In previous post i already explained about the Valve Timing Drives - Development.
Today i would like to share the mechanism and function of each parts on the Hydraulic Valve Lash Adjustment, see the explaiantion below :
Hydraulic Valve Lash Adjustment
Example : Tappet |
| Engine HLA Control |
- Function
(Cam Lift)- The Tappet is loaded
- By engine valve spring force and inertia forces.
- The Distance btween the piston and inner housing is reduced
- A small quantity of oil is forced out of the high pressure chamber through the leakage gap ⓐ.
- It is then returned to the oil reservoir ⓑ.
- At the end of the leak down phase, there is a small quantity of valve lash.
- A small quantity of oil and air are forced out through the inlet hole and / or the guidance gap .
Components:
①. Outer Housing
②. Piston
③. Inner Housing
④. Valve Ball
⑤. Valve Spring
⑥. Valve Cover
⑦. Return Spring
②. Piston
③. Inner Housing
④. Valve Ball
⑤. Valve Spring
⑥. Valve Cover
⑦. Return Spring
- Function
Adjustment Phase (Base Circle)
- The return spring pushes the piston and the inner housing apart until the valve lash is eliminated.
- The ball check valve opens due to the pressure differential between the high pressure chamber and the oil reservoir (piston).
- Oil flows from the oil reservoir ⑩ through the oil transfer reaces, the oil reservoir ⑨ and the ball check valve into the high pressure chamberⓓ.
- The ball check valve closes and the force transmission in the valve train is restored.
Components:
⑧. Oil transfer recess.
⑨. Oil reservoir (piston).
⑩. Oil Reservoir (outer housing).
⑪. Leakage Gap
⑫. Guidance Gap.
⑬. High Pressure Chamber.
⑭. Oil Feed Groove.
⑮. Inlet Hole.
In the next posting i will share the explanation of Hydraulic Valve Lash Adjustment Elements and feature.
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