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Title: Hydraulically actuated fuel injector including a pilot operated spool valve assembly and hydraulic system using same

The present invention relates to hydraulic systems including hydraulically actuated fuel injectors that have a pilot operated spool valve assembly. One class of hydraulically actuated fuel injectors includes a solenoid driven pilot valve that controls the initiation of the injection event. However, during cold start conditions, hydraulic fluid, typically engine lubricating oil, is particularly viscous and is often difficult to displace through the relatively small drain path that is defined past the pilot valve member. Because the spool valve typically responds slower than expected during cold start due to the difficulty in displacing the relatively viscous oil, accurate start of injection timing can be difficult to achieve. There also exists a greater difficulty in reaching the higher end of the cold operating speed range. Therefore, the present invention utilizes a fluid evacuation valve to aid in displacement of the relatively viscous oil during cold start conditions.
  1. (Morton, IL)
Issue Date:
OSTI Identifier:
Caterpillar Inc. (Peoria, IL) ORO
Patent Number(s):
US 6354270
Contract Number:
Research Org:
Caterpillar Inc. (Peoria, IL)
Country of Publication:
United States
hydraulically; actuated; fuel; injector; including; pilot; operated; spool; valve; assembly; hydraulic; relates; systems; injectors; solenoid; driven; controls; initiation; injection; event; cold; start; conditions; fluid; typically; engine; lubricating; oil; viscous; difficult; displace; drain; path; defined; past; responds; slower; expected; due; difficulty; displacing; accurate; timing; achieve; exists; reaching; operating; speed; range; utilizes; evacuation; displacement; fuel injector; systems including; /123/137/239/