Accumulator fuel injection system
First Claim
1. A method of reducing undesired premixed burning in an internal combustion engine, comprising:
- A. lifting an injector needle of a fuel injector a constant low-lift increment from a valve seat of said fuel injector;
thenB. preventing lifting of said needle beyond said low-lift increment for a sufficient interval of time to inject a relatively small initial fuel charge into the engine, said interval terminating when lifting forces imposed on said needle overcome holding forces imposed on said needle by a stop plate, said stop plate having opposed first and second surfaces exposed to an ambient fluid pressure and to a fluid vapor pressure, respectively; and
thenC. lifting said needle to a higher lift position to inject a main fuel charge into the engine.
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Accused Products
Abstract
A series of method and apparatus advances in the accumulator-type fuel injector art, applicable to both intensified and unintensified accumulator injectors, which cooperate to provide major improvements in internal combustion engine fuel economy, reduction of noise, and reduction of undesirable exhaust emissions, including smoke, oxides of nitrogen and hydrocarbons. According to the invention, injector needle closure speed is increased for sharper fuel cutoff and better atomization proximate closure, and needle closure bounce is minimized to minimize fuel dribble proximate closure by reducing both mass and length of the needle, which can be accomplished by a longitudinally divided needle. Hydraulic damping also damps and cushions both needle closing and needle opening. The accumulator cavity and needle spring cavity are separated, enabling the accumulator cavity to be as small as desired for high accumulator closing pressure, while nevertheless enabling a strong, fast-acting spring to be used, both factors cumulatively contributing to good closure atomization. A two-stage needle lift is provided for first injecting a pilot fuel charge for preignition, and then injecting the main fuel charge, thereby eliminating the usual adverse premixed burning. The injection spray pattern is automatically varied for improved engine efficiency over the engine power spectrum by utilizing a pintle-type injector nozzle which is variably controlled according to the quantity of fuel delivered.
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Citations
34 Claims
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1. A method of reducing undesired premixed burning in an internal combustion engine, comprising:
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A. lifting an injector needle of a fuel injector a constant low-lift increment from a valve seat of said fuel injector;
thenB. preventing lifting of said needle beyond said low-lift increment for a sufficient interval of time to inject a relatively small initial fuel charge into the engine, said interval terminating when lifting forces imposed on said needle overcome holding forces imposed on said needle by a stop plate, said stop plate having opposed first and second surfaces exposed to an ambient fluid pressure and to a fluid vapor pressure, respectively; and
thenC. lifting said needle to a higher lift position to inject a main fuel charge into the engine. - View Dependent Claims (2, 3, 4, 5)
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6. A fuel injector for an internal combustion engine comprising:
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A. an injector body; B. a nozzle provided on said injector body and defining an injector needle valve seat; C. an injector needle slidably received in said injector body and being normally seated on said valve seat; and D. a stop plate disposed in said injector body and being normally positioned so as to have opposed first and second surfaces thereof exposed to an ambient fluid pressure and to a fluid vapor pressure, respectively. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of reducing undesirable premixed burning in an internal combustion engine, comprising
A. raising an injector needle of an accumulator-type fuel injector off its valve seat a small constant low-lift increment for a sufficient interval of time to inject a small initial fuel charge into the engine; - and then
B. raising the needle to a higher lift position to inject a main fuel charge into the engine.
- and then
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21. A fuel injector comprising:
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A. an injector body having (1) a longitudinal bore formed therein, (2) a nozzle formed in a bottom end of said bore and defining a needle valve seat, and (3) a pressurized cavity formed therein located above and in communication with an upper end of said bore; B. an injector needle slidably received in said bore and having a lower end normally seated on said valve seat and an upper end normally disposed proximate a junction between said pressurized cavity and said bore; and C. a stop plate disposed in said pressurized cavity and having (1) an upper surface exposed to an ambient fluid pressure in said cavity, (2) a lower surface sealingly contacting a shoulder of said injector body, and (3) a hole formed therethrough permitting the imposition of forces, generated by said ambient fluid pressure in said pressurized cavity, on said upper end of said injector needle. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A method of reducing undesired premixed burning of fuel in an internal combustion engine, comprising:
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A. first injecting a small initial charge of fuel from an accumulator-type fuel injector into said engine at a relatively low rate, said initial fuel charge being injected through a relatively small substantially constant needle aperture for a first time interval; and
thenB. injecting a main fuel charge into said engine at a relatively high rate which gradually decreases from an initial peak rate, said main fuel charge being injected through a relatively large substantially constant needle valve aperture for a second time interval, said relatively high rate of injection decreasing during said second time interval.
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28. In an internal combustion engine accumulator-type fuel injector, a method of reducing undesirable premixed burning in the engine which comprises:
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A. raising an injector needle off its valve seat a small low-lift increment for a sufficient interval of time to inject a small initial fuel charge into the engine; B. then lifting the needle to a full lift position to inject the main fuel charge into the engine; and C. controlling needle lift by controlled venting of pressurized liquid from a pressurized zone located above said needle. - View Dependent Claims (29, 30, 31, 32, 33, 34)
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Specification