(19)
(11)EP 3 239 514 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
04.11.2020 Bulletin 2020/45

(21)Application number: 17167344.5

(22)Date of filing:  20.04.2017
(51)International Patent Classification (IPC): 
F02M 59/44(2006.01)
F04B 39/00(2006.01)
F02M 59/46(2006.01)

(54)

HIGH PRESSURE FUEL PUMP

HOCHDRUCKBRENNSTOFFPUMPE

POMPE À CARBURANT HAUTE PRESSION


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 27.04.2016 GB 201607311

(43)Date of publication of application:
01.11.2017 Bulletin 2017/44

(73)Proprietor: Delphi Technologies IP Limited
St. Michael (BB)

(72)Inventor:
  • CUST, Daniel P.
    Tunbridge Wells, Kent TN2 4NS (GB)

(74)Representative: Delphi France SAS 
c/o Delphi Technologies Campus Saint Christophe Bâtiment Galilée 2 10, avenue de l'Entreprise
95863 Cergy Pontoise Cedex
95863 Cergy Pontoise Cedex (FR)


(56)References cited: : 
EP-A1- 2 492 506
DE-A1-102008 040 088
KR-A- 20120 045 270
DE-A1- 19 854 716
DE-A1-102008 041 176
US-A1- 2008 224 417
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    TECHNICAL FIELD



    [0001] The present invention relates to a cam actuated high pressure pump and more particularly to a plunger arrangement.

    BACKGROUND OF THE INVENTION



    [0002] A diesel internal combustion engine (ICE) comprises a fuel injection equipment wherein fuel sucked from a low pressure tank is pressurized at 2000 bars or higher in a cam actuated high pressure pump, prior to be delivered to a high pressure reservoir, or common rail, to which are connected a plurality of fuel injectors. A command unit controls the equipment as a function of the demand of fuel from the ICE.

    [0003] In the high pressure pump, fuel is pressurized in a compression chamber defined between the head end of a plunger and the blind end of a bore. The plunger reciprocates in the bore therein performing a pumping cycle during which the inner volume of the compression chamber is varied. As said volume reduces instead of being pressurized, part of the fuel leaks between the plunger and the bore, through a clearance that enlarges as the pressure in the chamber rises.

    [0004] To limit or reduce said leaks to the minimum acceptable and still enabling plunger to bore lubrication several solutions have been tested such as plungers provided with a deep recess opening on their head end. In operation the recess is filled with fuel and, when the pressure rises the peripheral wall of the recess slightly expands and closes, at least partially, the clearance.

    [0005] Unfortunately, the recess augments the quantity of pressurized fuel above the necessary engine demand then, the pressure of said undelivered over-quantity alternatively rises and drops, this representing important energy losses. KR1020120045270 discloses a pump of the prior art.

    SUMMARY OF THE INVENTION



    [0006] Accordingly, it is an object of the present invention to resolve the above mentioned problems in providing a high pressure fuel pump having a pumping head wherein a compression chamber is defined between the blind end of a bore and the head end of a plunger slidably adjusted in said bore and adapted to perform therein a pumping cycle varying the volume of said compression chamber.

    [0007] The pump is further provided with inlet and outlet valve assemblies for controlling fuel flowing in and out of said compression chamber.

    [0008] Advantageously, the plunger is provided with an inner chamber arranged in the head end of the plunger that is in the vicinity of the compression chamber, said inner chamber being in fluid communication with the compression chamber via an opening orifice arranged in the head end of the plunger.

    [0009] According to the invention said plunger inner chamber is defined by a peripheral wall adapted to expand when the plunger inner chamber is under pressure.

    [0010] The high pressure fuel pump is provided with a check valve assembly arranged to control said fluid communication.

    [0011] Also, said check valve assembly is normally in a closed state of the opening orifice and is arranged to open the fluid communication only when the pressure in the compression chamber exceeds the pressure in the plunger inner chamber.

    [0012] Said check valve assembly comprises a spring member biasing a valve member against a seating face surrounding said opening.

    [0013] Also, the valve member and the spring member are both arranged inside the plunger inner chamber.

    [0014] More precisely, the plunger is provided with a recess arranged on its head end, said recess defining the inner chamber, the peripheral wall axially extending toward a top circular extremity. Said peripheral wall receiving a plugging cap adjusted and fixed to said top circular extremity. The plugging cap is provided with a central opening defining the fluid communication between the compression chamber and the plunger inner chamber and, wherein the valve member and the spring member are arranged in the inner chamber prior to the fixation of the plugging cap on top circular extremity.

    [0015] Also, the plugging cap is screwed within the peripheral wall of the recess.

    [0016] The plunger comprises a main part onto which is adjusted and fixed a tubular head member defining the inner chamber, and the check valve assembly being arranged in place prior to fixing the head member.

    [0017] Also, said head member has a cylindrical peripheral wall extending from a lower end, adapted to be complementary adjusted and fixed onto the main part of the plunger, to an upper end provided with a radial shoulder face provided with the opening orifice.

    [0018] Furthermore, the check valve assembly is arranged in the plunger inner chamber by insertion through the opening orifice, the valve member being adjusted in sliding fit in the orifice of the fluid communication and, having at least one retractable arm member adapted to retract when inserted through said orifice and, to expand once inside the inner chamber, said retractable arm member preventing exit of the check valve assembly through the opening orifice.

    [0019] Said retractable arm member is a flexible arm extending from a first extremity, fixed to said closing member, to a distant free extremity, the arm extending substantially along the lateral face of the closing member while distancing slightly from it, the first extremity being inserted first through the opening orifice when the check valve assembly is inserted in the plunger inner chamber.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0020] The present invention is now described by way of example with reference to the accompanying drawings in which:

    Figure 1 is a general section of a high pressure pump as per the invention.

    Figure 2 is magnified portion of the compression chamber of the pump of figure 1 as per a first embodiment.

    Figure 3 is similar to figure 2 representing a second embodiment of the invention.

    Figures 4 and 5 represent a third alternative of the invention.


    DESCRIPTION OF THE PREFERRED EMBODIMENTS



    [0021] In reference to figure 1 is described a high pressure fuel pump 10 adapted to be arranged in a diesel fuel injection equipment not represented.

    [0022] The pump 10 comprises a body 12 wherein a camshaft 14 having a cam 16 is arranged to rotate between two bearings about a cam axis Y. On the body 12 is fixedly arranged a pumping head 18 wherein fuel entering via an inlet 20 in a compression chamber 22 exits after being pressurized via an outlet 24.

    [0023] In use, fuel compression occurs during a pumping cycle wherein a plunger 26 reciprocally slides between a bottom dead center (BDC) position and a top dead center (TDC) position in a bore 28 of the pumping head 18. The plunger 26 extends along a pumping axis X, perpendicular to the cam axis Y, from a foot end 30, protruding outward the pumping head 18 and cooperating with the cam 16 via a cam follower 32, to a head end 34 that is in the bore and which extreme transverse face 36, or top face 36 of the plunger, partly defines the compression chamber 22.

    [0024] The inlet 20 in controlled by an inlet valve member 38 arranged at the end of the bore 28 and, the outlet 24 radially arranged relative to the compression chamber 22 in controlled by an outlet valve member 40, which in the representation of figure 1 is a check valve with a ball biased by a coil spring in a closed position against a conical seating face.

    [0025] The compression chamber 22 is fully defined by the space comprised between said extreme transverse face 36 of the plunger and the end of the bore 28, being a cylindrical end of the bore and the under face of the inlet valve member 38.

    [0026] Finally a spring pump 42 compressed between the pumping head 18 and the cam follower 32 permanently bias said follower 32 against the cam 16.

    [0027] In use, when the camshaft 14 rotates, the cam 16 imparts to the plunger 26 said reciprocating movement performing said pumping cycle during which the inner volume of the compression chamber 22 is varied.

    [0028] The region of the compression chamber 22 is now detailed in reference to figure 2, where is shown that the outlet 24 radially opens in the final portion 44 of the bore and where the head end 34 of the plunger extends in said enlarged portion 44 when in TDC. In order to avoid closing the outlet 24 by the plunger 26, said final portion 44 of the plunger is slightly enlarged in section.

    [0029] Also, the plunger 26 is provided on its head end 34 with an inner plunger chamber 46 in fluid communication FC with the compression chamber 22 via a top orifice 48 opening in the transverse top face 36. Said fluid communication FC is controlled by a check valve 50 arranged inside the chamber 46.

    [0030] A first embodiment of the invention is presented on figure 2 where a deep recess provided at the head end of the plunger 26 defines a thin peripheral wall 52 threaded 54 in the region opening in the transverse top face 36. The deepness D of the recess is such that, when in TDC, the peripheral wall 52 extends in the enlarged portion 44 of the bore and also in the lower main part of the bore that is not enlarged. Therefore, the outer face of the peripheral wall 52 is slidably guided against said main bore face. A male threaded plugging cap 56 is complementary screwed in the threaded area of the peripheral wall of the plunger, said cap 56 defining the top transverse face 34 of the plunger and, at the opposite, a top face 58 of the inner chamber 46. Said top face 58 is centrally provided with a conical face so as to form a valve seating face 59, the orifice 48, creating the fluid communication FC, being provided from the tip of said conical or sloped seating face 59 to the opposite top transverse face 36. The position of the cap 56 is permanently secured via a weld seam 60 or any other known fixation means.

    [0031] Inside the chamber 46 the check valve 50 is arrange prior to screwing the cap 56. The check valve 50 comprises a valve member 62, which in this first embodiment is a ball, permanently biased by a valve spring 64 against the seating face 59. As will be explained, the valve spring 64 has a relatively low stiffness and is just adapted to maintain the ball 62 in biasing contact against the seating face 58.

    [0032] During the very first pumping cycle, when the plunger is at BDC, non-pressurized fuel has filed the bore, the pressure inside the inner chamber 44 is low and the orifice 48 is closed by the check valve 50.

    [0033] As the camshaft rotates, the plunger initiates a move from BDC toward TDC, the pressure in the compression chamber rises and the check valve 50 opens letting fuel to enter the inner chamber 46, the pressure rising in said chamber 46.

    [0034] As the plunger approaches TDC, the pressure in the compression chamber and inside the inner chamber 46 are substantially equal.

    [0035] After delivering the pressurized fuel through the outlet 24 and emptying the compression chamber, the pressure in the compression chamber drops and the check valve 50 closes the fluid communication FC, the pressure in the inner chamber 46 remaining very high.

    [0036] During the subsequent pumping cycles, the pressure in the compression chamber varies upon the demand of the engine while the pressure in the inner chamber 46 remains at said very high level. In fact, the fluid communication FC only opens when the pressure in the compression chamber gets higher than the pressure in the inner chamber 46 and consequently, said pressure in the inner chamber 46 permanently remains very high. The stiffness of the spring 64 is chosen to be low in order to enable the fluid communication FC to open upon superior pressure in the compression chamber 22. When the pressure in the inner chamber 46 is the highest, the spring 62 positions the ball 62 against the seating face 58 while said high inner pressure generates on the ball a biasing force ensuring closing of the fluid communication FC.

    [0037] Under the influence of said high pressure inside the inner chamber 46, the peripheral wall 52 radially expands and reduces the functional gap between the main non-enlarged portion of the bore, and the plunger and, in doing this the fuel leakages around the plunger are reduced.

    [0038] A second embodiment of the invention is now described in reference to figure 3 and by ways of differences to the first embodiment. The main difference is that in the first embodiment the peripheral wall of the inner chamber is integral to the plunger while, in the second embodiment said wall is integral to an elongated head member 66 screwed at the end of the plunger.

    [0039] More in details, as shown on figure 3, the plunger 26 is shorter than previously and its very end portion has a reduced diameter which is threaded 54 for complementary arrangement of the elongated up-side-down cup-like head member 66 forming the complete head end 34 of the plunger and defining the inner chamber 46. Said elongated head member 66 has a peripheral tubular wall 68 externally adjusted to be in sliding fit against the main non-enlarged part of the bore. The inner chamber 46 is defined inside said peripheral wall 68 which extends, from a bottom end internally threaded for complementary arrangement on the top of the plunger, to an opposite transverse wall forming the transverse top face 36 and centrally pierced with the top orifice 48 which inner opening is surrounded by the seating face 59. The final positioning of the elongated head member 66 on the plunger is secured via a weld seam 60 or via any other known fixing means.

    [0040] Here again the check-valve 50, which is identical to the check valve of the first embodiment, is arranged inside the inner chamber 46 before screwing the head member 66 in place.

    [0041] The operation of this second embodiment is identical to the previous description.

    [0042] A third embodiment is now described in reference to figures 4 and 5 where the inner chamber is integrally formed in the head 34 of the plunger and, another check valve 70 is arranged in place by insertion through the top orifice 48. For easiness of manufacturing, the inner chamber 48 can be provided either fully integral to the plunger as represented on figure 4, or can alternatively be in the form of either one of the previous embodiments, with a plugging cap or an elongated cap. The main difference with the first or second embodiments is said another check-valve 70 is designed to be inserted through the top orifice 48. The valve member 72 of said another check valve comprises a cylindrical portion that is adjusted in a sliding fit with the orifice 48. It is further provided with side arms 74, one, two or more, that upwardly and radially extend from a first end attached to said cylindrical portion to a distant second end. The side arms can be articulated at their first end or can be designed flexible. The spring 64 of the check valve is attached to the valve member 72 and, as represented, a foot member 76 can be attached to the lower end of the spring. When arranged in place, the foot member 76 is engaged first, the spring follows and, when the valve member 72 is engaged the first end of the arms 74 engage first in the top orifice 48 and the arms 74 retracts and align in order to enable full engagement of the valve member 72. Once fully engaged and the arms 74 totally inside the inner chamber 46, the arms 74 radially expand and prevent any exit of the check valve. The spring forces the valve member 72 toward the outside while the arms 74 forbid such move.

    [0043] The operation is globally the same as previously described to the difference that the sliding fit of the valve member 72 into the orifice 48 does not perfectly seal the orifice as well as in the previous cases. So, in operation, when the pressure in the compression chamber 22 drops below the pressure in the inner chamber 46, pressurized fuel captured in the inner chamber may partially leak between the valve member 72 and the top orifice 48 and reach the compression chamber.

    LIST OF REFERENCES



    [0044] 
    X
    pumping axis
    Y cam
    axis
    BDC
    bottom dead center position
    TDC
    top dead center position
    FC
    fluid communication
    D
    deepness of the recess
    10
    pump
    12
    pump body
    14
    camshaft
    16
    cam
    18
    pumping head
    20
    inlet
    22
    compression chamber
    24
    outlet
    26
    plunger
    28
    bore
    30
    foot end of the plunger
    32
    cam follower
    34
    head end of the plunger
    36
    transverse face - top face
    38
    inlet valve member
    40
    outlet valve member
    42
    spring pump
    44
    final enlarged portion of the bore
    46
    inner chamber of the plunger
    48
    top orifice
    50
    check valve
    52
    peripheral wall
    54
    thread
    56
    plugging cap
    58
    top face of the inner chamber
    59
    seating face
    60
    weld seam
    62
    valve member - ball
    64
    spring
    66
    elongated tubular head member
    68
    peripheral wall of the elongated cap
    70
    another check valve
    72
    valve member
    74
    side arms
    76
    foot member



    Claims

    1. High pressure fuel pump (10) having a pumping head (18) wherein a compression chamber (22) is defined between the blind end of a bore (28) and the head end (34) of a plunger slidably adjusted in said bore (28) and adapted to perform therein a pumping cycle varying the volume of said compression chamber (22),
    the pump (10) being further provided with inlet (20) and outlet (24) valve assemblies for controlling fuel flowing in and out of said compression chamber (22),
    characterized in that
    the plunger (26) is provided with an inner chamber (46) arranged in the head end (34) of the plunger that is in the vicinity of the compression chamber (22), said inner chamber (46) being in fluid communication (FC) with the compression chamber (22) via an opening orifice (48) arranged in the head end (34) of the plunger and wherein,
    said plunger inner chamber (46) is defined by a peripheral wall (52) adapted to expand when the plunger inner chamber (46) is under pressure,
    the high pressure fuel pump (10) being further provided with a check valve assembly (50) arranged to control said fluid communication (FC).
     
    2. High pressure fuel pump (10) as claimed in claim 1 wherein said check valve assembly (50) is normally in a closed state of the opening orifice (48) and is arranged to open the fluid communication (FC) only when the pressure in the compression chamber (22) exceeds the pressure in the plunger inner chamber (46).
     
    3. High pressure fuel pump (10) as claimed claims 1 or 2 wherein said check valve assembly (50) comprises a spring member (64) biasing a valve member (62) against a seating face (59) surrounding said opening.
     
    4. High pressure fuel pump (10) as claimed in claim 3 wherein the valve member (62) and the spring member (64) are both arranged inside the plunger inner chamber (46).
     
    5. High pressure fuel pump (10) as claimed in any one of the preceding claims wherein the plunger (26) is provided with a recess arranged on its head end (34), said recess defining the inner chamber (46), the peripheral wall (52) axially extending toward a top circular extremity, said peripheral wall (52) receiving a plugging cap (56) adjusted and fixed to said top circular extremity, the plugging cap (56) being provided with a central opening defining the fluid communication (FC) between the compression chamber (22) and the plunger inner chamber (46), and wherein the valve member (62) and the spring member (64) are arranged in the inner chamber (46) prior to the fixation of the plugging cap (56) on top circular extremity.
     
    6. High pressure fuel pump (10) as claimed in claim 5 wherein the plugging cap (56) is screwed within the peripheral wall (52) of the recess.
     
    7. High pressure fuel pump (10) as claimed in any one of the claims 1 to 4 wherein the plunger (26) comprises a main part onto which is adjusted and fixed a tubular head member (66) defining the inner chamber (46), the check valve assembly (50) being arranged in place prior to fixing the head member (34).
     
    8. High pressure fuel pump (10) as claimed in claim 7 wherein said head member (34) has a cylindrical peripheral wall (52) extending from a lower end, adapted to be complementary adjusted and fixed onto the main part of the plunger (26), to an upper end provided with a radial shoulder face provided with the opening orifice.
     
    9. High pressure fuel pump (10) as claimed in any one of the claims 1 or 2 wherein the check valve assembly (70) is arranged in the plunger inner chamber (46) by insertion through the opening orifice (48), the valve member (72) being adjusted in sliding fit in the orifice (48) of the fluid communication (FC) and, having at least one retractable arm member (74) adapted to retract when inserted through said orifice (48) and, to expand once inside the inner chamber (46), said retractable arm member (74) preventing exit of the check valve assembly (70) through the opening orifice.
     
    10. High pressure fuel pump (10) as claimed in claim 9 wherein said retractable arm member (74) is a flexible arm extending from a first extremity, fixed to said closing member, to a distant free extremity, the arm extending substantially along the lateral face of the closing member while distancing slightly from it, the first extremity being inserted first through the opening orifice when the check valve assembly (50) is inserted in the plunger inner chamber (46).
     


    Ansprüche

    1. Hochdruckkraftstoffpumpe (10) mit einem Pumpkopf (18), wobei eine Kompressionskammer (22) zwischen dem blinden Ende einer Bohrung (28) und dem Kopfende (34) eines Kolbens definiert ist, der in der Bohrung (28) verschiebbar angepasst ist und ausgebildet ist, um darin einen Pumpzyklus durchzuführen, der das Volumen der Kompressionskammer (22) variiert,
    wobei die Pumpe (10) weiter mit Einlass- (20) und Auslass- (24)-Ventilanordnungen zur Steuerung eines in die Kompressionskammer (22) hineinströmenden und aus dieser herausströmenden Kraftstoffs versehen ist,
    dadurch gekennzeichnet, dass
    der Kolben (26) mit einer Innenkammer (46) versehen ist, die in dem Kopfende (34) des Kolbens angeordnet ist, das in der Nähe der Kompressionskammer (22) ist, wobei die Innenkammer (46) in Fluidverbindung (FC - fluid communication) mit der Kompressionskammer (22) über eine Öffnungsöffnung (48) ist, die in dem Kopfende (34) des Kolbens angeordnet ist, und wobei
    die Kolbeninnenkammer (46) durch eine Umfangswand (52) definiert ist, die ausgebildet ist, sich auszudehnen, wenn die Kolbeninnenkammer (46) unter Druck steht,
    wobei die Hochdruckkraftstoffpumpe (10) weiter mit einer Rückschlagventilanordnung (50) versehen ist, die ausgebildet ist zum Steuern der Fluidverbindung (FC).
     
    2. Hochdruckkraftstoffpumpe (10) gemäß Anspruch 1, wobei die Rückschlagventilanordnung (50) normalerweise in einem geschlossenen Zustand der Öffnungsöffnung (48) ist und ausgebildet ist, die Fluidverbindung (FC) nur dann zu öffnen, wenn der Druck in der Kompressionskammer (22) den Druck in der Kolbeninnenkammer (46) übersteigt.
     
    3. Hochdruckkraftstoffpumpe (10) gemäß den Ansprüchen 1 oder 2, wobei die Rückschlagventilanordnung (50) ein Federelement (64) aufweist, das ein Ventilelement (62) gegen eine die Öffnung umgebende Sitzfläche (59) beeinflusst.
     
    4. Hochdruckkraftstoffpumpe (10) gemäß Anspruch 3, wobei das Ventilelement (62) und das Federelement (64) beide innerhalb der Kolbeninnenkammer (46) angeordnet sind.
     
    5. Hochdruckkraftstoffpumpe (10) gemäß einem der vorhergehenden Ansprüche, wobei der Kolben (26) mit einer Aussparung versehen ist, die an seinem Kopfende (34) angeordnet ist, wobei die Aussparung die Innenkammer (46) definiert, wobei sich die Umfangswand (52) axial in Richtung eines oberen kreisförmigen Endes erstreckt, wobei die Umfangswand (52) eine Verschlusskappe (56) aufnimmt, die an dem oberen kreisförmigen Ende angepasst und befestigt ist, wobei die Verschlusskappe (56) mit einer zentralen Öffnung versehen ist, die die Fluidverbindung (FC) zwischen der Kompressionskammer (22) und der Kolbeninnenkammer (46) definiert, und wobei das Ventilelement (62) und das Federelement (64) vor der Befestigung der Verschlusskappe (46) an dem oberen kreisförmigen Ende in der Innenkammer (46) angeordnet werden.
     
    6. Hochdruckkraftstoffpumpe (10) gemäß Anspruch 5, wobei die Verschlusskappe (56) in die Umfangswand (52) der Aussparung eingeschraubt ist.
     
    7. Hochdruckkraftstoffpumpe (10) gemäß einem der Ansprüche 1 bis 4, wobei der Kolben (26) einen Hauptteil aufweist, an dem ein Rohrkopfelement (66) angepasst und befestigt ist, das die Innenkammer (46) definiert, wobei Rückschlagventilanordnung (50) vor dem Befestigen des Kopfelements (34) an Ort und Stelle angeordnet wird.
     
    8. Hochdruckkraftstoffpumpe (10) gemäß Anspruch 7, wobei das Kopfelement (34) eine zylindrische Umfangswand (52) hat, die sich von einem unteren Ende, das ausgebildet ist, an dem Hauptteil des Kolbens (26) komplementär angepasst und befestigt zu werden, zu einem oberen Ende erstreckt, das mit einer radialen Schulterfläche versehen ist, die mit der Öffnungsöffnung versehen ist.
     
    9. Hochdruckkraftstoffpumpe (10) gemäß einem der Ansprüche 1 oder 2, wobei die Rückschlagventilanordnung (70) in der Kolbeninnenkammer (46) durch Einführen durch die Öffnungsöffnung (48) angeordnet ist, das Ventilelement (72) in Gleitpassung in der Öffnung (48) der Fluidverbindung (FC) angepasst ist, und zumindest ein einziehbares Armelement (74) hat, das ausgebildet ist, bei einem Einführen durch die Öffnung (48) einzufahren und, sobald es innerhalb der Innenkammer (46) ist, auszufahren, wobei das einziehbare Armelement (74) ein Austreten der Rückschlagventilanordnung (70) durch die Öffnungsöffnung verhindert.
     
    10. Hochdruckkraftstoffpumpe (10) gemäß Anspruch 9, wobei das einziehbare Armelement (74) ein flexibler Arm ist, der sich von einem ersten Ende, das an dem schließenden Element befestigt ist, zu einem entfernten freien Ende erstreckt, wobei sich der Arm im Wesentlichen entlang der Seitenfläche des schließenden Elements erstreckt, während es etwas von diesem entfernt ist, wobei das erste Ende zuerst durch die Öffnungsöffnung eingeführt wird, wenn die Rückschlagventilanordnung (50) in die Kolbeninnenkammer (46) eingeführt wird.
     


    Revendications

    1. Pompe à carburant à haute pression (10) ayant une tête de pompage (18) dans laquelle une chambre de compression (22) est définie entre l'extrémité borgne d'un perçage (28) et l'extrémité de tête (34) d'un plongeur ajusté avec faculté de coulissement dans ledit perçage (28) et adapté pour effectuer dans celui-ci un cycle de pompage qui fait varier le volume de ladite chambre de compression (22),
    la pompe (10) étant en outre dotée d'un ensemble formant valve d'entrée (20) et d'un ensemble formant valve de sortie (24) afin de commander l'écoulement du carburant entrant et sortant dans ladite chambre de compression (22),
    caractérisée en ce que
    le plongeur (26) est doté d'une chambre intérieure (46) agencée dans l'extrémité de tête (34) du plongeur qui est au voisinage de la chambre de compression (22), ladite chambre intérieure (46) étant en communication fluidique (FC) avec la chambre de compression (22) via un orifice d'ouverture (48) agencé dans l'extrémité de tête (34) du plongeur, et dans laquelle
    ladite chambre intérieure (46) du plongeur est définie par une paroi périphérique (52) adaptée pour être dilatée quand la chambre intérieure (46) du plongeur est sous pression,
    la pompe à carburant à haute pression (10) étant en outre dotée d'un ensemble formant clapet antiretour (50) agencé pour commander ladite communication fluidique (FC).
     
    2. Pompe à carburant à haute pression (10) selon la revendication 1, dans laquelle ledit ensemble formant clapet antiretour (50) est normalement dans un état fermé de l'orifice d'ouverture (48) et est agencé pour ouvrir la communication fluidique (FC) uniquement quand la pression dans la chambre de compression (22) excède la pression dans la chambre intérieure (46) du plongeur.
     
    3. Pompe à carburant à haute pression (10) selon les revendications 1 ou 2, dans laquelle ledit ensemble formant clapet antiretour (50) comprend un élément de ressort (64) qui sollicite un élément de valve (62) contre une face de siège (59) qui entoure ladite ouverture.
     
    4. Pompe à carburant à haute pression (10) selon la revendication 3, dans laquelle l'élément de valve (62) et l'élément de ressort (64) sont agencés tous les deux à l'intérieur de la chambre intérieure (46) du plongeur.
     
    5. Pompe à carburant à haute pression (10) selon l'une quelconque des revendications précédentes, dans laquelle le plongeur (26) est pourvu d'un évidement agencé sur son extrémité de tête (34), ledit évidement définissant la chambre intérieure (46), la paroi périphérique (52) s'étendant axialement en direction d'une extrémité circulaire supérieure, ladite paroi périphérique (52) recevant un capuchon de fermeture (56) ajusté et fixé sur ladite extrémité circulaire supérieure, le capuchon de fermeture (56) étant doté d'une ouverture centrale définissant la communication fluidique (FC) entre la chambre de compression (22) et la chambre intérieure (46) du plongeur, et dans laquelle l'élément de valve (62) et l'élément de ressort (64) sont agencés dans la chambre intérieure (46) avant la fixation du capuchon de fermeture (56) sur l'extrémité circulaire supérieure.
     
    6. Pompe à carburant à haute pression (10) selon la revendication 5, dans laquelle le capuchon de fermeture (56) est vissé à l'intérieur de la paroi périphérique (52) de l'évidement.
     
    7. Pompe à carburant à haute pression (10) selon l'une quelconque des revendications 1 à 4, dans laquelle le plongeur (26) comprend une partie principale sur laquelle est ajusté et fixé un élément de tête tubulaire (66) qui définit la chambre intérieure (46), l'ensemble formant clapet antiretour (50) étant agencé en place avant la fixation de l'élément de tête (34).
     
    8. Pompe à carburant à haute pression (10) selon la revendication 7, dans laquelle ledit élément de tête (34) a une paroi périphérique cylindrique (52) s'étendant depuis une extrémité inférieure, adaptée pour être ajustée et fixée de façon complémentaire sur la partie principale du plongeur (26), jusqu'à une extrémité supérieure dotée d'une face d'épaulement radiale pourvue de l'orifice d'ouverture.
     
    9. Pompe à carburant à haute pression (10) selon l'une quelconque des revendications 1 ou 2, dans laquelle l'ensemble formant clapet antiretour (70) est agencé dans la chambre intérieure (46) du plongeur par insertion à travers l'orifice d'ouverture (48), l'élément de valve (72) est ajusté dans un assemblage à coulissement dans l'orifice (48) de la communication fluidique (FC) et ayant au moins un élément de bras rétractable (74) adapté pour se rétracter lorsqu'il est inséré à travers ledit orifice (48) et pour se dilater une fois à l'intérieur de la chambre intérieure (46), ledit élément de bras rétractable (74) empêchant la sortie de l'ensemble formant clapet antiretour (70) à travers l'orifice d'ouverture.
     
    10. Pompe à carburant à haute pression (10) selon la revendication 9, dans laquelle ledit élément de bras rétractable (74) est un bras flexible qui s'étend depuis une première extrémité, fixée audit élément de fermeture, jusqu'à une extrémité libre à distance, le bras s'étendant sensiblement le long de la face latérale de l'élément de fermeture tout en s'éloignant légèrement de celui-ci, la première extrémité étant insérée d'abord à travers l'orifice d'ouverture quand l'ensemble formant clapet antiretour (50) est inséré dans la chambre intérieure (46) du plongeur.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description