Valve In Valve For VCR

A valve inside a valve. Outer valve performs induction of fresh charge/air or exhaust gases outflow from combustion chamber. Inner valve changes the compression ratio by varying the clearance volume.


  • Non-availability of a compact variable compression ratio (VCR) mechanism
  • Constrain of part-load emission control
  • Compromise power in Bi-Fuel, Dual Fuel, Flex Fuel system


  • Variable compression ration by Valve in the valve mechanism
  • Valve in the valve is the most compact of all VCR mechanisms available today
  • Valvetrain mechanism modification
  • Compatible with Side overhead cam, Direct overhead cam,and Camless mechanism

Additional Information


1. Step Cam operated

2.Camless VCR.

1. Step Cam Valve in Valve

Challenges and their solutions

Simulation Performed for VCR

2. Camless VCR

Dead Volumes in the combustion chamber

Change in CR via Internal valve lift

  • Valve in Valve VCR needs hollow stem with required strength- Hollow stem valves already in the market with proven technology.
  • Internal valve overhauling during Peak combustion pressure- Self-locking threads.
  • Possible pressure loss from the periphery of the internal valve- seals as present today which don’t allow oil from engine top to the combustion chamber via the valve.