(19)
(11) EP 0 092 987 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Mention of the grant of the patent:
02.12.1987 Bulletin 1987/49

(21) Application number: 83302288.2

(22) Date of filing: 22.04.1983
(51) International Patent Classification (IPC)4F15B 15/06

(54)

Rotary fluid pressure actuator

Druckmittelbetätigter Drehantrieb

Dispositif rotatif à pression de fluide


(84) Designated Contracting States:
AT BE CH DE FR GB IT LI LU NL SE

(30) Priority: 24.04.1982 ES 264705

(43) Date of publication of application:
02.11.1983 Bulletin 1983/44

(71) Applicants:
  • Triado-Isern, Joaquin
    Figueres Girona (ES)
  • Cantenys-Soler, Fermin
    Figueres Girona (ES)

(72) Inventors:
  • Triado-Isern, Joaquin
    Figueres Girona (ES)
  • Cantenys-Soler, Fermin
    Figueres Girona (ES)

(74) Representative: Carter, Gerald et al
Arthur R. Davies & Co. 27 Imperial Square
Cheltenham, Gloucestershire GL50 1RQ
Cheltenham, Gloucestershire GL50 1RQ (GB)


(56) References cited: : 
   
       
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The invention relates to a mechanism for turning a shaft, the said mechanism being of the type comprising a chamber within which a pair of pistons are oppositely movable, each piston being provided with a toothed arm forming a rack engageable with a shaft crossing the said chamber and arranged to be turned, the walls of the chamber being provided with holes to allow the circulation of a fluid for exerting a pressure against the faces of the two pistons, to move them in one or other direction.

    [0002] Up to the present, in mechanisms of the described type, in order that the chamber could be as small as possible, and at the same time the pistons could perform a stroke as long as possible, the front plates or portions of the latter had to have the smallest possible thickness. Although this condition involved an improvement in the length of the stroke, prejudicial vibrations simultaneously appeared, to the detriment of efficient and operational life of the mechanism.

    [0003] Prior Patent Specification WO-A-80/01 096 discloses a rotary actuator having opposite stroke pistons having racks thereon and hollow spaces in the ends of the pistons remote from the racks for the mounting of helical springs.

    [0004] It is the object of this invention to provide an improved mechanism of the type referred to for turning a shaft which is not subject to the disadvantages of the prior art, while achieving useful and reliable operation.

    [0005] In accordance with the present invention there is provided a mechanism for turning a shaft comprising a body defining a chamber, the shaft extending across the chamber and projecting from the body, a pair of oppositely disposed pistons movable within the chamber towards and away from one another, the shaft extending between the pistons, each piston including an axially extending toothed arm forming a rack portion, said toothed arm having a hollow structure and being at least partly shaped to conform with the contour of the interior of the chamber, said rack portions meshing with a pinion on the shaft, so that movement of the pistons, under the influence of fluid pressure, results in turning of the shaft, and each piston having, on its face opposite to its toothed arm, several hollow spaces for receiving respective helical springs, characterised in that each toothed arm comprises a first portion projecting from the respective piston and having a hollow structure reinforced by equidistantly distributed walls and being adapted to the inner contour of the chamber; that said toothed arm comprises a second substantially flat and toothed portion projecting axially from said first portion; that each piston comprises a hollow structural projecting portion being adapted to the inner contour of the chamber and arranged to engage the first portion of the toothed arm of the other piston when the pistons reach the nearest position to each other, and that each piston is provided with a slot to receive the free end of the second portion of the toothed arm of the opposite piston when the pistons move closely together.

    [0006] By this means, it has been possible to widen the contour of the pistons, but in such a manner that the thickness of their walls is smaller than that of the conventional ones, so that weight reduction is achieved, the shape of said pistons is such as to include several helical springs for applying force in opposition to the action of fluid under pressure that acts on the pistons in the centre of the chamber.

    [0007] The following is a detailed description of an embodiment of the invention, reference being made to the accompanying drawings in which:

    Figure 1 is a longitudinal section of the mechanism showing the pistons in the nearest position to each other, and

    Figure 2 is a cross section of the mechanism on the line II-II in Figure 1.



    [0008] The mechanism comprises a body defining an interior generally cylindrical chamber 1. The body has ducts for entry of fluid under pressure, to the space within the chamber. End covers 2 enclose the ends of the generally cylindrical chamber 1.

    [0009] A pair of oppositely disposed pistons 3 are movably mounted within the chamber for movement towards and away from one another. Each piston 3 has an integral hollow arm 3"' protruding eccentrically from the front of the piston 3, having a portion with a contour of the same shape as that of the chamber interior. One of the faces of each arm 3"' is toothed in order to form a rack toothed surface engageable with a pinion 4 formed on the shaft 5, which is transversely mounted across the centre of the chamber 1.

    [0010] Diametrically opposed to the arms 3"', the pistons are provided with projecting portions 3", the contour of these also being partially shaped to conform with that of the chamber. These are staggered with respect to the arms 3"'. When the pistons reach their nearest positions to each other, the said portions co-operate with corresponding hollow portions formed in the said arms 3'".

    [0011] The hollow spaces of the arms 3"', as well as the projecting portions 3", are reinforced by several equidistant vertically arranged walls 7. Several hollow spaces 8 are also formed in opposite faces of the pistons, said spaces 8 being arranged for operative mounting of respective helical springs. This arrangement is specially devised for mechanisms of the type described in which fluid under pressure is only received, as previously indicated, through a point in the middle of the chamber, but where the mechanism is designed to receive fluid for application to both the front and rear of the pistons, the springs may be omitted. The hollow spaces 8 then serve to reduce the weight of the pistons, in spite of their enlarged contour width. The pistons are each provided with an enlarged slot 9 to accommodate the end of the toothed arm 3"' on the opposite piston, thus substantially increasing the length of the piston stroke within the chamber.


    Claims

    A mechanism for turning a shaft (5), comprising a body defining a chamber (1), the shaft extending across the chamber and projecting from the body, a pair of oppositely disposed pistons (3) movable within the chamber (1) towards and away from one another, the shaft (5) extending between the pistons (3), each piston (3) including an axially extending toothed arm (3"') forming a rack portion, said toothed arm (3"') having a hollow structure and being at least partly shaped to conform with the contour of the interior of the chamber (1), said rack portions meshing with a pinion (4) on the shaft, so that movement of the pistons (3), under the influence of fluid pressure, results in turning of the shaft (5), and each piston (3) having, on its face opposite to its toothed arm (3'''), several hollow spaces (8) for receiving respective helical springs, characterised in that each toothed arm (3"') comprises as first portion projecting from the respective piston (3) and having a hollow structure reinforced by equidistantly distributed walls (7) and being adapted to the inner contour of the chamber (1); that said toothed arm (3"') comprises a second substantially flat and toothed portion projecting axially from said first portion; that each piston (3) comprises a hollow structural projecting portion (3") being adapted to the inner contour of the chamber (1) and arranged to engage the first portion of the toothed arm (3''') of the other piston when the pistons (3) reach the nearest position to each other, and that each piston is provided with a slot (9) to receive the free end of the second portion of the toothed arm (3"') of the opposite piston when the pistons (3) move closely together.
     


    Ansprüche

    Vorrichtung zum Drehen einer Welle (5), mit einem eine Kammer (1) bildenden Körper, wobei die Welle sich durch die Kammer erstreckt und aus dem Körper hervorsteht, einem Paar gegenüberliegenden Kolben (3), welche in der Kammer (1) aufeinander zu und voneinander weg bewegbar sind, wobei die Welle (5) sich zwischen den Kolben (3) erstreckt, jeder Kolben (3) einen sich axial erstreckenden, mit Zähnen versehenen Arm (3"') hat, welcher einen Zahnstangenteil bildet, der gezahnte Arm (3"') hohl und mindestens teilweise geformt ist, um sich der Form des Inneren der Kammer (1) anzupassen, die Zahnstangenteile in ein Ritzel (4) auf der Welle eingreifen, so dass die Bewegung der Kolben (3) unter dem Einfluss des Fluidumdruckes in einem Drehen der Welle (5) resultiert und jeder Kolben (3) auf seiner dem gezahnten Arm (3"') gegenüberliegenden Seite mehrere Hohlräume (8) zur Aufnahme entsprechender Schraubenfedern hat, dadurch gekennzeichnet, dass jeder gezahnte Arm (3"') einen ersten Teil umfasst, welcher von dem entsprechenden Kolben (3) vorsteht und eine Hohlstruktur hat, welche durch in gleichem Abstand verteilte Wände (7) verstärkt ist und ausgelegt ist, um sich der inneren Form der Kammer (1) anzupassen, dass der gezahnte Arm (3"') einen zweiten im wesentlichen ebenen und gezahnten Teil hat, welcher axial von dem ersten Teil absteht, dass jeder Kolben (3) einen hohlen, vorstehenden Strukturteil (3") hat, welcher der inneren Form der Kammer (1) angepasst und angeordnet ist, um den ersten Teil des gezahnten Armes (3"') des anderen Kolbens zu berühren, wenn die Kolben (3) ihre Stellung erreichen, in welcher sie sich am nächsten liegen, und dass jeder Kolben mit einem Schlitz (9) zur aufnahme des freien Endes des zweiten Teiles des gezahnten Armes (3"') des gegenüberliegenden Kolbens, wenn die Kolben (3) sich eng aufeinander zu bewegen, versehen ist.
     


    Revendications

    Mécanisme pour tourner un arbre (5), comprenant un corps définissant une chambre (1), l'arbre s'étendant à travers ladite chambre et dépassant ledit corps, une paire de pistons (3) disposé l'un en face de l'autre et mobiles dans ladite chambre (1) l'un vers l'autre et l'un de l'autre, l'arbre (5) s'étendant entre les pistons (3), chaque piston (3) comprenant un bras (3"') s'étendant axialement et pourvu de dents pour former une partie de crémaillère, ledit bras (3"') pourvu de dents étant d'une structure creuse et étant au moins partiellement formé pour s'adapter au contour de l'intérieur de la chambre (1), lesdites parties de crémaillère mordant sur un pignon (4) sur ledit arbre, de sorte que le mouvement des pistons (3), sous l'influence de pression fluide, résultent en une rotation de l'arbre (5), et chaque piston (3) ayant, sur sa face opposée à son bras (3"') pourvu de dents, plusieurs espaces creux (8) pour recevoir des ressorts à boudin correspondants, caractérisé en ce que chaque bras (3"') pourvu de dents comprend une première partie s'étendant à partir du piston (3) respectif et ayant une structure creuse renforcée par des parois (7) distribuées de façon équidistantes et étant adaptées au contour intérieur de la chambre (1), ledit bras (3"') pourvu de dents comprenant une seconde partie, substantiellement plane et pourvue de dents, s'étendant axialement à partir de ladite première partie, que chaque piston (3) comprend une partie (3") en saillie de structure creuse adaptée au contour intérieur de la chambre (1) et disposée pour engager la première partie du bras (3"') pourvu de dents de l'autre piston, quand les pistons (3) atteignent leur position de plus grand rapprochement et que chaque piston est pourvu d'une fente (9) pour recevoir l'extrémité libre de la seconde partie du bras (3"') pourvu de dents du piston opposé, quand les pistons (3) se déplacent très étroitement l'un vers l'autre.
     




    Drawing