IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0477246
(2002-09-10)
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국제출원번호 |
PCT//US02/28685
(2003-11-10)
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§371/§102 date |
20031110
(20031110)
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국제공개번호 |
WO03//02323
(2003-03-20)
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발명자
/ 주소 |
|
출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
4 인용 특허 :
6 |
초록
▼
The invention is directed to the combination of fuel rail pressure control at lower speed using high pressure regulation plus fuel rail pressure control at higher speed using any of a variety of forms of inlet metering. The partial filing control at high speed can in one embodiment include pre-meter
The invention is directed to the combination of fuel rail pressure control at lower speed using high pressure regulation plus fuel rail pressure control at higher speed using any of a variety of forms of inlet metering. The partial filing control at high speed can in one embodiment include pre-metering the quantity of feed fuel delivered to each pumping chamber, for example by modulating the feed pressure at the pumping chamber inlet. Another embodiment includes passing the feed fuel from the inlet passage through a fixed, calibrated orifice sized to pass sufficient feed fuel to fill the pumping chambers in the charging phase during operation of the engine in the low speed range, while in the high speed range the flow resistance of the orifice prevents the pumping chamber from filling in the charging phase, thereby monotonically decreasing the quantity of high pressure fuel delivered to the discharge passage in the discharge phase per engine revolution, with increasing speed above the transition speed.
대표청구항
▼
1. In a high pressure common rail fuel supply system for delivering fuel to an internal combustion engine having a plurality of combustion cylinders and a respective plurality of fuel injectors fluidly connected to the common rail for injecting fuel into the cylinders at the pressure of the common r
1. In a high pressure common rail fuel supply system for delivering fuel to an internal combustion engine having a plurality of combustion cylinders and a respective plurality of fuel injectors fluidly connected to the common rail for injecting fuel into the cylinders at the pressure of the common rail for operating the engine at speeds ranging from cranking speed to a maximum speed, the system including a high pressure fuel supply pump with radial pistons reciprocating in pumping chambers and driven by the engine at a pump speed proportional to the engine speed, a method of pumping fuel to the common rail at a rail target pressure, comprising:continuously delivering feed fuel at a low pressure, to an inlet port of the pump; during operation of the engine in a low speed range below a transition speed, (a) (1) filling each pumping chamber during a charging phase, from inlet passages in fluid communication with the inlet port, (2) pressurizing the charged fuel in the pumping chambers by displacing the respective pistons during a discharge phase, and (3) delivering the discharged fuel to a discharge passageway in fluid communication with the common rail, and (b) maintaining the rail target pressure by continually diverting at least some of the pressurized fuel in at least one of the discharge passage or the common rail, to a low pressure sink; during operation of the engine in a high-speed range above the transition speed, (c) (1) partially filling each pumping chamber during the charging phase, from said inlet passages, (2) pressurizing the charged fuel in the pumping chambers by displacing the respective pistons during the discharge phase, and (3) delivering the discharged fuel to the discharge passageway, and (d) maintaining the rail target pressure by continually diverting at least some of the pressurized fuel in at least one of the discharge passage or the common rail, to the low pressure sink. 2. The method of claim 1, wherein the step (c) (1) includes pre-metering the quantity of feed fuel delivered to each pumping chamber.3. The method of claim 2, wherein the pre-metering is performed by an electronically operated valve.4. The method of claim 3, wherein the pre-metering is performed by a proportional solenoid valve.5. The method of claim 1, wherein the step (c) (1) includes controlling the quantity of low pressure fuel delivered to each pumping chamber by modulating a proportional solenoid valve.6. The method of claim 2, wherein the step (a) (1) includes passing the feed fuel from the inlet port through an unrestricted aperture sized to pass sufficient feed fuel through the inlet passages to fill the pumping chambers in the charging phase during operation of the engine in the low speed range, and the step (c) (1) includes modulating the size of the aperture such that flow resistance of the aperture prevents the pumping chambers from filling in the charging phase, thereby decreasing the quantity of high pressure fuel delivered to the discharge passage in the discharge phase per engine revolution, with increasing speed above said transition.7. The method of claim 2, wherein the step (a) (1) includes passing the feed fuel from the inlet port through an unrestricted aperture sized to pass sufficient feed fuel through the inlet passages to fill the pumping chambers in the charging phase during operation of the engine in the low speed range, and the step (c) (1) includes modulating a time interval during which the aperture is open such that the charging flow quantity varies to prevent the pumping chamber from filling in the charging phase, thereby decreasing the quantity of high pressure fuel delivered to the discharge passage in the discharge phase per engine revolution, with increasing speed above said transition.8. The method of claim 1, wherein the step (a) (1) includes passing the feed fuel from the inlet port through a fixed, calibrated orifice sized to pass sufficient feed fuel through the inlet passages to fill the pumping chambers in the charging phase during operation of the engine in the low speed range, and the step (c) (1) includes passing the feed fuel through said orifice such that flow resistance of the orifice prevents the pumping chamber from filling in the charging phase, thereby monotonically decreasing the quantity of high pressure fuel delivered to the discharge passage in the discharge phase per engine revolution, with increasing speed above said transition.9. The method of claim 8, whereinthe supply pump has a maximum quantity delivery rate per engine revolution, corresponding to full filling of the pumping chambers, the engine has a maximum speed corresponding to wide open throttle (WOT) and a fuel quantity demand per engine revolution corresponding to WOT, that is less than said pump maximum delivery rate per engine revolution, and the orifice is calibrated such that the quantity of high pressure fuel discharged into the discharge passage per engine revolution at the maximum engine speed, is greater than the fuel quantity demand per engine revolution corresponding to WOT, but no greater than about 75% of the pump maximum quantity delivery rate per engine revolution. 10. The method of claim 9, whereinthe engine has a speed corresponding to the engine maximum torque, which is lower than the speed corresponding to WOT, and a fuel demand per engine revolution corresponding to the maximum torque that is less than said pump maximum delivery rate per engine revolution, and the method further comprises reducing the pressure of the feed fuel delivered to the pump inlet port when the engine speed is above the transition speed but below the speed corresponding to WOT. 11. The method of claim 1, wherein steps (b) and (d) include exposing the fuel in the discharge line to a hydro/mechanical pressure limiting valve having a back side in fluid communication with the inlet port and a variable accumulator volume whereby pressure transients resulting from small excess quantities of pumped fuel are absorbed within the accumulator volume without fluid transfer through the back side of the valve, and pressure transients resulting from large excess quantities of pumped fuel are relieved by exposure to the low pressure sink pressure of the inlet port.12. The method of claim 1, wherein an inlet sump cavity is situated within the pump between the inlet port and the inlet passageways for the pumping chambers, and the steps (a) (1) and (c) (1) are performed between the inlet sump and pumping chambers.13. The method of claim 1, wherein the inlet passageways to the pumping chambers include calibrated orifices through the piston chamber walls, for delivering of feed fuel during the charging phase.14. The method of claim 1, wherein the pistons are anti-cavity shuttle pistons.15. The method of claim 1, wherein steps (b) and (d) include electronically controlling the rail target pressure.16. The method of claim 11, wherein steps (b) and (d) include controlling the target rail pressure by adjusting the pressure differential at which the pressure limiting valve opens.17. A high pressure fuel supply pump for receiving fuel from a fuel tank at low feed pressure discharging high pressure fuel to a common rail for delivery to an internal combustion engine having a plurality of combustion cylinders and a respective plurality of fuel injectors fluidly connected to the common rail for injecting fuel into the cylinders at the pressure of the common rail for operating the engine at speeds ranging from cranking speed to a maximum speed, said pump comprising:a housing, a pump shaft situated within the housing, a plurality of radial pistons mounted for reciprocation in respective pumping chambers and for actuation by the engine at a pump speed proportional to the engine speed; an inlet port for receiving feed fuel at said feed pressure, and inlet passages fluidly connected in parallel between the inlet port and the pumping chambers for delivering feed fuel to the pumping chambers during a charging phase of operation; a discharge port for discharging high pressure fuel to the common rail, and discharge passageways from the pumping chambers to the discharge port for delivering high pressure fuel from the pumping chambers during a pumping phase of operation; a pressure regulator for fluidly connecting the discharge passageways to the inlet passageways to divert at least some high pressure discharged fuel to low pressure feed fuel when the discharge pressure exceeds a limit value and for maintaining full discharge flow from the discharge passageways to the outlet port when the discharge pressure is below said limit value; and means situated between the inlet port and the parallel fluid passages, for restricting the flow of feed fuel through the inlet passages to the pumping chambers when the pump speed exceeds a predetermined threshold value. 18. The pump of claim 17, wherein the means for restricting the flow of feed fuel includes an electronic control unit that generates a feed fuel control signal responsive to engine speed.19. The pump of claim 18, wherein the includes an electronically controlled valve responsive to said control signal.20. The pump of claim 18, wherein the means for restricting the flow of feed fuel consists of a calibrated flow orifice.21. The pump of claim 18, wherein the pistons include an anti-cavitation chamber inside of each pumping plunger piston, formed by a coaxial cylindrical cavity and a loose pin such that during the charging event the anti-cavitation chamber and the main pumping chamber are both fully filled to a degree depending on the relationship between sump pressure P2 and modulated charging pressure P1, whereby before high pumping pressure can be generated the fuel in the anti-cavitation chamber must expelled.
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