An injector sealing sleeve for opposed-piston engines

Title of Invention:
Double Floating Sealing Sleeve (DFSS)

Name of Inventor or Inventors:
Feng Song Liu

Date of Disclosure:
May 14, 2010

In opposed-piston, two-stroke engines, the injectors must be embedded in the cylinder wall passing through the block from the exterior. There is coolant fluid running between the cylinder wall and the block. The injector nozzle goes through the hole in the block, passing the coolant fluid and into the injector hole in the cylinder wall to reach the cylinder interior. To prevent the gas pressure from leaking out and the coolant fluid from leaking into the cylinder and out of the block, a sleeve with sealing mechanisms on both ends is placed over the injector to seal between the:

  • Cylinder and the coolant fluid
  • Coolant fluid and block exterior

Current, state-of-the-art solutions on injector sealing for opposed-piston engines feature sealing sleeves over the injector. These sleeves are fixed to either the cylinder wall or to the block where the cylinder is housed. The sleeve has sealing interfaces (e.g. high temperature sealing members or clamping metallic sealing faces) at the front end for cylinder pressure sealing and/or at the back end for block sealing of the coolant fluid.

With the opposed-piston architecture, the injectors must be inserted into the cylinder walls at multiple places. The misalignment at the injector holes—between the cylinder and the block—causes sealing problems with fixed injector sleeves. As a result, there is engine performance degradation and potential failure due to cylinder pressure and coolant fluid leakage into the cylinder.

This injector sleeve sealing mechanism, known as the Double Floating Sealing Sleeve (DFSS), consists of:

  • A straight sleeve made out of metallic material (e.g. steel, aluminum, bronze) that is jointed at one, or both, end(s) by a washer (of either metallic or ceramic material) through a universal swivel joint interface (e.g. spherical surface mating with conical surface).
  • One swivel washer is located in the block to receive the injector. There may be another swivel washer in the cylinder wall.
  • The swivel washers may contain a sealing element.
  • The swivel washer at the block end may be clamped to the block.
  • The inside diameter of the sleeve is machined to a pre-determined clearance to the injector nozzle outside the diameter.
  • The outside diameter of the sleeve has a high temperature sealing element at the front end for the cylinder wall sealing and a fluid sealing element at the back end for block sealing.
  • The sleeve’s front seal engages with the cylinder wall, sealing the cylinder pressure, while the back seal engages with the block, sealing the coolant fluid.
  • The sleeve is free to move in a pre-determined space between the swivel washers or between the swivel washer and the cylinder wall.
  • The sleeve is suspended between the two seals to comply with the misalignment of the cylinder and the block. This double sealing floating mechanism minimizes the adverse effect of the inevitable cylinder/block injector hole misalignment in all opposed-piston engines, which directly causes the leaking of the injector sleeve seals.