Direct needle control fuel injectors and methods
Direct needle control fuel injectors and methods disclosed. The preferred embodiment injectors have a needle within a needle chamber for movement between a closed position preventing injection of fuel and an open position allowing injection of fuel, a source of high pressure fuel coupled to the needle chamber to provide fuel for injection and to hydraulically urge the needle to the open position by pressurizing a first hydraulic area associated with the needle, a needle control hydraulic area having a second hydraulic area disposed to urge the needle to the closed position when the second hydraulic area is exposed to fuel under pressure, and valving coupled to the source of high pressure fuel and a vent to controllably couple the hydraulic area of the needle control member to the high pressure fuel or to the vent.
1. A fuel injector comprising:
a needle within a needle chamber for movement between a closed position preventing injection of fuel and an open position allowing injection of fuel;
a source of high pressure fuel coupled to the needle chamber to provide fuel for injection and to hydraulically urge the needle to the open position by pressurizing a first hydraulic area associated with the needle;
a needle control hydraulic area having a second hydraulic area disposed to urge the needle to the closed position when the needle control hydraulic area is exposed to fuel under pressure; and,
a spool poppet valve having a spool valve housing with a spool valve member therein having a poppet valve at one end thereof and moveable between first and second positions, the spool valve housing having a poppet valve seat disposed to cooperate with the poppet valve when the spool valve member is in the first position to block fuel flow through the poppet valve seat;
the poppet valve member being coupled to fuel under pressure and to the needle control hydraulic area, the poppet valve seat being coupled to a low pressure vent, the poppet valve member being configured to couple fuel under pressure to the needle control hydraulic area and to block fuel flow from the needle control hydraulic area to the poppet valve seat when in the first position, and to block fuel under pressure from the needle control hydraulic area and to couple the needle control hydraulic area to the poppet valve seat when in the second position.
2. The fuel injector of claim 1 further comprised of a spring disposed to urge the needle to the closed position.
3. The fuel injector of claim 1 wherein the needle control hydraulic area is larger than the hydraulic area that will urge the needle to the open position.
4. The fuel injector of claim 3 further comprising a check valve allowing relatively unrestricted flow of high pressure fuel from the source of high pressure fuel to the needle control hydraulic area, and relatively restricted flow from the needle control hydraulic area back to the vent.
5. The fuel injector of claim 1 wherein the position of the spool valve member is controlled by a solenoid actuator.
6. A fuel injector comprising:
a needle within a needle chamber for movement between a closed position preventing injection of fuel and an open position allowing injection of fuel;
a source of high pressure fuel coupled to the needle chamber to provide fuel for injection and to hydraulically urge the needle to the open position by pressurizing a first hydraulic area associated with the needle;
a needle control hydraulic area having a second hydraulic area disposed to urge the needle to the closed position when the needle control hydraulic area is exposed to fuel under pressure; and,
a spool poppet valve having a spool valve housing with a spool valve member therein having a poppet valve at one end thereof and moveable between first and second positions, the spool valve housing having a poppet valve seat disposed to cooperate with the poppet valve when the spool valve member is in the first position to block fuel flow through the poppet valve seat, and to allow fuel flow through the poppet valve seat when the spool valve member is in the second position;
the poppet valve member being coupled to fuel under pressure and to the needle control hydraulic area, the poppet valve seat being coupled to a low pressure vent, the poppet valve member being configured to couple fuel under pressure to the needle control hydraulic area and to block fuel flow from the needle control hydraulic area to the poppet valve seat when in the first position, and to block fuel under pressure from the needle control hydraulic area and to couple the needle control hydraulic area to the poppet valve seat when in the second position; and,
a solenoid actuator coupled to control the position of the spool valve member.
7. The fuel injector of claim 6 further comprised of a spring disposed to urge the needle to the closed position.
8. The fuel injector of claim 6 wherein the needle control hydraulic area is larger than the hydraulic area that will urge the needle to the open position.
9. The fuel injector of claim 8 further comprising a check valve allowing relatively unrestricted flow of high pressure fuel, from the source of high pressure fuel to the needle control hydraulic area, and relatively restricted flow from the needle control hydraulic area back to the vent.