Compression release retarding system

• Main Author: QUENNEVILLE, RAYMOND N
• Format: Patent
• Language: English; French; German
• Published: 12.06.1991
• Subjects: BLASTING; COMBUSTION ENGINES; COMBUSTION ENGINES IN GENERAL; CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES; ENGINE PLANTS IN GENERAL; HEATING; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS; INTERNAL-COMBUSTION PISTON ENGINES; LIGHTING; MACHINES OR ENGINES IN GENERAL; MECHANICAL ENGINEERING; STEAM ENGINES; WEAPONS

An improved compression release engine retarder or engine brake stores hydraulic fluid under pressure and then releases the fluid at an appropriate time in each engine cycle to displace a slave piston and thereby open the exhaust valves for compression release. In one aspect of the improved brake, the hydraulic fluid is released by a master piston of variable length. The variable length master piston travels a fixed distance to the pressure release point so that the timing of the compression release is precisely controlled and independent of installation and engine component tolerances. In another aspect of the improved brake, an anti-jacking valve ensures that the hydraulic pressure displacing the slave piston and exhaust valves is dissipated thereby preventing the exhaust valves from remaining jacked open. In a further aspect of the improvement, the slave piston establishes and maintains a zero lash clearance with the valve crosshead during braking cycles. A slave piston is also disclosed in which a stroke limiting valve restricts the distance the slave piston can move in one engine cycle.