US 6,655,602 B2 · Fuel injector having a hydraulically actuated control valve and hydraulic system using same

Abstract

In some hydraulically actuated fuel injectors, a pressure communication passage extends from a pilot valve to the underside of a spool valve to control movement of the same. For the spool valve to move, a substantial amount of fluid flow past the pilot valve is required due to the relatively large amount of fluid that must be displaced by movement of the spool valve member. However, during cold start, when the oil in the pressure communication passage is relatively viscous, it is difficult to move enough fluid past the relatively small flow area through the pilot valve to allow the spool valve to advance to its upper position. Therefore, the fuel injector of the present invention includes a pressure communication passage that is connected to the underside of the spool valve to be separated from the branch that passes through the pilot valve.

Claims20

Dependent claims

A valve assembly comprising:

a valve body defining a first passage, a second passage and a variable pressure passage;
a spool valve member being positioned in said valve body and being movable between a first position in which said first passage is open to said variable pressure passage and a second position in which said second passage is open to said variable pressure passage;
a spool control volume being defined by at least one of said valve body and said spool valve member;
a control valve member being positioned in said valve body and being movable between an open position in which said first passage is in fluid communication with said spool control volume and a closed position in which said first passage is blocked from fluid communication with said spool control volume, and said control valve member including a hydraulic surface defining a hydraulic force direction;
and
a biaser operably in contact with said control valve member to produce a biasing force in opposition to said hydraulic force direction.

3 more elements

A hydraulically actuated device comprising:

a device body defining a high pressure passage, a low pressure passage and a variable pressure passage;
a source of high pressure actuation fluid being connected to said high pressure passage;
a low pressure reservoir being connected to said low pressure passage;
a spool valve member being movably positioned in said device body;
a spool control volume being defined by at least one of said device body and said spool valve member;
a control valve member being movably positioned in said device body and including a hydraulic surface defining a hydraulic force direction;
said hydraulic surface being exposed to said high pressure passage when said control valve member is in a first position and being exposed to said low pressure passage when said control valve member is in a second position;
said hydraulic surface being exposed to fluid pressure in a pressure cavity that is fluidly isolated from said spool control volume;
a biaser operably in contact with said control valve member to produce a biasing force in opposition to said hydraulic force direction;
and
a reciprocating piston having a hydraulic surface exposed to fluid pressure in said variable pressure passage.

8 more elements

Dependencies are inferred from the claim text.

Fuel injector having a hydraulically actuated control valve and hydraulic system using same

Life of this patent

Fuel injector having a hydraulically actuated control valve and hydraulic system using same

Life of this patent

Abstract

Claims20