material and less head material transfer heat better. However, better heat transfer may also cause stem seal damage if the upper portion of stem is not in contact with the water jacket of the cylinder head.

In the most stressed areas (fillet area) temperature reductions of 50°C to 70°C can be seen. At the same level of allowable stress (same Safety Factor), about 70°C difference makes possible to step down from Nimonic (EMS210) solid to X50 (EMS247) hollow valve.
thermometric analysis of solid valve versus hollow valve

Hollow valve design types

Types of hollow engine valves

Advantages and disadvantages of hollow valve types

 

Tube to Tip
TTT

Tube to Solid
TTS

Top of Head
TOH

drilled stem & head

drilled head

w/plug & laser weld

w/ball & stellite weld

Advantages

No need for plug and laser welding

No weld in combustion chamber

 

No need for plug and laser welding

No weld in combustion chamber

 

Design freedom with sodium cavity length (better cooling effect)

Friction welding position independent from sodium cavity end

Reduced amount of austenitic/Ni-based material and optimized costs

Design freedom with sodium cavity length (better cooling effect)

Friction welding position independent from sodium cavity end

Reduced amount of austenitic/Ni-based material and optimized costs

Disadvantages

Good thermal exchange force tube to arrive closer to guide cold end side using more Austenitic/Ni-based material (high cost)

Friction welding operation issues, even bigger than with standard friction welding

Upper tube to be drilled

Many quality problems and failures from field in the past

Good thermal exchange forcing tube to arrive closer to guide cold end side using more Austenitic/Ni-based material (high cost)

Friction welding operation issues

 

Welded area in combustion chamber

Sodium in contact with plug (welded area)

Longer drilling length in stems

 

Sphere plug, fitting operation and stellite welding

Weld presence in combustion chamber