PatentDe  


Dokumentenidentifikation EP0564455 31.08.1995
EP-Veröffentlichungsnummer 0564455
Titel VERFAHREN ZUM HERSTELLEN EINES KOLBENS SOWIE EIN STELLANTRIEB MIT EINEM KOLBEN.
Anmelder Allied-Signal Inc., Morristown, N.J., US
Erfinder FLUGA, Gerry, Ervin, BREMEN, Indiana IN 46506, US;
COUCH, Brian, Phillip, South Bend, IN 46615, US
Vertreter derzeit kein Vertreter bestellt
DE-Aktenzeichen 69111617
Vertragsstaaten DE, FR, GB
Sprache des Dokument En
EP-Anmeldetag 05.09.1991
EP-Aktenzeichen 919167734
WO-Anmeldetag 05.09.1991
PCT-Aktenzeichen US9106349
WO-Veröffentlichungsnummer 9211128
WO-Veröffentlichungsdatum 09.07.1992
EP-Offenlegungsdatum 13.10.1993
EP date of grant 26.07.1995
Veröffentlichungstag im Patentblatt 31.08.1995
IPC-Hauptklasse B29C 70/00
IPC-Nebenklasse F16J 1/01   

Beschreibung[en]

This invention relates to a method of manufacturing a piston through which an output force is supplied to a member in response to pressurized fluid supplied to a bore in an actuator of an aircraft hydraulic system. The piston has a cylindrical body made by triaxially braided continuous carbon fiber layers over a mandrel and spacers which are impregnated with a thermoset resin. Curing the resin results in a unitary solid structure capable of transmitting the output force to the member.

In the development of new aircraft, it is desirable to reduce the total overall weight of the aircraft through the reduction in weight of various component parts to improve payload and fuel efficiency. Heretofore, certain advances in the development of materials has resulted in the use of lightweight composite materials in the manufacture of at least non-structural components. As an example, the substitution of carbon brakes for steel brakes has resulted in a 30-40% weight reduction in the brakes systems in many aircrafts. In addition, a molded phenolic piston has been suggested for use with pressurized fluid for actuating a brake system. While molded resin pistons may be adequate to meet the requirement of a brake system where the stroke of the piston is limited, when the stroke is extended, lateral forces could place a strain on the connection between a connecting rod and the piston which may result in a structural failure. Plastic tubes such as disclosed in U.S. Patent 4,065,339 and DE Patent 3,616,791 have been reinforced with knitted fabric held in a resin matrix. However such tubes do not experience compression loads such as are requires to transfer loads of an actuator of the type used in aircraft applications.

The present invention discloses a method of manufacturing an integral piston and rod assembly wherein a thermoset resin body is continuously reinforced by a plurality of plys of triaxially braided carbon fibers to provide lateral and axial strength sufficient to transmit an output force from an actuator to a member in response to pressurized fluid supplied to a bore to meet an operational requirement in an actuation system.

In this method of manufacturing a lightweight piston with an integral output rod, a first layer of carbon fibers is triaxially braided on a mandrel having a cylindrical body with a first diameter on a first end and a second diameter on a second end. The cylindrical body has a taper that transitions the first diameter into the second diameter. Thereafter, first and second spacers are located on the first ply adjacent the first and second ends, respectively. A second layer of carbon fibers is triaxially braided over the first layer and first and second spacers. Thereafter, third and fourth spacers are located on the second layer over the first and second spacers, respectively. A third layer of carbon fibers is triaxially braided over the second layer and third and fourth spacers. The mandrel with the first, second and third layers of carbon fibers are removed from the braiding machine and transported to a chamber where a thermoset resin completely impregnates the carbon fibers. Thereafter, the resin is cured on the mandrel to define a unitary solid structure. The solid structure when removed from the cylindrical body has a peripheral surface with a first diameter separated from a second diameter by a taper. The end of the cylindrical body has an annular projection formed by the first and third spacers that extends from the first diameter while the taper which is formed by the second and fourth spacers is located adjacent the second end. After attaching a fitting to the second end of the cylindrical body, a seal is placed on the annular projection and the structure is inserted into the bore of a housing. The annular projection and seal engage the bore and when pressurized fluid is supplied to the bore, an output force develops which is communicated through the cylindrical body to the fitting for moving a member according to an operational requirement.

It is an object of this invention to provide a method of manufacturing a piston for use in an actuator, the piston having a cylindrical body which is reinforced by a plurality of triaxially braided carbon fibers retained in a thermoset resin matrix.

An advantage of this method of manufacturing a piston according to the principals disclosed herein resides in the continuous reinforcement of the cylindrical body in the axial and radial planes through the use of triaxially braided carbon fibers held in a thermoset resin matrix.

It is a further object of this invention to provide an actuator with a lightweight hydraulic piston responsive to pressurized fluid in a bore to provide an input force for moving a member.

These objects and advantages should be apparent from reading this specification and viewing the drawings wherein :

  • Figure 1 is a sectional view of an actuator having a piston manufactured according to the method of this invention disclosed herein;
  • Figure 2 is a sectional view of a mandrel on which the carbon fibers in the piston of Figure l are triaxially braided to reinforce the cylindrical body, head and attachment of the piston;
  • Figure 3 is a schematic illustration of a braiding mechanism for placing the carbon fibers on the mandrel; and
  • Figure 4 is an illustration of the triaxial braid of the carbon fibers which provide the axial and lateral reinforcement for the piston of Figure l.

The actuator 10 shown in Figure 1 has a piston 12 located in a bore 14 of a cylinder member or housing 15 for supplying a member with a force to meet an operation demand in response to pressurized fluid being supplied to the bore 14. The lightweight piston 12 is made of a plurality of triaxially braided carbon fibers layers held in a phenolic cyanate resin matrix.

The carbon fibers which are purchased from Amoco Performance Products have a nominal tensile strength of 513 Kgs/sq cm (730,000 psi) are braided in a machine 16 of the type illustrated in Figure 3. The braiding machine 16 is essentially made up of a plurality of movable carriers 18, 18'...18n located on a track plate 20, stationary carriers 17, 17'...17n, a former or guide ring 22 and mandrel 24. The track plate 20 supports the carriers 18, 18'...18n which move along a path controlled by horngears in a Maypole fashion. The carriers 17,17'...17n and 18, 18'...18n, which hold the carbon fiber, control the tension of the carbon fiber onto the mandrel 24. Braid forms at a predetermined rate based on the speed of the movement of the mandrel 24 away from the point of braiding, the number of carriers 18, 18'... 18n, the orientation of the carbon fiber and the width of the braid. The basic braided fabric consists of a tubular cloth formed by intertwined, carbon fibers having a triaxial braid as illustrated in Figure 4 wherein strands 26 from stationary carrier 17, 17'...17n are axially aligned with 0° orientation while strands 28 and 30 from carriers 18, 18'...18n have from 30-40° (nominally 35°) of orientation down the mandrel 24. The angles of strands 28 and 30 are identical but have opposite signs at any point along the braid. Strands 28 and 30 are intertwined, but do not intersect with each other, and cylindrically parallel to each other but cylindrically orthogonal from each other. To interlace the strands 28 and 30 one half of the carriers 18,18''...18n-1 are moved in a clockwise motion toward the center of the track 20 while and the other half of the carriers 18', 18''...18n are moved in a counterclockwise motion away from the center of the track 20. At the same time the carbon fibers are moving in and out in a radial direction, they are also moving along the circumference of the mandrel 24.

The mandrel 24 as best shown in figure 2 has a cylindrical body with a first diameter 32 that transitions into a second diameter 34 by taper 36. The taper 36 is approximately at a 15° angle from the first and second diameters 32 and 34. The first and second diameters 32 and 34 being selected in accordance with the desired load required to be supplied by the actuator 10. In the instant application, the first diameter is 2.118 cm (0.839 inches) and the second diameter is 0.953 cm (0.375 inches).

After mandrel 24 is sprayed with a release agent, to prevent the thermoset resin from sticking to the mandrel 24, the mandrel 24 is placed in a fixture in axial alignment with the braiding machine 16. The end of the strands of the carbon fibers 26, 28 and 30 are held by a clamp 38 on the second diameter 34 of mandrel 24 and the mandrel 24 moved in an axial direction away from the braiding machine 16 as the carriers 18, 18'...18n are moved around the mandrel 24 to produce a first ply 40 of triaxial braided carbon fabric. The shape of the first ply 40 is substantially identical to the contour of the mandrel 24. When the triaxially braided carbon fabric reaches a preset length on the first diameter 32, a clamp (not shown) is placed around the braid, the plurality of strands 26, 28 and 30 are cut and the mandrel 24 moved toward the braiding machine 16 to repeat the braiding operation by braiding a second ply 42 over the top of the first ply 40 to produce a first layer of carbon fiber fabric. After laying down the second ply 42 and retaining the same with clamp 38, a first-preformed spacer 44 is located over the first layer on the first diameter 32 while a second preformed spacer 46 is placed on the second diameter 34. In order to provide continuity for the resulting piston 12, spacer 44 is made from monolithic carbon and spacer 46 is made from carbon fiber although other spacer materials could also be used such as aluminum. The first spacer 44 has a cylindrical base 48 with an interior diameter substantially identical to the peripheral surface of the second ply 42 and an apex 50 that extends from the base to a point approximately one half the distance to the desired diameter of piston 12. The second spacer 46 which is a braided carbon fibers at ± 80°, has a cylindrical and taper shape substantially concentric to the second diameter 34 and taper 36 of mandrel 24.

After spacers 44 and 46 are placed on the first layer, mandrel 24 is again aligned with braiding machine 16 and the end of the strands of the carbon fibers 26, 28 and 30 are held by a clamp 38 on the second diameter 34 of mandrel 24. Thereafter, mandrel 24 is moved in an axial direction away from the braiding machine 16 as the carriers 18, 18'...18n are moved around the mandrel 24 to produce a third ply 52 of triaxial braided carbon fabric over the second ply 42 and first and second spacers 44 and 46. When the braided carbon fabric reaches a predetermined distance on the second diameter 34, the strands 26, 28 and 30 are cut and this triaxial braiding step repeated to create a fourth ply 54 on this third ply 52 to produce a second layer of carbon fiber fabric. After the fourth ply 54 is triaxially braided on the third ply 52, strands 26, 28 and 30 are cut and one half 56 of a third spacer is placed on the second layer and moved into engagement with the other half 58 of the third spacer in a position over the first spacer 44. A fourth spacer 60 is placed on the fourth layer 54. As with the first and second spacers 44 and 46, the third 56, 58 and fourth spacer 60 are made from monolithic carbon and carbon fibers, respectively. The third spacer 56, 58 has a base that matches the apex 50 and sides of the first spacer 44 and an exterior surface with side angles of approximately 40° that terminate at a flat top 64. The fourth spacer 60 is made of braided carbon fibers with a surface concentric to the second spacer 46 and taper 36 and second diameter 34 on mandrel 24.

After third and fourth spacers are placed on the second layer, mandrel 24 is again aligned with braiding machine 16 and the end of the strands of the carbon fibers 26, 28 and 30 are held by a clamp 38 on the second diameter 34 of mandrel 24. Thereafter, mandrel 24 is moved in an axial direction away from the braiding machine 16 as the carrier 18, 18'...18n are moved around the mandrel 24 to produce a fifth ply 62 of triaxial braided carbon fabric over the second layer 54 and third and fourth spacers 56, 58 and 60. When the braided carbon fabric reaches a predetermined distance on the first diameter 32, the strands 26, 28 and 30 are cut and this triaxial braiding step repeated to create a sixth ply 66 on the fifth ply 62 to produce a third layer of carbon fiber fabric.

Initial stress calculations indicated additional reinforcement would be required to transmit the force created across the annular projection on the first diameter into the reduced second diameter section of piston 12. Therefore, a fifth spacer 68 is placed over the fourth spacer 60 and strands of the carbon fibers 26, 28 and 30 are held by a clamp 38 on the second diameter 34 of mandrel 24. Thereafter, mandrel 34 is moved in an axial direction away from the braiding machine 16 as the carriers 18, 18'...18n are moved around the mandrel 24 to produce a seventh ply 70 of triaxial braided carbon fabric over the third layer and fifth spacer 68. When the braided carbon fabric reaches a predetermined distance on the second diameter 34, the strands 26, 28 and 30 are cut and this triaxial braiding step repeated to create an eighth ply 71 on the seventh ply 70 to produce a fourth layer of carbon fiber fabric. The mandrel 24 with the triaxial braided carbon fibers located thereon is removed from the fixture and transported to a mold or chamber where a thermoset resin such as phenolic cyanate resin used herein and disclosed in U.S. Patent 4,831,086 impregnates the carbon fibers. Thereafter, the phenolic cyanate resin is cured in the mold or chamber having a temperature of approximately 143° C (290° F) for about 1.5 hours to produce a solid unitary structure. The solid structure or piston 12 as best shown in Figure 1 when removed from the mandrel 24 has a cylindrical body 72 with a peripheral surface with a first diameter 74 separated from a second diameter 76 by a taper 78. The ends 80 and 84 of the cylindrical body 72 are machined to produce flat surfaces. Annular projection 82 formed by the first and third spacers extends from the first diameter 74 adjacent end 80 while the taper 78 which is formed by the second and fourth spacers is located adjacent the second end 84.

An actuator closure member 102 having a plurality of seals 104 is placed on the first diameter 74 of the cylindrical body and a cone 88 inserted into the interior bore 73. Cone 88 has a peripheral surface that is concentric to the taper 36 and second diameter 34 of the mandrel 24 and a threaded shaft 90 that extends through opening 85 on end 84 of the cylindrical body 72. A collar 94 which is placed on the second end 84 surrounds the second diameter surface 76 and tapered surface 78 although it is anticipated that for some applications that the collar 94 would not need to surround the tapered surface 78. A nut 96 is screwed onto threads on shaft 90 to hold the tapered section and second diameter section of the cylindrical body 72 between the cone 88 and collar 94. Thereafter an end cap 98 having an eyelet 100 is screwed onto collar 94 to provide a mechanical connection between the second end 84 and a member to which an output force is to be applied. An expandable position sensor 106 attached to cone 88 and connector 110 is located in chamber 108 formed by housing 15 and piston 12.

A shrink fit or expandable seal 112 is placed on the annular projection 82 and piston 12 placed in bore 14. Seal 112 essentially seals chamber 108 from chamber 114. Thereafter, closure member 102 is screwed into housing 15 to complete the manufacture of the actuator 10.

Actuator 10 is of the type wherein pressurized fluid is communicated through either port 19' or 19 in housing 15. When pressurized fluid is presented to chamber 108, the pressurized fluid acts on end 80 and face 81 of annular projection 82 of piston 12 and surface 87 of cone 88 to provide an output force that is communicated through eyelet 100 to a member. As annular projection 82 moves in bore 14 toward closure member 102, fluid in chamber 114 is returned to a storage chamber associated with the source of pressurized fluid. Similarly, when it is desired to move the piston 12 away from closure member 102, pressurized fluid is communicated through port 19 and acts on face 83 of the annular projection 82 to create a force that moves piston 12 toward port 19'.

In evaluating the structural integrity of piston 12, loads were applied to test the strength of annular projection 82 and the reduced area of the taper 78, cylindrical body 72 and second diameter 76. A force of 13,000 Kgs (28,600 pounds) was required to fail the triaxially braided carbon fiber reinforced phenolic cyanate resin piston 12 in compression while a force of 8318 Kgs (18,300 pounds) created a failure in tension. Piston 12, according to this test, is the equivalent of a similar lightweight metal piston and connection rod members used in current actuators but weighs about two thirds as much and should be competitive in price.


Anspruch[de]
  1. Verfahren zur Herstellung eines Kolbens (12), der auf Druckflüssigkeit, die einer Bohrung (14) eines Zylinder (15) zugeführt wird, so anspricht, daß er eine Ausgangskraft erzeugt, die der Druckflüssigkeit entspricht, wobei das Verfahren die folgenden Schritte umfaßt:

       die triaxiale Flechtung einer ersten Schicht (40, 42) von Kohlenstoff-Fasern (26, 28, 30) an einem Dorn (24) mit einem zylinderförmigen Körper mit einem ersten Ende und einem zweiten Ende, wobei der genannte zylinderförmige Körper einen ersten Abschnitt (32) aufweist, der sich von dem ersten Ende zu einem konisch zulaufenden Abschnitt (36) erstreckt, der mit einem zweiten Abschnitt (34) verbunden ist, der sich von dem zweiten Ende erstreckt, wobei der erste Abschnitt (32) einen ersten Durchmesser aufweist, während der zweite Abschnitt (34) einen zweiten Durchmesser aufweist;

       die Anbringung eines ersten Abstandshalters (44) auf der ersten Schicht (40, 42) über dem ersten Abschnitt (32) und in Nachbarschaft zu dem ersten Ende;

       die Anbringung eines zweiten Abstandshalters (46) auf der ersten Schicht (40, 42) über dem zweiten Abschnitt (34) und in Nachbarschaft zu dem zweiten Ende;

       die triaxiale Flechtung einer zweiten Schicht (52, 54) von Kohlenstoff-Fasern (26, 28, 30) über der ersten Schicht (40, 42) und den ersten (44) und zweiten (46) Abstandshaltern;

       die Anbringung eines dritten Abstandshalters (56, 58) auf der zweiten Schicht (52, 54) über dem zweiten Abstandshalter (46);

       die Anbringung eines vierten Abstandshalters (60) auf der zweiten Schicht (52, 54) über dem zweiten Abstandshalter (46);

       die triaxiale Flechtung einer dritten Schicht (62, 66) von Kohlenstoff-Fasern (26, 28, 30) über der zweiten Schicht (52, 54) und den dritten (56, 58) und vierten (60) Abstandshaltern;

       die Imprägnierung der ersten (40, 42), zweiten (52, 54) und dritten (62, 66) Schichten der Kohlenstoff-Fasern (26, 28, 30) mit einem wärmehärtbaren Harz;

       die Härtung des Harzes, so daß eine unitäre, feste Struktur gebildet wird;

       die Entfernung der unitären, festen Struktur von dem Dorn (24), wobei die unitäre, feste Struktur einen zylinderförmigen Körper mit einem ersten Ende (80) und einem zweiten Ende (84) umfaßt, wobei die zylinderförmige Körperoberfläche einen ersten Durchmesser (74) aufweist, der von einem zweiten Durchmesser (76) durch eine Konizität (78) getrennt ist, und mit einem ringförmigen Vorsprung (82), der durch die ersten (44) und dritten (56, 58) Abstandshalter neben dem ersten Ende (80) gebildet wird, wobei die Konizität (78) durch die zweiten (46) und vierten (60) Abstandshalter gebildet wird, die sich neben dem zweiten Ende (84) befinden;

       die Anbringung eines Anschlußstücks (88, 94, 98) an dem zweiten Ende (84) der unitären, festen Struktur; und

       die Einführung der unitären, festen Struktur in die Bohrung (14), wobei der ringförmige Vorsprung (82) mit der Bohrung (14) eingreift und auf eine Kraft anspricht, die an dem ersten Ende (80) durch Druckflüssigkeit erzeugt wird, die der Bohrung (14) zugeführt wird, so daß durch das Anschlußstück (88, 94, 98) Ausgangskraft auf ein anderes Element übertragen wird.
  2. Verfahren nach Anspruch 1, wobei das Verfahren ferner folgenden Schritt umfaßt:

       die Anbringung einer Dichtung (112) an dem ringförmigen Vorsprung (82) vor der Einführung des unitären, festen Struktur in die Bohrung (14), um dadurch zu vermeiden, daß Flüssigkeit um den ringförmigen Vorsprung (82) fließt, wenn der Bohrung (14) Druckflüssigkeit zugeführt wird, um den zylinderförmigen Körper in die Bohrung (14) zu bewegen.
  3. Verfahren nach Anspruch 2, wobei die Anbringung des Anschlußstücks (88, 94, 98) folgende Schritte umfaßt:

       die Einführung eines Konusses (88) in die unitäre, feste Struktur, wobei der Konus (88) einen Schaft (90) aufweist, der sich an dem zweiten Ende (84) durch die unitäre, feste Struktur erstreckt;

       die Anbringung eines Kragens (94) an dem zweiten Ende (84), wobei der Kragen (94) mit dem zweiten Durchmesser (76) eingreift, um eine Ausgangskraft von dem Kolben (12) zu übertragen; und

       die Anbringung eines Befestigungselements (96) an dem Schaft (90), um den Konus (88) und den Kragen (94) zur Vervollständigung des Kolbens (12) an dem zylinderförmigen Körper zu halten.
  4. Verfahren nach Anspruch 3, wobei der Schritt der triaxialen Flechtung der Kohlenstoff-Fasern (26, 28, 30) folgenden Schritt umfaßt:

       die Anordnung der einzelnen Stränge der Träger (17, 17', ..., 17n)(18, 18', ..., 18n) in einer 0/±30-40° Ausrichtung, und zwar durch Regelung des Führungsmechanismuses (22) bei der Positionierung der Kohlenstoff-Fasern (26, 28, 30) auf dem Dorn (24).
  5. Verfahren nach Anspruch 4, wobei der Schritt der triaxialen Flechtung der ersten (40, 42), zweiten (52, 54) und dritten (62, 66) Schichten von Kohlenstoff-Fasern folgendes umfaßt:

       die Schichtung von mindestens zwei Gewebelagen in jeder der ersten (40, 42), zweiten (52, 54) und dritten (62, 66) Schichten, um eine ausreichende axiale und transversale Festigkeit vorzusehen, um Belastungen zu widerstehen, die durch Druckflüssigkeit in der Bohrung (14) auf die Vorrichtung (10) ausgeübt werden.
  6. Verfahren nach Anspruch 5, wobei das Verfahren ferner die folgenden Schritte umfaßt:

       die Anbringung eines fünften (68) Abstandshalters an der dritten Schicht (62, 66) über den zweiten (46) und dritten (60) Abstandshaltern; und

       die triaxiale Flechtung einer vierten (70) Schicht von Kohlenstoff-Fasern (26, 28, 30) über der dritten Schicht (62, 66) und dem fünften (68) Abstandshalter, um das zweite Ende (84) des resultierenden zylinderförmigen Körpers weiter zu verstärken.
  7. Erzeugnis, das durch das Verfahren gemäß Anspruch 6 erzeugt wird.
  8. Stellantrieb mit einem Kolben (12), der auf Druckflüssigkeit anspricht, die einer Bohrung (14) eines Gehäuses (15) zugeführt wird, so daß eine Ausgangskraft erzeugt wird, die der Druckflüssigkeit entspricht, wobei die Verbesserung des Kolbens (12) folgendes umfaßt:

       einen ringförmigen Vorsprung (82), der durch einen zylinderförmigen Körper (74) mit einem konisch zulaufenden Ende (78) verbunden ist, wobei der ringförmige Vorsprung (82), der zylinderförmige Körper (74) und das konisch zulaufende Ende (78), die aus einer Harzmatrix hergestellt werden, durch triaxial ausgerichtete Kohlenstoff-Fasern (26, 28, 30) eine kontinuierliche Verstärkung vorsehen.
  9. Stellantrieb nach Anspruch 8, ferner umfassend:

       einen Konus (88), der konzentrisch zu dem konisch zulaufenden Ende (78) ist und der einen Schaft (90) aufweist, der sich durch den zylinderförmigen Körper (74) erstreckt; und

       einen Kragen (94), der zur Kraftübertragung von dem zylinderförmigen Körper (74) auf ein anderes Element an dem Schaft (90) angebracht ist.
Anspruch[en]
  1. A method of manufacturing a piston (12) responsive to pressurized fluid supplied to a bore (14) of a cylinder (15) to develop an output force corresponding to the pressurized fluid, comprising the steps of:

       triaxially braiding a first layer (40,42) of carbon fibers (26,28,30) on a mandrel (24) having a cylindrical body with a first end and a second end, said cylindrical body having a first section (32) that extends from said first end to a tapered section (36) connected to a second section (34) that extends from said second end, said first section (32) having a first diameter and said second section (34) having a second diameter;

       locating a first spacer (44) on said first layer (40,42) over said first section (32) and adjacent said first end;

       locating a second spacer (46) on said first layer (40,42) over said second section (34) and adjacent said second end;

       triaxially braiding a second layer (52,54) of carbon fibers (26,28,30) over said first layer (40,42) and said first (44) and second (46) spacers;

       locating a third spacer (56,58) on said second layer (52,54) over said first spacer (44);

       locating a fourth spacer (60) on said second layer (52,54) over said second spacer (46);

       triaxially braiding a third layer (62,66) of carbon fibers (26,28,30) over said second layer (52,54) and said third (56,58) and fourth (60) spacers;

       impregnating said first (40,42), second (52,54) and third (62,66) layers of carbon fibers (26,28,30) with a thermoset resin;

       curing said resin to define a unitary solid structure;

       removing said unitary solid structure from said mandrel (24), said unitary solid structure having a cylindrical body with a first end (80) and a second end (84), said cylindrical body surface having a first diameter (74) separated from a second diameter (76) by a taper (78) and an annular projection (82) formed adjacent said first end (80) by said first (44) and third (56,58) spacers, said taper (78) being formed by said second (46) and fourth (60) spacers located adjacent said second end (84);

       attaching a fitting (88,94,98) to said second end (84) of said unitary solid structure; and

       inserting said unitary solid structure in said bore (14), said annular projection (82) engaging said bore (14) and responding to a force developed across the first end (80) by pressurized fluid supplied to said bore (14) to transmit an output force to another member through said fitting (88,94,98).
  2. The method as recited in claim 1 further includes the step of:

       placing a seal (112) on said annular projection (82) before inserting the unitary solid structure into said bore (14) to prevent fluid from flowing around said annular projection (82) when pressurized fluid is supplied to said bore (14) to move the cylindrical body within the bore (14).
  3. The method as recited in claim 2 wherein attaching said fitting (88,94,98) includes the steps of:

       inserting a cone (88) in said unitary solid structure, said cone (88) having a shaft (90) which extends through said unitary solid structure at said second end (84);

       placing a collar (94) on said second end (84), said collar (94) engaging said second diameter (76) for transmitting an output force from the piston (12); and

       attaching a fastener (96) to said shaft (90) for holding said cone (88) and collar (94) on said cylindrical body to complete said piston (12).
  4. The method as recited in claim 3 wherein said step of triaxial braiding of said carbon fibers (26,28,30) includes the step of:

       locating the individual strands from carriers (17,17'...17n)(18,18'...18n) in a 0/±30-40° orientation by controlling the guide mechanism (22) as the carbon fibers (26,28,30) are placed on said mandrel (24).
  5. The method as recited in claim 4 wherein said step of triaxially braiding said first (40,42), second (52,54) and third (62,66) layers of carbon fiber consists of :

       layering at least two plys of fabric in each of said first (40,42), second (52,54) and third (62,66) layers to provide sufficient axial and transverse strength to withstand the loads applied to the fixture (10) from pressurized fluid in said bore (14).
  6. The method as recited in claim 5 further includes the step of:

       locating a fifth (68) spacer on said third layer (62,66) over said second (46) and fourth (60) spacers; and

       triaxially braiding a fourth (70) layer of carbon fibers (26,28,30) over said third layer (62,66) and said fifth (68) spacer to further strengthen the second end (84) of said resulting cylindrical body.
  7. The product produced by the method as recited in claim 6.
  8. An actuator having a piston (12) responsive to pressurized fluid supplied to a bore (14) of a housing (15) to develop an output force corresponding to the pressurized fluid, the improvement in the piston (12) comprising:

       an annular projection (82) connected to a tapered end (78) by a cylindrical body (74), said annular projection (82), cylindrical body (74) and tapered end (78) being made of a resin matrix continually reinforced by triaxially orientated carbon fibers (26,28,30).
  9. The actuator as recited in claim 8 further including:

       a cone (88) concentric to said tapered end (78) and having a shaft (90) that extends through the cylindrical body (74); and

       a collar (94) attached to said shaft (90) to transmit forces from the cylindrical body (74) to another member.
Anspruch[fr]
  1. Procédé de fabrication d'un piston (12) sensible à du fluide sous pression introduit dans l'alésage (14) d'un cylindre (15) pour produire une force de sortie en rapport avec le fluide sous pression, comportant les opérations suivantes de:
    • tresser selon trois axes une première couche (40, 42) de fibres de carbone (26, 28, 30) sur un mandrin (24) présentant un corps cylindrique pourvu d'une première extrémité et d'une seconde extrémité, ledit corps cylindrique présentant une première partie (32) s'étendant de ladite première extrémité à une partie conique (36) reliée à une seconde partie s'étendant à partir de ladite seconde extrémité, ladite première partie (32) présentant un premier diamètre et ladite seconde partie (34) présentant un second diamètre;
    • disposer une première pièce d'écartement (44) sur ladite première couche (40, 42) par dessus ladite première partie (32) et adjacente à ladite première extrémité;
    • disposer une seconde pièce d'écartement (46) sur ladite première couche (40, 42) par dessus ladite seconde partie (34) et adjacente à ladite seconde extrémité;
    • tresser selon trois axes une seconde couche (52, 54) de fibres de carbone (26, 28, 30) par dessus ladite première couche (40, 42) et lesdites première et seconde pièces d'écartement (44, 46);
    • disposer une troisième pièce d'écartement (56, 58) sur ladite seconde couche (52, 54) par dessus ladite première pièce d'écartement (44);
    • disposer une quatrième pièce d'écartement (60) sur ladite seconde couche (52, 54) par dessus ladite seconde pièce d'écartement (46);
    • tresser selon trois axes une troisième couche (62, 66) de fibres de carbone (26, 28, 30) par dessus ladite seconde couche (52, 54) et lesdites troisième (56, 58) et quatrième (60) pièces d'écartement;
    • imprégner lesdites première (40, 42), seconde (52, 54) et troisième (62, 66) couches de fibres de carbone (26, 28, 30) avec une résine thermodurcissable;
    • faire polymériser la résine pour obtenir une structure unitaire solide;
    • retirer ladite structure unitaire solide dudit mandrin (24), ladite structure unitaire solide présentant un corps cylindrique avec une première extrémité (80) et une seconde extrémité (84), la surface dudit corps cylindrique présentant une portion de premier diamètre (74) séparée d'une portion de second diamètre (76) par une portion conique (78) et une projection annulaire (82) adjacente à ladite première extrémité (80) et réalisée par lesdites première (44) et troisième (56, 58) pièces d'écartement, ladite portion conique (78) étant réalisée par lesdites seconde (46) et quatrième (60) pièces d'écartement disposées adjacentes à ladite seconde extrémité (84);
    • solidariser une garniture (88, 94, 98) à ladite seconde extrémité (84) de ladite structure unitaire solide; et
    • insérer ladite structure unitaire solide dans ledit alésage (14), ladite projection annulaire (82) venant au contact dudit alésage (14) et en réponse à une force créée en travers de ladite première extrémité (80) par du fluide sous pression introduit dans l'alésage (14) transmettant une force de sortie à un autre élément par l'intermédiaire de ladite garniture (88, 94, 98).
  2. Procédé selon la revendication 1, comportant de plus l'opération de:
    • placer un joint (112) sur ladite projection annulaire (82) avant d'insérer la structure unitaire solide dans ledit alésage (14) pour éviter le passage de fluide autour de la projection annulaire (82) lorsque du fluide sous pression est introduit dans ledit alésage (14) pour déplacer ledit corps cylindrique dans ledit alésage (14).
  3. Procédé selon la revendication 2, dans lequel la solidarisation de la garniture (88, 94, 98) comporte les opérations de:
    • insérer un cône (88) dans ladite structure unitaire solide, ledit cône (88) comportant un arbre (90) se projetant au travers de ladite structure unitaire solide à ladite seconde extrémité (84);
    • placer un collier (94) sur ladite seconde extrémité (84), ledit collier (94) venant en appui sur ladite portion de second diamètre (76) pour transmettre une force de sortie à partir du piston (12); et
    • fixer une attache (96) sur ledit arbre (90) pour tenir ledit cône (88) et ledit collier (94) sur ledit corps cylindrique pour compléter ledit piston (12).
  4. Procédé selon la revendication 3, dans lequel ladite opération de tresser selon trois axes les fibres de carbone (26, 28, 30) comporte l'opération de:
    • disposer les brins unitaires à partir des éléments porteurs (17, 17',...17n) (18, 18',...18n) selon une orientation 0/±30-40° en contrôlant le mécanisme de guidage (22) lorsque les fibres de carbone sont placées sur ledit mandrin (24).
  5. Procédé selon la revendication 4, dans lequel l'opération de tresser selon trois axes les première (40, 42), seconde (52, 54) et troisième (62, 66) couches de fibres de carbone consiste à:
    • déposer au moins deux épaisseurs de tissu dans chacune desdites première (40, 42), seconde (52, 54) et troisième (62, 66) couches pour fournir une résistance axiale et transverse suffisante pour supporter des charges appliquées sur le dispositif (10) et résultant de l'introduction de fluide sous pression dans ledit alésage (14).
  6. Procédé selon la revendication 5 comportant de plus l'opération de:
    • disposer une cinquième pièce d'écartement (68) sur ladite troisième couche (62, 66) par dessus lesdites seconde (46) et quatrième (60) pièces d'écartement; et
    • tresser selon trois axes une quatrième couche de fibres de carbone (26, 28, 30) sur ladite troisième couche (62, 66) et ladite cinquième pièce d'écartement (68) pour renforcer ladite seconde extrémité (84) dudit corps cylindrique ainsi fabriqué.
  7. Produit obtenu par le procédé défini à la revendication 6.
  8. Actuateur comportant un piston (12) sensible à du fluide sous pression introduit dans un alésage (14) prévu dans un boîtier (15) pour produire une force de sortie en rapport avec le fluide sous pression, l'amélioration dans le piston (12) comportant:
    • une projection annulaire (82) reliée à une extrémité conique (78) par un corps cylindrique (74), lesdites projection (82), corps cylindrique (74) et extrémité conique (78) étant réalisés par une matrice en résine renforcée de façon continue par des fibres de carbone (26, 28, 30) orientées selon trois axes.
  9. Actuateur selon la revendication 8, comportant de plus:
    • un cône (88) relié à ladite extrémité conique (78) et présentant un arbre (90) se projetant au travers du corps cylindrique (74); et
    • un collier (94) attaché audit arbre (90) pour transmettre des forces à partir du corps cylindrique (74) à un autre élément.






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