EP2113653A1 - Fluid Pump - Google Patents
Fluid Pump Download PDFInfo
- Publication number
- EP2113653A1 EP2113653A1 EP08155497A EP08155497A EP2113653A1 EP 2113653 A1 EP2113653 A1 EP 2113653A1 EP 08155497 A EP08155497 A EP 08155497A EP 08155497 A EP08155497 A EP 08155497A EP 2113653 A1 EP2113653 A1 EP 2113653A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- pump
- bearing
- drive shaft
- fluid
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
- F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
- F02M59/10—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by the piston-drive
- F02M59/102—Mechanical drive, e.g. tappets or cams
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
- F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
- F02M59/04—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by special arrangement of cylinders with respect to piston-driving shaft, e.g. arranged parallel to that shaft or swash-plate type pumps
- F02M59/06—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by special arrangement of cylinders with respect to piston-driving shaft, e.g. arranged parallel to that shaft or swash-plate type pumps with cylinders arranged radially to driving shaft, e.g. in V or star arrangement
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
- F04B1/0404—Details or component parts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
- F04B1/0404—Details or component parts
- F04B1/0413—Cams
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
- F04B53/08—Cooling; Heating; Preventing freezing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
- F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
- F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails
Definitions
- the invention relates to a fluid pump.
- the invention relates to a pump for delivering pressurised fuel to a fuel injection system of an internal combustion engine.
- the fuel pump In known common rail engines, the fuel pump typically pressurises fuel at relatively low pressure to in excess of 2000 bar for delivery to the associated fuel injection equipment.
- Such fuel pumps commonly take the form of a positive displacement pump.
- Positive displacement pumps work by receiving a known volume of relatively low pressure fuel and subsequently displacing the volume of fuel once pressurised.
- One such positive displacement pump is a radial pump housing a plurality of pump assemblies, all of which are driven by a common drive shaft.
- the drive shaft which carries a cam, is supported in a drive shaft housing by a front bearing and a rear bearing and is driven by the engine.
- the present invention provides a means of modifying the drive shaft housing to reduce the operational temperature of the rear bearing and, in so doing, increases the service life of the pump and the speeds and loads which can be applied to the bearings.
- a fluid pump comprises a drive shaft for driving at least one pumping plunger, a drive shaft housing and a bearing for supporting the drive shaft within the drive shaft housing.
- the fluid pump further comprises means for supplying fluid to the bearing, and means for maintaining a fluid pressure difference across the bearing to maintain fluid flow across the bearing to effect cooling thereof.
- the invention is particularly useful when applied to a fuel pump where, preferably, the fluid is fuel.
- the fuel pump may be for use in delivering fuel to a common rail of an internal combustion engine.
- the pump may be a radial pump having a plurality of pumping plungers radially spaced around the drive shaft.
- the fluid pressure difference is maintained between a first chamber at one end of the bearing and a second chamber spaced from the first chamber along the length of the bearing.
- the second chamber is positioned at the opposite end of the bearing from the first chamber.
- the first chamber of the pump forms a rear chamber located at a rear end of the bearing
- the second chamber of the pump forms a front chamber which defines a cam box of the pump suitable for housing a cam carried by the drive shaft.
- the bearing is a rear bearing carried towards the rear of the drive shaft, the drive shaft carrying a front bearing also towards its front end.
- a source of pressurised fluid may be used for supplying fluid to the first and second chambers through a flow path.
- the flow path communicates with the first chamber directly so that the pressure of fluid in the flow path is substantially the same as that within the first chamber.
- the flow path also communicates with the second chamber, but through an orifice, which serves to lower the fluid pressure in the second chamber with respect to the fluid pressure in the first chamber, therefore maintaining the pressure difference across the two chambers.
- One such source of pressurised fluid takes the form of a pump, for example a transfer pump or electric lift pump.
- the fuel pump 10 takes the form of a radial pump having three pump assemblies 12 arranged at equally spaced locations around a drive shaft 14. Each pump assembly 12 includes a plunger 16 which is driven by means of a tappet 18 so as to pressurise fuel within an associated pumping chamber 19.
- An engine-driven drive shaft 14 carrying a cam 20 extends through a housing bore 24 provided in a drive shaft housing 26.
- the drive shaft 14 is mounted on a front bearing (not shown) provided in a front region of the housing bore 24 (referred to as the front housing bore 28) and on a rear bearing 30 provided in a rear region of the housing bore 24 (referred to as the rear housing bore 32).
- the front housing bore 28 is so-called because it is the region of the pump 10 that is nearest to the engine (not shown).
- the cam 20 is located adjacent to a shoulder 34 between the front housing bore 28 and the rear housing bore 32 and, therefore, the front housing bore 28 defines a chamber in the form of the engine's cam box 36.
- the drive shaft 14 carries a cam rider 33 which, on its internal diameter, cooperates with the drive shaft 14 and, on its external diameter, is provided with three flats 35, each of which cooperates with a respective one of the tappets 18.
- the tappets 18 As the cam 20 rotates with the drive shaft 14, cooperation between the rider 33 and the tappets 18 causes the tappets 18 to be driven radially outward from the drive shaft 14 in a phased cyclical manner.
- the tappets 18 return along the same path, in a radially inward direction, under the influence of an associated spring 38. Movement of the tappets 18 causes the plungers 16 to perform a pumping cycle including a pumping stroke in which the plungers 16 are driven radially outwards from the drive shaft 14, and a return stroke in which the plungers 16 are returned radially inwards towards the drive shaft 14.
- Fuel is drawn into the pumping chambers 19 during the return stroke from a relatively low pressure source of fuel 40 and fuel that is pressurised during the pumping stroke is delivered through an associated outlet valve 41 to an accumulator volume (the common rail, not shown) that is common to all three pump assemblies 12.
- Fuel within the pumping chambers 19 is typically pressurised to a level in excess of 2000 bar and, thus, the pumping loads acting on the plungers 16, and hence on the tappets 18 and the drive shaft 14, are high. As a consequence, considerable heating of the front and rear bearings occurs, and particularly the rear bearing 30.
- the rear housing bore 32 has a region of enlarged diameter at its rear end to provide a chamber 42 which is in communication with the cam box 36 by way of a bearing drilling 44.
- One end of the bearing drilling 44 opens into the cam box 36 at the shoulder 34 between the front housing bore 28 and the rear housing bore 32 and the other end of the bearing drilling 44 opens into the chamber 42.
- the bearing drilling 44 extends along the length of the rear bearing 30 parallel to the rear housing bore 32.
- the rear bearing 30 supports the drive shaft 14 in the rear housing bore 32 and allows the drive shaft 14 to rotate about its axis 46.
- FIG. 5 shows the fuel flow paths to and from the fuel pump 10.
- An outlet 47 from the pressurised fuel source 40 delivers fuel to the pumping chambers 19, as described above, and to a flow path 56 which communicates with the cam box 36 via a pressure-reducing orifice 48, which serves to reduce the pressure of the fluid going into the cam box 36 relative to that at the outlet 47.
- Fuel delivered to the cam box 36 is able to flow through the bearing drilling 44 into the chamber 42 and is also able to flow through a clearance (or clearances) between the rear bearing 30 and the rear housing bore 32.
- Fuel delivered to the cam box 36 is also able to flow back to the engine fuel tank via a backleak passage 50, ensuring a constant supply of fuel through the cam box 36.
- the pumping chambers 19 deliver pressurised fuel to a high pressure circuit 52 for delivery to the common rail.
- the fuel pressure distribution across the bearing drilling 44 connecting the chamber 42 to the cam box 36 is substantially uniform, so that there is only a minimal net fluid flow between the chamber 42 and the cam box 36.
- a uniform pressure distribution also exists across the clearances between the rear bearing 30 and the rear housing bore 32, which also connect the chamber 42 to the cam box 36, and across internal clearances of the rear bearing 30.
- the present invention improves the above-described pump by modifying the drive shaft housing 26 to reduce the operational temperature of the rear bearing 30 by increasing the effect of convection cooling.
- the construction of the drive shaft housing 26 is the same as described previously, in terms of the front and rear bearings, the housing bore 24 and the cam box 36, but differs in key respects.
- the bearing drilling 44 of the known pump, between the chamber 42 and the cam box 36, is removed.
- the flow path 56 from the pressurised fuel source 40 is connected to the chamber 42 at the rear end of the rear housing bore 32.
- the pressurised fuel source 40 is in direct communication with the chamber 42, rather than communicating with the chamber 42 only via the orifice 48 and the cam box 36.
- Fuel from the pressurised fuel source 40 which is delivered to the cam box 36 is therefore divided into two fuel streams: one fuel stream flows through the orifice 48 and into the cam box 36 directly and a second fuel stream flows into the chamber 42 at the rear end of the rear housing bore 32 and from there into the cam box 36 through the clearances between the rear bearing 30 and the rear housing bore 32.
- Fuel pressure in the cam box 36 is substantially equal to fuel pressure at the outlet of the orifice 48
- fuel pressure in the chamber 42 is substantially equal to fuel pressure delivered from the outlet 47 of the pressurised fuel source 40. Therefore, a substantial pressure difference exists across the rear bearing 30, between the chamber 42 and the cam box 36, which is maintained during pump operation meaning that a net flow of fuel is maintained through the internal clearances of the rear bearing 30 and between the rear housing bore 32 and the rear bearing 30.
- connection of the outlet 47 of the pressurised fuel source 40 to the chamber 42 at the rear end of the rear housing bore 32 provides a means of maintaining a pressure difference across the rear bearing 30 to cause fuel to flow from the chamber 42, through the internal clearances of the rear bearing 30 and into the cam box 36, thereby increasing cooling of the rear bearing 30 by convection.
- the present invention is not limited to the type of pump described with references to Figures 1 to 5 .
- the invention could be applied to any type of fluid pump, and not necessarily a fuel pump, where the support bearings for the drive shaft are prone to wear due to heating effects.
- the pump may include any number of pump assemblies and plungers (e.g. one, two, three or more than three) and may be applied to pump configurations other than radial.
- the means for establishing a significant pressure difference across the rear bearing need not derive from a transfer pump, but may be any other source of pressurised fluid or fuel. In some applications it is possible for a fluid source other than a fuel to be used to cool the rear bearing.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Fuel-Injection Apparatus (AREA)
Abstract
Description
- The invention relates to a fluid pump. In particular, but not exclusively, the invention relates to a pump for delivering pressurised fuel to a fuel injection system of an internal combustion engine.
- In known common rail engines, the fuel pump typically pressurises fuel at relatively low pressure to in excess of 2000 bar for delivery to the associated fuel injection equipment. Such fuel pumps commonly take the form of a positive displacement pump. Positive displacement pumps work by receiving a known volume of relatively low pressure fuel and subsequently displacing the volume of fuel once pressurised.
- One such positive displacement pump is a radial pump housing a plurality of pump assemblies, all of which are driven by a common drive shaft. The drive shaft, which carries a cam, is supported in a drive shaft housing by a front bearing and a rear bearing and is driven by the engine.
- Because the pump is required to pressurise fuel to several thousand bar, high pumping loads are transmitted to the drive shaft and, hence, to the front and rear bearings. In known pumps, the rear bearing is commonly recognised as the weakest bearing due to inadequate cooling, often leading to pump failure.
- The present invention provides a means of modifying the drive shaft housing to reduce the operational temperature of the rear bearing and, in so doing, increases the service life of the pump and the speeds and loads which can be applied to the bearings.
- According to the invention, a fluid pump comprises a drive shaft for driving at least one pumping plunger, a drive shaft housing and a bearing for supporting the drive shaft within the drive shaft housing. The fluid pump further comprises means for supplying fluid to the bearing, and means for maintaining a fluid pressure difference across the bearing to maintain fluid flow across the bearing to effect cooling thereof.
- The invention is particularly useful when applied to a fuel pump where, preferably, the fluid is fuel. For example, the fuel pump may be for use in delivering fuel to a common rail of an internal combustion engine. The pump may be a radial pump having a plurality of pumping plungers radially spaced around the drive shaft.
- In the above mentioned application, because the bearing is continually cooled by the fluid flow across it, the operational fatigue experienced by the bearing is reduced and, as a result, the service life and the performance of the pump is increased.
- In one embodiment the fluid pressure difference is maintained between a first chamber at one end of the bearing and a second chamber spaced from the first chamber along the length of the bearing. In a preferred embodiment of the invention, the second chamber is positioned at the opposite end of the bearing from the first chamber.
- Preferably the first chamber of the pump forms a rear chamber located at a rear end of the bearing, and the second chamber of the pump forms a front chamber which defines a cam box of the pump suitable for housing a cam carried by the drive shaft. Typically the bearing is a rear bearing carried towards the rear of the drive shaft, the drive shaft carrying a front bearing also towards its front end.
- A source of pressurised fluid may be used for supplying fluid to the first and second chambers through a flow path. The flow path communicates with the first chamber directly so that the pressure of fluid in the flow path is substantially the same as that within the first chamber. The flow path also communicates with the second chamber, but through an orifice, which serves to lower the fluid pressure in the second chamber with respect to the fluid pressure in the first chamber, therefore maintaining the pressure difference across the two chambers. One such source of pressurised fluid takes the form of a pump, for example a transfer pump or electric lift pump.
- The state of the art and the preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
-
Figure 1 is a sectional view of a state of the art fuel pump; -
Figure 2 is a cross-sectional view of a drive shaft housing of the pump inFigure 1 prior to assembly with the drive shaft and associated bearings; -
Figure 3 is a sectional view of the drive shaft housing inFigure 2 ; -
Figure 4 is a cross-sectional view of the drive shaft housing inFigures 2 and 3 with the rear bearing and drive shaft assembled; -
Figure 5 is a fuel flow circuit diagram of the pump inFigures 1 to 4 ; and, -
Figure 6 is a fuel flow circuit diagram of a fuel pump of the present invention. - An example of a known fuel pump suitable for delivering pressurised fuel to the fuel injection system of an engine is the common rail diesel fuel pump described in
EP 1629191 . Referring toFigures 1 to 4 , thefuel pump 10 takes the form of a radial pump having threepump assemblies 12 arranged at equally spaced locations around adrive shaft 14. Eachpump assembly 12 includes aplunger 16 which is driven by means of atappet 18 so as to pressurise fuel within an associatedpumping chamber 19. - An engine-driven
drive shaft 14 carrying a cam 20 extends through ahousing bore 24 provided in adrive shaft housing 26. Thedrive shaft 14 is mounted on a front bearing (not shown) provided in a front region of the housing bore 24 (referred to as the front housing bore 28) and on arear bearing 30 provided in a rear region of the housing bore 24 (referred to as the rear housing bore 32). The front housing bore 28 is so-called because it is the region of thepump 10 that is nearest to the engine (not shown). The cam 20 is located adjacent to ashoulder 34 between the front housing bore 28 and the rear housing bore 32 and, therefore, the front housing bore 28 defines a chamber in the form of the engine'scam box 36. Thedrive shaft 14 carries acam rider 33 which, on its internal diameter, cooperates with thedrive shaft 14 and, on its external diameter, is provided with threeflats 35, each of which cooperates with a respective one of thetappets 18. - As the cam 20 rotates with the
drive shaft 14, cooperation between therider 33 and thetappets 18 causes thetappets 18 to be driven radially outward from thedrive shaft 14 in a phased cyclical manner. Thetappets 18 return along the same path, in a radially inward direction, under the influence of an associatedspring 38. Movement of thetappets 18 causes theplungers 16 to perform a pumping cycle including a pumping stroke in which theplungers 16 are driven radially outwards from thedrive shaft 14, and a return stroke in which theplungers 16 are returned radially inwards towards thedrive shaft 14. Fuel is drawn into thepumping chambers 19 during the return stroke from a relatively low pressure source offuel 40 and fuel that is pressurised during the pumping stroke is delivered through an associatedoutlet valve 41 to an accumulator volume (the common rail, not shown) that is common to all threepump assemblies 12. - Fuel within the
pumping chambers 19 is typically pressurised to a level in excess of 2000 bar and, thus, the pumping loads acting on theplungers 16, and hence on thetappets 18 and thedrive shaft 14, are high. As a consequence, considerable heating of the front and rear bearings occurs, and particularly the rear bearing 30. - The
rear housing bore 32 has a region of enlarged diameter at its rear end to provide achamber 42 which is in communication with thecam box 36 by way of abearing drilling 44. One end of thebearing drilling 44 opens into thecam box 36 at theshoulder 34 between the front housing bore 28 and the rear housing bore 32 and the other end of thebearing drilling 44 opens into thechamber 42. Thebearing drilling 44 extends along the length of the rear bearing 30 parallel to therear housing bore 32. Therear bearing 30 supports thedrive shaft 14 in therear housing bore 32 and allows thedrive shaft 14 to rotate about itsaxis 46. - The purpose of the
bearing drilling 44 in thedrive shaft housing 26 is illustrated with reference toFigure 5 which shows the fuel flow paths to and from thefuel pump 10. Anoutlet 47 from thepressurised fuel source 40 delivers fuel to thepumping chambers 19, as described above, and to aflow path 56 which communicates with thecam box 36 via a pressure-reducingorifice 48, which serves to reduce the pressure of the fluid going into thecam box 36 relative to that at theoutlet 47. Fuel delivered to thecam box 36 is able to flow through the bearing drilling 44 into thechamber 42 and is also able to flow through a clearance (or clearances) between the rear bearing 30 and therear housing bore 32. Fuel delivered to thecam box 36 is also able to flow back to the engine fuel tank via abackleak passage 50, ensuring a constant supply of fuel through thecam box 36. Thepumping chambers 19 deliver pressurised fuel to ahigh pressure circuit 52 for delivery to the common rail. - The fuel pressure distribution across the bearing drilling 44 connecting the
chamber 42 to thecam box 36 is substantially uniform, so that there is only a minimal net fluid flow between thechamber 42 and thecam box 36. A uniform pressure distribution also exists across the clearances between the rear bearing 30 and therear housing bore 32, which also connect thechamber 42 to thecam box 36, and across internal clearances of therear bearing 30. As the pressure difference across thebearing drilling 44 is minimal or non-existent, only a moderate amount of heat transfer (or substantially no heat transfer) away from therear bearing 30 is achieved by convection due to the limited flow through thebearing drilling 44, resulting in a concentration of hot fuel in thechamber 42. Likewise, there is only minimal, or substantially no, heat transfer by convection due to lack of a fuel pressure difference across the bearing clearances or between the rear bearing 30 and the rear housing bore 32. The amount of heat transfer through conduction is not sufficient to remove the concentration of hot fuel in thechamber 42 and, therefore, the extent of cooling of the rear bearing 30 is relatively low and has been found to be inadequate in certain circumstances. - The present invention improves the above-described pump by modifying the
drive shaft housing 26 to reduce the operational temperature of the rear bearing 30 by increasing the effect of convection cooling. The construction of thedrive shaft housing 26 is the same as described previously, in terms of the front and rear bearings, the housing bore 24 and thecam box 36, but differs in key respects. - Referring to
Figure 6 , in the present invention the bearingdrilling 44 of the known pump, between thechamber 42 and thecam box 36, is removed. In addition, theflow path 56 from the pressurisedfuel source 40 is connected to thechamber 42 at the rear end of the rear housing bore 32. In other words, the pressurisedfuel source 40 is in direct communication with thechamber 42, rather than communicating with thechamber 42 only via theorifice 48 and thecam box 36. - Fuel from the pressurised
fuel source 40 which is delivered to thecam box 36 is therefore divided into two fuel streams: one fuel stream flows through theorifice 48 and into thecam box 36 directly and a second fuel stream flows into thechamber 42 at the rear end of the rear housing bore 32 and from there into thecam box 36 through the clearances between therear bearing 30 and the rear housing bore 32. Fuel pressure in thecam box 36 is substantially equal to fuel pressure at the outlet of theorifice 48, and fuel pressure in thechamber 42 is substantially equal to fuel pressure delivered from theoutlet 47 of the pressurisedfuel source 40. Therefore, a substantial pressure difference exists across therear bearing 30, between thechamber 42 and thecam box 36, which is maintained during pump operation meaning that a net flow of fuel is maintained through the internal clearances of therear bearing 30 and between the rear housing bore 32 and therear bearing 30. - The connection of the
outlet 47 of the pressurisedfuel source 40 to thechamber 42 at the rear end of the rear housing bore 32 provides a means of maintaining a pressure difference across therear bearing 30 to cause fuel to flow from thechamber 42, through the internal clearances of therear bearing 30 and into thecam box 36, thereby increasing cooling of therear bearing 30 by convection. - It will be appreciated that the present invention is not limited to the type of pump described with references to
Figures 1 to 5 . The invention could be applied to any type of fluid pump, and not necessarily a fuel pump, where the support bearings for the drive shaft are prone to wear due to heating effects. The pump may include any number of pump assemblies and plungers (e.g. one, two, three or more than three) and may be applied to pump configurations other than radial. Also, the means for establishing a significant pressure difference across the rear bearing need not derive from a transfer pump, but may be any other source of pressurised fluid or fuel. In some applications it is possible for a fluid source other than a fuel to be used to cool the rear bearing.
Claims (11)
- A fluid pump comprising a drive shaft (14) for driving at least one pumping plunger (16), a drive shaft housing (26), a bearing (30) for supporting the drive shaft (14) within the draft shaft housing (26), means (56, 48) for supplying fluid to the bearing (30), and means (40) for maintaining a fluid pressure difference across the bearing (30) to maintain fluid flow across the bearing (30) to effect cooling thereof.
- The pump as claimed in claim 1, wherein the means for supplying fluid includes a flow path (56) provided with an orifice (48) through which fluid flows into the drive shaft housing (26).
- The pump as claimed in claim 2, including a source of pressurised fluid for supplying fluid to the flow path (56).
- The pump as claimed in claim 3, wherein the source of pressurised fluid is a pump (40).
- The pump as claimed in any one of claims 2 to 4, wherein the drive shaft housing (26) includes a first chamber (42) at one end of the bearing (30) and a second chamber (36) spaced from the first chamber (42) along the bearing (30), whereby the fluid pressure difference is maintained across the first and second chambers (42, 36).
- The pump as claimed in claim 5, wherein the second chamber (36) is at the other end of the bearing (30).
- The pump as claimed in claim 5 or claim 6, wherein the flow path (56) communicates with the second chamber (36) through the orifice (48).
- The pump as claimed in claim 7, wherein the flow path (56) communicates with the first chamber (42) directly so that the pressure of fluid in the flow path (56) is substantially the same as that within the first chamber (42).
- The pump as claimed in any one of claims 1 to 8, wherein the fluid is fuel.
- The pump as claimed in claim 9, for use in delivering fuel to a common rail of an internal combustion engine.
- The pump as claimed in claim 10, wherein the pump is a radial pump (10) having a plurality of pumping plungers (16) radially spaced around the drive shaft (14).
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP08155497A EP2113653A1 (en) | 2008-04-30 | 2008-04-30 | Fluid Pump |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP08155497A EP2113653A1 (en) | 2008-04-30 | 2008-04-30 | Fluid Pump |
Publications (1)
Publication Number | Publication Date |
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EP2113653A1 true EP2113653A1 (en) | 2009-11-04 |
Family
ID=39832612
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP08155497A Withdrawn EP2113653A1 (en) | 2008-04-30 | 2008-04-30 | Fluid Pump |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP2113653A1 (en) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1992016738A1 (en) * | 1991-03-22 | 1992-10-01 | Robert Bosch Gmbh | Fuel injection pump |
US6077050A (en) * | 1996-04-04 | 2000-06-20 | Brueninghaus Hydromatik Gmbh | Axial piston machine with internal flushing circuit |
EP1629191A1 (en) | 2003-05-22 | 2006-03-01 | Delphi Technologies, Inc. | Pump assembly |
DE102006013165A1 (en) * | 2006-03-22 | 2007-09-27 | Robert Bosch Gmbh | High-pressure fuel pump and fuel injection system for an internal combustion engine |
DE102006045899A1 (en) * | 2006-09-28 | 2008-04-03 | Siemens Ag | Crank drive for crank drive pump and use in a fuel pump |
-
2008
- 2008-04-30 EP EP08155497A patent/EP2113653A1/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1992016738A1 (en) * | 1991-03-22 | 1992-10-01 | Robert Bosch Gmbh | Fuel injection pump |
US6077050A (en) * | 1996-04-04 | 2000-06-20 | Brueninghaus Hydromatik Gmbh | Axial piston machine with internal flushing circuit |
EP1629191A1 (en) | 2003-05-22 | 2006-03-01 | Delphi Technologies, Inc. | Pump assembly |
DE102006013165A1 (en) * | 2006-03-22 | 2007-09-27 | Robert Bosch Gmbh | High-pressure fuel pump and fuel injection system for an internal combustion engine |
DE102006045899A1 (en) * | 2006-09-28 | 2008-04-03 | Siemens Ag | Crank drive for crank drive pump and use in a fuel pump |
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