EP0007279A1 - Hydraulic safety switch - Google Patents

Hydraulic safety switch Download PDF

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Publication number
EP0007279A1
EP0007279A1 EP79400484A EP79400484A EP0007279A1 EP 0007279 A1 EP0007279 A1 EP 0007279A1 EP 79400484 A EP79400484 A EP 79400484A EP 79400484 A EP79400484 A EP 79400484A EP 0007279 A1 EP0007279 A1 EP 0007279A1
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EP
European Patent Office
Prior art keywords
compartment
piston
chamber
orifice
pressure
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Granted
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EP79400484A
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German (de)
French (fr)
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EP0007279B1 (en
Inventor
Gilbert Kervagoret
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DBA SA
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DBA SA
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Priority claimed from FR7820816A external-priority patent/FR2431051A2/en
Application filed by DBA SA filed Critical DBA SA
Publication of EP0007279A1 publication Critical patent/EP0007279A1/en
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Publication of EP0007279B1 publication Critical patent/EP0007279B1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/02—Installations or systems with accumulators
    • F15B1/027—Installations or systems with accumulators having accumulator charging devices

Definitions

  • a hydraulic circuit breaker comprising a housing with an inlet port to be connected to the outlet of a hydraulic pump, a first outlet port to be connected to the pressure chamber of a hydraulic accumulator. , and a second outlet orifice to be connected to an open-center hydraulic circuit, a stepped bore formed in this housing receiving a differential piston which defines therein an inlet chamber in communication with the inlet orifice and a control chamber , a throttle orifice with variable cross section depending on the position of the differential piston being disposed between the inlet chamber and the second outlet orifice, said inlet chamber communicating with the control chamber by a first passage comprising a first restriction and being further connected to the first outlet orifice by a connection comprising a non-return valve, this contactor-circuit breaker further comprising an elastic capacity with a compartment nt variable volume which is connected to the control chamber, said capacity being provided to put said compartment in communication with a second leakage passage forming a restriction when the pressure in said compartment reaches a first
  • the elastic capacity which equips this hydraulic circuit breaker has the role of spreading over time the pressure variations which occur during the transient rise or fall regimes. drop in pump pressure while charging the accumulator.
  • the elastic capacity is constituted by a second bore formed parallel to the stepped bore in the case of the contactor-circuit breaker, bore inside which is received a second piston which divides it into a first compartment constituting the variable volume compartment and into a second compartment, this second piston being subjected to the action of elastic means and comprising an axial passage making it possible to put the two compartments in communication under the control of a valve elastic that a fixed pusher element automatically lifts when this second piston has moved a distance corresponding to the first predetermined value of the pressure in said compartment, that is to say in the control chamber.
  • the object of the present invention is to remedy these drawbacks by reducing the number of machining operations required, by improving the compactness of the hydraulic circuit-breaker, and by making the elastic capacity more easily accessible for the needs of a possible adjustment of its operating characteristics.
  • the elastic capacity is constituted by an interchangeable capsule housed coaxially in the large diameter portion of the stepped bore which constitutes the control chamber, this capsule containing a second piston. which is slidably mounted therein and which divides its interior into a first compartment defining the variable volume compartment and into a second compartment, said second piston being biased towards the end of the first compartment by elastic means arranged in the second compartment , a step axial sage intended to put in communication the two compartments being provided in the piston and opening towards the first compartment to define a valve seat which cooperates with a valve element elastically urged against said seat, a pusher element fixed relative to the capsule being disposed in the axial passage of the second piston and being capable of lifting from its seat the formand valve element to authorize the flow of the fluid in the leakage passage when the second piston has moved by a given distance which corresponds to the first predetermined value of the pressure in said first compartment, the leakage passage then being constituted by the space defined between
  • the elastic capacity is thus contained in a capsule which takes the place previously occupied by a passive stop, which does not require any additional machining of the case of the contactor-circuit breaker and contributes to reducing its overall dimensions, while its interchangeability allows easily extract and possibly replace it with another elastic capacity of different characteristics.
  • the hydraulic circuit breaker 10 comprises a housing 12 provided with an inlet port 13, with a first outlet port 14 and a second outlet orifice 16.
  • the inlet orifice 13 is intended to be connected to a hydraulic pump with a substantially constant volumetric flow rate.
  • the first outlet orifice 14 is intended to be connected to the pressure chamber of a pressurized fluid accumulator (not shown) which is itself intended to supply pressurized fluid to a assistance circuit of the center type closed, such as a hydraulic brake booster.
  • the second outlet 16 is connected, its side, to an assistance circuit of the open center type, such as for example a power steering valve (not also shown in the drawing).
  • the housing 12 has a stepped bore 20 including three portions of different diameters, which are separated from each other by two shoulders 22 and 24.
  • the larger diameter portion of this bore 20 defines a control chamber 26, while that of smaller diameter opens towards the first outlet orifice 14.
  • the portion of average diameter of the bore 20 defines, in association with a piston 30 of the differential type received with sliding in this bore, an inlet chamber 28 which communicates with the 'inlet orifice 13.
  • the piston 30 has a large diameter portion which projects into the control chamber 26, and a small diameter portion which slides in the smaller diameter portion of the bore 20 and whose end is subjected to the pressure prevailing in the first outlet orifice 14.
  • the piston 30 has one or more longitudinal grooves 32 which are intended to put the inlet chamber 28 into communication with the second outlet orifice 16.
  • the depth of these grooves increases as one moves away from the shoulder of the differential piston 30.
  • These grooves cooperate with the shoulder 24 to form a throttling orifice on the fluid flow path between the inlet orifice 13 and the second outlet orifice 16, this throttle orifice having a variable section depending on the position of the piston 30.
  • the latter also comprises an axial passage 34 which is connected to the inlet chamber 28 by a radial passage 36.
  • the axial passage 34 communicates with the control chamber 26 by means of a restriction 38, which in the example considered consists of a stack of pellets crimped and pierced.
  • the passages 34 and 36 provide communication between the inlet chamber 28 and the first outlet orifice 14.
  • a non-return valve 40 constituted in the example represented by a ball.
  • a spring 42 disposed in the control chamber 26 resiliently biases the piston 30 against the action of the pressure prevailing in the inlet chamber 28, on the one hand, and of the pres - sion of the fluid accumulator connected to the first outlet orifice 14, on the other hand.
  • a stop which, as we will expose it below, is constituted by the own elastic capacity of the contactor-circuit breaker; the stop 30 is preferably applied by means of a washer 44 made of elastomeric material, which ensures for this position of the piston 30 the interruption of the communication existing between the axial passage 34 and the control chamber 26.
  • the elastic capacity which equips the hydraulic circuit breaker 10, and which is generally designated by the reference numeral 50 consists of an interchangeable capsule housed coaxially in the large diameter portion of the bore 20 which delimits the control chamber 26.
  • This capsule is constituted by the assembly of two bowls 52 and 54, preferably made of plastic material, and held tight against one another with the interposition of a seal 56 by compression of the spring 42 which abutsinstalltl'ensemble applied con - be a removable snap ring 58.
  • the upper bowl 52 is formed with an exhaust port 60, via which it can be connected to a source of low pressure fluid, such as for example the cover of the hydraulic system.
  • the lower bowl 54 is itself pierced with a passage 62 which places the interior of the capsule in communication with the control chamber 26.
  • a piston 64 sliding in leaktight manner, which divides the interior of the capsule into a first compartment 66 communicating through the passage 62 with the control chamber 26, and into a second compartment 68 which communicates with the exhaust port 60.
  • the piston 64 In the rest position, the piston 64 is urged against the end of the compartment 66 by a spring 70 housed inside the compartment 68 and coaxially surrounding this piston.
  • the piston 64 is itself pierced with an axial passage 72 intended to put the two compartments 66 and 68 into communication.
  • This passage opens into the first compartment 66 by defining a valve seat 74 which cooperates with a valve 76 (here constituted by a ball) elastically urged against this seat by a light spring 78.
  • a valve 76 here constituted by a ball
  • a light spring 78 In the axial passage 72 is disposed a particularly a magnet 80 fixed relative to the capsule, which ends with a finger 82.
  • the end of the finger 82 is set back with respect to the plane of the valve seat 74, and the ball 76 is kept applied to this seat by the associated spring 78.
  • Another spring 84 disposed in the passage 72 and surrounding the finger 82, has a length greater than that of this finger but however insufficient to urge the ball 76. Between the pusher 80 and the bore defining the passage 72 is provided a limited radial clearance which allows the fluid to communicate between the first compartment 66 and the second compartment 68 when the valve 76 is moved away from its seat 74.
  • the increase in pressure which occurs in the control chamber 26 is communicated to the first compartment 66 and has the effect of pushing the piston 64 upwards.
  • the valve 76 accompanies the piston 64 and comes into contact with the free end of the spring 84 which it compresses, the end of this first phase corresponding to the instant when the valve 76 comes into contact with the end of the finger 82.
  • the force of the spring 70 and the length of the pusher 80,82 can be chosen so that the opening of the valve formed by the ball 76 occurs for a displacement of the piston 64 corresponding to a predetermined value of the pressure in the compartment 66 and therefore in the control chamber 26, this predetermined pressure value being called "opening pressure: The latter being proportional to the pressure prevailing in the inlet chamber 28, it is thus possible to obtain that l opening of the valve formed by the ball 76 occurs when the pressure in the inlet chamber 28 reaches the value corresponding to the accumulator cut-out pressure, that is to say, the maximum pressure at which it must be recharged.
  • valve of the elastic capacity opens at the moment when the associated accumulator is suitably recharged.
  • the valve formed by the ball 76 remains open until the piston 64 has retreated a sufficient distance to that this ball has resumed contact with its seat 74.
  • the valve is then closed again, and the communication of fluid between the compartments 66 and 68 is interrupted.
  • the length of the spring 84 is calculated so that this reduction in the communication of fluid between the two compartments occurs when the pressure in the compartment 66 has decreased by a given quantity AP to reach a so-called closing value.
  • the latter is fixed in such a way that the pressure prevailing in the inlet chamber 28 has become lower than the pressure prevailing in the control chamber 26 at the moment when the ball 76 resumes contact with its seat 74.
  • the closing pressure it is necessary for the closing pressure to have a value lower than the conjunct-disjunction range of the accumulator.
  • the third phase of operation begins when the elastic capacity valve is closed again.
  • the hydraulic fluid then flows from compartment 66 and from the control chamber 26 to the pump, via the restriction 38, the axial passage 34, the radial passage 36 and the inlet chamber 28, this up to 'that the capacity is completely relaxed.
  • This operation is greatly facilitated by the design of the elastic capacity 50 according to the present invention, since it suffices in such a case to extract the locking ring 58 in order to be able to remove the capsule constituting this elastic capacity all in one piece, and replace it with another that meets the desired characteristics.
  • the intervention requires only a short time and does not require the disassembly of the hydraulic circuit breaker or its removal from the vehicle on which it is mounted.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Supply Devices, Intensifiers, Converters, And Telemotors (AREA)

Abstract

1. A hydraulic circuit breaker comprising a housing (12) having an inlet orifice (13) for connecting to the outlet of a hydraulic pump, a first outlet orifice (14) for connecting to the pressure chamber of a hydraulic accumulator, and a second outlet orifice (16) for connecting to an open-centre hydraulic circuit, a stepped bore (20) formed in the housing (12) receiving a differential piston (30) which defines an inlet chamber (28) therein in communication with the inlet orifice (13) and a control chamber (26), a constriction orifice (32) having a cross-section which varies in dependence of the position of the differential piston (30) being disposed between the inlet chamber (28) and the second outlet orifice (16), the inlet chamber (28) communicating with the control chamber (26) via a first passage (34, 36) comprising a first constriction (38) and also communicating with the first outlet orifice (14) via a connection (34) comprising a check valve (40), the circuit breaker also comprising a resilient vessel having a variable-volume compartment connected to the control chamber (26), said vessel being adapted to connect the compartment with a leak passage forming a constriction when the pressure in the compartment reaches a first predetermined value, and the communication with the leak passage being interrupted when the pressure in the compartment falls below a second predetermined value, characterized in that said resilient vessel is comprised of an interchangeable capsule (50) placed coaxially in the large-diameter or control-chamber portion (26) of the stepped bore (20), said capsule containing a second piston (64) slidably mounted therein sealing-tight manner and dividing its interior into a first compartment (66) defining said variable-volume compartment and a second compartment (68), said second piston (64) being urged towards the end of said first compartment (66) by resilient means (70) disposed in said second compartment (68), an axial passage (72) for connecting the two compartments being provided in said piston (64) and opening into the first compartment (66) to define a valve seat (74) which cooperates with a valve element (76) from its seat (74) so that fluid can flow in the leak passage (72) when the second piston (64) has moved a given distance corresponding to said first predetermined pressure in said first compartment (64), the leak passage (72) then comprising the space defined between said push-rod element and said axial passage, and said second compartment (68) being connected by a leak orifice (60) to a low-pressure fluid tank.

Description

La Demanderesse a décrit,dans sa demande de Brevet Européen N° 78 400 021.8 du 14 juin 1978 (N° de publication : 0 000 303), un conjoncteur-disjoncteur hydraulique destiné en particulier à charger un accumulateur de fluide sous pression à partir d'une pompe hydraulique.The Applicant has described, in its European Patent application No. 78 400 021.8 of June 14, 1978 (Publication No.: 0 000 303), a hydraulic circuit breaker intended in particular to charge a pressurized fluid accumulator from '' a hydraulic pump.

Il s'agit plus précisément d'un conjoncteur-disjoncteur hydraulique comportant un boîtier avec un orifice d'entrée à relier à la sortie d'une pompe hydraulique, un premier orifice de sortie à relier à la chambre de pression d'un accumulateur hydraulique, et un second orifice de sortie à relier à un circuit hydraulique à centre ouvert, un alésage étagé formé dans ce boîtier recevant un piston différentiel qui y définit une chambre d'entrée en communication avec l'orifice d'entrée et une chambre de contrôle, un orifice d'étranglement à section variable en fonction de la position du piston différentiel étant disposé entre la chambre d'entrée et le deuxième orifice de sortie, ladite chambre d'entrée communiquant avec la chambre de contrôle par un premier passage comportant une première restriction et étant en outre reliée au premier orifice de sortie par une connexion comprenant un clapet anti- retour, ce conjoncteur-disjoncteur comprenant en outre une capacité élastique avec un compartiment à volume variable qui est relié à le chambre de contrôle, ladite capacité étant prévue pour mettre en communication ledit compartiment avec un deuxième passage de fuite formant restriction lorsque la pression dans ledit compartiment atteint une première valeur prédéterminée, et ladite communication avec le passage de fuite étant interrompue lorsque la valeur de la pression dans le compartiment retombe en-dessous d'une deuxième valeur prédéterminée.More specifically, it is a hydraulic circuit breaker comprising a housing with an inlet port to be connected to the outlet of a hydraulic pump, a first outlet port to be connected to the pressure chamber of a hydraulic accumulator. , and a second outlet orifice to be connected to an open-center hydraulic circuit, a stepped bore formed in this housing receiving a differential piston which defines therein an inlet chamber in communication with the inlet orifice and a control chamber , a throttle orifice with variable cross section depending on the position of the differential piston being disposed between the inlet chamber and the second outlet orifice, said inlet chamber communicating with the control chamber by a first passage comprising a first restriction and being further connected to the first outlet orifice by a connection comprising a non-return valve, this contactor-circuit breaker further comprising an elastic capacity with a compartment nt variable volume which is connected to the control chamber, said capacity being provided to put said compartment in communication with a second leakage passage forming a restriction when the pressure in said compartment reaches a first predetermined value, and said communication with the passage of leakage being interrupted when the value of the pressure in the compartment falls below a second predetermined value.

La capacité élastique qui équipe ce conjoncteur-disjoncteur hydraulique a pour rôle d'étaler dans le temps les variations de pression qui se produisent au cours des régimes transitoires de montée ou de baisse de la pression de la pompe pendant la charge de l'accumulateur.The elastic capacity which equips this hydraulic circuit breaker has the role of spreading over time the pressure variations which occur during the transient rise or fall regimes. drop in pump pressure while charging the accumulator.

Dans une forme préférentielle de réalisation décrite dans la demande de Brevet précitée, la capacité élastique est constituée par un deuxième alésage formé parallèlement à l'alésage étagé dans le boîtier du conjoncteur-disjoncteur, alésage à l'intérieur duquel est reçu un deuxième piston qui le divise en un premier compartiment constituant le compartiment à volume variable et en un deuxième compartiment, ce deuxième piston étant soumis à l'action de moyens élastiques et comportant un passage axial permettant de mettre en communication les deux compartiments sous le contrôle d'un clapet élastique qu'un élément fixe formant poussoir soulève automatiquement lorsque ce deuxième piston s'est déplacé d'une distance corresponsant à la première valeur prédéterminée de la pression dans ledit compartiment, c'est-à-dire dans la chambre de contrôle.In a preferred embodiment described in the aforementioned patent application, the elastic capacity is constituted by a second bore formed parallel to the stepped bore in the case of the contactor-circuit breaker, bore inside which is received a second piston which divides it into a first compartment constituting the variable volume compartment and into a second compartment, this second piston being subjected to the action of elastic means and comprising an axial passage making it possible to put the two compartments in communication under the control of a valve elastic that a fixed pusher element automatically lifts when this second piston has moved a distance corresponding to the first predetermined value of the pressure in said compartment, that is to say in the control chamber.

Tout en fonctionnant de manière satisfaisante, cet agencement présente cependant l'inconvénient de nécessiter l'usinage d'un deuxième alésage dans le boîtier du conjoncteur-disjoncteur, dont le volume cbit être prévu en conséquence. En outre, toute modification des caractéristiques de fonctionnement de la capacité élastique, telle par exemple qu'un réglage de la force des moyens élastiques agissant sur le deuxième piston, nécessite le démontage du mécanisme, ce qui peut se révéler incommode ou même impossible lorsque le conjoncteur-disjoncteur est monté à bord d'un véhicule automobile.While operating satisfactorily, this arrangement however has the drawback of requiring the machining of a second bore in the case of the contactor-circuit breaker, the volume of which is to be provided accordingly. In addition, any modification of the operating characteristics of the elastic capacity, such as for example adjusting the force of the elastic means acting on the second piston, requires disassembly of the mechanism, which may prove inconvenient or even impossible when the contactor-circuit breaker is mounted on board a motor vehicle.

La présente invention se donne pour but de remédier à ces incm- vénients en réduisant le nombre des opérations d'usinage nécessaires, en améliorant la compacité du conjoncteur-disjoncteur hydraulique, et en rendant la capacité élastique plus facilement accessible pour les besoins d'un réglage éventuel de ses caractéristiques de fonctionnenent.The object of the present invention is to remedy these drawbacks by reducing the number of machining operations required, by improving the compactness of the hydraulic circuit-breaker, and by making the elastic capacity more easily accessible for the needs of a possible adjustment of its operating characteristics.

Ces buts sont atteints, conformément à la présente invention, grâce au fait que la capacité élastique est constituée par une capsule interchangeable logée coaxialement dans la portion de grand diamètre de l'alésage étagé qui constitue la chambre de contrôle, cette capsule contenant un deuxième piston qui y est monté coulissant de façon étanche et qui divise son intérieur en un premier compartiment définissant le compartiment à volume variable et en un deuxième compartiment, ledit deuxième piston étant sollicité vers l'extrémité du premier compartiment par des moyens élastiques disposés dans le second compartiment, un passage axial destiné à mettre en communication les deux compartiments étant prévu dans le piston et ouvrant vers le premier compartiment pour définir un siège de valve qui coopère avec un élément formant clapet sollicité élastiquement contre ledit siège, un élément formant poussoir fixe par rapport à la capsule étant disposé dans le passage axial du deuxième piston et étant susceptible de soulever de son siège l'élément formand clapet pour autoriser l'écoulement du fluide dans le passage de fuite lorsque le deuxième piston s'est déplacé d'une distance donnée qui correspond à la première valeur prédéterminée de la pression dans ledit premier compartiment, le passage de fuite étant alors constitué par l'espace défini entre l'élément formant poussoir et le passage axial, et ledit deuxième compartiment étant mis en communication par un orifice d'échappement avec un réservoir de fluide basse pression.These aims are achieved, in accordance with the present invention, thanks to the fact that the elastic capacity is constituted by an interchangeable capsule housed coaxially in the large diameter portion of the stepped bore which constitutes the control chamber, this capsule containing a second piston. which is slidably mounted therein and which divides its interior into a first compartment defining the variable volume compartment and into a second compartment, said second piston being biased towards the end of the first compartment by elastic means arranged in the second compartment , a step axial sage intended to put in communication the two compartments being provided in the piston and opening towards the first compartment to define a valve seat which cooperates with a valve element elastically urged against said seat, a pusher element fixed relative to the capsule being disposed in the axial passage of the second piston and being capable of lifting from its seat the formand valve element to authorize the flow of the fluid in the leakage passage when the second piston has moved by a given distance which corresponds to the first predetermined value of the pressure in said first compartment, the leakage passage then being constituted by the space defined between the pusher element and the axial passage, and said second compartment being placed in communication by an exhaust orifice a low pressure fluid reservoir.

La capacité élastique se trouve ainsi contenue dans une capsule qui prend la place précédemment occupée par une butée passive, ce qui ne nécessite aucun usinage supplémentaire du boitier du conjoncteur-disjoncteur et contribue à réduire son encombrement général, tandis que son interchangeabilité permet de l'extraire facilement et de la remplacer éventuellement par une autre capacité élastique de caractéristiques différentes.The elastic capacity is thus contained in a capsule which takes the place previously occupied by a passive stop, which does not require any additional machining of the case of the contactor-circuit breaker and contributes to reducing its overall dimensions, while its interchangeability allows easily extract and possibly replace it with another elastic capacity of different characteristics.

L'invention sera à présent décrite à propos d'une forme préférentielle de réalisation, donnée à simple titre d'exemple illustratif, et en se référant à l'unique figure de dessin ci-annexée qui représente une vue en coupe d'un conjoncteur-disjoncteur hydraulique selon la présente invention.The invention will now be described with reference to a preferred embodiment, given simply by way of illustrative example, and with reference to the single appended drawing figure which represents a sectional view of a contactor. -hydraulic circuit breaker according to the present invention.

Comme dans le cas de la demande de Brevet à laquelle référence a été faite ci-dessus, le conjoncteur-disjoncteur hydraulique 10 selon la présente invention comporte un boîtier 12 pourvu d'un orifice d'entrée 13, d'un premier orifice de sortie 14 et d'un deuxième orifice de sortie 16. L'orifice d'entrée 13 est destiné à être relié à une pompe hydraulique à débit volumétrique sensiblement constant. Le premier orifice de sortie 14 est destiné à être relié à la chambre de pression d'un accumulateur de fluide sous pression (non représenté) qui est lui-même destiné à fournir du fluide sous pression à un circuit d'assistance du type à centre fermé, tel par exemple qu'un amplificateur hydraulique de freinage. Le deuxième orifice de sortie 16 est relié, de son côté, à un circuit d'assistance du type à centre ouvert, tel par exemple qu'une valve de direction assistée(non représentée elle aussi sur le dessin).As in the case of the patent application to which reference was made above, the hydraulic circuit breaker 10 according to the present invention comprises a housing 12 provided with an inlet port 13, with a first outlet port 14 and a second outlet orifice 16. The inlet orifice 13 is intended to be connected to a hydraulic pump with a substantially constant volumetric flow rate. The first outlet orifice 14 is intended to be connected to the pressure chamber of a pressurized fluid accumulator (not shown) which is itself intended to supply pressurized fluid to a assistance circuit of the center type closed, such as a hydraulic brake booster. The second outlet 16 is connected, its side, to an assistance circuit of the open center type, such as for example a power steering valve (not also shown in the drawing).

Le boîtier 12 comporte un alésage étagé 20 incluant trois portions de diamètres différents, lesquelles sont séparées les unes des autres par deux épaulements 22 et 24. La portion de plus grand diamètre de cet alésage 20 définit une chambre de contrôle 26, tandis que celle de plus petit diamètre débouche vers le premier orifice de sortie 14. La portion de diamètre moyen de l'alésage 20 définit, en association avec un piston 30 de type différentiel reçu à coulissement dans cet alésage, une chambre d'entrée 28 qui communique avec l'orifice d'entrée 13. Le piston 30 comporte une portion de grand diamètre qui fait saillie dans la chambre de contrôle 26, et une portion de petit diamètre qui coulisse dans la portion de plus petit diamètre de l'alésage 20 et dont l'extrémité est soumise à la pression régnant dans le premier orifice de sortie 14. Le piston 30 comporte une ou plusieurs rainures longitudinales 32 qui sont destinées à mettre en communication la chambre d'entrée 28 avec le deuxième orifice de sortie 16. La profondeur de ces rainures est croissante au fur et à mesure que l'on s'éloigne de l'épaulement du piston différentiel 30. Ces rainures coopèrent avec l'épaulement 24 pour constituer un orifice d'étranglement sur le chemin d'écoulement du fluide entre l'orifice d'entrée 13 et le deuxième orifice de sortie 16, cet orifice d'étranglement ayant une section variable en fonction de la position du piston 30. Celui-ci comporte en outre un passage axial 34 qui est relié à la chambre d'entrée 28 par un passage radial 36. Le passage axial 34 communique avec la chambre de contrôle 26 par l'intermédiaire d'une restriction 38, qui dans l'exemple considéré est constituée par un empilage de pastilles serties et percées. Les passages 34 et 36 réalisent une communication entre la chambre d'entrée 28 et le premier orifice de sortie 14. qui est contrôlée par un clapet antiretour 40, constitué dans l'exemple représenté par une bille. On notera encore qu'un ressort 42 disposé dans la chambre de contrôle 26 sollicite élastiquement le piston 30 à l'encontre de l'action de la pression qui règne dans la chambre d'entrée 28, d'une part, et de la pres- sion de l'accumulateur de fluide raccordé au premier orifice de sortie 14,d'autre part. La pénétration du piston différentiel 30 dans la chambre de contrôle 26 est enfin limitée par une butée, qui, ainsi qu'on l'exposera ci-dessous, est constituée par la propre capacité élastique du conjoncteur-disjoncteur ; l'application en butée du piston 30 se fait de préférence par l'intermédiaire d'une rondelle 44 en matériau élastomère, laquelle assure pour cette position du piston 30 l'interruption de la communication existant entre le passage axial 34 et la chambre de contrôle 26.The housing 12 has a stepped bore 20 including three portions of different diameters, which are separated from each other by two shoulders 22 and 24. The larger diameter portion of this bore 20 defines a control chamber 26, while that of smaller diameter opens towards the first outlet orifice 14. The portion of average diameter of the bore 20 defines, in association with a piston 30 of the differential type received with sliding in this bore, an inlet chamber 28 which communicates with the 'inlet orifice 13. The piston 30 has a large diameter portion which projects into the control chamber 26, and a small diameter portion which slides in the smaller diameter portion of the bore 20 and whose end is subjected to the pressure prevailing in the first outlet orifice 14. The piston 30 has one or more longitudinal grooves 32 which are intended to put the inlet chamber 28 into communication with the second outlet orifice 16. The depth of these grooves increases as one moves away from the shoulder of the differential piston 30. These grooves cooperate with the shoulder 24 to form a throttling orifice on the fluid flow path between the inlet orifice 13 and the second outlet orifice 16, this throttle orifice having a variable section depending on the position of the piston 30. The latter also comprises an axial passage 34 which is connected to the inlet chamber 28 by a radial passage 36. The axial passage 34 communicates with the control chamber 26 by means of a restriction 38, which in the example considered consists of a stack of pellets crimped and pierced. The passages 34 and 36 provide communication between the inlet chamber 28 and the first outlet orifice 14. which is controlled by a non-return valve 40, constituted in the example represented by a ball. It will also be noted that a spring 42 disposed in the control chamber 26 resiliently biases the piston 30 against the action of the pressure prevailing in the inlet chamber 28, on the one hand, and of the pres - sion of the fluid accumulator connected to the first outlet orifice 14, on the other hand. The penetration of the differential piston 30 into the control chamber 26 is finally limited by a stop, which, as we will expose it below, is constituted by the own elastic capacity of the contactor-circuit breaker; the stop 30 is preferably applied by means of a washer 44 made of elastomeric material, which ensures for this position of the piston 30 the interruption of the communication existing between the axial passage 34 and the control chamber 26.

Conformément à la présente invention, la capacité élastique qui équipe le conjoncteur-disjoncteur hydraulique 10, et qui est désignée dans son ensemble par le repère numérique 50, est constituée par une capsule interchangeable logée coaxialement dans la portion de grand diamètre de l'alésage 20 qui délimite la chambre de contrôle 26. Cette capsule est constituée par l'assemblage de deux cuvettes 52 et 54, de préférence réalisées en matière plastique, et maintenues serrées l'une contre l'autre avec interposition d'un joint d'étanchéité 56 par la compression du ressort 42 qui maintientl'ensemble appliqué en butée con- tre un jonc élastique amovible 58. La cuvette supérieure 52 est percée d'un orifice d'échappement 60, par l'intermédiaire duquel elle peut être raccordée à une source de fluide basse pression, telle par exemple que la bâche du système hydraulique. La cuvette inférieure 54 est elle-même percée d'un passage 62 qui met en communication l'intérieur de la capsule avec la chambre de contrôle 26.In accordance with the present invention, the elastic capacity which equips the hydraulic circuit breaker 10, and which is generally designated by the reference numeral 50, consists of an interchangeable capsule housed coaxially in the large diameter portion of the bore 20 which delimits the control chamber 26. This capsule is constituted by the assembly of two bowls 52 and 54, preferably made of plastic material, and held tight against one another with the interposition of a seal 56 by compression of the spring 42 which abuts maintientl'ensemble applied con - be a removable snap ring 58. the upper bowl 52 is formed with an exhaust port 60, via which it can be connected to a source of low pressure fluid, such as for example the cover of the hydraulic system. The lower bowl 54 is itself pierced with a passage 62 which places the interior of the capsule in communication with the control chamber 26.

A l'intérieur de la capsule constituée par l'assemblage des cu- . vettes 52 et 54 est disposé un piston 64 coulissant de façon étanche, qui divise l'intérieur de la capsule en un premier compartiment 66 communiquant par le passage 62 avec la chambre de contrôle 26, et en un deuxième compartiment 68 qui communique avec l'orifice d'échappement 60. En position de repos, le piston 64 est sollicité contre l'extrémité du compartiment 66 par un ressort 70 logé à l'intérieur du compartiment 68 et entourant coaxialement ce piston.Inside the capsule formed by the assembly of the cu-. vettes 52 and 54 is disposed a piston 64 sliding in leaktight manner, which divides the interior of the capsule into a first compartment 66 communicating through the passage 62 with the control chamber 26, and into a second compartment 68 which communicates with the exhaust port 60. In the rest position, the piston 64 is urged against the end of the compartment 66 by a spring 70 housed inside the compartment 68 and coaxially surrounding this piston.

Le piston 64 est lui-même percé d'un passage axial 72 destiné à mettre.en communication les deux compartiments 66 et 68. Ce passage débouche dans le premier compartiment 66 en définissant un siège de valve 74 qui coopère avec un clapet 76 (ici constitué par une bille) sollicité élastiquement contre ce siège par un léger ressort 78. Dans le passage axial 72 est disposé un poussoil 80 fixe par rapport à la capsule, lequel se termine par un doigt 82. Dans la position de repos représentée sur le dessin, pour laquelle le piston 64 est sollicité au maximum vers le premier compartiment 66 par le ressort 70, l'extrémité du doigt 82 est en retrait par rapport au plan du siège de valve 74, et la bille 76 est maintenue appliquée sur ce siège par le ressort associé 78. Un autre ressort 84, disposé dans le passage 72 et entourant le doigt 82, a une longueur supérieure à celle de ce doigt mais cependant insuffisante pour solliciter la bille 76. Entre le poussoir 80 et l'alésage définissant le passage 72 est ménagé un jeu radial restreint qui permet au fluide de communiquer entre le premier compartiment 66 et le deuxième compartiment 68 lorsque le clapet 76 est écarté de son siège 74.The piston 64 is itself pierced with an axial passage 72 intended to put the two compartments 66 and 68 into communication. This passage opens into the first compartment 66 by defining a valve seat 74 which cooperates with a valve 76 (here constituted by a ball) elastically urged against this seat by a light spring 78. In the axial passage 72 is disposed a poussoil 80 fixed relative to the capsule, which ends with a finger 82. In the rest position shown in the drawing , for which the piston 64 is stressed to the maximum towards the first compartment 66 by the spring 70, the end of the finger 82 is set back with respect to the plane of the valve seat 74, and the ball 76 is kept applied to this seat by the associated spring 78. Another spring 84, disposed in the passage 72 and surrounding the finger 82, has a length greater than that of this finger but however insufficient to urge the ball 76. Between the pusher 80 and the bore defining the passage 72 is provided a limited radial clearance which allows the fluid to communicate between the first compartment 66 and the second compartment 68 when the valve 76 is moved away from its seat 74.

Le conjoncteur-disjoncteur hydraulique ci-dessus décrit fonctionne de la manière suivante :

  • Dans la position de repos illustrée par le dessin, l'accumulateur raccordé au premier orifice de sortie 14 est supposé chargé. La pression régnant dans cet accumulateur maintient fermé le clapet 40 et sollicite le piston différentiel 30 vers le haut, permettant ainsi un écoulement normal de fluide entre l'orifice d'entrée 13 et le second orifice de sortie 16, c'est-à-dire entre la pompe hydraulique et la valve de direction assitée. La capacité élastique occupe la position représentée sur le dessin et le clapet 76 est maintenu appliqué sur son siège 74 par le ressort associé 78.
The above-described hydraulic circuit breaker works as follows:
  • In the rest position illustrated in the drawing, the accumulator connected to the first outlet orifice 14 is assumed to be charged. The pressure prevailing in this accumulator keeps the valve 40 closed and urges the differential piston 30 upwards, thus allowing a normal flow of fluid between the inlet port 13 and the second outlet port 16, that is to say say between the hydraulic pump and the power steering valve. The elastic capacity occupies the position shown in the drawing and the valve 76 is kept applied on its seat 74 by the associated spring 78.

Si l'on suppose à présent que la pression dans l'accumulateur de fluide tombe en-dessous de la pression dite de conjonction, autrement dit, de la pression minimale d'utilisation, le piston différentiel est repoussé par le ressort 42 et provoque une réduction de section de passage entre la chambre d'entrée 28 et le deuxième orifice de sortie 16. Il en résulte une augmentation de pression dans la chambre d'entrée 28, et par voie de conséquence un écoulement de fluide de cette chambre vers la chambre de contrôle 26 par l'intermédiaire de la restriction 38. Ceci entraîne une charge progressive de la capacité élastique 50 par l'intermédiaire du passage 62. 'L'augmentation de pression dans la chambre de contrôle 26 ajoute ses effets à ceux du ressort 42, et le processus se poursuit de façon progressive jusqu'à ce que la pression délivrée par la pompe atteigne la valeur dite de conjonction. Le clapet 40 est alors soulevé de son siège et une partie du fluide délivré par la pompe est dirigée vers l'accumulateur qui commence à se recharger. A partir de cet instant, la pression de la pompe continue à croitre, mais avec un taux d'augmentation plus réduit.If it is now assumed that the pressure in the fluid accumulator falls below the so-called conjunction pressure, in other words, the minimum operating pressure, the differential piston is pushed back by the spring 42 and causes a reduction in cross section between the inlet chamber 28 and the second outlet orifice 16. This results in an increase in pressure in the inlet chamber 28, and consequently a flow of fluid from this chamber to the chamber 26 through the restriction 38. This causes a progressive loading of the elastic capacity 50 through the passage 62. The increase in pressure in the control chamber 26 adds its effects to those of the spring 42 , and the process continues gradually until the pressure delivered by the pump reaches the so-called conjunction value. The valve 40 is then lifted from its seat and part of the fluid delivered by the pump is directed to the accumulator which begins to recharge. From this moment, the pump pressure continues to increase, but with a more reduced rate of increase.

A l'intérieur de la capacité élastique 50, l'augmentation de pression qui se produit dans la chambre de contrôle 26 se communique au premier compartiment 66 et a pour effet de repousser le piston 64 vers le haut. Dans une première phase de son déplacement, le clapet 76 accompagne le piston 64 et vient au contact de l'extrémité libre du ressort 84 qu'il comprime, la fin de cette première phase correspondant à l'instant où le clapet 76 entre en contact avec l'extrémité du doigt 82.Inside the elastic capacity 50, the increase in pressure which occurs in the control chamber 26 is communicated to the first compartment 66 and has the effect of pushing the piston 64 upwards. In a first phase of its movement, the valve 76 accompanies the piston 64 and comes into contact with the free end of the spring 84 which it compresses, the end of this first phase corresponding to the instant when the valve 76 comes into contact with the end of the finger 82.

Au début de la seconde phase, un léger déplacement supplémentaire du piston 64 a pour effet d'écarter la bille 76 du siège de valve 74, et l'égalisation des pressions qui s'effectue de part et d'autre de cette bille permet au ressort 84 de se détendre et d'écarter franchement la bille de son siège. La force du ressort 70 et la longueur du poussoir 80,82 peuvent être choisies de manière à ce que l'ouverture du clapet constitué par la bille 76 se produise pour un déplacement du piston 64 correspondant à une valeur prédéterminée de la pression dans le compartiment 66 et donc dans la chambre de contrôle 26, cette valeur prédéterminée de la pression étant appelée "pression d'ouverture: Cette dernière étant proportionnelle à la pression qui règne dans la chambre d'entrée 28, il est ainsi possible d'obtenir que l'ouverture du clapet constitué par la bille 76 se produise lorsque la pression dans la chambre d'entrée 28 atteint la valeur correspondant à la pression de disjonction de l'accumulateur, c'est-à-dire, la pression maximale à laquelle il doit être rechargé.At the start of the second phase, a slight additional movement of the piston 64 has the effect of moving the ball 76 away from the valve seat 74, and the pressure equalization which takes place on either side of this ball allows the spring 84 to relax and openly move the ball away from its seat. The force of the spring 70 and the length of the pusher 80,82 can be chosen so that the opening of the valve formed by the ball 76 occurs for a displacement of the piston 64 corresponding to a predetermined value of the pressure in the compartment 66 and therefore in the control chamber 26, this predetermined pressure value being called "opening pressure: The latter being proportional to the pressure prevailing in the inlet chamber 28, it is thus possible to obtain that l opening of the valve formed by the ball 76 occurs when the pressure in the inlet chamber 28 reaches the value corresponding to the accumulator cut-out pressure, that is to say, the maximum pressure at which it must be recharged.

En d'autres termes, le clapet de la capacité élastique s'ouvre à l'instant où l'accumulateur associé est convenablement rechargé.In other words, the valve of the elastic capacity opens at the moment when the associated accumulator is suitably recharged.

Dès l'ouverture du clapet, il se produit un écoulement laminaire de fluide vers l'orifice d'échappement 60, par l'intermédiaire du passage de fuite défini entre le poussoir 80 et l'alésage du piston 64. Il en résulte une réduction progressive de la pression dans le premier compartiment 66 ainsi que dans la chambre de contrôle 26. Le piston différentiel 30 recule dès lors à l'encontre de l'action du ressort 42, ce qui a pour effet d'augmenter la section de l'étranglement entre la chambre d'entrée 28 et le second orifice de sortie 16, avec pour conséquence une diminution progressive de la pression qui règne dans cette chambre d'entrée 28. A l'intérieur de la capacité élastique 50, la baisse de pression dans le compartiment 66 provoque un retour progressif du piston 64 vers sa position de repos sous l'influence du res sort 70. En raison de l'excédent de longueur du ressort 84 par rapport au doigt 82 du poussoir 80, le clapet constitué par la bille 76 reste ouvert jusqu'à l'instant où le piston 64 a reculé d'une distance suffisante pour que cette bille ait repris contact avec son siège 74. Le clapet est alors à nouveau fermé, et la communication de fluide entre les compartiments 66 et 68 est interrompue. La longueur du ressort 84 est calculée pour que cette réduction de la communication de fluide entre les deux compartiments intervienne lorsque la pression dans le compartiment 66 a diminué d'une quantitéAP donnée pour atteindre une valeur dite de fermeture. Cette dernière est fixée de manière à ce que la pression régnant dans la chambre d'entrée 28 soit devenue inféneure à la pression qui règne dans la chambre de contrôle 26 à l'instant où la bille 76 reprend contact avec son siège 74.As soon as the valve is opened, a laminar flow of fluid occurs towards the exhaust orifice 60, via the leakage passage defined between the pusher 80 and the bore of the piston 64. This results in a reduction progressive pressure in the first compartment 66 and in the control chamber 26. The differential piston 30 therefore recedes against the action of the spring 42, which has the effect of increasing the section of the constriction between the inlet chamber 28 and the second outlet orifice 16, with the consequence of a progressive reduction in the pressure prevailing in this inlet chamber 28. Within the elastic capacity 50, the drop in pressure in compartment 66 causes a progressive return of piston 64 to its rest position under the influence of res comes out 70. Due to the excess length of the spring 84 relative to the finger 82 of the pusher 80, the valve formed by the ball 76 remains open until the piston 64 has retreated a sufficient distance to that this ball has resumed contact with its seat 74. The valve is then closed again, and the communication of fluid between the compartments 66 and 68 is interrupted. The length of the spring 84 is calculated so that this reduction in the communication of fluid between the two compartments occurs when the pressure in the compartment 66 has decreased by a given quantity AP to reach a so-called closing value. The latter is fixed in such a way that the pressure prevailing in the inlet chamber 28 has become lower than the pressure prevailing in the control chamber 26 at the moment when the ball 76 resumes contact with its seat 74.

Il est en l'occurrence nécessaire que la pression de fermeture possède une valeur inférieure à la plage de conjoction-disjonction de l'accumulateur.In this case, it is necessary for the closing pressure to have a value lower than the conjunct-disjunction range of the accumulator.

La troisième phase du fonctionnement commence à l'instant où le clapet de la capacité élastique est à nouveau fermé. Le fluide hydraulique s'écoule alors du compartiment 66 et de la chambre de contrôle 26 vers la pompe, par l'intermédiaire de la restriction 38, du passage axial 34, du passage radial 36 et de la chambre d'entrée 28, ceci jusqu'à ce que la capacité soit complètement détendue.The third phase of operation begins when the elastic capacity valve is closed again. The hydraulic fluid then flows from compartment 66 and from the control chamber 26 to the pump, via the restriction 38, the axial passage 34, the radial passage 36 and the inlet chamber 28, this up to 'that the capacity is completely relaxed.

Il ressort de la description précédente que les caractéristiques de fonctionnement de la capacité élastique 50, et par conséquent du conjoncteur-disjoncteur hydraulique 10 qu'elle équipe, dépendent dans une large mesure d'un certain nombre de paramètres constructifs, notamment de la force du ressort 70, de la longueur relative du poussoir 80,82 et du piston 64, de la longueur du ressort 84, etc.. C'est donc en agissant sur ces divers paramètres constructifs que l'on peut modifier les caractéristiques du conjoncteur-disjoncteur hydraulique. Cette opération se trouve grandement facilitée par la conception de la capacité élastique 50 selon la présente invention, puisqu'il suffit en pareil cas d'extraire le jonc de blocage 58 pour pouvoir retirer la capsule constituant cette capacité élastique tout d'une pièce, et la remplacer par une autre répondant aux caractéristiques désirées. L'intervention ne demande que peu de temps et ne nécessite pas le démontage du conjoncteur-disjoncteur hydraulique ni son enlèvement du véhicule sur lequel il est mont6.It appears from the preceding description that the operating characteristics of the elastic capacity 50, and consequently of the hydraulic contactor-circuit breaker 10 which it equips, depend to a large extent on a number of constructive parameters, in particular the strength of the spring 70, of the relative length of the pusher 80.82 and of the piston 64, of the length of the spring 84, etc. It is therefore by acting on these various constructive parameters that one can modify the characteristics of the contactor-circuit breaker hydraulic. This operation is greatly facilitated by the design of the elastic capacity 50 according to the present invention, since it suffices in such a case to extract the locking ring 58 in order to be able to remove the capsule constituting this elastic capacity all in one piece, and replace it with another that meets the desired characteristics. The intervention requires only a short time and does not require the disassembly of the hydraulic circuit breaker or its removal from the vehicle on which it is mounted.

Claims (5)

1. Conjoncteur-disjoncteur hydraulique comportant un boitier avec un orifice d'entrée à relier à la sortie d'uhe pompe hydrau-- lique, un premier orifice de sortie à relier à la chambre de pression d'un accumulateur hydraulique, et un second orifice de sortie à relier à un circuit hydraulique à centre ouvert, un alésage étagé formé dans le boitier recevant un piston différentiel qui y définit une chambre d'entrée en communication avec l'orifice d'entrée et une chambre de contrôle, un orifice d'étranglement à section variable en fonction de la position du piston différentiel étant disposé entre la chambre d'entrée et le deuxième orifice de sortie, ladite chambre d'entrée communiquant a/ec la chambre de contrôle par un premier passage comportant une première restriction et étant en outre reliée au premier orifice de sortie par une connexion comprenant un clapet antiretour, ce conjoncteur-dis joncteur comprenant en outre une capacité élastique avec un compartiment à volume variable qui est relié à la chambre de contrôle, ladite capacité étant prévue pour mettre en communication ledit compartiment avec un deuxième passage de fuite formant restriction lorsque la pression dans ledit compartiment atteint une première valeur prédéterminée, et laJite communication avec le passage de fuite étant interrompue lorsque la valeur de la pression dans le compartiment retombe en dessous d'une deuxième valeur prédéterminée, caractérisé en ce que la capacité élastioue est constituée par une capsule interchangeable (50) logée coaxialement dans la portion de grand diamètre de l'alésage étagé qui constitue la chambre de contrôle (26), cette capsule contenant un deuxième piston (64) qui y est monté coulissant de façon étanche et qui divise son intérieur en un premier compartiment (66) définissant le compartiment à volume variable et en un deuxième compartiment (68), ledit deuxième piston étant sollicité vers l'extrémité du premier compartiment par des moyens élastiques (70) disposés dans le second compartiment, un passage axial (72) destiné à mettre en communication les deux compartiments étant prévu dans le piston et ouvrant vers le premier compartiment pour définir un siège de valve (74) qui coopère avec un élément formant clapet (76) sollicité élastiquement contre ledit siège, un élément (80,82) formant poussoir fixe par rapport à la capsule étant disposé dans le passage axial du deuxième piston et étant susceptible de soulever de son siège l'élément formant clapet pour autoriser l'écoulement du fluide dans le passage de fuite lorsque le deuxième piston s'est déplacé d'une distance donnée qui correspond à la première valeur prédéterminée de la pression dans ledit premier compartiment, le passage de fuite étant alors constitué par l'espace défini entre l'élément formant poussoir et le passage axial, et ledit deuxième compartiment étant mis en communication par un orifice d'échappement (60) avec un réservoir de fluide basse pression.1. Hydraulic Contactor circuit breaker comprising a housing with an inlet port for connection with the output of HEU pump hydraulically - lic, a first outlet port connecting the pressure chamber of a hydraulic accumulator, and a second outlet port to be connected to an open-center hydraulic circuit, a stepped bore formed in the housing receiving a differential piston which defines therein an inlet chamber in communication with the inlet port and a control chamber, an orifice '' variable section throttle depending on the position of the differential piston being disposed between the inlet chamber and the second outlet orifice, said inlet chamber communicating with / between the control chamber by a first passage comprising a first restriction and being further connected to the first outlet via a connection comprising a non-return valve, this contactor-circuit breaker further comprising an elastic capacity with a variable volume compartment which e st connected to the control chamber, said capacity being provided to put said compartment in communication with a second leakage passage forming a restriction when the pressure in said compartment reaches a first predetermined value, and the communication with the leakage passage being interrupted when the value of the pressure in the compartment falls below a second predetermined value, characterized in that the elastic capacity consists of an interchangeable capsule (50) housed coaxially in the large diameter portion of the stepped bore which constitutes the chamber control (26), this capsule containing a second piston (64) which is slidably mounted therein and which divides its interior into a first compartment (66) defining the variable volume compartment and into a second compartment (68), said second piston being urged towards the end of the first compartment by elastic means (70) arranged in the second compartment, an axial passage (72) intended to put the two compartments in communication being provided in the piston and opening towards the first compartment to define a valve seat (74) which cooperates with a valve member (76) resiliently biased against said seat, an element (80,82) forming a fixed pusher relative to the capsule being disposed in the axial passage of the second piston and being capable of lifting the element forming a valve to allow the flow of fluid in the leakage passage when the second piston has moved a given distance which corresponds to the first predetermined value of the pressure in said first compartment, the leakage passage then being constituted by the space defined between the pusher element and the axial passage, and said second compartment being placed in communication by an exhaust orifice (60) with a low pressure fluid reservoir. 2. Conjoncteur-disjoncteur hydraulique selon la revendication 1, caracterisé en ce qu'un ressort (84) est monté dans le passage axial du deuxième piston entre l'élément formant poussoir et l'élément formant clapet pour écarter ce dernier de son siège après le soulèvement dudit clapet, et pour maintenir ledit clapet dans sa position d'ouverture jusqu'à ce que le deuxième piston ait reculé d'une certaine distance, consécutivement à une chute de pression donnée dans le premier compartiment.2. Hydraulic circuit breaker according to claim 1, characterized in that a spring (84) is mounted in the axial passage of the second piston between the pusher member and the valve member to move the latter from its seat after the lifting of said valve, and to maintain said valve in its open position until the second piston has moved back a certain distance, following a given pressure drop in the first compartment. 3. Conjoncteur-disjoncteur hydraulique selon l'une des revendications 1 ou 2, caractérisé en ce que la capsule constituant la capacité élastique est dimensionnée de façon à jouer le rôle de butée limitant la pénétration du piston différentiel (30) dans la chambre de contrôle (26).3. Hydraulic circuit breaker according to one of claims 1 or 2, characterized in that the capsule constituting the elastic capacity is dimensioned so as to act as a stop limiting the penetration of the differential piston (30) in the control chamber (26). 4. Conjoncteur- disjoncteur hydraulique selon la revendication 3, caractérisé en ce que la surface de butée offerte par la capsule au piston différentiel est garnie d'une rondelle d'étanchéité (44) conçue pour interrompre la communication entre la chambre d'entrée (28) et-la chambre de contrôle (26).4. Hydraulic circuit breaker according to claim 3, characterized in that the abutment surface offered by the capsule to the differential piston is provided with a sealing washer (44) designed to interrupt the communication between the inlet chamber ( 28) and the control chamber (26). 5. Conjoncteur-disjoncteur hydraulique selon l'une quelconque des revendications 1 à 4, caractérisé en ce que la capsule est constituée par l'assemblage de deux cuvettes (52,54), de préférence en matière plastique, dont l'une comporte un orifice (62) de mise en communication du compartiment à volume variable avec la chambre de contrôle, et dont l'autre est pourvue d'un orifice d'échappement (60) à relier au réservoir de fluide basse pression.5. Hydraulic circuit breaker according to any one of claims 1 to 4, characterized in that the capsule is constituted by the assembly of two cuvettes (52,54), preferably made of plastic, one of which has a orifice (62) for communicating the variable volume compartment with the control chamber, and the other of which is provided with an exhaust orifice (60) to be connected to the low pressure fluid reservoir.
EP19790400484 1978-07-12 1979-07-10 Hydraulic safety switch Expired EP0007279B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7820816 1978-07-12
FR7820816A FR2431051A2 (en) 1977-06-21 1978-07-12 Control valve for vehicle hydraulic brakes - houses interchangeable cartridge forming capacity limiter and acting as stop for differential piston

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EP0007279A1 true EP0007279A1 (en) 1980-01-23
EP0007279B1 EP0007279B1 (en) 1981-09-02

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2627816A1 (en) * 1988-02-29 1989-09-01 Bendix France Pressure relief valve for hydraulic system - includes piston moving under effect of thermal expansion caused by adjacent electric heating element
DE10333014A1 (en) * 2003-07-18 2005-02-03 Volkswagen Ag Hydraulic oil pressure reservoir for automobile hydraulics with valves for hydraulic pressure circuit combined with pressure reservoir connection fitting
CN106439143A (en) * 2016-11-16 2017-02-22 江南工业集团有限公司 Pneumatically controlled pressure relief valve and pressure relief method

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FR2350486A1 (en) * 1976-05-07 1977-12-02 Dba HYDRAULIC CIRCUIT BREAKER
EP0000303A1 (en) * 1977-06-21 1979-01-10 Societe Anonyme D.B.A. Automatic hydraulic valve

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2350486A1 (en) * 1976-05-07 1977-12-02 Dba HYDRAULIC CIRCUIT BREAKER
EP0000303A1 (en) * 1977-06-21 1979-01-10 Societe Anonyme D.B.A. Automatic hydraulic valve

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2627816A1 (en) * 1988-02-29 1989-09-01 Bendix France Pressure relief valve for hydraulic system - includes piston moving under effect of thermal expansion caused by adjacent electric heating element
DE10333014A1 (en) * 2003-07-18 2005-02-03 Volkswagen Ag Hydraulic oil pressure reservoir for automobile hydraulics with valves for hydraulic pressure circuit combined with pressure reservoir connection fitting
CN106439143A (en) * 2016-11-16 2017-02-22 江南工业集团有限公司 Pneumatically controlled pressure relief valve and pressure relief method

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EP0007279B1 (en) 1981-09-02
DE2960735D1 (en) 1981-11-26

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