(19)
(11)EP 3 138 749 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
07.08.2019 Bulletin 2019/32

(21)Application number: 15807526.7

(22)Date of filing:  09.06.2015
(51)International Patent Classification (IPC): 
B60T 11/16(2006.01)
F16J 15/16(2006.01)
B60T 11/20(2006.01)
B60T 11/228(2006.01)
(86)International application number:
PCT/KR2015/005769
(87)International publication number:
WO 2015/190800 (17.12.2015 Gazette  2015/50)

(54)

PISTON FOR MASTER CYLINDER

KOLBEN FÜR HAUPTZYLINDER

PISTON POUR MAÎTRE-CYLINDRE


(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: 13.06.2014 KR 20140071819

(43)Date of publication of application:
08.03.2017 Bulletin 2017/10

(73)Proprietor: erae AMS Co., Ltd.
Daegu 42981 (KR)

(72)Inventors:
  • MUN, Bu-Geun
    Dalseong-gun Daegu 711-712 (KR)
  • WEON, Jong-Dae
    Dalseong-gun Daegu 711-712 (KR)
  • SEO, Yu-Jong
    Dalseong-gun Daegu 711-712 (KR)

(74)Representative: Manitz Finsterwald Patent- und Rechtsanwaltspartnerschaft mbB 
Martin-Greif-Strasse 1
80336 München
80336 München (DE)


(56)References cited: : 
JP-A- 2005 112 188
JP-A- 2014 100 947
JP-A- 2012 076 550
KR-A- 20120 047 464
  
      
    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 piston for a master cylinder of a vehicle.

    [Background Art]



    [0002] A master cylinder is a device for generating hydraulic power in a hydraulic brake system.

    [0003] A master cylinder includes a cylinder housing and a piston which is movably disposed in the cylinder housing. Further, a sealing member which is installed in an inner surface of the housing, and the piston is provided with a communication hole. The sealing member has a cup shape and is also called a cup seal.

    [0004] The cylinder housing and the piston form cooperatively a pressure chamber for generating hydraulic pressure at a side toward which the piston moves forward, and a hydraulic supplying chamber which communicates with a reservoir is formed between the cylinder housing and an outer surface of the piston. The sealing member partitions the hydraulic supplying chamber and the pressure chamber.

    [0005] In this configuration, a shape of the sealing member is changed during the movement of the piston, and if the changed shape of the sealing member does not return to its original shape during the movement of the piston, an oil passage may be blocked and thus there may be problems of meaningless backward movement and of residual pressure.

    [0006] A master cylinder with the features of the preamble of claims 1, 2, and 4 and a piston with the features of the preamble of claims 5, 6, and 8 are known from JP 2012 076550 A.

    [Detailed Description of the Invention]


    [Technical Problem]



    [0007] The present invention has been made in an effort to provide a piston for a master cylinder which minimizes meaningless backward movement and delay of braking release.

    [Technical Solution]



    [0008] A master cylinder according to an exemplary embodiment of the present invention includes: a cylinder housing; a piston which is movably disposed in the cylinder housing so as to form a pressure chamber and a hydraulic fluid supplying chamber; a sealing member which is interposed between the cylinder housing and the piston. The piston has a plurality of communication holes for connecting the pressure chamber and the hydraulic fluid supplying chamber, and the plurality of communication holes are formed on a slanted surface which is provided to an outer surface of the piston.

    [0009] The plurality of communication holes may be arranged to move sequentially in a rearward direction and subsequently move sequentially in a forward direction from the communication hole which is front-most disposed.

    [0010] The plurality of communication holes may be arranged to move sequentially in a rearward direction so that the communication hole which is front-most disposed and the communication hole which is rear-most disposed are disposed to be adjacent in a state of being spaced from one another by a predetermined distance.

    [0011] A center line of the communication hole may be perpendicular to a longitudinal direction of the piston.

    [0012] The plurality of the communication holes may include the communication hole having a center line perpendicular to a longitudinal direction of the piston and the communication hole having a center line inclined with respect to the longitudinal direction of the piston such that a radial outer end thereof becomes closer to a rear side of the piston.

    [0013] In an exemplary embodiment of the present invention, a piston which is installed in a cylinder housing of a master cylinder includes a plurality of communication holes which are respectively configured to communicate with an inner side and an outer side thereof. The plurality of communication holes are formed on a slanted surface which is provided to an outer surface of the piston.

    [Advantageous Effects]



    [0014] According to the present invention, hydraulic fluid can be effectively discharged from the pressure chamber when a piston moves rearward so that delay of braking release can be minimized.

    [Brief Description of the Drawings]



    [0015] 

    FIG. 1 is a sectional view of a master cylinder according to an embodiment of the present invention.

    FIG. 2 is a partial enlarged view of a master cylinder according to an embodiment of the present invention.

    FIG. 3 is a perspective view of a piston of a master cylinder according to an embodiment of the present invention.

    FIG. 4 is a drawing showing a piston according to an embodiment of the present invention.

    FIG. 5 is a drawing showing a piston according to another embodiment of the present invention.

    FIG. 6 is a drawing showing a piston according to yet another embodiment of the present invention.


    [Detailed Description of the Embodiments]



    [0016] Embodiments of the present invention will be described in detail with reference to the accompanying drawings hereinafter.

    [0017] Referring to FIG. 1, a master cylinder includes a cylinder housing 10 and a first piston 20 and a second piston 30 which are respectively disposed therein to be movable forward and rearward. In detail, the cylinder housing 10 defines a bore 11 which is extended in a longitudinal direction thereof, and the first piston 20 and the second piston 30 are movably disposed in the bore 11. Meanwhile, not shown in the drawings, the master cylinder is connected to a hydraulic fluid reservoir (not shown) so as to be supplied with hydraulic fluid.

    [0018] The first piston 20 is elastically supported against the second piston 30 by a first resilient spring 21, and the second piston 30 is elastically supported against the cylinder housing 10 by a second resilient spring 31.

    [0019] A first pressure chamber 22 is formed between the first piston 20 and the second piston 30, and a second pressure chamber 32 is formed between the second piston 30 and a frontal wall of the cylinder housing 10. The pressurized fluid (e.g., hydraulic oil) may be respectively supplied to brake driving cylinders (not shown) via fluid discharging passages.

    [0020] Hydraulic fluid supplying chambers 23 and 33 are respectively formed between outer circumferential surfaces of the first piston 20 and the second piston 30 and an inner circumferential surface of the cylinder housing 10. The hydraulic fluid supplying chambers 23 and 33 are respectively connected to the hydraulic fluid reservoir via fluid passages. Accordingly, the hydraulic fluid of the hydraulic fluid reservoir may be supplied to the hydraulic fluid supplying chambers via the fluid passages.

    [0021] A first sealing member 40 and a second sealing member 50 are respectively interposed between the first piston 20 and the second piston 30 and an inner circumferential surface of the cylinder housing 10. For example, the first sealing member 40 and the second sealing member 50 may be disposed in grooves which are respectively formed on an inner circumferential surface of the cylinder housing 10. The first sealing member 40 and the second sealing member 50 contact both the inner circumferential surface of the cylinder housing 10 and the outer circumferential surfaces of the first piston 20 and the second piston 30 so as to partition the hydraulic fluid supplying chambers 23 and 33 and the pressure chambers 22 and 32. Meanwhile, referring to FIG. 3, a plurality of communication holes 25 and 35 are respectively formed in the first piston 20 and the second piston 30. The communication holes 25 and 35 may be through holes which extend from an inner circumferential surface to an outer circumferential surface of the first piston 20 and the second piston 30.

    [0022] The pressure chambers 22 and 32 and the hydraulic fluid supplying chambers 23 and 33 are selectively communicated with one another depending on the relative positions between the communication holes 25 and 35 and the sealing members 40 and 50. That is, in case that the first piston 20 and the second piston 30 move forward so that the communication holes 25 and 35 are positioned in the front side of the sealing members 40 and 50 (i.e., brake applying state), the pressure chambers 22 and 32 and the hydraulic fluid supplying chambers 23 and 33 are blocked from one another by the sealing of the sealing members 40 and 50, and on the other hand, in case that the first piston 20 and the second piston 30 move rearward so that the communication holes 25 and 35 are positioned in the rear side of the sealing members 40 and 50 (i.e., brake release state), the pressure chambers 22 and 32 and the hydraulic fluid supplying chambers 23 and 33 are communicated with one another.

    [0023] Referring to FIG. 4, a piston for a master cylinder according to an embodiment of the present invention will be described.

    [0024] The pistons 20 and 30 respectively have a plurality of communication holes 25 and 35, and the plurality of communication holes 25 and 35 are arranged along circumferential direction of the pistons 20 and 30. At this time, referring to FIG. 4, the plurality of communication holes 25 and 35 are not disposed at one position along a longitudinal direction (a horizontal direction in FIG. 4) of the pistons 20 and 30, but are arranged at different positions in a longitudinal direction, and the plurality of communication holes 25 and 35 which are respectively arranged along a circumferential direction are arranged to move sequentially in a rearward direction from a front side of the pistons 20 and 30 and subsequently move sequentially in a forward direction. That is, at one side of the pistons 20 and 30, as shown in FIG. 4, the communication holes 25 and 35 are arranged such that the lower one moves gradually rearward so that lines CL connecting centers of the communication holes 25 and 35 are inclined to form an angle A relative to lines PL which is perpendicular to the longitudinal direction of the pistons 20 and 30, and on the contrary, at the other side of the pistons 20 and 30, the communication holes 25 and 35 are arranged such that the upper one moves gradually forward.

    [0025] At this time, as shown in a dotted line of FIG. 4, the plurality of communication holes 25 and 35 may be disposed on slanted surfaces 26 and 36 of the pistons 20 and 30. At this time, centers of the communication holes of the pistons 20 and 30 which are respectively disposed at a front-most side may be disposed at starting points of the slanted surfaces 26 and 36.

    [0026] Referring to FIG. 5, a piston for a master cylinder according to another embodiment of the present invention will be described.

    [0027] The disposition of the communication holes 25 and 35 of this embodiment is equal to FIG. 3, but the communication holes 25 and 35 includes communication holes 25a and 35a having center lines perpendicular to a longitudinal direction of the pistons 20 and 30, and communication holes 25b and 35b having a center line inclined with respective to a line perpendicular to a longitudinal direction of the pistons 20 and 30. That is, the communication holes 25b and 35b are formed to be inclined such that radial outer ends thereof become closer to a rear side of the pistons 20 and 30.

    [0028] Referring to FIG. 6, a piston for a master cylinder according to yet another embodiment of the present invention will be described.

    [0029] The pistons 20 and 30 respectively have a plurality of communication holes 25 and 35, and the communication holes 25 and 35 are arranged along circumferential directions of the pistons 20 and 30. At this time, referring to FIG. 6, the plurality of communication holes 25 and 35 are not disposed at one position along a longitudinal direction (a horizontal direction in FIG. 4) of the pistons 20 and 30, but are arranged at different positions in a longitudinal direction, and the plurality of communication holes 25 and 35 which are respectively arranged along a circumferential direction are arranged to move sequentially in a rearward direction from a front side of the pistons 20 and 30. Accordingly, as shown in a dotted-line circle, the communication hole which is front-most disposed and the communication hole which is rear-most disposed are disposed to be adjacent in a state of being spaced from one another by a predetermined distance in a longitudinal directions of the piston.

    [0030] At this time, as shown in a dotted line of FIG. 4, the plurality of communication holes 25 and 35 may be disposed on slanted surfaces 26 and 36 of the pistons 20 and 30. At this time, centers of the communication holes of the pistons 20 and 30 which are respectively disposed at a front-most side may be disposed at starting points of the slanted surfaces 26 and 36.

    [Industrial Applicability]



    [0031] The present invention relates to a piston for a master cylinder of a vehicle, so the present invention has an industrial applicability.


    Claims

    1. A master cylinder comprising:

    a cylinder housing (10);

    a piston (20, 30) which is movably disposed in the cylinder housing (10) so as to form a pressure chamber (22, 32) and a hydraulic fluid supplying chamber (23, 33); and

    a sealing member (40, 50) which is interposed between the cylinder housing (10) and the piston (20, 30),

    wherein the piston (20, 30) has a plurality of communication holes (25, 35) for connecting the pressure chamber (22, 32) and the hydraulic fluid supplying chamber (23, 33),

    characterized in that

    the plurality of communication holes (25, 35) are formed on a slanted surface (26, 36) which is provided to an outer surface of the piston (20, 30),

    wherein the plurality of communication holes (25, 35) are arranged to move sequentially in a rearward direction and subsequently move sequentially in a forward direction from the communication hole which is front-most disposed.


     
    2. A master cylinder comprising:

    a cylinder housing (10);

    a piston (20, 30) which is movably disposed in the cylinder housing (10) so as to form a pressure chamber (22, 32) and a hydraulic fluid supplying chamber (23, 33); and

    a sealing member (40, 50) which is interposed between the cylinder housing (10) and the piston (20, 30),

    wherein the piston (20, 30) has a plurality of communication holes (25, 35) for connecting the pressure chamber (22, 32) and the hydraulic fluid supplying chamber (23, 33),

    characterized in that

    the plurality of communication holes (25, 35) are formed on a slanted surface (26, 36) which is provided to an outer surface of the piston (20, 30),

    wherein the plurality of communication holes (25, 35) are arranged to move sequentially in a rearward direction so that the communication hole which is front-most disposed and the communication hole which is rear-most disposed are disposed to be adjacent in a state of being spaced from one another by a predetermined distance.


     
    3. The master cylinder of one of claims 1 and 2, wherein a center line of the communication hole is perpendicular to a longitudinal direction of the piston (20, 30).
     
    4. A master cylinder comprising:

    a cylinder housing (10);

    a piston (20, 30) which is movably disposed in the cylinder housing (10) so as to form a pressure chamber (22, 32) and a hydraulic fluid supplying chamber (23, 33); and

    a sealing member (40, 50) which is interposed between the cylinder housing (10) and the piston (20, 30),

    wherein the piston (20, 30) has a plurality of communication holes (25, 35) for connecting the pressure chamber (22, 32) and the hydraulic fluid supplying chamber (23, 33),

    characterized in that

    the plurality of communication holes (25, 35) are formed on a slanted surface (26, 36) which is provided to an outer surface of the piston (20, 30),

    wherein the plurality of the communication holes (25, 35) comprise the communication hole having a center line perpendicular to a longitudinal direction of the piston (20, 30) and the communication hole having a center line inclined with respect to the longitudinal direction of the piston (20, 30) such that a radial outer end thereof becomes closer to a rear side of the piston.


     
    5. A piston (20, 30) which is installable in a cylinder (10) housing of a master cylinder, comprising a plurality of communication holes (25, 35) which are respectively configured to communicate with an inner side and an outer side thereof,
    characterized in that
    the plurality of communication holes (25, 35) are formed on a slanted surface (26, 36) which is provided to an outer surface of the piston (20, 30),
    wherein the plurality of communication holes (25, 35) are arranged to move sequentially in a rearward direction and subsequently move sequentially in a forward direction from the communication hole which is front-most disposed.
     
    6. A piston (20, 30) which is installable in a cylinder (10) housing of a master cylinder, comprising a plurality of communication holes (25, 35) which are respectively configured to communicate with an inner side and an outer side thereof,
    characterized in that
    wherein the plurality of communication holes (25, 35) are formed on a slanted surface (26, 36) which is provided to an outer surface of the piston (20, 30),
    wherein the plurality of communication holes (25, 35) are arranged to move sequentially in a rearward direction so that the communication hole which is front-most disposed and the communication hole which is rear-most disposed are disposed to be adjacent in a state of being spaced from one another by a predetermined distance.
     
    7. The piston of one of claims 5 and 6, wherein a center line of the communication hole is perpendicular to a longitudinal direction of the piston (20, 30).
     
    8. A piston (20, 30) which is installable in a cylinder (10) housing of a master cylinder, comprising a plurality of communication holes (25, 35) which are respectively configured to communicate with an inner side and an outer side thereof,
    characterized in that
    the plurality of communication holes (25, 35) are formed on a slanted surface (26, 36) which is provided to an outer surface of the piston (20, 30),
    wherein the plurality of the communication holes (25, 35) comprise the communication hole having a center line perpendicular to a longitudinal direction of the piston (10, 20) and the communication hole having a center line inclined with respect to the longitudinal direction of the piston (10, 20) such that a radial outer end thereof becomes closer to a rear side of the piston.
     


    Ansprüche

    1. Hauptzylinder, umfassend:

    ein Zylindergehäuse (10);

    einen Kolben (20, 30), der bewegbar in dem Zylindergehäuse (10) angeordnet ist, um eine Druckkammer (22, 32) und eine Hydraulikfluidlieferkammer (23, 33) zu bilden; und

    ein Dichtungselement (40, 50), das zwischen dem Zylindergehäuse (10) und dem Kolben (20, 30) angeordnet ist,

    wobei der Kolben (20, 30) eine Mehrzahl von Kommunikationslöchern (25, 35) zum Verbinden der Druckkammer (22, 32) und der Hydraulikfluidlieferkammer (23, 33) aufweist,

    dadurch gekennzeichnet, dass

    die Mehrzahl von Kommunikationslöchern (25, 35) an einer geneigten Fläche (26, 36) geformt sind, die an einer Außenfläche des Kolbens (20, 30) vorgesehen ist,

    wobei die Mehrzahl von Kommunikationslöchern (25, 35) so angeordnet sind, dass sie sich sequentiell in einer Rückwärtsrichtung bewegen und sich anschließend sequentiell in einer Vorwärtsrichtung von dem Kommunikationsloch, das am vordersten angeordnet ist, bewegen.


     
    2. Hauptzylinder, umfassend:

    ein Zylindergehäuse (10);

    einen Kolben (20, 30), der bewegbar in dem Zylindergehäuse (10) angeordnet ist, um eine Druckkammer (22, 32) und eine Hydraulikfluidlieferkammer (23, 33) zu bilden; und

    ein Dichtungselement (40, 50), das zwischen dem Zylindergehäuse (10) und dem Kolben (20, 30) angeordnet ist,

    wobei der Kolben (20, 30) eine Mehrzahl von Kommunikationslöchern (25, 35) zum Verbinden der Druckkammer (22, 32) und der Hydraulikfluidlieferkammer (23, 33) aufweist,

    dadurch gekennzeichnet, dass

    die Mehrzahl von Kommunikationslöchern (25, 35) an einer geneigten Fläche (26, 36) geformt sind, die an einer Außenfläche des Kolbens (20, 30) vorgesehen ist,

    wobei die Mehrzahl von Kommunikationslöchern (25, 35) so angeordnet sind, dass sie sich sequentiell in einer rückwärtigen Richtung bewegen, so dass das Kommunikationsloch, das am vordersten angeordnet ist, und das Kommunikationsloch, das am hintersten angeordnet ist, so angeordnet sind, dass sie in einem Zustand, in dem sie voneinander um eine vorbestimmte Distanz beabstandet sind, benachbart sind.


     
    3. Hauptzylinder nach einem der Ansprüche 1 und 2, wobei eine Mittellinie des Kommunikationslochs rechtwinklig zu einer Längsrichtung des Kolbens (20, 30) ist.
     
    4. Hauptzylinder, umfassend:

    ein Zylindergehäuse (10);

    einen Kolben (20, 30), der bewegbar in dem Zylindergehäuse (10) angeordnet ist, um eine Druckkammer (22, 32) und eine Hydraulikfluidlieferkammer (23, 33) zu bilden; und

    ein Dichtungselement (40, 50), das zwischen dem Zylindergehäuse (10) und dem Kolben (20, 30) angeordnet ist,

    wobei der Kolben (20, 30) eine Mehrzahl von Kommunikationslöchern (25, 35) zum Verbinden der Druckkammer (22, 32) und der Hydraulikfluidlieferkammer (23, 33) aufweist,

    dadurch gekennzeichnet, dass

    die Mehrzahl von Kommunikationslöchern (25, 35) an einer geneigten Fläche (26, 36) geformt sind, die an einer Außenfläche des Kolbens (20, 30) vorgesehen ist,

    wobei die Mehrzahl der Kommunikationslöcher (25, 35) das Kommunikationsloch, das eine Mittellinie rechtwinklig zu einer Längsrichtung des Kolbens (20, 30) aufweist, und das Kommunikationsloch umfasst, das eine Mittellinie aufweist, die in Bezug auf die Längsrichtung des Kolbens (20, 30) schräggestellt ist, so dass ein radiales äußeres Ende davon näher an eine Rückseite des Kolbens heranrückt.


     
    5. Kolben (20, 30), der in einem Zylindergehäuse (10) eines Hauptzylinders installierbar ist, umfassend eine Mehrzahl von Kommunikationslöchern (25, 35), die jeweils konfiguriert sind, um mit einer Innenseite und einer Außenseite davon zu kommunizieren,
    dadurch gekennzeichnet, dass
    die Mehrzahl von Kommunikationslöchern (25, 35) an einer geneigten Fläche (26, 36) geformt sind, die an einer Außenfläche des Kolbens (20, 30) vorgesehen ist,
    wobei die Mehrzahl von Kommunikationslöchern (25, 35) so angeordnet sind, dass sie sich sequentiell in einer Rückwärtsrichtung bewegen und sich anschließend sequentiell in einer Vorwärtsrichtung von dem Kommunikationsloch, das am vordersten angeordnet ist, bewegen.
     
    6. Kolben (20, 30), der in einem Zylindergehäuse (10)eines Hauptzylinders installierbar ist, umfassend eine Mehrzahl von Kommunikationslöchern (25, 35), die jeweils konfiguriert sind, um mit einer Innenseite und einer Außenseite davon zu kommunizieren,
    dadurch gekennzeichnet, dass
    die Mehrzahl von Kommunikationslöchern (25, 35) an einer geneigten Fläche (26, 36) geformt ist, die an einer Außenfläche des Kolbens (20, 30) vorgesehen ist,
    wobei die Mehrzahl von Kommunikationslöchern (25, 35) so angeordnet sind, dass sie sich sequentiell in einer rückwärtigen Richtung bewegen, so dass das Kommunikationsloch, das am vordersten angeordnet ist, und das Kommunikationsloch, das am hintersten angeordnet ist, so angeordnet sind, dass sie in einem Zustand, in dem sie voneinander um eine vorbestimmte Distanz beabstandet sind, benachbart sind.
     
    7. Kolben nach einem der Ansprüche 5 oder 6, wobei eine Mittellinie des Kommunikationslochs rechtwinklig zu einer Längsrichtung des Kolbens (20, 30) ist.
     
    8. Kolben (20, 30), der in einem Zylindergehäuse (10) eines Hauptzylinders installierbar ist, umfassend eine Mehrzahl von Kommunikationslöchern (25, 35), die jeweils konfiguriert sind, um mit einer Innenseite und einer Außenseite davon zu kommunizieren,
    dadurch gekennzeichnet, dass
    die Mehrzahl von Kommunikationslöchern (25, 35) an einer geneigten Fläche (26, 36) geformt sind, die an einer Außenfläche des Kolbens (20, 30) vorgesehen ist,
    wobei die Mehrzahl der Kommunikationslöcher (25, 35) das Kommunikationsloch, das eine Mittellinie rechtwinklig zu einer Längsrichtung des Kolbens (10, 20) aufweist, und das Kommunikationsloch umfasst, das eine Mittellinie aufweist, die in Bezug auf die Längsrichtung des Kolbens (10, 20) schräggestellt ist, so dass ein radiales äußeres Ende davon näher an eine Rückseite des Kolbens heranrückt.
     


    Revendications

    1. Maître-cylindre comprenant :

    un boîtier cylindrique (10) ;

    un piston (20, 30) qui est disposé de façon déplaçable dans le boîtier cylindrique (10) de manière à former une chambre de pression (22, 32) et une chambre d'alimentation de fluide hydraulique (23, 33) ; et

    un élément d'étanchéité (40, 50) qui est interposé entre le boîtier cylindrique (10) et le piston (20, 30),

    dans lequel le piston (20, 30) a une pluralité de trous de communication (25, 35) pour connecter la chambre de pression (22, 32) et la chambre d'alimentation de fluide hydraulique (23, 33),

    caractérisé en ce que

    la pluralité de trous de communication (25, 35) sont formés sur une surface oblique (26, 36) qui est prévue sur une surface extérieure du piston (20, 30),

    dans lequel la pluralité de trous de communication (25, 35) sont agencés pour se déplacer séquentiellement dans une direction vers l'arrière et ultérieurement pour se déplacer séquentiellement dans une direction vers l'avant à partir du trou de communication qui est disposé le plus à l'avant.


     
    2. Maître-cylindre comprenant :

    un boîtier cylindrique (10) ;

    un piston (20, 30) qui est disposé de façon déplaçable dans le boîtier cylindrique (10) de manière à former une chambre de pression (22, 32) et une chambre d'alimentation de fluide hydraulique (23, 33) ; et

    un élément d'étanchéité (40, 50) qui est interposé entre le boîtier cylindrique (10) et le piston (20, 30),

    dans lequel le piston (20, 30) a une pluralité de trous de communication (25, 35) pour connecter la chambre de pression (22, 32) et la chambre d'alimentation de fluide hydraulique (23, 33),

    caractérisé en ce que

    la pluralité de trous de communication (25, 35) sont formés sur une surface oblique (26, 36) qui est prévue sur une surface extérieure du piston (20, 30),

    dans lequel la pluralité de trous de communication (25, 35) sont agencés pour se déplacer séquentiellement dans une direction vers l'arrière de sorte que le trou de communication qui est disposé le plus à l'avant et le trou de communication qui est disposé le plus à l'arrière sont disposés de manière à être adjacents dans un état dans lequel ils sont espacés l'un de l'autre d'une distance prédéterminée.


     
    3. Maître-cylindre selon l'une des revendications 1 et 2, dans lequel une ligne centrale du trou de communication est perpendiculaire à une direction longitudinale du piston (20, 30).
     
    4. Maître-cylindre comprenant :

    un boîtier cylindrique (10) ;

    un piston (20, 30) qui est disposé de façon déplaçable dans le boîtier cylindrique (10) de manière à former une chambre de pression (22, 32) et une chambre d'alimentation de fluide hydraulique (23, 33) ; et

    un élément d'étanchéité (40, 50) qui est interposé entre le boîtier cylindrique (10) et le piston (20, 30),

    dans lequel le piston (20, 30) a une pluralité de trous de communication (25, 35) pour connecter la chambre de pression (22, 32) et la chambre d'alimentation de fluide hydraulique (23, 33),

    caractérisé en ce que

    la pluralité de trous de communication (25, 35) sont formés sur une surface oblique (26, 36) qui est prévue sur une surface extérieure du piston (20, 30),

    dans lequel la pluralité de trous de communication (25, 35) comprennent un trou de communication ayant une ligne centrale perpendiculaire à une direction longitudinale du piston (20, 30) et un trou de communication ayant une ligne centrale inclinée par rapport à la direction longitudinale de piston (20, 30) de sorte qu'une extrémité radialement extérieure de celui-ci devient plus proche d'un côté arrière du piston.


     
    5. Piston (20, 30) qui est susceptible d'être installé dans un boîtier cylindrique (10) d'un maître-cylindre, comprenant une pluralité de trous de communication (25, 35) qui sont respectivement configurés pour communiquer avec un côté intérieur et avec un côté extérieur de celui-ci,
    caractérisé en ce que
    la pluralité de trous de communication (25, 35) sont formés sur une surface oblique (26, 36) qui est prévue sur une surface extérieure du piston (20, 30),
    dans lequel la pluralité de trous de communication (25, 35) sont agencés pour se déplacer séquentiellement dans une direction vers l'arrière et ultérieurement pour se déplacer séquentiellement dans une direction vers l'avant à partir du trou de communication qui est disposé le plus à l'avant.
     
    6. Piston (20, 30) qui est susceptible d'être installé dans un boîtier cylindrique (10) d'un maître-cylindre, comprenant une pluralité de trous de communication (25, 35) qui sont respectivement configurés pour communiquer avec un côté intérieur et avec un côté extérieur de celui-ci,
    caractérisé en ce que
    la pluralité de trous de communication (25, 35) sont formés sur une surface oblique (26, 36) qui est prévue sur une surface extérieure du piston (20, 30),
    dans lequel la pluralité de trous de communication (25, 35) sont agencés pour se déplacer séquentiellement dans une direction vers l'arrière de sorte que le trou de communication qui est disposé le plus à l'avant et le trou de communication qui est disposé le plus à l'arrière sont disposés pour être adjacents dans un état dans lequel ils sont espacés l'un de l'autre d'une distance prédéterminée.
     
    7. Piston selon l'une des revendications 5 et 6, dans lequel une ligne centrale du trou de communication est perpendiculaire à une direction longitudinale du piston (20, 30).
     
    8. Piston (20, 30) qui est susceptible d'être installé dans un boîtier cylindrique (10) d'un maître-cylindre, comprenant une pluralité de trous de communication (25, 35) qui sont respectivement configurés pour communiquer avec un côté intérieur et avec un côté extérieur de celui-ci,
    caractérisé en ce que
    la pluralité de trous de communication (25, 35) sont formés sur une surface oblique (26, 36) qui est prévue sur une surface extérieure du piston (20, 30),
    dans lequel la pluralité de trous de communication (25, 35) comprennent un trou de communication ayant une ligne centrale perpendiculaire à une direction longitudinale du piston (10, 20) et un trou de communication ayant une ligne centrale inclinée par rapport à la direction longitudinale du piston (10, 20) de sorte qu'une extrémité radialement extérieure de celui-ci devient plus proche d'un côté arrière du piston.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description