A common rail fuel pump for an internal combustion engine includes a pumping plunger (10) that is reciprocable within a plunger bore (14) provided in a pump housing (16) under the influence of a drive arrangement (18, 20) to cause fuel pressurisation within a pump chamber (12). An inlet metering val
A common rail fuel pump for an internal combustion engine includes a pumping plunger (10) that is reciprocable within a plunger bore (14) provided in a pump housing (16) under the influence of a drive arrangement (18, 20) to cause fuel pressurisation within a pump chamber (12). An inlet metering valve (46) is operable to meter the quantity of fuel supplied to the pump chamber (12) during the return stroke of the plunger (10). An outlet valve (58) controls the supply of pressurised fuel from the pumping chamber (12) through an outlet passage (30) to the common rail fuel volume in circumstances in which the inlet metering valve is closed. The outlet passage (30) has a pump outlet (38), from where fuel is supplied to the common rail fuel volume. The inlet metering valve (46), the plunger (10) and the pump outlet (38) are arranged in axial alignment, providing a compact and lightweight pump for installation in existing and purpose-built engines.
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The invention claimed is: 1. A common rail fuel pump for supplying fuel to a common rail fuel volume of an internal combustion engine, the fuel pump comprising: a pumping plunger that is reciprocable within a plunger bore provided in a pump housing under the influence of a cam drive arrangement to
The invention claimed is: 1. A common rail fuel pump for supplying fuel to a common rail fuel volume of an internal combustion engine, the fuel pump comprising: a pumping plunger that is reciprocable within a plunger bore provided in a pump housing under the influence of a cam drive arrangement to cause fuel pressurization within a pump chamber, wherein the drive arrangement includes a cam driven drive member coupled to the plunger to impart drive thereto, in use, so that the plunger performs a pumping cycle including a pumping stroke and a return stroke; an inlet metering valve operable to permit control of the quantity of fuel supplied to the pump chamber during the return stroke of the plunger; and an outlet valve for controlling the supply of pressurized fuel from the pump chamber, through an outlet passage to the common rail fuel volume during the pumping stroke in circumstances in which the inlet metering valve is closed; wherein the outlet passage communicates with a pump outlet that is substantially co-axially aligned with the inlet metering valve and the plunger; wherein the inlet metering valve is operable: i) to open during the return stroke to permit fuel to be supplied to the pump chamber from a low pressure source, and ii) to close part way through the return stroke in order to meter the quantity of fuel that is supplied to the pump chamber during the return stroke. 2. The common rail fuel pump as claimed in claim 1, wherein the inlet metering valve comprises an elongate inlet valve member that is co-axially aligned with the plunger. 3. The common rail fuel pump as claimed in claim 1, wherein the inlet metering valve is housed within a valve housing, the valve housing being arranged so chat respective drillings provided in the valve housing and the pump housing align to define, at least in part, the outlet passage. 4. The common rail fuel pump as claimed in claim 1, wherein the outlet valve of the pump assembly is a hydraulically operable non-return valve located within the outlet passage. 5. The common rail fuel pump as claimed in claim 1, the inlet metering valve being further operable to allow opening thereof during the return stroke to permit filling of the pump chamber and to allow closure thereof following an initial period of the pumping stroke, thereby to permit a quantity of fuel within the pump chamber to be dispelled through the inlet metering valve to low pressure during the initial period. 6. The common rail fuel pump as claimed in claim 1, wherein the inlet metering valve is further operable to allow opening thereof prior to a final period of the pumping stroke so as to minimize Hertz stresses on a cam of the cain drive arrangement. 7. The common rail fuel pump as claimed in claim 1, wherein the plunger bore is provided with filling port, and wherein the plunger is co-operable with the filling port so that, when the plunger covers the filling port, fuel is unable to flow into the pump chamber through the filling port, and so that, when the plunger uncovers the filling port, fuel is able to flow into the pump chamber through the filling port. 8. The common rail fuel pump as claimed in claim 7, wherein the filling port is defined at one end of a filling passage provided in the pump housing, wherein said filling passage communicates with a low pressure fuel reservoir. 9. The common rail fuel pump as claimed in claim 1, wherein the inlet metering valve is a two-position, single seat valve. 10. A common rail fuel supply system, for use in an internal combustion engine, the system comprising a common rail fuel volume for supplying fuel to a plurality of fuel injectors of the engine and at least one common rail fuel pump, wherein said at least one common rail fuel pump comprises: a pumping plunger that is reciprocable within a plunger bore provided in a pump housing under the influence of a cam drive arrangement to cause fuel pressurization within a pump chamber, wherein the drive arrangement includes a cam driven drive member coupled to the plunger to impart drive thereto, in use, so that the plunger performs a pumping cycle including a pumping stroke and a return stroke; an inlet metering valve operable to permit control of the quantity of fuel supplied to the pump chamber during the return stroke of the plunger; and an outlet valve for controlling the supply of pressurized fuel from the pump chamber, through an outlet passage to the common rail fuel volume during the pumping stroke in circumstances in which the inlet metering valve is closed; wherein the outlet passage communicates with a pump outlet that is substantiauy co-axially aligned with the inlet metering valve and the plunger; wherein the inlet metering valve is operable: i) to open during the return stroke to permit fuel to be supplied to the pump chamber from a low pressure source, and ii) to close part way through the return stroke in order to meter the quantity of fuel that is supplied to the pump chamber during the return stroke; and wherein the or each common rail fuel pump is arranged to supply fuel through a respective pump outlet to the common rail fuel volume. 11. The common rail fuel supply system as claimed in claim 10, further comprising a plurality of common rail fuel pumps. 12. A control method for a common rail fuel pump as claimed in claim 1 comprising the steps of: holding the inlet metering valve open during the return stroke to permit fuel to be supplied to the pump chamber from a low pressure source, closing the inlet valve to permit pressurization of fuel within the pump chamber during the subsequent pumping stroke, and opening the inlet metering valve prior to a final period of the pumping stroke so as to terminate pressurization of fuel within the pump chamber and to ensure Hertz stresses on a cam of the cam drive arrangement are minimized. 13. The control method as claimed in claim 12, further comprising the step of closing the inlet metering valve after an initial period of the pumping stroke so as to dispel a proportion of fuel that is supplied to the pump chamber during the return stroke back to low pressure, thereby to control the quantity of fuel which is pressurized within the pump chamber during the pumping cycle.
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이 특허에 인용된 특허 (9)
Gibson Dennis H. (Chillicothe IL) Hefler Gregory W. (Dunlap IL) Shinogle Ronald D. (Peoria IL) Sommars Mark F. (Sparland IL), Electronically-controlled fluid injector system having pre-injection pressurizable fluid storage chamber and direct-oper.
Coldren, Dana R.; Funke, Steven J.; Donaldson, George E., Method of reducing noise in a mechanically actuated fuel injection system and engine using same.
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