EP0097429B1 - Fuel pump-injector unit - Google Patents
Fuel pump-injector unit Download PDFInfo
- Publication number
- EP0097429B1 EP0097429B1 EP83302947A EP83302947A EP0097429B1 EP 0097429 B1 EP0097429 B1 EP 0097429B1 EP 83302947 A EP83302947 A EP 83302947A EP 83302947 A EP83302947 A EP 83302947A EP 0097429 B1 EP0097429 B1 EP 0097429B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- injector
- pump
- assembly
- sleeve
- fluid
- 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.)
- Expired
Links
- 239000000446 fuel Substances 0.000 title claims description 32
- 239000012530 fluid Substances 0.000 claims description 41
- 238000002347 injection Methods 0.000 claims description 5
- 239000007924 injection Substances 0.000 claims description 5
- 230000000717 retained effect Effects 0.000 claims description 5
- 238000000926 separation method Methods 0.000 claims description 4
- 238000004891 communication Methods 0.000 claims description 3
- 230000014759 maintenance of location Effects 0.000 claims description 2
- 239000007921 spray Substances 0.000 description 23
- 238000002485 combustion reaction Methods 0.000 description 7
- 125000006850 spacer group Chemical group 0.000 description 7
- 238000005086 pumping Methods 0.000 description 6
- 238000007789 sealing Methods 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000002775 capsule Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
Images
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
- F02M57/00—Fuel-injectors combined or associated with other devices
- F02M57/02—Injectors structurally combined with fuel-injection pumps
-
- 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
- F02M57/00—Fuel-injectors combined or associated with other devices
- F02M57/02—Injectors structurally combined with fuel-injection pumps
- F02M57/022—Injectors structurally combined with fuel-injection pumps characterised by the pump drive
- F02M57/023—Injectors structurally combined with fuel-injection pumps characterised by the pump drive mechanical
Definitions
- This invention relates to a modular fuel pump-injector unit for delivering fuel directly to the combustion chambers of a compression-ignition engine.
- the amount of high pressure fuel leakage between the internal components is also very sensitive to the quality of surface finish and parallelism of the numerous abutting sealing end surfaces of those parts. Excessive fuel leakage erodes and thereby irreparably damages the sealing end surfaces and also helps to cause undesirably large tolerances on injector fuel flow rate and injector valve opening pressure.
- the entire pump-injector must be disassembled for servicing or rebuilding even though it is usually only the spray tip of the injector assembly that requires replacement or cleaning since only the spray tip is directly exposed to the severe environment of the engine combustion chamber.
- the combustion by-products build up carbon and corrosive elements in the seat area between the spray tip and nut, in addition to the spray tip orifices, making it difficult to disassemble and clean the spray tip and nut.
- the injector assembly of the pump-injector must be disassembled even though it may be only the pump assembly that requires servicing.
- the modular fuel pump-injector assembly disclosed in US-A-3,055,593 overcomes some of the above problems. It comprises a housing; an pump assembly having a pump cylinder and a plunger therein for developing an injection charge of pressurized fluid; an injector assembly having a valve and a valve body for injecting the charge of fluid through a nozzle outlet; a first sleeve-type nut removably mounted on the housing and removably retaining the pump cylinder; and a second sleeve type nut axially aligned with and removably mounted on the first sleeve-type nut and retaining the injector assembly, the second sleeve-type nut and the injector assembly being removable in the direction of the nozzle outlet independently of the retention of the first sleeve-type nut on the housing.
- Such a pump-injector assembly is hereinafter referred to as of the kind described.
- a modular pump-injector unit assembly of the kind described is characterised in that the pump cylinder is removable out of the first sleeve type nut in the direction away from the injector assembly and is retained in its mounted position, with its one end furthest from the injector assembly against the housing, by retaining means supporting the other end of the pump cylinder and in that the second sleeve-type nut removably retains the injector assembly against the retaining means.
- the present invention thus provides a modular unit fluid pump-injector having two joints for separately sealed clamping the internal components thereby facilitating easier assembling and servicing of the pump-injector. With fewer internal parts clamped between each joint, the pump-injector is less prone to high pressure fluid leakage and having the plunger bind in the pump cylinder. Also, either the pump or injector assembly can be serviced without disturbing the other one relative to the first retaining means.
- FIG. 1 and 2 wherein similar reference numbers designate the same parts in the two views, the preferred embodiment of a modular fluid pump-injector 10 is shown after it has been assembled and then seated against an internal frusto-conical seat or surface 12 located within a stepped bore 14 of a cylinder head 16.
- the upper portion of the pump-injector is conventional and comprises a housing 18 and a pump assembly 20.
- a two-prong clamp 22 and a bolt 24 fasten the housing 18 to the cylinder head 16.
- the lower portion of the pump-injector 10 is unconventional and comprises a first means 26 for removably retaining a portion of the pump assembly 20 against the housing 18, an injector assembly 28, and a second means 30 for removably retaining the injector assembly 28 against the first retaining means 26 so that the injector assembly 28 may be removed from or assembled to the first retaining means 26 without requiring removal of the first retaining means 26 or even altering the position or arrangement of the pump assembly 20 relative to the first retaining means 26.
- the pump assembly 20 may be removed from or assembled to the first retaining means 26 without requiring removal of the second retaining means 30 or even altering the position or arrangement of the injector assembly 28 relative to the first retaining means 26.
- the pump assembly 20 includes a pump cylinder or barrel 32 and a plunger 34.
- the pump cylinder 32 has upper and lower fluid ports 36, 38 which communicate with an internal pumping chamber 40.
- the pump cylinder 32 also includes a reduced-diameter external end portion 42 which is piloted into the housing 18 and is sealably seated against the housing 18 at a housing shoulder 44.
- the plunger 34 having an internal transverse channel 46 communicating wtih an internal longitudinal channel 48 and a helical fluid-metering groove 50, is slidably positioned within the pumping chamber 40 and is rotatably clasped by a bifurcated follower 52 which is reciprocable within the housing 18.
- a plunger return spring 54 cooperates with a pivotal rocker 56, a push rod 58, and an engine-driven rotatable camshaft 60 in effecting reciprocation of follower 52 and plunger 34.
- the plunger 34 is also rotatable within the pump cylinder 32 and has external splines 62 which slidably engage a rotatable pinion gear 64 and slidable rack 66 positioned in the housing 18.
- the first retaining means 26 includes a first elongate sleeve-type nut or retainer 68, and a pump cylinder retainer 70.
- the first nut 68 has stepped large, intermediate, and small diameter bores 72, 74, 76, whereby the intermediate and small diameter bores 74, 76 define a shoulder 78.
- the pump cylinder 32 is positioned in the large diameter bore 72 and the pump cylinder retainer 70 is positioned within the intermediate diameter bore 74 and is sealably seated between the pump cylinder 32 and the shoulder 78.
- the inner upper portion of the first nut 68 has a first internally- threaded portion 80 which is threadably mated to the housing 18 and the first nut 68 may be tightened against it by a wrench which engages a hexagonal-shaped exterior surface 82 on the first nut 68.
- An annular seal 84 is positioned between the first threaded portion 80 and housing 18.
- annular fluid reservoir 86 Located concentrically between the first nut 68 and the pump cylinder 32 is an annular fluid reservoir 86 which communicates with upper and lower fluid ports 36, 38.
- the first nut 68 also includes fluid supply and return ports 88, 90, which communicate with the fluid reservoir 86 and also with an annular space 92 in the cylinder head bore 14 which communicates with a fluid supply manifold (not shown).
- a plurality of annular fluid seals 94 are externally positioned on the first nut 68 above and below the fluid supply ports 88,90.
- the pump cylinder retainer 70 includes a centrally-located fluid delivery opening 96, which connects the pumping chamber 40 and the injector assembly 28, and a means 98 for returning fluid leakage from the small diameter bore 76 of the first nut 68 to the annular fluid reservoir 86.
- the fluid leakage return means 98 is a passage angularly drilled in the pump cylinder retainer 70.
- the injector assembly 28 is located partially in the small diameter bore 76 of the first nut 68 and includes a valve body 100, a valve 102 position within the valve body 100, a means 104 for resiliently biasing the valve 102, and a formed case 106 sealably encircling or encapsulating the valve body 100 and the resilient biasing means 104 and retaining them against separation.
- the valve body 100 includes a spray tip 108 having a valve seat 110 and at least one outlet or spray orifice 112, a spacer block or spring cage 114 sealably abutting the spray tip 108, and a spring retainer 116 abutting the spacer block 114 and also sealably abutting the pump cylinder retainer 70.
- Internal portions of the spray tip 108, spacer block 114, and spring retainer 116 define at least one fluid charge delivery passage 118 which communicates between the fluid delivery opening 96 of the pump cylinder retainer 70 and the outlet 112 of the spray tip 108.
- the middle portion of the spray tip 108 defines a cardioidal or heart- shaped fluid pressure chamber 121 in the passage 118.
- the spray tip 108 and spacer block 114 define a centrally-disposed longitudinal stepped bore 120 which houses the slidable valve 102 and resilient biasing means 104.
- the resilient biasing means 104 includes a helical compression spring 122 and optionally one or more annular spring-preload shims 124.
- the valve 102 includes a conical tip portion 126, a cylindrical needle portion 128, an annular convex surface portion 130 positioned in the cardioid chamber 121, a relatively larger diameter guide portion 132, a spring seat portion 134, and a stop portion 136.
- the valve 102 is movable between a first position at which the tip portion 126 is seated on valve seat 110, thereby blocking fluid communication between the fluid charge delivery passage 118 and the outlet 112, and a second position at which the tip portion 126 is upwardly spaced from the valve seat 110 thereby opening fluid communication.
- the spring retainer 116 has a centrally disposed cavity 138, facing the fluid delivery opening 96 of the pump cylinder retainer 70, and houses a reverse-flow check valve 140.
- the check valve 140 in response to differential fluid pressure and gravity is movable between a first position at which the check valve 140 is spaced from the opening 96 and a second position at which the check valve 140 seats against the pump cylinder retainer 70 and blocks the opening 96.
- the case 106 of the injector assembly 28 is preferably formed of a ductile metal having good heat conducting properties and is pressed or coined to the shape illustrated around the spray tip 108, spacer block 114, and spring retainer 116.
- the case 106 is substantially tubular and has a frusto-conical end portion 142 which mates with a frusto-conical end portion 144 ofthe spray tip 108.
- the case 106 and spacer block 114 define a fluid bleed-off passage 146 which communicates with the valve body bore 120 and the fluid leakage return means 98 of the pump cylinder retainer 70.
- the second retaining means 30 includes a second sleeve-type nut or retainer 148 having a substantially tubular portion 150 with a longitudinally splined exterior surface 152 and a frusto-conical end portion 154 which is positioned in close proximity to the interiorly disposed cardioidal chamber 121 of the spray tip 108 and which seats against the internal frusto-conical seat 12 of the cylinder head 16.
- the first nut 68 has a second externally-threaded portion 156 which threadably mates with the tubular portion 150 of the second nut 148.
- An annular fluid seal 158 is provided adjacent the second threaded portion 156 and second nut 148.
- the injector assembly 28 is sealably and removably retained between the pump cylinder retainer 70 and the frusto-conical end portion 154 of the second nut 148.
- the sandwiched frusto-conical end portions 144, 142, 154 of the spray tip 108, case 106, and second nut 148, respectively, have the same included angles S, C, N and are selected from the range of about 40° to 80°, and, more preferably are about 50°.
- This frusto-conical configuration of the end portions 144, 142, 154 in assembled cooperation with the tightened clamp 22 ensures adequate sealing between the seat 12 and these mating end portions relative to the combustion chamber.
- This configuration also induces a preselected compressive-stress state in the close proximity region of the spray tip 108 defining the cardioidal chamber 121, to prevent tensile-stress induced cracking and improve the fluid-pressure loading capability and fatigue life of that spray tip region, and yet prevent a loss of optimal guiding, sliding, and fluid leakage clearance between the bore 120 and the slidable valve guide portion 132 when the second nut 148 is tightened.
- the angles S, C, and N are selected to prevent unacceptable stress in the inner surface of the second nut 148 when it is tightened.
- a fluid for example diesel fuel
- a fluid for example diesel fuel
- the valve 102 is seated and the reciprocable plunger 34 is at the top of its stroke thereby uncovering the lower port 38 and allowing fuel to flow from the annular reservoir 92 into the pumping chamber 40 and fluid charge delivery passage 118.
- the plunger 34 As the plunger 34 descends under the cooperative influence of the engine-driven rotatable camshaft 60, pushrod 58, pivotal rocker 56, and reciprocable follower 52, the plunger 34 first covers the lower port 38 and then pumps fuel through internal channels 46, 48, metering groove 50, out through upper port 36, and back to the annular fluid reservoir 86 until the metering groove 50 no longer communicates with the upper port 36.
- the modular design of the unit fluid pump-injector having one threaded joint which removably and sealably clamps the pump cylinder 32 between the pump cylinder retainer 70 and the housing 18 and another threaded joint which removably and sealably clamps the injector assembly 28 to the pump cylinder retainer 70, advantageously is less prone to high pressure fuel leakage or to having the plunger bind during assembly since fewer parts are stacked and clamped together.
- the modular design also advantageously allows merely the second nut 148 to be threadably unfastened from the first nut 68 so that the injector assembly 28 can be removed, for easier servicing or replacement, from the small diameter bore 76 of the first nut 68 without requiring removal of the first nut 68 or altering the position or arrangement of the pump assembly 20 relative to the first nut 68.
- the housing 18 may be threadably removed from the first nut 68 so that the pump assembly 20 can be removed from the large diameter bore 72 of the first nut 68 without requiring removal of the second nut 148 or altering the position or arrangement of the injector assembly 28 relative to the first nut 68.
- the configuration of the injector assembly 28 advantageously allows the spray tip 108, spacer block 114, spring retainer 116, and resilient biasing means 104 to be clamped together in a test fixture for testing, adjustment, and close control of desired operating characteristics such as fuel flow rate, valve lift, and valve opening fuel pressure. Afterwards these parts are substantially encapsulated and retained against separation by the tamper proof case 106.
- the injector assembly 28 may then be coded for identification of its operating characteristics and selectively installed as a new or replacement part in a new or rebuilt unit fuel pump-injector.
- the sandwiched frusto-conical end portions 154, 142, 144 of the second nut 148, case 106, and spray tip 108, respectively, which seat at surface 12 in the bore 14 of the cylinder head 16 provide a tight seal against carbon formation from the combustion chamber thus facilitating easier removal and servicing of the injector assembly 28.
- the sandwiched frusto-conical end portions in seated cooperation with the tightened clamp 22 and cylinder head seat 12 create a preselected compressive stress state in the close proximity region of the spray tip 108 defining the cardioidal chamber 121 to prevent cracking and improve the fluid-pressure loading capability and fatigue life of that spray tip region.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fuel-Injection Apparatus (AREA)
Description
- This invention relates to a modular fuel pump-injector unit for delivering fuel directly to the combustion chambers of a compression-ignition engine.
- In prior art unit fuel pump-injectors, such as disclosed in US-A-3,006,556, it has been conventional to provide a single elongate sleeve-type nut which substantially encloses a stacked plurality of both injector and pump components. The nut is threadably mated and tightened to a housing in order to retain the components against separation and thereby join the respective abutting high pressure sealing end surfaces of these internal components.
- A number of problems are encountered with this typical unit fuel pump-injector configuration. Firstly, a relatively large number of internal components, such as a spray tip, spring cage, spring retainer, and fuel pump cylinder, are stacked and clamped between the single nut and the housing. Thus, for example, the degree of success in assembling the pump injector and tightening the nut without undesirably binding the reciprocable plunger in the pump cylinder, is at least partly dependent on the quality of surface finish and parallelism of each of the numerous abutting high pressure sealing end surfaces of the components.
- Even if the required quality of surface finish and parallelism is achieved during manufacture of the components, the problem of the plunger binding in the pump cylinder can arise in attempting to reassemble a used and worn pump-injector that had been disassembled for cleaning or rebuilding. In such cases, the nut must be loosened or removed and the internal components must be shifted around several times or even relapped at their end surfaces before the nut can be properly tightened.
- Secondly, the amount of high pressure fuel leakage between the internal components is also very sensitive to the quality of surface finish and parallelism of the numerous abutting sealing end surfaces of those parts. Excessive fuel leakage erodes and thereby irreparably damages the sealing end surfaces and also helps to cause undesirably large tolerances on injector fuel flow rate and injector valve opening pressure.
- Thirdly, the entire pump-injector must be disassembled for servicing or rebuilding even though it is usually only the spray tip of the injector assembly that requires replacement or cleaning since only the spray tip is directly exposed to the severe environment of the engine combustion chamber. The combustion by-products build up carbon and corrosive elements in the seat area between the spray tip and nut, in addition to the spray tip orifices, making it difficult to disassemble and clean the spray tip and nut. Conversely, the injector assembly of the pump-injector must be disassembled even though it may be only the pump assembly that requires servicing.
- Fourthly, evaluation and quality control of performance parameters such as fuel injector flow rate, fuel internal leakage rate, and injector valve opening pressure of the pump-injector is time consuming since the entire pump-injector must be carefully assembled, bench tested, and then completely disassembled in order to substitute injector spring shims or other internal components which will bring the parameters within acceptable tolerances.
- The modular fuel pump-injector assembly disclosed in US-A-3,055,593 overcomes some of the above problems. It comprises a housing; an pump assembly having a pump cylinder and a plunger therein for developing an injection charge of pressurized fluid; an injector assembly having a valve and a valve body for injecting the charge of fluid through a nozzle outlet; a first sleeve-type nut removably mounted on the housing and removably retaining the pump cylinder; and a second sleeve type nut axially aligned with and removably mounted on the first sleeve-type nut and retaining the injector assembly, the second sleeve-type nut and the injector assembly being removable in the direction of the nozzle outlet independently of the retention of the first sleeve-type nut on the housing.
- Such a pump-injector assembly is hereinafter referred to as of the kind described.
- In US-A-2,560,799, there is disclosed a capsule which contains an injection valve and nozzle assembly to permit the assembly to be bench tested and observed in operation without connecting it to an engine. However, these teachings have never been adapted or applied to an injector assembly for a unit fuel pump-injector.
- According to the invention, a modular pump-injector unit assembly of the kind described is characterised in that the pump cylinder is removable out of the first sleeve type nut in the direction away from the injector assembly and is retained in its mounted position, with its one end furthest from the injector assembly against the housing, by retaining means supporting the other end of the pump cylinder and in that the second sleeve-type nut removably retains the injector assembly against the retaining means.
- The present invention thus provides a modular unit fluid pump-injector having two joints for separately sealed clamping the internal components thereby facilitating easier assembling and servicing of the pump-injector. With fewer internal parts clamped between each joint, the pump-injector is less prone to high pressure fluid leakage and having the plunger bind in the pump cylinder. Also, either the pump or injector assembly can be serviced without disturbing the other one relative to the first retaining means.
- One example of a modular pump-injector according to the invention will now be described with reference to the accompanying drawings in which:-
- Figure 1 is a diagrammatic cross-sectional view of an example of the present invention as incorporated in a cylinder head of an internal combustion engine.
- Figure 2 is a diagrammatic enlarged partial view of Figure 1 in the area of the injector assembly.
- Referring to Figures 1 and 2 wherein similar reference numbers designate the same parts in the two views, the preferred embodiment of a modular fluid pump-
injector 10 is shown after it has been assembled and then seated against an internal frusto-conical seat orsurface 12 located within a stepped bore 14 of acylinder head 16. - The upper portion of the pump-injector is conventional and comprises a
housing 18 and apump assembly 20. As is well known in the art, a two-prong clamp 22 and abolt 24 fasten thehousing 18 to thecylinder head 16. - The lower portion of the pump-
injector 10 is unconventional and comprises afirst means 26 for removably retaining a portion of thepump assembly 20 against thehousing 18, aninjector assembly 28, and asecond means 30 for removably retaining theinjector assembly 28 against the first retaining means 26 so that theinjector assembly 28 may be removed from or assembled to thefirst retaining means 26 without requiring removal of thefirst retaining means 26 or even altering the position or arrangement of thepump assembly 20 relative to thefirst retaining means 26. Conversely thepump assembly 20 may be removed from or assembled to the first retaining means 26 without requiring removal of the second retaining means 30 or even altering the position or arrangement of theinjector assembly 28 relative to the first retaining means 26. - The
pump assembly 20 includes a pump cylinder orbarrel 32 and a plunger 34. Thepump cylinder 32 has upper andlower fluid ports 36, 38 which communicate with aninternal pumping chamber 40. Thepump cylinder 32 also includes a reduced-diameterexternal end portion 42 which is piloted into thehousing 18 and is sealably seated against thehousing 18 at ahousing shoulder 44. - The plunger 34, having an internal transverse channel 46 communicating wtih an internal
longitudinal channel 48 and a helical fluid-metering groove 50, is slidably positioned within thepumping chamber 40 and is rotatably clasped by a bifurcated follower 52 which is reciprocable within thehousing 18. Aplunger return spring 54 cooperates with apivotal rocker 56, a push rod 58, and an engine-drivenrotatable camshaft 60 in effecting reciprocation of follower 52 and plunger 34. - The plunger 34 is also rotatable within the
pump cylinder 32 and hasexternal splines 62 which slidably engage a rotatable pinion gear 64 and slidable rack 66 positioned in thehousing 18. - The first retaining means 26 includes a first elongate sleeve-type nut or
retainer 68, and apump cylinder retainer 70. Thefirst nut 68 has stepped large, intermediate, andsmall diameter bores small diameter bores shoulder 78. Thepump cylinder 32 is positioned in thelarge diameter bore 72 and thepump cylinder retainer 70 is positioned within theintermediate diameter bore 74 and is sealably seated between thepump cylinder 32 and theshoulder 78. The inner upper portion of thefirst nut 68 has a first internally- threadedportion 80 which is threadably mated to thehousing 18 and thefirst nut 68 may be tightened against it by a wrench which engages a hexagonal-shapedexterior surface 82 on thefirst nut 68. Anannular seal 84 is positioned between the first threadedportion 80 and housing 18. Once thefirst nut 68 is tightened, thepump cylinder 32 is sealably and removably retained between thehousing shoulder 44 and thepump cylinder retainer 70. - Located concentrically between the
first nut 68 and thepump cylinder 32 is anannular fluid reservoir 86 which communicates with upper andlower fluid ports 36, 38. Thefirst nut 68 also includes fluid supply andreturn ports 88, 90, which communicate with thefluid reservoir 86 and also with anannular space 92 in the cylinder head bore 14 which communicates with a fluid supply manifold (not shown). A plurality ofannular fluid seals 94 are externally positioned on thefirst nut 68 above and below thefluid supply ports 88,90. - The
pump cylinder retainer 70 includes a centrally-located fluid delivery opening 96, which connects thepumping chamber 40 and theinjector assembly 28, and ameans 98 for returning fluid leakage from thesmall diameter bore 76 of thefirst nut 68 to theannular fluid reservoir 86. Preferably, the fluid leakage return means 98 is a passage angularly drilled in thepump cylinder retainer 70. - The
injector assembly 28 is located partially in thesmall diameter bore 76 of thefirst nut 68 and includes avalve body 100, avalve 102 position within thevalve body 100, ameans 104 for resiliently biasing thevalve 102, and a formedcase 106 sealably encircling or encapsulating thevalve body 100 and the resilient biasing means 104 and retaining them against separation. - The
valve body 100 includes aspray tip 108 having avalve seat 110 and at least one outlet orspray orifice 112, a spacer block orspring cage 114 sealably abutting thespray tip 108, and aspring retainer 116 abutting thespacer block 114 and also sealably abutting thepump cylinder retainer 70. Internal portions of thespray tip 108,spacer block 114, andspring retainer 116 define at least one fluidcharge delivery passage 118 which communicates between the fluid delivery opening 96 of thepump cylinder retainer 70 and theoutlet 112 of thespray tip 108. The middle portion of thespray tip 108 defines a cardioidal or heart- shapedfluid pressure chamber 121 in thepassage 118. - The
spray tip 108 andspacer block 114 define a centrally-disposed longitudinalstepped bore 120 which houses theslidable valve 102 and resilient biasing means 104. Preferably, the resilient biasing means 104 includes ahelical compression spring 122 and optionally one or more annular spring-preload shims 124. Thevalve 102 includes aconical tip portion 126, acylindrical needle portion 128, an annular convex surface portion 130 positioned in thecardioid chamber 121, a relatively larger diameter guide portion 132, a spring seat portion 134, and astop portion 136. Thevalve 102 is movable between a first position at which thetip portion 126 is seated onvalve seat 110, thereby blocking fluid communication between the fluidcharge delivery passage 118 and theoutlet 112, and a second position at which thetip portion 126 is upwardly spaced from thevalve seat 110 thereby opening fluid communication. - The
spring retainer 116 has a centrally disposedcavity 138, facing the fluid delivery opening 96 of thepump cylinder retainer 70, and houses a reverse-flow check valve 140. Thecheck valve 140 in response to differential fluid pressure and gravity is movable between a first position at which thecheck valve 140 is spaced from the opening 96 and a second position at which thecheck valve 140 seats against thepump cylinder retainer 70 and blocks theopening 96. - The
case 106 of theinjector assembly 28 is preferably formed of a ductile metal having good heat conducting properties and is pressed or coined to the shape illustrated around thespray tip 108,spacer block 114, andspring retainer 116. Thecase 106 is substantially tubular and has a frusto-conical end portion 142 which mates with a frusto-conical end portion 144 ofthespray tip 108. Thecase 106 andspacer block 114 define a fluid bleed-offpassage 146 which communicates with the valve body bore 120 and the fluid leakage return means 98 of thepump cylinder retainer 70. - The second retaining means 30 includes a second sleeve-type nut or
retainer 148 having a substantially tubular portion 150 with a longitudinally splinedexterior surface 152 and a frusto-conical end portion 154 which is positioned in close proximity to the interiorly disposedcardioidal chamber 121 of thespray tip 108 and which seats against the internal frusto-conical seat 12 of thecylinder head 16. Thefirst nut 68 has a second externally-threadedportion 156 which threadably mates with the tubular portion 150 of thesecond nut 148. Anannular fluid seal 158 is provided adjacent the second threadedportion 156 andsecond nut 148. Once thesecond nut 148 is tightened, theinjector assembly 28 is sealably and removably retained between thepump cylinder retainer 70 and the frusto-conical end portion 154 of thesecond nut 148. The sandwiched frusto-conical end portions spray tip 108,case 106, andsecond nut 148, respectively, have the same included angles S, C, N and are selected from the range of about 40° to 80°, and, more preferably are about 50°. - This frusto-conical configuration of the
end portions clamp 22 ensures adequate sealing between theseat 12 and these mating end portions relative to the combustion chamber. This configuration also induces a preselected compressive-stress state in the close proximity region of thespray tip 108 defining thecardioidal chamber 121, to prevent tensile-stress induced cracking and improve the fluid-pressure loading capability and fatigue life of that spray tip region, and yet prevent a loss of optimal guiding, sliding, and fluid leakage clearance between thebore 120 and the slidable valve guide portion 132 when thesecond nut 148 is tightened. Moreover, the angles S, C, and N are selected to prevent unacceptable stress in the inner surface of thesecond nut 148 when it is tightened. - While the operation of the present invention is believed clearly apparent from the foregoing description, further amplification will be made in the following brief summary of such operation.
- In operation, a fluid, for example diesel fuel, is supplied under relatively low pressure to the
annular reservoir 86 from the fuel manifold (not shown), through theannular space 92 andfluid supply port 88. In the position shown, thevalve 102 is seated and the reciprocable plunger 34 is at the top of its stroke thereby uncovering the lower port 38 and allowing fuel to flow from theannular reservoir 92 into the pumpingchamber 40 and fluidcharge delivery passage 118. As the plunger 34 descends under the cooperative influence of the engine-drivenrotatable camshaft 60, pushrod 58,pivotal rocker 56, and reciprocable follower 52, the plunger 34 first covers the lower port 38 and then pumps fuel throughinternal channels 46, 48, metering groove 50, out throughupper port 36, and back to theannular fluid reservoir 86 until the metering groove 50 no longer communicates with theupper port 36. As the plunger 34 continues descending afterupper port 36 is blocked, the fuel pressure rises rapidly in both thepumping chamber 40 and the fluidcharge delivery passage 118 until the high fuel pressure incardioidal chamber 121 acting on the exposed annular surface portion 130 of thevalve 102 is sufficient to slightly lift the resiliently biasedvalve 102 off itsseat 110 thereby additionally exposing theconical tip portion 126 of thevalve 102 to high fuel pressure and causing thevalve 102 to further lift until itsstop portion 136 abuts thespring retainer 116. When thevalve 102 is unseated from thevalve seat 110, high pressure fuel is injected into the combustion chamber (not shown) through theoutlets 112. The injection continues under the influence of the downwardly moving plunger 34 until the metering groove 50 communicates with the lower port 38 thereby bypassing the remaining fuel in thepumping chamber 40 to theannular reservoir 86 and relieving the high fuel pressure which then allows thespring 122 to seat thevalve 102 and terminate fuel injection until the cycle is repeated. - The modular design of the unit fluid pump-injector, having one threaded joint which removably and sealably clamps the
pump cylinder 32 between thepump cylinder retainer 70 and thehousing 18 and another threaded joint which removably and sealably clamps theinjector assembly 28 to thepump cylinder retainer 70, advantageously is less prone to high pressure fuel leakage or to having the plunger bind during assembly since fewer parts are stacked and clamped together. - The modular design also advantageously allows merely the
second nut 148 to be threadably unfastened from thefirst nut 68 so that theinjector assembly 28 can be removed, for easier servicing or replacement, from the small diameter bore 76 of thefirst nut 68 without requiring removal of thefirst nut 68 or altering the position or arrangement of thepump assembly 20 relative to thefirst nut 68. - Conversely, the
housing 18 may be threadably removed from thefirst nut 68 so that thepump assembly 20 can be removed from the large diameter bore 72 of thefirst nut 68 without requiring removal of thesecond nut 148 or altering the position or arrangement of theinjector assembly 28 relative to thefirst nut 68. - The configuration of the
injector assembly 28 advantageously allows thespray tip 108,spacer block 114,spring retainer 116, and resilient biasing means 104 to be clamped together in a test fixture for testing, adjustment, and close control of desired operating characteristics such as fuel flow rate, valve lift, and valve opening fuel pressure. Afterwards these parts are substantially encapsulated and retained against separation by thetamper proof case 106. Theinjector assembly 28 may then be coded for identification of its operating characteristics and selectively installed as a new or replacement part in a new or rebuilt unit fuel pump-injector. - The sandwiched frusto-
conical end portions second nut 148,case 106, andspray tip 108, respectively, which seat atsurface 12 in the bore 14 of thecylinder head 16 provide a tight seal against carbon formation from the combustion chamber thus facilitating easier removal and servicing of theinjector assembly 28. Moreover, the sandwiched frusto-conical end portions in seated cooperation with the tightenedclamp 22 andcylinder head seat 12 create a preselected compressive stress state in the close proximity region of thespray tip 108 defining thecardioidal chamber 121 to prevent cracking and improve the fluid-pressure loading capability and fatigue life of that spray tip region.
Claims (5)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US38963682A | 1982-06-18 | 1982-06-18 | |
US389636 | 1982-06-18 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0097429A1 EP0097429A1 (en) | 1984-01-04 |
EP0097429B1 true EP0097429B1 (en) | 1987-07-22 |
Family
ID=23539074
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP83302947A Expired EP0097429B1 (en) | 1982-06-18 | 1983-05-23 | Fuel pump-injector unit |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0097429B1 (en) |
JP (1) | JPS595870A (en) |
CA (1) | CA1188582A (en) |
DE (1) | DE3372645D1 (en) |
MY (1) | MY101909A (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AT385819B (en) * | 1984-03-08 | 1988-05-25 | Steyr Daimler Puch Ag | FUEL INJECTION UNIT FOR ONE CYLINDER OF A DIESEL ENGINE |
JPS62117577U (en) * | 1986-01-20 | 1987-07-25 | ||
GB2268543B (en) * | 1992-07-10 | 1996-01-10 | Volkswagen Ag | Cylinder head,having a pumping nozzle unit,for an internal combustion engine |
GB2311558A (en) * | 1996-03-28 | 1997-10-01 | Stanadyne Automotive Corp | Fuel injection nozzle with compressive radial pre-loading |
DE102015211780A1 (en) * | 2015-06-25 | 2016-12-29 | Robert Bosch Gmbh | Fuel injector and method for assembling a fuel injector |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2082808A (en) * | 1934-09-10 | 1937-06-08 | Murphy Diesel Company Ltd | Fuel injection apparatus |
US2408288A (en) * | 1942-11-13 | 1946-09-24 | Bendix Aviat Corp | Fuel injection apparatus |
US3055593A (en) * | 1960-05-02 | 1962-09-25 | Walker Mfg Co | Fuel injection nozzle |
US3006556A (en) * | 1961-01-03 | 1961-10-31 | Gen Motors Corp | Unit fuel pump-injector |
JPS5028573A (en) * | 1973-07-13 | 1975-03-24 | ||
DE2424800C2 (en) * | 1974-05-22 | 1986-01-02 | Daimler-Benz Ag, 7000 Stuttgart | Injection device for injecting an additional, small amount of fuel into an externally ignited internal combustion engine that works according to the stratified charge principle |
-
1983
- 1983-03-21 CA CA000424060A patent/CA1188582A/en not_active Expired
- 1983-05-12 JP JP58081837A patent/JPS595870A/en active Pending
- 1983-05-23 DE DE8383302947T patent/DE3372645D1/en not_active Expired
- 1983-05-23 EP EP83302947A patent/EP0097429B1/en not_active Expired
-
1987
- 1987-09-28 MY MYPI87002065A patent/MY101909A/en unknown
Also Published As
Publication number | Publication date |
---|---|
CA1188582A (en) | 1985-06-11 |
DE3372645D1 (en) | 1987-08-27 |
MY101909A (en) | 1992-02-15 |
JPS595870A (en) | 1984-01-12 |
EP0097429A1 (en) | 1984-01-04 |
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