EP0180510B1 - Hydraulic piston pump with positively driven inlet valves - Google Patents

Hydraulic piston pump with positively driven inlet valves Download PDF

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Publication number
EP0180510B1
EP0180510B1 EP19850402018 EP85402018A EP0180510B1 EP 0180510 B1 EP0180510 B1 EP 0180510B1 EP 19850402018 EP19850402018 EP 19850402018 EP 85402018 A EP85402018 A EP 85402018A EP 0180510 B1 EP0180510 B1 EP 0180510B1
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EP
European Patent Office
Prior art keywords
cam
valve
piston
spring
urged
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EP19850402018
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German (de)
French (fr)
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EP0180510A1 (en
Inventor
Louis Claude Porel
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Hydro Rene Leduc SA
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Hydro Rene Leduc SA
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B7/00—Piston machines or pumps characterised by having positively-driven valving
    • F04B7/0042—Piston machines or pumps characterised by having positively-driven valving with specific kinematics of the distribution member
    • F04B7/0053—Piston machines or pumps characterised by having positively-driven valving with specific kinematics of the distribution member for reciprocating distribution members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/14—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having stationary cylinders
    • F04B1/18—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having stationary cylinders having self-acting distribution members, i.e. actuated by working fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
    • F04B53/10—Valves; Arrangement of valves
    • F04B53/102—Disc valves
    • F04B53/1022—Disc valves having means for guiding the closure member axially

Definitions

  • the present invention relates to improvements in hydraulic piston pumps and controlled suction valves.
  • Hydraulic piston pumps generally comprise a plurality of reciprocating pistons by means of a cam; this cam can be connected to the drive shaft, the pistons sliding in cylinders hollowed out in the pump body, or the cam is fixed and the pistons slide in cylinders hollowed out in a rotating barrel driven by the shaft d 'training.
  • the cam can be of any suitable shape, for example an eccentric, the pistons being radial or a bias plate, the pistons then being parallel to the drive shaft of the pump.
  • the first drawback stems from the fact that the direction of rotation of the pump drive shaft must always be the same, without which suction and delivery can no longer take place.
  • French patent 2,394,692 it has been proposed in French patent 2,394,692 to place the front face of the bias plate, without the lunula, a plate which can pivot 180 °, this plate being itself provided with a lunula: it is then possible by a simple rotation of the plate on the front face of the bias plate to reverse the suction and delivery phases and therefore reverse the direction of rotation of the pump.
  • this rotation of the plate on the face of the bias plate cannot be done automatically and requires manual intervention each time.
  • the second drawback stems from the fact that the hydraulic liquids having a non-negligible compressibility at these high pressures (200 bars and beyond), it is necessary to angularly offset the start of the lunula relative to the line of greatest slope of the face of the bias plate so as to prevent the intake phase from starting before the liquid inside the piston has finished expanding. If such a precaution is not taken, the pressurized liquid flows back into the suction circuit, which lowers the efficiency of the pump.
  • the magnitude of this offset is a function of the speed of rotation of the pump and the compressibility rate of the fluid conveyed. The latter depends on the pressure, the temperature, the amount of air dissolved in the fluid etc.
  • the Applicant has replaced the supply system by means of a lunula and sliding pads with suction valves.
  • main patent No. 79 29037 (FR-A-2 470 266) a bias plate pump comprising for each piston an intake valve subjected to the action of two opposing springs: a first spring pushing it towards the closing and a second spring pushing it towards the opening, this second spring being associated with a cam linked in rotation to the drive shaft of the pump so that the force exerted by this second spring becomes substantially equal to that exerted in the opposite direction by the first to start of the suction phase.
  • n ° 80.09780 (FR-A-2 481 757) the cam is formed so as to be able to be placed in two positions offset from each other by 180 °, which allows to reverse the direction of pump rotation.
  • the pump according to the present invention is a hydraulic pump comprising at least one piston which moves back and forth, each piston being associated with a suction valve which is returned to the closed position by a return spring, characterized by the causes said return spring (16) to be associated with a plunger (15) actuated cyclically by a cam (21) driven by the drive shaft (1) of the pump; so that, when the pusher (15) is actuated by the cam (21) the action of the spring (16) on the valve (11) is canceled during the suction phase and restored at the end of said phase, which has the result that the valve (11) is free during this period and opens only if the suction pressure is greater than the residual pressure prevailing in the cylinder (6) associated with said valve.
  • FIG. 1 shows a hydraulic pump with axial pistons and bias plate.
  • This pump is constituted by a drive shaft 1 carrying a bias plate 2 on the front face 2a of which bear a plurality of pistons 3, each piston 3 resting against said front face 2a of the bias plate 2 by a sliding pad 4.
  • Each piston 3 is held in abutment on its shoe 4 by a spring 5 and moves in a cylinder 6.
  • Each cylinder 6 communicates by an orifice 7 with an intake chamber 8 which, itself, communicates with the reservoir 9 by a pipe 10.
  • Each orifice 7 is provided with a suction valve 11.
  • Each valve 11 has a rod 12 which slides freely in a bearing 13 and which projects into a bore 14 inside which a hollow piston 15 which can be pushed back can slide by a spring 16.
  • the rod 12 of the valve 11 penetrates inside the hollow piston 15 through an orifice 17 in which it slides.
  • the rod 12 of the valve 11 has a stop 18 which in FIG. 1 is constituted by a circlip and which in FIGS. 2 and 3 is schematically represented by a disc integral with the end of the rod 12.
  • a housing 19 in which is disposed, with a certain clearance, a ball 20 which bears against a cam 21 carried by a rod 22 driven by the shaft 1.
  • valve 11 is pushed at the end n of the suction phase in the closed position by a spring 16 which is determined so as to exert a forceful closing reminder; but that from the start of the suction phase, the effect of this return spring 16 is eliminated by the cam 21, the valve 11 then being a free valve.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)

Description

La présente invention est relative à des perfectionnements aux pompes hydrauliques à pistons et à clapets d'aspiration commandées.The present invention relates to improvements in hydraulic piston pumps and controlled suction valves.

Les pompes hydrauliques à pistons comportent, d'une manière générale, une pluralité de pistons animés d'un mouvement alternatif par le moyen d'une came ; cette came peut être reliée à l'arbre d'entraînement, les pistons coulissant dans des cylindres creusés dans le corps de pompe, ou bien la came est fixe et les pistons coulissent dans des cylindres creusés dans un barillet tournant entraîné par l'arbre d'entraînement.Hydraulic piston pumps generally comprise a plurality of reciprocating pistons by means of a cam; this cam can be connected to the drive shaft, the pistons sliding in cylinders hollowed out in the pump body, or the cam is fixed and the pistons slide in cylinders hollowed out in a rotating barrel driven by the shaft d 'training.

Il est connu, dans ce genre de pompes, d'employer des pistons creux qui sont traversés par le liquide hydraulique pompé, ce liquide pénétrant à l'intérieur du piston par la tête de ce dernier et ressortant par son autre extrémité. Dans un tel cas, les pistons reposent sur la face inclinée de la came par l'intermédiaire de patins qui glissent sur la surface de ladite came, ces patins étant traversés de part en part par un orifice central et venant, pendant leur course d'aspiration, chevaucher une lunule gravée sur la surface de ladite came. Lorsqu'un patin glisse ainsi au-dessus de la lunule, il y a communication fluidique entre la chambre dans laquelle se meut la came et l'intérieur du piston creux correspondant par ladite lunule, ledit orifice central du patin de glissement et la tête du piston, également percée d'un orifice central. Cette communication est interrompue lorsque le patin quitte la lunule et glisse sur la face lisse de la came : le liquide contenu à l'intérieur du piston et comprimé par le mouvement de ce dernier est alors évacué par un clapet à ressort situé au fond du cylindre.It is known, in this kind of pumps, to use hollow pistons which are traversed by the pumped hydraulic fluid, this liquid penetrating inside the piston by the head of the latter and emerging from its other end. In such a case, the pistons rest on the inclined face of the cam by means of pads which slide on the surface of said cam, these pads being traversed right through by a central orifice and coming, during their travel from suction, overlap a lunula engraved on the surface of said cam. When a shoe thus slides above the lunula, there is fluid communication between the chamber in which the cam moves and the interior of the corresponding hollow piston by said lunula, said central orifice of the sliding shoe and the head of the piston, also with a central hole. This communication is interrupted when the pad leaves the lunula and slides on the smooth face of the cam: the liquid contained inside the piston and compressed by the movement of the latter is then evacuated by a spring valve located at the bottom of the cylinder. .

La came peut être de toutes formes appropriées, par exemple un excentrique, les pistons étant radiaux ou un plateau biais, les pistons étant alors parallèles à l'arbre d'entraînement de la pompe.The cam can be of any suitable shape, for example an eccentric, the pistons being radial or a bias plate, the pistons then being parallel to the drive shaft of the pump.

Les pompes de ce genre présentent deux inconvénients.Pumps of this kind have two drawbacks.

Le premier inconvénient provient de ce que le sens de rotation de l'arbre d'entraînement de la pompe doit toujours être le même, sans quoi l'aspiration et le refoulement ne peuvent plus se faire. Pour remédier à cet inconvénient, on a proposé dans le brevet français 2 394 692 de placer la face avant du plateau biais, démuni de lunule, une plaque pouvant pivoter de 180°, cette plaque étant elle, munie d'une lunule : il est alors possible par une simple rotation de la plaque sur la face avant du plateau biais d'inverser les phases d'aspiration et de refoulement et donc d'inverser le sens de rotation de la pompe. Malheureusement, cette rotation de la plaque sur la face du plateau biais ne peut pas se faire de façon automatique et nécessite à chaque fois une intervention manuelle.The first drawback stems from the fact that the direction of rotation of the pump drive shaft must always be the same, without which suction and delivery can no longer take place. To remedy this drawback, it has been proposed in French patent 2,394,692 to place the front face of the bias plate, without the lunula, a plate which can pivot 180 °, this plate being itself provided with a lunula: it is then possible by a simple rotation of the plate on the front face of the bias plate to reverse the suction and delivery phases and therefore reverse the direction of rotation of the pump. Unfortunately, this rotation of the plate on the face of the bias plate cannot be done automatically and requires manual intervention each time.

Le deuxième inconvénient provient de ce que les liquides hydrauliques présentant une compressibilité non négligeable à ces pressions élevées (200 bars et au-delà), il est nécessaire de décaler angulairement le début de la lunule par rapport à la ligne de plus grande pente de la face du plateau biais de façon à éviter que la phase d'admission ne commence avant que le liquide qui se trouve à l'intérieur du piston n'ait fini de se détendre. Si une telle précaution n'est pas prise, le liquide sous pression refoule dans le circuit d'aspiration, ce qui fait baisser le rendement de la pompe. L'importance de ce décalage est fonction de la vitesse de rotation de la pompe et du taux de compressibilité du fluide véhiculé. Ce dernier dépend de la pression, de la température, de la quantité d'air dissoute dans le fluide etc. de sorte qu'il faudrait pouvoir adapter ce décalage aux variations de ces diverses variables, mais on n'a pas pu, jusqu'à ce jour réaliser des pompes dans lesquelles le décalage angulaire de la lunule peut être modifié à volonté de sorte que l'on détermine une valeur moyenne de ce décalage qui est un compromis entre les valeurs extrêmes des paramètres de fonctionnement de la pompe. Il en résulte que la pompe ne fonctionne de façon optimum que pour des conditions très aléatoires.The second drawback stems from the fact that the hydraulic liquids having a non-negligible compressibility at these high pressures (200 bars and beyond), it is necessary to angularly offset the start of the lunula relative to the line of greatest slope of the face of the bias plate so as to prevent the intake phase from starting before the liquid inside the piston has finished expanding. If such a precaution is not taken, the pressurized liquid flows back into the suction circuit, which lowers the efficiency of the pump. The magnitude of this offset is a function of the speed of rotation of the pump and the compressibility rate of the fluid conveyed. The latter depends on the pressure, the temperature, the amount of air dissolved in the fluid etc. so that it would be necessary to be able to adapt this offset to variations in these various variables, but to date we have not been able to produce pumps in which the angular offset of the lunula can be modified at will so that the 'an average value of this offset is determined which is a compromise between the extreme values of the operating parameters of the pump. As a result, the pump only works optimally for very random conditions.

Pour pallier ces inconvénients, la demanderesse a remplacé le système d'alimentation au moyen d'une lunule et de patins glissants par des clapets d'aspiration.To overcome these drawbacks, the Applicant has replaced the supply system by means of a lunula and sliding pads with suction valves.

Pour qu'une pompe munie de clapets d'aspiration puisse fonctionner correctement et tourner à grande vitesse (au lieu d'une lunule telle que décrite plus haut), il faut que les clapets d'aspiration se referment très vite. On évite ainsi les phénomènes de rebondissement, de mauvaise fermeture et d'interférence avec la phase de refoulement de la pompe.In order for a pump fitted with suction valves to function properly and to rotate at high speed (instead of a lunula as described above), the suction valves must close very quickly. This prevents rebounding, poor closing and interference with the pump discharge phase.

Pour que les clapets d'aspiration se referment vite et bien, il est nécessaire de les pousser par des ressorts puissants. Mais alors, en phase d'aspiration, le piston devra vaincre l'effort important qui appuie sur le clapet d'aspiration. En général, son pouvoir d'aspiration n'est pas compatible avec l'effort de rappel du clapet. L'aspiration ne se fait pas et la pompe ne fonctionne pas. Même si l'on arrive à trouver un compromis rappel-pouvoir aspirant, on affecte le pouvoir aspirant du piston au moins de la valeur de la charge du clapet d'aspiration. La pompe perd alors une grande part de ses performances volumétriques.In order for the suction valves to close quickly and well, it is necessary to push them with strong springs. But then, during the suction phase, the piston will have to overcome the significant force which presses on the suction valve. In general, its suction power is not compatible with the return force of the valve. The suction is not done and the pump does not work. Even if a compromise between suction and suction power is found, the suction power of the piston is affected at least by the value of the load on the suction valve. The pump then loses a large part of its volumetric performance.

Pour résoudre cette difficulté, la demanderesse a décrit dans le brevet principal n° 79 29037 (FR-A-2 470 266) une pompe à plateau biais comportant pour chaque piston un clapet d'admission soumis à l'action de deux ressorts antagonistes : un premier ressort la poussant vers la fermeture et un deuxième ressort la poussant vers l'ouverture, ce deuxième ressort étant associé à une came liée en rotation à l'arbre d'entraînement de la pompe de façon que la force exercée par ce deuxième ressort devienne sensiblement égale à celle exercée en sens inverse par le premier au début de la phase d'aspiration. Selon l'addition n° 80.09780 (FR-A-2 481 757) la came est constituée de façon à pourvoir être placée dans deux positions décalées l'une de l'autre de 180°, ce qui permet d'inverser le sens de rotation de la pompe.To resolve this difficulty, the applicant has described in main patent No. 79 29037 (FR-A-2 470 266) a bias plate pump comprising for each piston an intake valve subjected to the action of two opposing springs: a first spring pushing it towards the closing and a second spring pushing it towards the opening, this second spring being associated with a cam linked in rotation to the drive shaft of the pump so that the force exerted by this second spring becomes substantially equal to that exerted in the opposite direction by the first to start of the suction phase. According to the addition n ° 80.09780 (FR-A-2 481 757) the cam is formed so as to be able to be placed in two positions offset from each other by 180 °, which allows to reverse the direction of pump rotation.

Cette disposition fonctionne de façon satisfaisante mais présente l'inconvénient d'être assez complexe et donc onéreuse et la présente invention concerne un dispositif simplifié perméttant d'obtenir les mêmes avantages.This arrangement works satisfactorily but has the drawback of being quite complex and therefore expensive, and the present invention relates to a simplified device which makes it possible to obtain the same advantages.

La pompe selon la présente invention est une pompe hydraulique comportant au moins un piston animé d'un mouvement de va et vient chaque piston étant associé à un clapet d'aspiration qui est rappelé en position de fermeture par un ressort de rappel, caractérisée par le fait que ledit ressort de rappel (16) est associé à un poussoir (15) actionné cycliquement par une came (21) entraînée par l'arbre d'entraînement (1) de la pompe ; de telle sorte que, lorsque le poussoir (15) est actionné par la came (21) l'action du ressort (16) sur le clapet (11) est annulée pendant la phase d'aspiration et rétablie à la fin de ladite phase, ce qui a pour résultat que le clapet (11) est libre pendant cette période et ne s'ouvre que si la pression d'aspiration est supérieure à la pression résiduelle régnant dans le cylindre (6) associé audit clapet.The pump according to the present invention is a hydraulic pump comprising at least one piston which moves back and forth, each piston being associated with a suction valve which is returned to the closed position by a return spring, characterized by the causes said return spring (16) to be associated with a plunger (15) actuated cyclically by a cam (21) driven by the drive shaft (1) of the pump; so that, when the pusher (15) is actuated by the cam (21) the action of the spring (16) on the valve (11) is canceled during the suction phase and restored at the end of said phase, which has the result that the valve (11) is free during this period and opens only if the suction pressure is greater than the residual pressure prevailing in the cylinder (6) associated with said valve.

A titre d'exemple non limitatif et pour faciliter la compréhension de l'invention, on a représenté aux dessins annexés :

  • Figure 1, une vue schématique en coupe longitudinale d'un mode de réalisation de l'invention ;
  • Figure 2, une vue partielle de face de la figure 1 illustrant la face avant du plateau biais ;
  • Figure 3, une vue partielle de la figure 1 à échelle agrandie montrant la soupape d'aspiration en position fermée ;
  • Figure 4, la même vue que la figure 2 montrant la soupape d'aspiration en position d'ouverture libre.
By way of nonlimiting example and to facilitate understanding of the invention, the accompanying drawings show:
  • Figure 1, a schematic view in longitudinal section of an embodiment of the invention;
  • Figure 2, a partial front view of Figure 1 illustrating the front face of the bias plate;
  • Figure 3, a partial view of Figure 1 on an enlarged scale showing the suction valve in the closed position;
  • Figure 4, the same view as Figure 2 showing the suction valve in the free open position.

La figure 1 représente une pompe hydraulique à pistons axiaux et à plateau biais. Cette pompe est constituée par un arbre d'entraînement 1 portant un plateau biais 2 sur la face avant 2a duquel prennent appui une pluralité de pistons 3, chaque piston 3 reposant contre ladite face avant 2a du plateau biais 2 par un patin de glissement 4. Chaque piston 3 est maintenu en appui sur son patin 4 par un ressort 5 et se déplace dans un cylindre 6. Chaque cylindre 6 communique par un orifice 7 avec une chambre d'admission 8 qui, elle-même, communique avec le réservoir 9 par une canalisation 10.Figure 1 shows a hydraulic pump with axial pistons and bias plate. This pump is constituted by a drive shaft 1 carrying a bias plate 2 on the front face 2a of which bear a plurality of pistons 3, each piston 3 resting against said front face 2a of the bias plate 2 by a sliding pad 4. Each piston 3 is held in abutment on its shoe 4 by a spring 5 and moves in a cylinder 6. Each cylinder 6 communicates by an orifice 7 with an intake chamber 8 which, itself, communicates with the reservoir 9 by a pipe 10.

Chaque orifice 7 est muni d'un clapet d'aspiration 11. Chaque clapet 11 comporte une tige 12 qui coulisse librement dans un palier 13 et qui fait saillie dans un alésage 14 à l'intérieur duquel peut coulisser un piston creux 15 qui est repoussé par un ressort 16. La tige 12 du clapet 11 pénètre à l'intérieur du piston creux 15 par un orifice 17 dans lequel elle coulisse. A son extrémité, la tige 12 du clapet 11 comporte une butée 18 qui à la figure 1 est constituée par un circlip et qui aux figures 2 et 3 est schématiquement représentée par un disque solidaire de l'extrémité de la tige 12. Ainsi, lorsque le ressort 16 repousse le piston 15, ce dernier entraîne la tige 12 du clapet 11 par la butée 18 dans le sens indiqué par la flèche F, ce qui provoque la fermeture de l'orifice 7 par le clapet 11 (figure 2).Each orifice 7 is provided with a suction valve 11. Each valve 11 has a rod 12 which slides freely in a bearing 13 and which projects into a bore 14 inside which a hollow piston 15 which can be pushed back can slide by a spring 16. The rod 12 of the valve 11 penetrates inside the hollow piston 15 through an orifice 17 in which it slides. At its end, the rod 12 of the valve 11 has a stop 18 which in FIG. 1 is constituted by a circlip and which in FIGS. 2 and 3 is schematically represented by a disc integral with the end of the rod 12. Thus, when the spring 16 pushes the piston 15, the latter drives the rod 12 of the valve 11 by the stop 18 in the direction indicated by the arrow F, which causes the opening of the orifice 7 by the valve 11 (Figure 2).

A l'extrémité arrière du piston 15 est disposé un logement 19 dans lequel est disposée, avec un certain jeu, une bille 20 qui prend appui contre une came 21 portée par une tige 22 entraînée par l'arbre 1.At the rear end of the piston 15 is disposed a housing 19 in which is disposed, with a certain clearance, a ball 20 which bears against a cam 21 carried by a rod 22 driven by the shaft 1.

En se reportant à la figure 3, on voit que, en tournant, la came 21 repousse, dans la direction indiquée par la flèche F2, la bille 20 qui arrive au fond de son logement 19 et repousse à son tour le piston 15 qui coulisse dans l'alésage 14 en comprimant le ressort 16. Le piston 15 n'exerce plus alors aucun effet de traction sur la tige 12 par l'intermédiaire de la butée 18, de sorte que le clapet 11 est alors libéré de l'action du ressort de rappel 16. Il en résulte que tant que le cylindre 6 sera en pression, le clapet 11 sera fermé par cette pression et qu'au contraire dès que ce cylindre 6 sera en dépression, même légère, le clapet 11 s'ouvrira pour laisser pénétrer dans ledit cylindre 6 le liquide en provenance de la chambre 8.Referring to Figure 3, we see that, by turning, the cam 21 pushes, in the direction indicated by the arrow F 2 , the ball 20 which reaches the bottom of its housing 19 and in turn pushes the piston 15 which slides in the bore 14 by compressing the spring 16. The piston 15 then no longer exerts any traction effect on the rod 12 by means of the stop 18, so that the valve 11 is then released from the action of the return spring 16. As a result, as long as the cylinder 6 is under pressure, the valve 11 will be closed by this pressure and, on the contrary, as soon as this cylinder 6 is in depression, even slight, the valve 11 will open to let the liquid coming from the chamber 8 penetrate into said cylinder 6.

Il en résulte que le clapet 11 est poussé à la fin n de la phase d'aspiration en position de fermeture par un ressort 16 qui est déterminé de façon à exercer un rappel de fermeture énergique ; mais que dès le début de la phase d'aspiration, l'effet de ce ressort de rappel 16 est supprimé par la came 21, le clapet 11 étant alors un clapet libre.It follows that the valve 11 is pushed at the end n of the suction phase in the closed position by a spring 16 which is determined so as to exert a forceful closing reminder; but that from the start of the suction phase, the effect of this return spring 16 is eliminated by the cam 21, the valve 11 then being a free valve.

Les moyens, par lesquels la tige 22 portant la came 21 est attelée à l'arbre 1 de façon à pouvoir se décaler automatiquement de 180° par rapport au plateau biais 2, ne sont pas décrits en détail parce qu'ils sont identiques à ceux décrits, dans le certificat d'addition (FR-A-2 481 757) ; ces moyens permettent d'inverser le sens de rotation de la pompe.The means by which the rod 22 carrying the cam 21 is coupled to the shaft 1 so as to be able to automatically shift 180 ° relative to the bias plate 2, are not described in detail because they are identical to those described in the certificate of addition (FR-A-2 481 757); these means make it possible to reverse the direction of rotation of the pump.

Claims (4)

1. An hydraulic pump having at least one reciprocably movable piston, each piston being associated with an inlet valve which is urged towards the closed position by a return spring, characterised by the fact that said return spring (16) is associated with a pusher element (15) actuated cyclically by a cam (21) driven by the pump drive shaft (1) ; such that, when the pusher element (15) is actuated by the cam (21), the action of the spring (16) on the valve (11) is nullified during the inlet phase and re-established at the end of said phase, which has the result that the valve (11) is free during this period and opens only if the inlet pressure is greater than the residual pressure prevailing in the cylinder (6) associated with said valve.
2. An hydraulic pump according to Claim 1, in which the inlet valve (11) is connected to a rod (12) coupled by an abutment (18) to a hollow piston (15) within which it can slide, said hollow piston being urged in the closing direction by the return spring (16) and urged in the opposite direction by the cam (21) such that when it is not so urged by the cam (21), the hollow piston (15), under the effect of the return spring (16), exerts a pull on the rod (12), which causes the valve (11) to close, whilst when it is urged by the cam (21), it compresses the spring (16), freeing the rod (12) of the valve (11).
3. An hydraulic pump according to Claim 2, in which the cam (21) acts on the piston (15) by means of a ball (20) disposed with clearance in a housing (19) formed at the end of the piston (15) opposed to that against which the spring (16) bears.
4. An hydraulic pump according to any one of Claims 1 to 3, in which the pistons (3) of the pump are reciprocably actuated by means of an inclined plate (2), the cam (21) being carried by a rod (22) driven by the engine shaft (1) by means permitting said cam (21) to be displaced by 180° with respect to the inclined plate (2) and thus to reverse the direction of rotation of the pump.
EP19850402018 1984-10-19 1985-10-18 Hydraulic piston pump with positively driven inlet valves Expired EP0180510B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8416051A FR2572138B1 (en) 1984-10-19 1984-10-19 HDRAULIC PUMP WITH CONTROLLED PISTONS AND SUCTION VALVES
FR8416051 1984-10-19

Publications (2)

Publication Number Publication Date
EP0180510A1 EP0180510A1 (en) 1986-05-07
EP0180510B1 true EP0180510B1 (en) 1988-11-30

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ID=9308834

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19850402018 Expired EP0180510B1 (en) 1984-10-19 1985-10-18 Hydraulic piston pump with positively driven inlet valves

Country Status (3)

Country Link
EP (1) EP0180510B1 (en)
DE (1) DE3566569D1 (en)
FR (1) FR2572138B1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19708922B4 (en) * 1996-03-13 2006-05-18 Volkswagen Ag Hydraulic axial piston pump with a housing

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE1015545A3 (en) * 2003-05-28 2005-06-07 Waudoit Claude Albert System energy conversion device volume.
WO2014091266A1 (en) 2012-12-10 2014-06-19 Kongsberg Automotive Ab Unitary fluid flow apparatus for inflating and deflating a device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB581735A (en) * 1942-09-23 1946-10-23 Oliver Bevir Improvements in and relating to hydraulic pumps
US4486152A (en) * 1979-11-26 1984-12-04 Hydro Rene Leduc Pump with spring loaded valve

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19708922B4 (en) * 1996-03-13 2006-05-18 Volkswagen Ag Hydraulic axial piston pump with a housing

Also Published As

Publication number Publication date
DE3566569D1 (en) 1989-01-05
EP0180510A1 (en) 1986-05-07
FR2572138B1 (en) 1987-01-23
FR2572138A1 (en) 1986-04-25

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