WO2005038234A1 - Fuel pump with multiple cams - Google Patents

Fuel pump with multiple cams Download PDF

Info

Publication number
WO2005038234A1
WO2005038234A1 PCT/GB2004/004387 GB2004004387W WO2005038234A1 WO 2005038234 A1 WO2005038234 A1 WO 2005038234A1 GB 2004004387 W GB2004004387 W GB 2004004387W WO 2005038234 A1 WO2005038234 A1 WO 2005038234A1
Authority
WO
WIPO (PCT)
Prior art keywords
drive shaft
cams
pump
cam
pumping
Prior art date
Application number
PCT/GB2004/004387
Other languages
French (fr)
Inventor
Paul Buckley
Christopher Wood
Original Assignee
Delphi Technologies, Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Delphi Technologies, Inc. filed Critical Delphi Technologies, Inc.
Priority to EP04768917A priority Critical patent/EP1685325B1/en
Priority to DE602004005489T priority patent/DE602004005489T2/en
Publication of WO2005038234A1 publication Critical patent/WO2005038234A1/en

Links

Classifications

    • 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
    • F02M63/0205—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 for cutting-out pumps or injectors in case of abnormal operation of the engine or the injection apparatus, e.g. over-speed, break-down of fuel pumps or injectors ; for cutting-out pumps for stopping the engine
    • 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
    • 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
    • F04B9/00—Piston machines or pumps characterised by the driving or driven means to or from their working members
    • F04B9/02—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical
    • F04B9/04—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical the means being cams, eccentrics or pin-and-slot mechanisms
    • F04B9/042—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical the means being cams, eccentrics or pin-and-slot mechanisms the means being cams

Definitions

  • the invention relates to a common rail fuel system for supplying high pressure fuel to an internal combustion engine.
  • the invention also relates to a pump for use in such a fuel system, and to a cam arrangement forming part of the fuel system.
  • Fuel systems are known in which the pump assembly includes a plurality of in- line pumping elements, each of which is driven by means of an associated shoe and roller arrangement.
  • the roller of each arrangement cooperates with an associated cam, each of which is mounted upon a common drive shaft (the pump drive shaft).
  • the shoe is arranged to cooperate with the pumping element such that as the rollers ride over their respective cam surfaces, the shoes are driven to cause the plungers to reciprocate within plunger bores, thereby causing pressurisation of fuel within an associated pumping chamber.
  • the pumping chambers communicate with a common rail resulting in the production of high pressure fuel pulses which are then supplied to a plurality of fuel injectors.
  • the pump drive shaft would be need to be driven at 5/6 of engine speed to give five pumping pulses per revolution of the crank shaft, and for an eight cylinder engine the pump drive shaft would need to be driven at 8/6 of engine speed to give eight pumping pulses per revolution of the crank shaft.
  • different gearing systems would need to be used with engines having different numbers of cylinders, despite the use of a common pump which is suitable for use in different engines.
  • an engine fuel system having an engine drive shaft and a multiple number of engine cylinders, the fuel system comprising at least three pump units, being less in total number than the number of engine cylinders, wherein each pump unit has a plunger and an associated drive arrangement including a cam mounted upon a pump drive shaft that is common to the cams of the other pump units, wherein first, second and third ones of the cams are shaped to include at least one rising flank to enable a plunger pumping stroke and at least one falling flank to enable a plunger return stroke, wherein the first and second cams are of similar form and the third cam is of dissimilar form, with the cams being oriented relative to each other on the pump drive shaft such that the pumping strokes of the plungers are substantially equally spaced in time and so that during a substantially complete revolution of the pump drive shaft they provide a total number of pumping strokes equal to the number of engine cylinders, thereby to permit the pump drive shaft to be driven at the same speed as the engine drive
  • the first embodiment of the present invention advantageously provides a fuel system which is suitable for use in a five cylinder engine without the need for dedicated or complex gearing between the pump drive shaft and the engine drive shaft, as the pump drive shaft may be run at the same speed as the engine drive shaft.
  • the fuel system may be used with a ten cylinder engine. This represents a significant cost saving and provides a system which can be standardised for a wide range of vehicles.
  • first, second and third cams are shaped to include at least one rising flank to enable a plunger pumping stroke of an associated plunger and at least one falling flank to enable a plunger return stroke, the first and second cams being of similar form or shape and the third cam being of dissimilar form or shape, and wherein the first, second and third cams are oriented relative to each other on the pump drive shaft such that the pumping strokes of the plungers are substantially equally spaced in time and so that during a substantially complete revolution of an associated pump drive shaft provide a total number of pumping strokes equal to the number of engine cylinders.
  • the pump drive shaft of the pump can therefore be driven at the same speed as the engine drive shaft, or at an integer multiple of the speed of the engine drive shaft.
  • Changing the cam arrangement of the pump thus enables the pump to be adapted for use in engines having different numbers of engine cylinders without having to change and/or provide additional gearing between the engine drive shaft and the pump drive shaft.
  • the first, second and third cams may, in one embodiment, be formed integrally with the pump drive shaft, so that the interchangeable cam arrangement includes an integral arrangement of the pump shaft and one or more cams.
  • one or more of the cams may be formed as a separate part and may be machined such that it forms an interference fit with the pump drive shaft.
  • At least one of the cams is shaped to delay onset of a return stroke of its associated plunger to define a dwell period. At least one of the return strokes is delayed so that the return strokes of that particular pump for a complete rotation of the pump drive shaft are not equally spaced in time. By delaying the onset of a return stroke in this way the plunger therefore dwells for a period of time at the top of its stroke, before the return stroke commences.
  • the first and second cams are formed or shaped such that upon substantially a complete revolution of the pump drive shaft, in use, the first and second plungers each perform two return strokes, two pumping strokes and a dwell period, and the third cam is shaped such that a third plunger performs one pumping stroke and one return stroke and a dwell period, and wherein the first, second and third cams are oriented relative to one another such that five substantially equally spaced pumping strokes are performed during each complete revolution of the pump drive shaft.
  • the cams are formed such that the dwell periods occur when the plungers are at their innermost positions in their respective bores, prior to the commencement of a return (or filling) stroke.
  • the cams may be formed such that the dwell periods occur prior to the commencement of a pumping stroke, when the plungers are at their outermost positions in their respective bores.
  • References to a complete revolution of the pump drive shaft are intended to mean a substantially 360 degree revolution of the pump drive shaft.
  • the first and second cams may be profiled such that, in use, the associated dwell period is arranged to continue for approximately 72 degrees of rotation of the pump drive shaft, and the third cam may be profiled such that the associated dwell period is arranged to continue for approximately 216 degrees of rotation of the pump drive shaft.
  • each pumping stroke is arranged to continue for approximately 72 degrees of rotation of the pump drive shaft, and each return stroke is also arranged to continue for approximately 72 degrees of rotation of the pump drive shaft.
  • the pump of the system preferably includes, in one embodiment, a drive arrangement for each plunger having a roller which is cooperable with an associated cam to drive a shoe.
  • the system is particularly applicable for use in a diesel internal combustion engine, and for delivering fuel at high pressures (150 to 2000 bar) to an accumulator volume, for example a common rail of the fuel system.
  • a pump for use in the fuel system of the first aspect of the invention, the pump including the at least three pump units thereof.
  • Figure 1 is a sectional side view of a known fuel pump which is suitable for use with the cam arrangement of the present invention
  • Figure 2 shows a cam arrangement forming part of the fuel pump in Figure 1 , for use in a six cylinder engine, for example;
  • Figure 3 shows the profiles of the surfaces of the identical first and second cams of the cam arrangement of Figure 2;
  • Figure 4 is a graph showing plunger lift for the fuel pump of Figure 1 incorporating the cam arrangement of Figure 2;
  • Figure 5 shows a cam arrangement of the present invention, which may be used in the fuel pump of Figure 1 in a five cylinder engine;
  • Figure 6 shows the profile of the surfaces of first and second identical cams of the cam arrangement of Figure 5;
  • Figure 7 shows the profile of the surface of a third, dissimilar cam of the cam arrangement of Figure 5.
  • Figure 8 is a graph showing plunger lift for the fuel pump of Figure 1 incorporating the cam arrangement of Figure 5.
  • a fuel pump 10 of generally known type which forms part of a fuel injection system of a diesel engine and which may be adapted in accordance with the present invention.
  • the fuel pump 10 includes three pump assemblies 12a, 12b, 12c which are arranged to supply fuel at high pressure to a common rail or accumulator volume (not shown) of the fuel injection system.
  • Each pump assembly 12a, 12b, 12c includes a respective pumping element or plunger 14a, 14b, 14c which is moveable within a plunger bore 32a,32b,32c provided in a first pump housing 16 to cause pressurisation of fuel within an associated pumping chamber 18a, 18b, 18c.
  • each pump assembly 12a, 12b, 12c is substantially identical to the others, only the structure and operation of the first pump assembly 12a will be described in detail.
  • the plunger 14a of the first pump assembly 12a is driven though a pumping cycle by means of a drive arrangement.
  • the drive arrangement includes a shoe 20a which is cooperable with a base end of the first plunger 14a, and a roller 22a which cooperates with a surface of a first cam 24a mounted upon a pump drive shaft 26 that is common to each pump assembly 12a, 12b, 12c.
  • the pump drive shaft 26 extends through a second pump housing 27 and is driven, in use, so that the roller 22a rides over the cam surface and drives the shoe 20a and plunger 14a to reduce the volume of the pumping chamber 18a (i.e. the plunger 14a is driven inwardly within its plunger bore 32a).
  • Each plunger 14a, 14b, 14c has an associated return spring 28a,28b,28c which serves to urge its respective plunger outwardly from its 32a,32b,32c bore to increase the volume of the pumping chamber 18a, 18b, 18c.
  • the second pump housing 27 is secured to an intermediate housing 25 mounted upon the first pump housing 16.
  • the intermediate housing 25 is shaped to define a chamber (not shown) through which a lower portion of the plunger 14a extends. This chamber is partially filled with engine oil which serves to lubricate the shoe and roller arrangement 20a, 22a so as to improve durability.
  • each pump assembly 12a,12b,12c includes a respective shoe and roller arrangement which is driven by an associated shaft mounted cam 24a,24b,24c.
  • the cams 24a,24b,24c are axially spaced along the pump drive shaft 26 and arranged such that the pumping plungers 14a, 14b, 14c reciprocate within their respective bores 32a,32b,32c as the pump drive shaft 26 is rotated at a speed associated with the engine.
  • fuel is supplied by means of a transfer pump 38 to an inlet metering valve (not shown).
  • the inlet metering valve is arranged to vary the rate of flow of fuel into the pumping chambers 18a,18b,18c through an inlet passage 19 via an inlet check valve arrangement (also not shown).
  • the transfer pump 38 typically takes the form of a conventional vane pump mounted upon the pump drive shaft 26 at a rear end of the second pump housing 27.
  • Each pump assembly 12a, 12b, 12c is also provided with an outlet delivery valve arrangement to control fuel flow between the pumping chambers 18a, 18b, 18c and a high pressure supply passage (not visible in Figure 1) to the common rail.
  • the pumping cycle through which the first pumping plunger 14a is driven, in use includes a pumping stroke and a return stroke.
  • the pumping plunger 14a adopts its innermost (i.e. uppermost in Figure 1) position within its plunger bore 32a, and fuel pressure within the pumping chamber 18a is high due to the pressurisation which has been caused during the pumping stroke.
  • the outlet valve arrangement is closed due to the equalisation of fuel pressures in the pumping chamber 18a and the common rail.
  • the pumping plunger 14a Upon commencement of its return stroke, the pumping plunger 14a is initially allowed to retract from its bore 32a due to decompression within the pumping chamber 18a and retraction of the shoe 20a under the force of the return spring 28a as the roller 22a rides over the surface of the first cam 24a.
  • the roller 22a is urged in an upward direction.
  • the roller 22a follows the surface of the first cam 24a, causing the shoe 20a to be urged in an upwards direction and hence the pumping plunger 14a to be driven inwardly within its plunger bore 32a.
  • Fuel within the pumping chamber 18a is unable to flow past the closed delivery valve due to high fuel pressure within the rail, and hence fuel pressure within the pumping chamber 18a starts to increase.
  • fuel within the pumping chamber 18a is pressurised to a sufficiently high level to cause the outlet delivery valve to open, thereby permitting pressurised fuel to flow from the pumping chamber 18a into the common rail.
  • the outlet delivery valve is caused to close due to high pressure fuel within the rail, thus holding fuel pressure within the rail at a high level.
  • the plunger 14a is urged outwardly from its bore 32a by a force due to the return spring 28a (acting in combination with residual fuel pressure within the pumping chamber 18a), to commence the next filling phase.
  • FIGS 2 and 3 show the cams 24a, 24b, 24c of the pump in Figure 1 in further detail, the cams 24a, 24b, 24 collectively being referred to as a cam arrangement 100.
  • Each cam includes two generally circular end regions in the form of a nose 50 and a base 52, a first generally flat side 54 and a second generally flat side 56.
  • the nose and base portions 50, 52 of the cam are substantially identical.
  • Each cam 24a, 24b, 24c is symmetrical about a minor diameter X-X, which extends between the first and the second flattened sides 54, 56, and about a major diameter Y-Y, which extends from the nose 50 to the base 52 of each cam.
  • each cam 24a, 24b, 24c having two rising flanks and two falling flanks so that the plungers 14a, 14b, 14c associated with each cam 24a, 24b, 24c perform two pumping strokes (one corresponding to or being enabled by the first rising flank and the other corresponding to or being enabled by the second rising flank) and two return strokes during a pumping cycle comprising one revolution of the pump drive shaft 26.
  • the cams 24a, 24b, 24c are oriented at angularly offset positions of 60 degrees with respect to one another, so that the cam arrangement 100 produces six equally spaced pumping pulses per revolution of the pump drive shaft 26.
  • the cam arrangement 100 is therefore suitable for use, in particular, with a six cylinder engine.
  • the profiles of the cam surfaces will now be described in further detail with reference to Figure 3.
  • the surfaces of the cams 24a, 24b, 24c comprise (starting from the centre of the first flattened side 54) a first bottom dwell portion 58, a first rising flank portion 60, a first top dwell portion 62, a first falling flank portion 64, a second bottom dwell portion 66, a second rising flank portion 68, a second top dwell portion 78, and lastly a second falling flank portion 72.
  • the dwell portions 58, 62, 66 and 78 are so-named because as the rollers 22a, 22b, 22c travel over these regions of their associated cam surface the associated plunger 14a, 14b, 14c is caused to 'dwell' or 'pause' for a while, not moving inwardly or outwardly from the plunger bore but maintaining a substantially constant position.
  • each of the first, second and third pumping plungers 14a, 14b, 14c performs the following sequence of events in response to respective rollers 22a, 22b, 22c following the cam profiles: a first pumping stroke, a first top dwell, a first return stroke, a first bottom dwell, a second pumping stroke, a second top dwell, a second return stroke, and a second bottom dwell.
  • the dwell portions are shaped to define dwell periods of relatively short duration, although it is also possible to shape the surfaces of the cams 24a, 24b, 24c to provide no short dwells at all.
  • the roller 22a of the first pump unit is in contact with the first bottom dwell portion of the first cam 24a and the first plunger 14a is at its outermost position within its bore 32a (i.e. at the bottom of its stroke).
  • the roller 22b of the second pump unit is in contact with the first falling flank portion 64 of the second cam 24b
  • the roller 22c of the third pump unit is in contact with the first rising flank portion 60 of the third cam 24c.
  • the roller 22a travels up the rising flank portion 60 of the first cam 24a. This causes the first plunger 14a to be raised within its bore 32a and the first pumping stroke to be commenced.
  • the first plunger 14a will be at its innermost position within its bore 32a with the roller 22a engaged with the nose 50 of the first cam 24a.
  • the first plunger 14a dwells at the top dwell portion 62 top of its stroke for a short period of time.
  • the roller 22a travels from the nose 50 of the cam down the first falling flank portion 64. During this period the first plunger 14a is lowered in its bore 32a as it performs its first return stroke.
  • the plunger 14a reaches the bottom of its stroke at 180 degrees, whereupon it dwells for a short period of time at the second bottom dwell portion 66.
  • the first cam 24a causes the first pumping plunger 14a to move up within its bore 32a, thereby performing the second pumping stroke as the roller 22a travels from the centre 56 of the second side to the base of the first cam 24a (along the second rising flank portion 68).
  • the first plunger 14a is raised to its innermost position in its bore (at 270 degrees) where it dwells briefly at the second top dwell portion 78.
  • the first plunger 14a then completes its second return stroke as the cam shaft rotates from 270 to 360 degrees, the roller 22a traversing the second falling flank portion 72 of the first cam 24a to return to the first bottom dwell portion 58.
  • the second 14b and third 14c plungers complete the same series of pumping events as the first plunger 14a, but with events out of phase with one another by 120 degrees. Due to the plungers being offset from one another by 60 degrees, the pumping events of the second pumping plunger 14b follow those of the first plunger 14a by substantially 60 degrees, and those of the third plunger 14c follow those of the second plunger 14b by substantially 60 degrees.
  • the first plunger 14a is at the top of its stroke at 30 degrees from reference position A
  • the second plunger 14b is at the top of its stroke at 90 degrees
  • the third plunger 14c is at the top of its stroke at 150 degrees
  • the first plunger 14a is at the top of its stroke again at 180 degrees, and so on.
  • the cam arrangement 100 of Figures 2 and 3 may also be used in a 12 cylinder engine by running the pump drive shaft 26 at twice the speed of the crank shaft.
  • the pump drive shaft 26 may, in theory, be run at any integer multiple speed of the engine drive shaft to provide an equal number of pumping strokes to the number of engine cylinders, with the pumping strokes being equally spaced in time.
  • the number of engine cylinders is not an integer multiple of the number of plungers of the pump (e.g. three).
  • the invention sets out to address this problem, and does so by providing a cam arrangement having three cams, but one of which is of different form to the other two, and providing the cams at selected angular positions on the drive shaft 26 to be able to drive the shaft 26 at engine speed (or at an integer multiple of engine speed), whilst providing the required number of pumping strokes per cycle to match the number of engine cylinders.
  • FIG. 5 there is shown a cam arrangement 101 of an embodiment of the present invention which is suitable use with a fuel pump 10 of the type shown in Figure 1 and which replaces the cam arrangement 100 shown in Figures 2 and 3.
  • the cam arrangement 101 comprises first, second and third cams 24a, 24b, 24c, which are arranged on the pump drive shaft 26 at axially spaced locations and oriented about the drive shaft at angularly offset positions.
  • the pump includes the cam arrangement 101 of Figure 5
  • the pump is suitable, in particular, for use in a five cylinder engine.
  • first 24a and second 24b cams of the cam arrangement 101 are of substantially identical form, and are similar in shape to conventional cams which comprise (in cross-section) a generally base-like section of part-circular form having a cam nose.
  • each of the first and second cams 24a, 24b has a base section 52 of substantially part-circular form having a radius R, the base section 52 being spaced apart from an opposite dominant cam nose 50 of substantially part-circular form and having a radius r (where R>r) by pinched (or concave) first and second sides, 54 and 56 respectively.
  • the first and second cams 24a, 24b therefore each have one rising flank and one falling flank on one cam side 54 and another rising flank and another falling flank on the other cam side 56.
  • the first rising flank corresponds to, or enables, a first pumping stroke and the second rising flank corresponds to, or enables, a second pumping stroke.
  • each of the associated plungers 14a, 14b is driven to perform two pumping strokes and two return strokes with each pumping cycle comprising one complete or full 360 degree revolution of the pump drive shaft 26 (when performing a pumping stroke, the roller 22a,22b rides up a rising flank of the associated cam 24a,24b as it rotates, and during a return stroke the roller rides down a falling flank).
  • the first and second 24a,24b cams are also profiled such that at the end of one of the plunger pumping strokes, but before the onset of the next return stroke, the roller 22a,22b dwells for a relatively long period of time at the peak of one of the rising flanks (referred to as long top dwell).
  • the cams 24a,24b may be profiled such that between one of the plunger pumping strokes and the following return stroke, the roller 22a,22b dwells for a short period of time at the peak of one of the rising flanks (referred to as short top dwell).
  • a period of short bottom dwell may also be provided so that, at the end of the return stroke, the roller 22a,22b dwells for a short period of time before commencing the following pumping stroke.
  • each of the cams 24a, 24b includes a first rising flank portion 60, a first short top dwell portion 62, a first falling flank portion 64, a first short bottom dwell portion 66, a second rising flank portion 68, a long top dwell portion 70, a second falling flank portion 72, and a second short bottom dwell portion 58.
  • the first pumping plunger 14a performs the following sequence of events in response to the roller 22a following the cam surface: a first pumping stroke over 60, a first short top dwell period over 62, a first return stroke over 64, a first short bottom dwell period over 66, a second pumping stroke over 68, a long top dwell period over 70, a second return stroke over 72, and a second short bottom dwell period over 58.
  • the second pumping plunger 14b performs an identical sequence of events to the first pumping plunger 14a, except that the second plunger events follow those of the first plunger by about 72 degrees, as will be explained in more detail below.
  • the third cam 24c is illustrated in Figure 7 and is different from the first and second cams 24a, 24b. This is an important feature of the cam arrangement 101.
  • the third cam 24c is of generally circular form and has a dwell portion, referred to generally as 76, and a slightly concave relief portion, referred to generally as 74, formed in its surface.
  • the surface of the third cam 24c further comprises a falling flank portion 64, a short bottom dwell portion 66, and a rising flank portion 60.
  • the third pumping plunger 14c Upon a complete 360 degree revolution of the drift shaft 26, the third pumping plunger 14c performs the following sequence of events in response to the third roller 22c following the profile of the third cam surface: a long dwell period over 76, a return stroke over (or enabled by) the falling flank 64, a short bottom dwell period over 66, and a pumping stroke over (or enabled by) the rising flank 60.
  • the third cam surface may be profiled such that no short bottom dwell period is provided.
  • the first, second and third cams 24a, 24b, 24c are mounted upon the pump drive shaft 26 such that the noses 50 of the first and second cams 24a, 24b and the concave relief portion 74 of the third cam 24c are angularly offset by substantially 72 degrees.
  • both the second 14b and third 14c pumping plungers are at their innermost positions within their respective bores 32b, 32c (i.e. at the top of the stroke), and the first pumping plunger 14a is at its outermost position within its bore 32a (i.e. at the bottom of the stroke).
  • the first roller 22a rides up the first rising flank 60 of the first cam 24a so that the first plunger 14a is raised within its bore 32a and the pumping stroke is commenced. While this is occurring, the second roller 22b rides down the second falling flank portion 72 of the second cam 24b thereby causing the second pumping plunger 14b to be lowered in its bore 32b (i.e. during the return stroke).
  • the third roller 22c meanwhile is maintained in contact with the generally part-circular dwell portion 76 of the third cam 24c so that the third plunger 14c remains at its innermost position within its bore 32c.
  • the first plunger 14a dwells briefly at the end of its first pumping stroke
  • the second plunger 14b dwells briefly at the end of its return stroke
  • the third plunger 14c remains at the top of its stroke.
  • the first roller 22a traverses from the first short top dwell portion 62 of the first cam 24a to the first falling flank portion 64, thereby causing the first plunger 14a to be lowered in its bore 32a.
  • the second roller 22b rides up the first rising flank portion 60 towards the second cam nose 50.
  • the third roller 22c is maintained in contact with the circular dwell portion 76 of the third cam 24c and so the third plunger 14c dwells at the end of its pumping stroke.
  • the first plunger 14a dwells briefly at the end of its return stroke
  • the second plunger 14b dwells brief at the end of its pumping stroke
  • the third plunger 14c remains innermost in its bore 32c at the end of its pumping stroke.
  • the first roller 22a travels along the second rising flank 68 of the first cam 24a and towards the base 52 thereof. This causes the first plunger 14a to move from its outermost to its innermost position within the bore 32a so as to perform a pumping stroke.
  • the second roller 22b travels down the first falling flank portion 64 of the second cam 24b, thereby causing the second plunger 14b to move from its innermost to outermost position within its bore 32b to carry out a return stroke.
  • the third roller 22c is again maintained in contact with the long dwell portion 76 of the third cam 24c and is thus kept at the top of its stroke.
  • the second plunger 14b dwells briefly at the bottom of its stroke, while both the first and third plungers 14a, 14c remain innermost in their respective bores 32a,32c.
  • the next period of the pumping cycle takes place between 216 and 287 degrees of revolution of the pump drive shaft 26.
  • the first roller 22a is travelling along the base 52 of the first cam 24a which defines the long top dwell portion 70, thereby causing the first plunger 14a to dwell at the top of its stroke for the whole of this period.
  • the second roller 22b travels along the second rising flank portion 68 of the second cam 24b thereby causing the second plunger 14b to rise from the bottom of its stroke to the top of its stroke and perform a second pumping stroke.
  • the third roller 22c meanwhile rides to the centre of the concave relief portion 74 of the third cam 24c causing the third plunger 14c to be lowered from its innermost to its outermost position within its bore 32c to perform a return stroke.
  • the third plunger 14c dwells briefly at the bottom of its stroke, while the first and second plungers 14a, 14b remain innermost in their respective bores 32a,32b.
  • the first roller 22a travels along the second falling flank portion 72 causing the first plunger 14a to be lowered from its innermost to its outermost position within its bore 32a to carry out a second return stroke.
  • the second roller 22b meanwhile travels along the long top dwell portion 70 of the second cam 24b, thereby causing it to dwell at the top of its stroke during this period.
  • the third roller 22c travels from the centre of the concave relief portion 74 of the third cam 24c to move the third plunger 14c from the bottom of its stroke to the top of its stroke such that a pumping stroke is performed.
  • first and second cams 24a, 24b of the cam arrangement 101 have been described as having short bottom dwell portions 66 and 58 and a short top dwell portion 62, and the third cam 24c has been described as having a short bottom dwell portion 66, it will be apparent to the skilled person that the first, second and third 24a, 24b, 24c cams may be profiled such that substantially no such short top and bottom dwell portions are provided. It is one feature of the cam arrangement 101 described previously that its implementation in a fuel pump of an engine having five (or ten) engine cylinders provides a regular spacing of pumping strokes per cycle to match the number of engine cylinders.
  • the pump drive shaft 26 can therefore be driven at engine speed (for a five cylinder engine), or at an integer multiple of engine speed (for a ten cylinder engine), matching pumping frequency to fuel injection frequency without the requirement for dedicated or complex gearing between the engine shaft and the pump drive shaft 26. It is a further advantageous feature of the invention that it can be readily be incorporated into existing pump installations by replacing the existing pump drive shaft and cams to co-operate with the existing plungers of the pump. So, for example, for an engine manufacturer, an existing type of pump can be adapted or converted conveniently for use in another engine by selecting a cam arrangement in accordance with the present invention, that is appropriate to provide the required number of pumping strokes per cycle for the number of engine cylinders. For example, the cam arrangement 101 in Figures 5 is also particularly suitable for use in a ten cylinder engine by running the camshaft at twice the speed of the crank shaft, again without the need for complex gearing.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Fuel-Injection Apparatus (AREA)
  • Reciprocating Pumps (AREA)

Abstract

An engine fuel system having a multiple number of engine cylinders and at least three pump units, but which are less in total number than the number of engine cylinders, with each pump unit having a plunger (14a, 14b, 14c) and an associated drive arrangement including a cam (24a, 24b, 24c) mounted upon a pump drive shaft (26) that is common to the cams of each of the other pump units. First and second ones of the cams (24a, 24b) are shaped to be substantially identical and to include at least one rising flank to enable a plunger pumping stroke and at least one falling flank to enable a plunger return stroke. A third one of the cams (24c) is shaped in a dissimilar manner, but also to include at least one rising flank to enable a plunger pumping stroke and at least one falling flank to enable a plunger return stroke. The first, second and third cams (24a, 24b, 24c) are oriented relative to each other on the pump drive shaft (26) such that the pumping strokes of the plungers (14a, 14b, 14c) are substantially equally spaced in time and so that during a substantially complete revolution of the pump drive shaft (26) provide a total number of pumping strokes equal to the number of engine cylinders. This enables the pump drive shaft (26) to be driven at the same speed as the drive shaft of the engine, or at an integer multiple of the speed of the engine drive shaft.

Description

FUEL SYSTEM
The invention relates to a common rail fuel system for supplying high pressure fuel to an internal combustion engine. The invention also relates to a pump for use in such a fuel system, and to a cam arrangement forming part of the fuel system.
Fuel systems are known in which the pump assembly includes a plurality of in- line pumping elements, each of which is driven by means of an associated shoe and roller arrangement. The roller of each arrangement cooperates with an associated cam, each of which is mounted upon a common drive shaft (the pump drive shaft). The shoe is arranged to cooperate with the pumping element such that as the rollers ride over their respective cam surfaces, the shoes are driven to cause the plungers to reciprocate within plunger bores, thereby causing pressurisation of fuel within an associated pumping chamber. The pumping chambers communicate with a common rail resulting in the production of high pressure fuel pulses which are then supplied to a plurality of fuel injectors.
In heavy duty vehicles in particular there is a problem with low pressure waves being set up in the fuel system when an injector is opened. These low pressure waves are reflected within the common rail and move to other injectors where they interfere with one another and cause "shot-to-shot" variations. This results in inefficient fuel use and degrades engine performance. It is therefore desirable to match pumping and fuel injection frequencies as this has the effect of minimising the interference between low pressure waves in the fuel system, thus improving engine performance.
It has previously been proposed for three plunger in-line type fuel pump assemblies to utilise cams having two lobes such that the pump assembly provides six pumping pulses per revolution of the pump drive shaft. For application in a four stroke, three cylinder engine, such a pump assembly may be used without special drive gearing between the engine crank shaft and the pump drive shaft. However, in a five or eight cylinder engine, special gearing would be required to turn the pump drive shaft at a different speed to the engine crank shaft (i.e. engine speed). So, for a five cylinder engine utilising a three plunger in-line assembly with each cam having two lobes, the pump drive shaft would be need to be driven at 5/6 of engine speed to give five pumping pulses per revolution of the crank shaft, and for an eight cylinder engine the pump drive shaft would need to be driven at 8/6 of engine speed to give eight pumping pulses per revolution of the crank shaft. Thus, different gearing systems would need to be used with engines having different numbers of cylinders, despite the use of a common pump which is suitable for use in different engines.
It is one object of the present invention to provide a cam arrangement that avoids or alleviates the aforementioned problems, and which is suitable for use in a range of engines having a different number of cylinders. It is a further object of the present invention to provide a fuel system and/or a fuel pump incorporating such a cam arrangement.
According to a first aspect of the present invention, there is provided an engine fuel system having an engine drive shaft and a multiple number of engine cylinders, the fuel system comprising at least three pump units, being less in total number than the number of engine cylinders, wherein each pump unit has a plunger and an associated drive arrangement including a cam mounted upon a pump drive shaft that is common to the cams of the other pump units, wherein first, second and third ones of the cams are shaped to include at least one rising flank to enable a plunger pumping stroke and at least one falling flank to enable a plunger return stroke, wherein the first and second cams are of similar form and the third cam is of dissimilar form, with the cams being oriented relative to each other on the pump drive shaft such that the pumping strokes of the plungers are substantially equally spaced in time and so that during a substantially complete revolution of the pump drive shaft they provide a total number of pumping strokes equal to the number of engine cylinders, thereby to permit the pump drive shaft to be driven at the same speed as the engine drive shaft or at an integer multiple of the speed of the engine drive shaft.
The first embodiment of the present invention advantageously provides a fuel system which is suitable for use in a five cylinder engine without the need for dedicated or complex gearing between the pump drive shaft and the engine drive shaft, as the pump drive shaft may be run at the same speed as the engine drive shaft. Alternatively, if the pump drive shaft is run at twice the speed of the engine drive shaft (and so does not require a complex gearing mechanism), the fuel system may be used with a ten cylinder engine. This represents a significant cost saving and provides a system which can be standardised for a wide range of vehicles. It is a particularly advantageous feature of the invention that known pumps, as will be described further later, can be modified for use in a five cylinder engine, for example, simply by interchanging the cam arrangement of the existing system with a cam arrangement in accordance with a second aspect of the invention.
In accordance with a second aspect of the invention, therefore, there is provided an interchangeable cam arrangement for use in a fuel system of the first aspect of the invention, wherein first, second and third cams are shaped to include at least one rising flank to enable a plunger pumping stroke of an associated plunger and at least one falling flank to enable a plunger return stroke, the first and second cams being of similar form or shape and the third cam being of dissimilar form or shape, and wherein the first, second and third cams are oriented relative to each other on the pump drive shaft such that the pumping strokes of the plungers are substantially equally spaced in time and so that during a substantially complete revolution of an associated pump drive shaft provide a total number of pumping strokes equal to the number of engine cylinders. When implementing this cam arrangement, the pump drive shaft of the pump can therefore be driven at the same speed as the engine drive shaft, or at an integer multiple of the speed of the engine drive shaft. Changing the cam arrangement of the pump thus enables the pump to be adapted for use in engines having different numbers of engine cylinders without having to change and/or provide additional gearing between the engine drive shaft and the pump drive shaft.
The first, second and third cams may, in one embodiment, be formed integrally with the pump drive shaft, so that the interchangeable cam arrangement includes an integral arrangement of the pump shaft and one or more cams.
Alternatively, one or more of the cams may be formed as a separate part and may be machined such that it forms an interference fit with the pump drive shaft.
Preferably, at least one of the cams is shaped to delay onset of a return stroke of its associated plunger to define a dwell period. At least one of the return strokes is delayed so that the return strokes of that particular pump for a complete rotation of the pump drive shaft are not equally spaced in time. By delaying the onset of a return stroke in this way the plunger therefore dwells for a period of time at the top of its stroke, before the return stroke commences.
In a preferred embodiment, the first and second cams are formed or shaped such that upon substantially a complete revolution of the pump drive shaft, in use, the first and second plungers each perform two return strokes, two pumping strokes and a dwell period, and the third cam is shaped such that a third plunger performs one pumping stroke and one return stroke and a dwell period, and wherein the first, second and third cams are oriented relative to one another such that five substantially equally spaced pumping strokes are performed during each complete revolution of the pump drive shaft.
Preferably, the cams are formed such that the dwell periods occur when the plungers are at their innermost positions in their respective bores, prior to the commencement of a return (or filling) stroke. This provides the advantage of mitigating the effects on inlet-metered filling of the pumping chambers. Alternatively, the cams may be formed such that the dwell periods occur prior to the commencement of a pumping stroke, when the plungers are at their outermost positions in their respective bores. References to a complete revolution of the pump drive shaft are intended to mean a substantially 360 degree revolution of the pump drive shaft.
The first and second cams may be profiled such that, in use, the associated dwell period is arranged to continue for approximately 72 degrees of rotation of the pump drive shaft, and the third cam may be profiled such that the associated dwell period is arranged to continue for approximately 216 degrees of rotation of the pump drive shaft.
Most preferably the surfaces of the first, second and third cams are further shaped such that, in use, each pumping stroke is arranged to continue for approximately 72 degrees of rotation of the pump drive shaft, and each return stroke is also arranged to continue for approximately 72 degrees of rotation of the pump drive shaft.
The pump of the system preferably includes, in one embodiment, a drive arrangement for each plunger having a roller which is cooperable with an associated cam to drive a shoe. The system is particularly applicable for use in a diesel internal combustion engine, and for delivering fuel at high pressures (150 to 2000 bar) to an accumulator volume, for example a common rail of the fuel system.
In accordance with a third aspect of the invention, there is provided a pump for use in the fuel system of the first aspect of the invention, the pump including the at least three pump units thereof.
Preferred embodiments 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 side view of a known fuel pump which is suitable for use with the cam arrangement of the present invention; Figure 2 shows a cam arrangement forming part of the fuel pump in Figure 1 , for use in a six cylinder engine, for example;
Figure 3 shows the profiles of the surfaces of the identical first and second cams of the cam arrangement of Figure 2;
Figure 4 is a graph showing plunger lift for the fuel pump of Figure 1 incorporating the cam arrangement of Figure 2;
Figure 5 shows a cam arrangement of the present invention, which may be used in the fuel pump of Figure 1 in a five cylinder engine;
Figure 6 shows the profile of the surfaces of first and second identical cams of the cam arrangement of Figure 5;
Figure 7 shows the profile of the surface of a third, dissimilar cam of the cam arrangement of Figure 5; and
Figure 8 is a graph showing plunger lift for the fuel pump of Figure 1 incorporating the cam arrangement of Figure 5.
Referring to Figure 1 , there is shown a fuel pump 10 of generally known type which forms part of a fuel injection system of a diesel engine and which may be adapted in accordance with the present invention. The fuel pump 10 includes three pump assemblies 12a, 12b, 12c which are arranged to supply fuel at high pressure to a common rail or accumulator volume (not shown) of the fuel injection system.
Each pump assembly 12a, 12b, 12c includes a respective pumping element or plunger 14a, 14b, 14c which is moveable within a plunger bore 32a,32b,32c provided in a first pump housing 16 to cause pressurisation of fuel within an associated pumping chamber 18a, 18b, 18c. As each pump assembly 12a, 12b, 12c is substantially identical to the others, only the structure and operation of the first pump assembly 12a will be described in detail. The plunger 14a of the first pump assembly 12a is driven though a pumping cycle by means of a drive arrangement. The drive arrangement includes a shoe 20a which is cooperable with a base end of the first plunger 14a, and a roller 22a which cooperates with a surface of a first cam 24a mounted upon a pump drive shaft 26 that is common to each pump assembly 12a, 12b, 12c. The pump drive shaft 26 extends through a second pump housing 27 and is driven, in use, so that the roller 22a rides over the cam surface and drives the shoe 20a and plunger 14a to reduce the volume of the pumping chamber 18a (i.e. the plunger 14a is driven inwardly within its plunger bore 32a). Each plunger 14a, 14b, 14c has an associated return spring 28a,28b,28c which serves to urge its respective plunger outwardly from its 32a,32b,32c bore to increase the volume of the pumping chamber 18a, 18b, 18c.
The second pump housing 27 is secured to an intermediate housing 25 mounted upon the first pump housing 16. The intermediate housing 25 is shaped to define a chamber (not shown) through which a lower portion of the plunger 14a extends. This chamber is partially filled with engine oil which serves to lubricate the shoe and roller arrangement 20a, 22a so as to improve durability.
As is stated above, each pump assembly 12a,12b,12c includes a respective shoe and roller arrangement which is driven by an associated shaft mounted cam 24a,24b,24c. The cams 24a,24b,24c are axially spaced along the pump drive shaft 26 and arranged such that the pumping plungers 14a, 14b, 14c reciprocate within their respective bores 32a,32b,32c as the pump drive shaft 26 is rotated at a speed associated with the engine.
In use, fuel is supplied by means of a transfer pump 38 to an inlet metering valve (not shown). The inlet metering valve is arranged to vary the rate of flow of fuel into the pumping chambers 18a,18b,18c through an inlet passage 19 via an inlet check valve arrangement (also not shown). The transfer pump 38 typically takes the form of a conventional vane pump mounted upon the pump drive shaft 26 at a rear end of the second pump housing 27. Each pump assembly 12a, 12b, 12c is also provided with an outlet delivery valve arrangement to control fuel flow between the pumping chambers 18a, 18b, 18c and a high pressure supply passage (not visible in Figure 1) to the common rail.
The pumping cycle through which the first pumping plunger 14a is driven, in use, includes a pumping stroke and a return stroke. At the end of the pumping stroke, the pumping plunger 14a adopts its innermost (i.e. uppermost in Figure 1) position within its plunger bore 32a, and fuel pressure within the pumping chamber 18a is high due to the pressurisation which has been caused during the pumping stroke. At this stage, the outlet valve arrangement is closed due to the equalisation of fuel pressures in the pumping chamber 18a and the common rail. Upon commencement of its return stroke, the pumping plunger 14a is initially allowed to retract from its bore 32a due to decompression within the pumping chamber 18a and retraction of the shoe 20a under the force of the return spring 28a as the roller 22a rides over the surface of the first cam 24a.
As the pumping chamber 18a is decompressed, a point is reached at which the pressure therein falls below the pressure required to open the inlet check valve, permitting fuel at transfer pressure to fill the pump chamber 18a during a filling phase.
After the plunger 14a reaches its outermost position within the plunger bore 32a at the end of the return stroke, the roller 22a is urged in an upward direction. The roller 22a follows the surface of the first cam 24a, causing the shoe 20a to be urged in an upwards direction and hence the pumping plunger 14a to be driven inwardly within its plunger bore 32a. Fuel within the pumping chamber 18a is unable to flow past the closed delivery valve due to high fuel pressure within the rail, and hence fuel pressure within the pumping chamber 18a starts to increase. As the pumping stroke continues, fuel within the pumping chamber 18a is pressurised to a sufficiently high level to cause the outlet delivery valve to open, thereby permitting pressurised fuel to flow from the pumping chamber 18a into the common rail.
When the pumping plunger 14a reaches the end of its range of travel (i.e. at the end of the pumping stroke), the outlet delivery valve is caused to close due to high pressure fuel within the rail, thus holding fuel pressure within the rail at a high level.
Subsequently, the plunger 14a is urged outwardly from its bore 32a by a force due to the return spring 28a (acting in combination with residual fuel pressure within the pumping chamber 18a), to commence the next filling phase.
Figures 2 and 3 show the cams 24a, 24b, 24c of the pump in Figure 1 in further detail, the cams 24a, 24b, 24 collectively being referred to as a cam arrangement 100. Each cam includes two generally circular end regions in the form of a nose 50 and a base 52, a first generally flat side 54 and a second generally flat side 56. The nose and base portions 50, 52 of the cam are substantially identical. Each cam 24a, 24b, 24c is symmetrical about a minor diameter X-X, which extends between the first and the second flattened sides 54, 56, and about a major diameter Y-Y, which extends from the nose 50 to the base 52 of each cam. The shape of these cam surfaces leads to each cam 24a, 24b, 24c having two rising flanks and two falling flanks so that the plungers 14a, 14b, 14c associated with each cam 24a, 24b, 24c perform two pumping strokes (one corresponding to or being enabled by the first rising flank and the other corresponding to or being enabled by the second rising flank) and two return strokes during a pumping cycle comprising one revolution of the pump drive shaft 26. The cams 24a, 24b, 24c are oriented at angularly offset positions of 60 degrees with respect to one another, so that the cam arrangement 100 produces six equally spaced pumping pulses per revolution of the pump drive shaft 26. The cam arrangement 100 is therefore suitable for use, in particular, with a six cylinder engine. The profiles of the cam surfaces will now be described in further detail with reference to Figure 3. The surfaces of the cams 24a, 24b, 24c comprise (starting from the centre of the first flattened side 54) a first bottom dwell portion 58, a first rising flank portion 60, a first top dwell portion 62, a first falling flank portion 64, a second bottom dwell portion 66, a second rising flank portion 68, a second top dwell portion 78, and lastly a second falling flank portion 72. The dwell portions 58, 62, 66 and 78 are so-named because as the rollers 22a, 22b, 22c travel over these regions of their associated cam surface the associated plunger 14a, 14b, 14c is caused to 'dwell' or 'pause' for a while, not moving inwardly or outwardly from the plunger bore but maintaining a substantially constant position. Thus, upon a single 360 degree revolution of the pump drive shaft 26, each of the first, second and third pumping plungers 14a, 14b, 14c performs the following sequence of events in response to respective rollers 22a, 22b, 22c following the cam profiles: a first pumping stroke, a first top dwell, a first return stroke, a first bottom dwell, a second pumping stroke, a second top dwell, a second return stroke, and a second bottom dwell.
The dwell portions are shaped to define dwell periods of relatively short duration, although it is also possible to shape the surfaces of the cams 24a, 24b, 24c to provide no short dwells at all.
The generation of the aforementioned sequence of pumping pulses will now be briefly described with reference to the lift diagram of Figure 4, which plots the height in millimetres by which the plungers 14a, 14b, 14c are raised within their respective bores 32a, 32b, 32c against the degree of rotation of the pump drive shaft 26 with respective to reference point A.
At the start of the pumping cycle (i.e. at zero degrees of rotation of the pump drive shaft 26 with respect to reference position A), the roller 22a of the first pump unit is in contact with the first bottom dwell portion of the first cam 24a and the first plunger 14a is at its outermost position within its bore 32a (i.e. at the bottom of its stroke). Meanwhile, the roller 22b of the second pump unit is in contact with the first falling flank portion 64 of the second cam 24b, and the roller 22c of the third pump unit is in contact with the first rising flank portion 60 of the third cam 24c.
As the pump drive shaft 26 is driven to rotate, the roller 22a travels up the rising flank portion 60 of the first cam 24a. This causes the first plunger 14a to be raised within its bore 32a and the first pumping stroke to be commenced. At 90 degrees from the reference position A, the first plunger 14a will be at its innermost position within its bore 32a with the roller 22a engaged with the nose 50 of the first cam 24a. The first plunger 14a dwells at the top dwell portion 62 top of its stroke for a short period of time. Then, as the cam shaft continues to rotate, the roller 22a travels from the nose 50 of the cam down the first falling flank portion 64. During this period the first plunger 14a is lowered in its bore 32a as it performs its first return stroke. The plunger 14a reaches the bottom of its stroke at 180 degrees, whereupon it dwells for a short period of time at the second bottom dwell portion 66. Continuing to rotate, the first cam 24a causes the first pumping plunger 14a to move up within its bore 32a, thereby performing the second pumping stroke as the roller 22a travels from the centre 56 of the second side to the base of the first cam 24a (along the second rising flank portion 68). During this period of the pumping cycle, the first plunger 14a is raised to its innermost position in its bore (at 270 degrees) where it dwells briefly at the second top dwell portion 78. The first plunger 14a then completes its second return stroke as the cam shaft rotates from 270 to 360 degrees, the roller 22a traversing the second falling flank portion 72 of the first cam 24a to return to the first bottom dwell portion 58.
It can be seen from the lines representing the second and third plunger positions, that the second 14b and third 14c plungers complete the same series of pumping events as the first plunger 14a, but with events out of phase with one another by 120 degrees. Due to the plungers being offset from one another by 60 degrees, the pumping events of the second pumping plunger 14b follow those of the first plunger 14a by substantially 60 degrees, and those of the third plunger 14c follow those of the second plunger 14b by substantially 60 degrees. So, for example, the first plunger 14a is at the top of its stroke at 30 degrees from reference position A, the second plunger 14b is at the top of its stroke at 90 degrees, the third plunger 14c is at the top of its stroke at 150 degrees, the first plunger 14a is at the top of its stroke again at 180 degrees, and so on. Thus, six equally spaced pumping events are generated upon each complete 360 degree revolution of the pump drive shaft 26.
As well as being suitable for use in a six cylinder engine, the cam arrangement 100 of Figures 2 and 3 may also be used in a 12 cylinder engine by running the pump drive shaft 26 at twice the speed of the crank shaft. The pump drive shaft 26 may, in theory, be run at any integer multiple speed of the engine drive shaft to provide an equal number of pumping strokes to the number of engine cylinders, with the pumping strokes being equally spaced in time.
A problem exists, however, if the fuel pump is to be used in an engine having an odd number of engine cylinders. For example, if the pump 10 is to be employed in a five cylinder engine, special gearing is required between the engine shaft and the pump drive shaft 26 if the number of pumping pulses (i.e. pumping strokes) is to be matched to the number of cylinders. A problem also exists if the number of engine cylinders is not an integer multiple of the number of plungers of the pump (e.g. three).
The invention sets out to address this problem, and does so by providing a cam arrangement having three cams, but one of which is of different form to the other two, and providing the cams at selected angular positions on the drive shaft 26 to be able to drive the shaft 26 at engine speed (or at an integer multiple of engine speed), whilst providing the required number of pumping strokes per cycle to match the number of engine cylinders.
Referring now to Figure 5, there is shown a cam arrangement 101 of an embodiment of the present invention which is suitable use with a fuel pump 10 of the type shown in Figure 1 and which replaces the cam arrangement 100 shown in Figures 2 and 3. The cam arrangement 101 comprises first, second and third cams 24a, 24b, 24c, which are arranged on the pump drive shaft 26 at axially spaced locations and oriented about the drive shaft at angularly offset positions. When the pump includes the cam arrangement 101 of Figure 5, the pump is suitable, in particular, for use in a five cylinder engine.
Referring also to Figure 6, the first 24a and second 24b cams of the cam arrangement 101 are of substantially identical form, and are similar in shape to conventional cams which comprise (in cross-section) a generally base-like section of part-circular form having a cam nose. However, rather than comprising a part-circular base and linear rising and falling flanks, as in a conventional 'rise-return' type cam for example, each of the first and second cams 24a, 24b has a base section 52 of substantially part-circular form having a radius R, the base section 52 being spaced apart from an opposite dominant cam nose 50 of substantially part-circular form and having a radius r (where R>r) by pinched (or concave) first and second sides, 54 and 56 respectively. The first and second cams 24a, 24b therefore each have one rising flank and one falling flank on one cam side 54 and another rising flank and another falling flank on the other cam side 56. The first rising flank corresponds to, or enables, a first pumping stroke and the second rising flank corresponds to, or enables, a second pumping stroke.
During a pumping cycle, each of the associated plungers 14a, 14b is driven to perform two pumping strokes and two return strokes with each pumping cycle comprising one complete or full 360 degree revolution of the pump drive shaft 26 (when performing a pumping stroke, the roller 22a,22b rides up a rising flank of the associated cam 24a,24b as it rotates, and during a return stroke the roller rides down a falling flank).
The first and second 24a,24b cams are also profiled such that at the end of one of the plunger pumping strokes, but before the onset of the next return stroke, the roller 22a,22b dwells for a relatively long period of time at the peak of one of the rising flanks (referred to as long top dwell). In addition to the long top dwell, the cams 24a,24b may be profiled such that between one of the plunger pumping strokes and the following return stroke, the roller 22a,22b dwells for a short period of time at the peak of one of the rising flanks (referred to as short top dwell). A period of short bottom dwell may also be provided so that, at the end of the return stroke, the roller 22a,22b dwells for a short period of time before commencing the following pumping stroke.
Starting from approximately a mid point on the first side 54, each of the cams 24a, 24b includes a first rising flank portion 60, a first short top dwell portion 62, a first falling flank portion 64, a first short bottom dwell portion 66, a second rising flank portion 68, a long top dwell portion 70, a second falling flank portion 72, and a second short bottom dwell portion 58. Thus, upon a complete 360 degree revolution of the pump drive shaft 26, the first pumping plunger 14a performs the following sequence of events in response to the roller 22a following the cam surface: a first pumping stroke over 60, a first short top dwell period over 62, a first return stroke over 64, a first short bottom dwell period over 66, a second pumping stroke over 68, a long top dwell period over 70, a second return stroke over 72, and a second short bottom dwell period over 58. The second pumping plunger 14b performs an identical sequence of events to the first pumping plunger 14a, except that the second plunger events follow those of the first plunger by about 72 degrees, as will be explained in more detail below.
The third cam 24c is illustrated in Figure 7 and is different from the first and second cams 24a, 24b. This is an important feature of the cam arrangement 101. The third cam 24c is of generally circular form and has a dwell portion, referred to generally as 76, and a slightly concave relief portion, referred to generally as 74, formed in its surface. The surface of the third cam 24c further comprises a falling flank portion 64, a short bottom dwell portion 66, and a rising flank portion 60. Upon a complete 360 degree revolution of the drift shaft 26, the third pumping plunger 14c performs the following sequence of events in response to the third roller 22c following the profile of the third cam surface: a long dwell period over 76, a return stroke over (or enabled by) the falling flank 64, a short bottom dwell period over 66, and a pumping stroke over (or enabled by) the rising flank 60. The third cam surface may be profiled such that no short bottom dwell period is provided. The first, second and third cams 24a, 24b, 24c are mounted upon the pump drive shaft 26 such that the noses 50 of the first and second cams 24a, 24b and the concave relief portion 74 of the third cam 24c are angularly offset by substantially 72 degrees. Thus, during a complete 360 degree revolution of the pump drive shaft 26, five equally spaced pumping pulses are generated: two by each of the first and second pumping plungers 14a, 14b and one by the third pumping plunger 14c. The generation of this sequence of pumping pulses will now be described with reference to the lift diagram of Figure 8 which plots the height in millimetres by which the plungers 14a, 14b, 14c are raised within their respective bores 32a,32b,32c against the degree of rotation of the pump drive shaft 26 with respective to reference point A. It will be appreciated from the following description that it is the dissimilarity of the third cam 24c from the identical first and second cams 24a, 24b, and the way in which the three cams 24a, 24b, 24c are orientated relative to one another, that provides advantages for the pump.
At the start of the pumping cycle (i.e. at zero degrees of rotation of the pump drive shaft 26 with respect to reference position A), the roller 22a of the first pump unit is in contact with the first short bottom dwell portion 58 of the slightly concave side 54 of the first cam 14a. The roller 22b of the second pump unit is in contact with the long dwell portion 70 situated towards the base 52 of the second cam 24b, and the third pump unit roller 22c is in contact with the part- circular dwell portion 76 of the third cam 24c. As a result, both the second 14b and third 14c pumping plungers are at their innermost positions within their respective bores 32b, 32c (i.e. at the top of the stroke), and the first pumping plunger 14a is at its outermost position within its bore 32a (i.e. at the bottom of the stroke).
As the pump drive shaft 26 is driven to rotate by the engine drive shaft, the first roller 22a rides up the first rising flank 60 of the first cam 24a so that the first plunger 14a is raised within its bore 32a and the pumping stroke is commenced. While this is occurring, the second roller 22b rides down the second falling flank portion 72 of the second cam 24b thereby causing the second pumping plunger 14b to be lowered in its bore 32b (i.e. during the return stroke). The third roller 22c meanwhile is maintained in contact with the generally part-circular dwell portion 76 of the third cam 24c so that the third plunger 14c remains at its innermost position within its bore 32c.
At 72 degrees of rotation of the pump drive shaft 26, the first plunger 14a dwells briefly at the end of its first pumping stroke, the second plunger 14b dwells briefly at the end of its return stroke, and the third plunger 14c remains at the top of its stroke.
As the pump drive shaft 26 continues to rotate from 72 degrees to 144 degrees, the first roller 22a traverses from the first short top dwell portion 62 of the first cam 24a to the first falling flank portion 64, thereby causing the first plunger 14a to be lowered in its bore 32a. In the same time period, the second roller 22b rides up the first rising flank portion 60 towards the second cam nose 50. As in the previous period, the third roller 22c is maintained in contact with the circular dwell portion 76 of the third cam 24c and so the third plunger 14c dwells at the end of its pumping stroke. Thus, at 144 degrees with respective to reference position A, the first plunger 14a dwells briefly at the end of its return stroke, the second plunger 14b dwells brief at the end of its pumping stroke, and the third plunger 14c remains innermost in its bore 32c at the end of its pumping stroke.
During the next period of the pumping cycle (i.e. from 144 to 215 degrees), the first roller 22a travels along the second rising flank 68 of the first cam 24a and towards the base 52 thereof. This causes the first plunger 14a to move from its outermost to its innermost position within the bore 32a so as to perform a pumping stroke. In the meantime, the second roller 22b travels down the first falling flank portion 64 of the second cam 24b, thereby causing the second plunger 14b to move from its innermost to outermost position within its bore 32b to carry out a return stroke. At the same time, the third roller 22c is again maintained in contact with the long dwell portion 76 of the third cam 24c and is thus kept at the top of its stroke. At 216 degrees, the second plunger 14b dwells briefly at the bottom of its stroke, while both the first and third plungers 14a, 14c remain innermost in their respective bores 32a,32c. The next period of the pumping cycle takes place between 216 and 287 degrees of revolution of the pump drive shaft 26. During this period, the first roller 22a is travelling along the base 52 of the first cam 24a which defines the long top dwell portion 70, thereby causing the first plunger 14a to dwell at the top of its stroke for the whole of this period. The second roller 22b, however, travels along the second rising flank portion 68 of the second cam 24b thereby causing the second plunger 14b to rise from the bottom of its stroke to the top of its stroke and perform a second pumping stroke. The third roller 22c meanwhile rides to the centre of the concave relief portion 74 of the third cam 24c causing the third plunger 14c to be lowered from its innermost to its outermost position within its bore 32c to perform a return stroke. Thus, at 288 degrees, the third plunger 14c dwells briefly at the bottom of its stroke, while the first and second plungers 14a, 14b remain innermost in their respective bores 32a,32b.
During the fifth, and final, period of the pumping cycle (from 289 to 360 degrees of revolution of the pump drive shaft 26), the first roller 22a travels along the second falling flank portion 72 causing the first plunger 14a to be lowered from its innermost to its outermost position within its bore 32a to carry out a second return stroke. The second roller 22b meanwhile travels along the long top dwell portion 70 of the second cam 24b, thereby causing it to dwell at the top of its stroke during this period. The third roller 22c travels from the centre of the concave relief portion 74 of the third cam 24c to move the third plunger 14c from the bottom of its stroke to the top of its stroke such that a pumping stroke is performed.
Although the first and second cams 24a, 24b of the cam arrangement 101 have been described as having short bottom dwell portions 66 and 58 and a short top dwell portion 62, and the third cam 24c has been described as having a short bottom dwell portion 66, it will be apparent to the skilled person that the first, second and third 24a, 24b, 24c cams may be profiled such that substantially no such short top and bottom dwell portions are provided. It is one feature of the cam arrangement 101 described previously that its implementation in a fuel pump of an engine having five (or ten) engine cylinders provides a regular spacing of pumping strokes per cycle to match the number of engine cylinders. The pump drive shaft 26 can therefore be driven at engine speed (for a five cylinder engine), or at an integer multiple of engine speed (for a ten cylinder engine), matching pumping frequency to fuel injection frequency without the requirement for dedicated or complex gearing between the engine shaft and the pump drive shaft 26. It is a further advantageous feature of the invention that it can be readily be incorporated into existing pump installations by replacing the existing pump drive shaft and cams to co-operate with the existing plungers of the pump. So, for example, for an engine manufacturer, an existing type of pump can be adapted or converted conveniently for use in another engine by selecting a cam arrangement in accordance with the present invention, that is appropriate to provide the required number of pumping strokes per cycle for the number of engine cylinders. For example, the cam arrangement 101 in Figures 5 is also particularly suitable for use in a ten cylinder engine by running the camshaft at twice the speed of the crank shaft, again without the need for complex gearing.
Having described a preferred embodiment of the present invention, it is to be appreciated that this is exemplary only and that variations and modifications such as will occur to those possessed of the appropriate knowledge and skills may be made without departure from the scope of the invention as set forth in the appended claims. It will be appreciated in particular that the use of the phrase "common rail" is not intended to be in any way limiting, and that the fuel pump described herein may be used for delivering fuel to any form of accumulator volume or store for pressurised fuel, from where fuel is subsequently supplied to injectors of an associated engine.
It will also be appreciated that references to upward and downward, or top and bottom, are used for convenience due to the orientation of the fuel pump described in Figure 1 , but equally the pump may be inverted or otherwise oriented whilst still operating in the same manner.

Claims

1. An engine fuel system having an engine drive shaft, a multiple number of engine cylinders, and a pump (10) including at least three pump units being less in total number than the number of engine cylinders, wherein each pump unit has a plunger (14a, 14b, 14c) that is driven, in use, by an associated drive arrangement including a cam (24a,24b,24c) mounted upon a pump drive shaft (26) that is common to the cams of the at least two other pump units, wherein first, second and third ones of the cams (24a, 24b, 24c) are shaped to include at least one rising flank to enable a plunger pumping stroke and at least one falling flank to enable a plunger return stroke, the first and second cams (24a, 24b) being of similar form and the third one of the cams (24c) being of dissimilar form and wherein the first, second and third cams (24a, 24b, 24c) are oriented relative to each other on the pump drive shaft (26) such that the pumping strokes of the plungers (14a,14b,14c) are substantially equally spaced in time and so that during a substantially complete revolution of the pump drive shaft (26) they provide a total number of pumping strokes equal to the number of engine cylinders, thereby to permit the pump drive shaft (26) to be driven at the same speed as the engine drive shaft or at an integer multiple of the speed of the engine drive shaft.
2. A fuel system as claimed in claim 1 , wherein at least one of the cams (24c) is shaped to delay onset of a return stroke of its associated plunger (14c) to define a dwell period for said plunger (14c).
3. A fuel system as claimed in claim 2, wherein the surfaces of the first and second cams (24a, 24b) are shaped to include first and second rising flanks (60, 68) and first and second falling flanks (64, 72) such that upon substantially a complete revolution of the pump drive shaft (26), in use, the first and second plungers (14a, 14b) each perform a first pumping stroke corresponding to the first rising flank (60), a second pumping stroke corresponding to the second rising flank (68), a first return stroke corresponding to the first falling flank (64), a second return stroke corresponding to the second falling flank (72) and at least one dwell period (62, 66, 70, 58), the third cam (24c) being shaped to include one rising flank (60) to perform one pumping stroke and one falling flank (64) to perform one return stroke and a dwell period (66, 76), and wherein the first, second and third cams (24a, 24b, 24c) are oriented relative to one another such that five substantially equally spaced pumping strokes are performed during each complete revolution of the pump drive shaft (26).
4. A fuel system as claimed in claim 3, wherein the cams are shaped so that, in use, the dwell periods (62, 76) occur when the plungers (14a, 14b, 14c) are at their innermost positions in their respective bores (32a, 32b, 32c), prior to the commencement of a return stroke.
5. A fuel system as claimed in claim 3, wherein the cams are shaped so that, in use, the dwell periods (66) occur when the plungers (14a, 14b, 14c) are at their outermost positions in their respective bores (32a, 32b, 32c), prior to the commencement of a pumping stroke.
6. A fuel system as claimed in any one of claims 3 to 5, wherein the first and second cams (24a, 24b) are profiled such that, in use, the associated dwell period is arranged to continue for approximately 72 degrees of rotation of the pump drive shaft (26).
7. A fuel system as claimed in any one of claims 3 to 6, wherein the third cam (24c) is profiled such that, in use, the associated dwell period is arranged to continue for approximately 216 degrees of rotation of the pump drive shaft (26).
8. A fuel system as claimed in any one of claims 3 to 7, wherein the surfaces of the first, second and third cams (24a, 24b, 24c) are further shaped such that, in use, each pumping stroke is arranged to continue for approximately 72 degrees of rotation of the pump drive shaft (26), and each return stroke is also arranged to continue for approximately 72 degrees of rotation of the pump drive shaft (26).
9. A fuel system as claimed in any one of claims 3 to 8, wherein the first and second cams (24a, 24b) have surface profiles substantially as shown in Figure 6 of the drawings.
10. A fuel system as claimed in any one of claims 3 to 9, wherein the third cam (24c) has a surface profile substantially as shown in Figure 7 of the drawings.
11. A fuel system as claimed in any one of claims 1 to 10, wherein the first, second and third cams (24a, 24b, 24c) are formed integrally with the pump drive shaft (26).
12. A fuel system as claimed in any one of claims 1 to 11 , wherein each drive arrangement includes a roller (22) which is cooperable with an associated cam (24a, 24b, 24c) to drive a shoe (20).
13. A pump (10) for use in the fuel system as claimed in any one of claims 1 to 12, including the at least three pump units thereof.
14. An interchangeable cam arrangement (101) for use in the fuel system as claimed in any one of claims 1 to 12, including the at least first and second cams (24a, 24b) of similar form and the third cam (24c) of dissimilar form, thereby to provide a means for adapting the pump for use in engines having different numbers of engine cylinders by changing the cam arrangement (101) without having to change and/or provide additional gearing between the engine drive shaft and the pump drive shaft (26).
15. The cam arrangement (100, 101) as claimed in claim 14, wherein at least one of the first, second or third cams (24a, 24b, 24c) is formed integrally with the pump drive shaft (26).
PCT/GB2004/004387 2003-10-16 2004-10-15 Fuel pump with multiple cams WO2005038234A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP04768917A EP1685325B1 (en) 2003-10-16 2004-10-15 Fuel pump with multiple cams
DE602004005489T DE602004005489T2 (en) 2003-10-16 2004-10-15 FUEL PUMP WITH MULTIPLE CAMS

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP03256531.9 2003-10-16
EP03256531 2003-10-16

Publications (1)

Publication Number Publication Date
WO2005038234A1 true WO2005038234A1 (en) 2005-04-28

Family

ID=34443072

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2004/004387 WO2005038234A1 (en) 2003-10-16 2004-10-15 Fuel pump with multiple cams

Country Status (4)

Country Link
EP (1) EP1685325B1 (en)
AT (1) ATE357589T1 (en)
DE (1) DE602004005489T2 (en)
WO (1) WO2005038234A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008055745A1 (en) * 2006-11-07 2008-05-15 Robert Bosch Gmbh Camshaft drive with geometric cam roller stabilization
EP2383460A1 (en) * 2009-01-26 2011-11-02 Mitsubishi Heavy Industries, Ltd. Device for controlling variation in pressure upstream of common rail
US20220049674A1 (en) * 2020-08-11 2022-02-17 Robert Bosch Gmbh High-Pressure Fuel Pump

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103768998A (en) * 2013-12-31 2014-05-07 郑州磨料磨具磨削研究所有限公司 Rotary type ultrahigh pressure supercharger of synthetic diamond cubic press

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5287840A (en) * 1992-07-30 1994-02-22 General Electric Canada Inc. Cam sections for a "V"-type diesel engine
EP1072787A2 (en) * 1999-07-28 2001-01-31 Toyota Jidosha Kabushiki Kaisha High-pressure fuel pump and cam for high-pressure fuel pump
EP1284367A1 (en) * 2000-04-18 2003-02-19 Toyota Jidosha Kabushiki Kaisha High-pressure fuel pump
JP2003184700A (en) * 2001-12-21 2003-07-03 Denso Corp High pressure fuel pump

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5287840A (en) * 1992-07-30 1994-02-22 General Electric Canada Inc. Cam sections for a "V"-type diesel engine
EP1072787A2 (en) * 1999-07-28 2001-01-31 Toyota Jidosha Kabushiki Kaisha High-pressure fuel pump and cam for high-pressure fuel pump
EP1284367A1 (en) * 2000-04-18 2003-02-19 Toyota Jidosha Kabushiki Kaisha High-pressure fuel pump
JP2003184700A (en) * 2001-12-21 2003-07-03 Denso Corp High pressure fuel pump

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 2003, no. 11 5 November 2003 (2003-11-05) *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008055745A1 (en) * 2006-11-07 2008-05-15 Robert Bosch Gmbh Camshaft drive with geometric cam roller stabilization
EP2383460A1 (en) * 2009-01-26 2011-11-02 Mitsubishi Heavy Industries, Ltd. Device for controlling variation in pressure upstream of common rail
EP2383460A4 (en) * 2009-01-26 2014-01-01 Mitsubishi Heavy Ind Ltd Device for controlling variation in pressure upstream of common rail
US8813721B2 (en) 2009-01-26 2014-08-26 Mitsubishi Heavy Industries, Ltd. Pressure fluctuation control device for controlling pressure fluctuation in upstream side of common rail
US20220049674A1 (en) * 2020-08-11 2022-02-17 Robert Bosch Gmbh High-Pressure Fuel Pump
US11808242B2 (en) * 2020-08-11 2023-11-07 Robert Bosch Gmbh High-pressure fuel pump

Also Published As

Publication number Publication date
DE602004005489D1 (en) 2007-05-03
EP1685325B1 (en) 2007-03-21
ATE357589T1 (en) 2007-04-15
DE602004005489T2 (en) 2007-11-29
EP1685325A1 (en) 2006-08-02

Similar Documents

Publication Publication Date Title
US6763808B2 (en) Fuel pump and fuel feeding device using the fuel pump
US5511956A (en) High pressure fuel pump for internal combustion engine
EP2177746B1 (en) Fuel pump assembly
US5688110A (en) Fuel pump arrangement having cam driven low and high pressure reciprocating plunger pump units
US8136508B2 (en) Selective displacement control of multi-plunger fuel pump
US20080008605A1 (en) Transfer pump with several pistons
CN101878364B (en) Synchronizing common rail pumping events with engine operation
US7406949B2 (en) Selective displacement control of multi-plunger fuel pump
EP2044321B1 (en) Fuel injection system
EP0898074B1 (en) Supply pump for common rail fuel injection system
EP1685325B1 (en) Fuel pump with multiple cams
US4564341A (en) Fuel injection pump for an internal combustion engine
US7308888B2 (en) Cam arrangement and fuel pump arrangement incorporating a cam arrangement
EP1489301B1 (en) Drive arrangement for a pump
EP2812560B1 (en) Improvements relating to fuel pumps
US6758184B1 (en) Method and apparatus for reducing oscillatory camshaft torque in an internal combustion engine
EP2261498B1 (en) Fuel injection system
JPH02176158A (en) Variable discharge high-pressure pump
EP1555432B1 (en) Hydraulic pump
JPH0571439A (en) Fuel injector
GB2385385A (en) Pump assembly
JP2001289138A (en) Fuel supply pump
JPH06117340A (en) Fuel feeding by fuel injection pump and its device
JPH11247736A (en) Distribution type fuel injection pump for unequal interval injection

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2004768917

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2004768917

Country of ref document: EP

WWG Wipo information: grant in national office

Ref document number: 2004768917

Country of ref document: EP