Accumulator fuel injection system
First Claim
1. In an internal combustion engine accumulator-type fuel injector, a method of reducing undesirable premixed burning in the engine which comprises:
- raising injector needle means off its valve seat a small constant low-lift increment for a sufficient interval of time to inject a small pilot fuel charge into the engine; and
then raising the needle means to a higher position to inject the main fuel charge into the engine.
7 Assignments
0 Petitions
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
93 Claims
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1. 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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raising injector needle means off its valve seat a small constant low-lift increment for a sufficient interval of time to inject a small pilot fuel charge into the engine; and then raising the needle means to a higher position to inject the main fuel charge into the engine. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. 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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raising injector needle means off its valve seat a small low-lift increment for a sufficient interval of time to inject a small pilot fuel charge into the engine; and then raising the needle means to a higher lift position to inject the main fuel charge into the engine; controlling needle lift by controlling venting of pressurized liquid from a pressurized zone located above said needle means; providing said pressurized zone in the form of cavity means above the upper end of said needle means; providing stop plate means in said cavity means normally disposed at a lower position in which there is an axial clearance space between said needle means upper end and a bottom surface of said plate means which defines said low-lift increment; establishing downward force-transmitting means generally axially directed through said plate means to said needle means upper end; sealing said plate means relative to wall means of said cavity means in said lower position of the plate means such that downward force on said needle means upper end from liquid pressure in said cavity means above said plate means is restricted to said force-transmitting means; establishing sufficient liquid pressure in said cavity means prior to initiation of an injection event for said force-transmitting means to, with the aid of needle closure spring force, hold said needle means down against its seat against upward force of accumulator pressure on said needle means; venting liquid pressure from said cavity means sufficiently for upward force of accumulator pressure on said needle means to overcome the combined downward forces of said force-transmitting means and the needle spring, but insufficient to overcome the downward force of liquid pressure in said cavity means against said plate means, causing said needle means to lift into engagement with said plate means bottom surface in said low-lift increment of needle movement; and further venting liquid pressure from said cavity means sufficiently for upward force of accumulator pressure on said needle means to overcome the combined downward forces of said force-transmitting means, the needle spring, and the force of liquid pressure in said cavity means on said plate means, causing said needle means to lift, together with said plate means, to its full lift position. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. 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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raising injector needle means off its valve seat a small low-lift increment for a sufficient interval of time to inject small pilot fuel charge into the engine; and then raising the needle means to a higher lift position to inject the main fuel charge into the engine; controlling needle lift by controlling venting of pressurized liquid from a pressurized zone located above said needle means, said controlled venting comprising first relatively slowly venting pressurized liquid from said pressurized zone to produce said low-lift increment of lift of said needle means; and then relatively rapidly venting pressurized liquid from said pressurized zone to produce said raising of said needle means to its full lift position. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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46. In an internal combustion engine accumulator-type fuel injector, apparatus for injecting a small pilot charge for reducing undesirable premixed burning of the main charge, which comprises:
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elongated valve element needle means longitudinally slideable in the body means of the injector having a lower tip adapted to close against the valve seat of the injector and having an upper end; cavity means defined within said body means above said needle means upper end; liquid inlet/vent conduit means communicating with said cavity means for sequentially introducing pressurized liquid into said cavity means and venting pressurized liquid from said cavity means; stop plate means in said cavity means normally disposed at a lower, seated position in which there is an axial clearance space between said needle means upper end and a downwardly facing surface of said plate means which defines a low-lift increment of movement of said needle means, said stop plate means having downward force-transmitting means generally axially directed therethrough to said needle means upper end; said plate means being sealed relative to wall means of said cavity means in said lower position of said plate means such that downward force on said needle means upper end from fluid pressure in said cavity means above said plate means is restricted to said force-transmitting means; fluid pressure introduced into said cavity means through said conduit means prior to an injection event being sufficient for said force-transmitting means, with the aid of the force of the needle closure spring, to hold said needle means down against its seat against upward force of accumulator pressure on said needle means; fluid pressure remaining in said cavity means after partial venting of fluid pressure from said cavity means through said conduit means being sufficiently reduced for upward force of accumulator pressure on said needle means to overcome the combined downward forces of said force-transmitting means and the needle spring, but still being sufficient for its downward force against said plate means to hold said plate means in its seated position, whereby said needle means will lift into engagement with said plate means downwardly facing surface in said low-lift increment of movement to inject said pilot charge; and further venting of fluid pressure from said cavity means enabling upward force of accumulator pressure on said needle means to overcome the combined downward forces of said force-transmitting means, the needle spring, and the force of fluid pressure in said cavity means on said plate means, whereby said needle means will lift, together with said plate means, to a higher lift position. - View Dependent Claims (47, 48, 49, 50, 51, 52)
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53. In an internal combustion engine accumulator-type fuel injector, apparatus for injecting a small pilot charge for reducing undesirable premixed burning of the main charge, which comprises:
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elongated valve element needle means longitudinally slideable in the body means of the injector adapted to close against the valve seat of the injector and having an upper end; a liquid pressure zone defined in said body means above said needle means upper end for applying downward force on said needle means upper end which increases with increased liquid pressure in said zone and decreases with decreased liquid pressure in said zone; and hydraulic circuit means in liquid communication with said zone through inlet/vent conduit means for first applying sufficient hydraulic pressure to said zone to hold said needle means down on its seat prior to initiation of an injection event, next partially venting liquid pressure from said zone sufficiently for said needle means to rise off of said seat a small constant low-lift increment for injection of a small pilot fuel charge into the engine, and then further venting liquid pressure from said zone sufficiently for said needle means to rise to a higher lift position for injection of the main fuel charge into the engine. - View Dependent Claims (54, 55, 56, 57, 58, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75)
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59. In an internal combustion engine accumulator-type fuel injector, apparatus for injecting a small pilot charge for reducing undesirable premixed burning of the main charge, which comprises:
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elongated valve element needle means longitudinally slideable in the body means of the injector adapted to close against the valve seat of the injector and having an upper end; a liquid pressure zone defined in said body means above said needle means upper end for applying downward force on said needle means upper end which increases with increased liquid pressure in said zone and decreases with decreased liquid pressure in said zone; hydraulic circuit means in liquid communication with said zone through inlet/vent conduit means for first applying sufficient hydraulic pressure to said zone to hold said needle means down on its seat prior to initiation of an injection event, next partially venting liquid pressure from said zone sufficiently for said needle means to rise off of said seat a small low-lift increment for injection of a small pilot fuel charge into the engine, and then further venting liquid pressure from said zone sufficiently for said needle means to rise to a full lift position for injection of the main fuel charge into the engine; said hydraulic circuit means being adapted to relatively slowly vent pressurized liquid from said zone to produce said low-lift increment of lift of said needle means, and them to relatively rapidly vent pressurized liquid from said zone to produce said raising of said needle means to its said full lift position; bleed orifice means in said hydraulic circuit means through which pressurized liquid is bled to produce said relatively slow venting; said hydraulic circuit means comprising primary vent conduit means; and control valve means in said hydraulic circuit means for isolating said primary vent conduit means from said zone prior to initiation of an injection event and during said relatively slow venting, and for placing said vent conduit means in communication with said primary vent conduit means to produce said relatively rapid venting. - View Dependent Claims (60, 61, 62, 63, 64, 65)
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76. 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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raising injector needle means off its valve seat a small low-lift increment for a sufficient interval of time to inject a small pilot fuel charge into the engine; and then raising the needle means to a higher lift position to inject the main fuel charge into the engine; controlling needle life by controlled venting of pressurized liquid from pressurized zone means located above upwardly facing surface means of said needle means; providing said pressurized zone means in the form of cavity means above said upwardly facing surface means of said needle means; providing stop plate means in said cavity means normally disposed at a lower position in which there is an axial clearance space between said upwardly facing surface means of said needle means and a downwardly facing surface of said plate means which defines said low-lift increment; establishing downward force-transmitting means generally axially directed through said plate means to said upwardly facing surface means of said needle means; sealing said plate means relative to wall means of said cavity means in said lower position of said plate means such that downward force on said upwardly facing surface means of said needle means for liquid pressure in said cavity means above said plate means is restricted to said force-transmitting means; establishing sufficient liquid pressure in said cavity means prior to initiation of an injection event for said force-transmitting means to, with the aid of needle closure spring force, hold said needle means down against its seat against upward force of accumulator pressure on said needle means; venting liquid pressure from said cavity means sufficiently for upward force of accumulator pressure on said needle means to overcome the combined downward forces of said force-transmitting means and the needle spring, but insufficient to overcome the downward force of liquid pressure in said cavity means against said plate means, causing said needle means to lift into engagement with said plate means bottom surface in said low-life increment of needle movement; and further venting liquid pressure from said cavity means sufficiently for upward force of accumulator pressure on said needle means to overcome the combined downward forces of said force-transmitting means, the needle spring, and the force of liquid pressure in said cavity means on said plate means, causing said needle means to lift, together with said plate means, to its said higher lift position. - View Dependent Claims (77, 78, 79, 80, 81, 82, 83, 84, 85, 86)
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87. In an internal combustion engine accumulator-type fuel injector, apparatus for injecting a small pilot charge for reducing undesirable premixed burning of the main charge, which comprises:
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elongated valve element needle means longitudinally slideable in the body means of the injector having a lower tip adapted to close against the valve seat of the injector and having an upper end, said needle means having upwardly facing surface means; cavity means defined within said body means above said surface means of said needle means; liquid inlet/vent conduit means communicating with said cavity means for sequentially introducing pressurized liquid into said cavity means and venting pressurized liquid from said cavity means; stop plate means in said cavity means normally disposed at a lower, seated position in which there is an axial clearance space between said surface means of said needle means and a downwardly facing surface of said plate means which defines a low-lift increment of movement of said needle means, said stop plate means having downward force-transmitting means generally axially directed therethrough to said surface means of said needle means; said plate means being sealed relative to wall means of said cavity means in said lower position of said plate means such that downward force on said surface means of said needle means from fluid pressure in said cavity means above said plate means is restricted to said force-transmitting means; fluid pressure introduced into said cavity means through said conduit means prior to an injection event being sufficient for said force-transmitting means, with the aid of the force of the needle closure spring, to hold said needle means down against its seat against upward force of accumulator pressure on said needle means; fluid pressure remaining in said cavity means after partial venting of fluid pressure from said cavity means through said conduit means being sufficiently reduced for upward force of accumulator pressure on said needle means to overcome the combined downward forces of said force-transmitting means and the needle spring, but still being sufficient for its downward force against said plate means to hold said plate means in its seated position, whereby said needle means will lift into engagement with said plate means downwardly facing surface in said low-lift increment of movement to inject said pilot charge; and further venting of fluid pressure from said cavity means enabling upward force of accumulator pressure on said needle means to overcome the combined downward forces of said force-transmitting means, the needle spring, and the force of fluid pressure in said cavity means on said plate means, whereby said needle means will lift, together with said plate means, to a higher lift position. - View Dependent Claims (88, 89, 90, 91, 92, 93)
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Specification