An engine structure for internal combustion engines

Description

[0001] The present invention relates to an engine structure for internal combustion engines.

[0002] The term "engine structure" is used to mean the assembly consisting of the engine block and crankcase and the built-in auxiliary services driven by the engine, in particular, the lubricating pump and the suction unit, that is, a device designed to continuously generate a vacuum in a chamber connected to the auxiliary services which require negative pressure for their operation, such as, for example, the brake system of modern cars.

[0003] In engines known up to now, said auxiliary services are separate from the engine block and are driven through transmission belts.

[0004] This type of installation has the serious disadvantage that, if a transmission belt breaks, the auxiliary service driven by that belt stops working, creating serious risks for the safety of the engine and for the vehicle on which the engine is installed.

[0005] From EP-0 305 689 is known a lubricating arrangement realised according to features of the preamble of Claim 1.

[0006] The lubricating arrangement attached end face at the engine housing of a reciprocating piston engine is surrounded by an oil pump housing which is composed of two housing parts cast of magnesium. The lubricating oil pumps are preassemblable in the oil pump housing. The lubricating arrangement comprises a pressure pump by means of which lubricating oil is fed to the bearing places of a V-engine, and a further gear pump which serves as suction pump for sucking lubricating oil out of the turbochargers.

[0007] In document US-4 586 468 a tandem pump arrangement is disclosed comprising a first pump having two meshing gears of different pitch diameter, the drive thereby of the gear having the smaller pitch diameter is at a higher speed. A second pump has an input connected to be driven by the gear with the smaller pitch diameter with the result that the second pump is driven through the first pump at increased speed with an overdrive ratio determined by the ratio of the pitch diameters of the gears. The aim of the present invention is to overcome the disadvantages mentioned above by providing an engine structure that utilizes existing space and does not therefore increase the overall dimensions of the engine.

[0008] One aspect of the present invention is to provide an engine structure that comprises an engine block, a crankshaft with at least one first gear wheel keyed to it, means for creating suction and means for distributing lubricating fluid under pressure and where the first gear wheel meshes with a second gear wheel that directly drives the means for creating suction and with a third gear wheel that drives the means for distributing lubricating fluid under pressure.

[0009] Another aspect of the present invention is to provide an engine structure that comprises an engine block, a crankshaft with at least one first gear wheel keyed to it and auxiliary means for creating suction or for distributing lubricating fluid under pressure and where the engine block has at least one hollow to house said auxiliary means. A further aspect of the present invention is to provide an engine structure that comprises an engine block, a crankshaft with at least one first gear wheel keyed to it, means for creating suction and means for distributing lubricating fluid under pressure through suitable supply and delivery ducts and where at least one of these ducts lies mainly outside the engine block.

[0010] Yet another aspect of the present invention is to provide an engine structure that comprises an engine block, a crankshaft with at least one first gear wheel keyed to it and consisting of a cup gear which provides enough space for an oil seal without increasing the overall dimensions.

[0011] The technical characteristics of the invention according to the above mentioned aim are described in the claims below and the advantages of the invention will become more apparent from the detailed description which follows, with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention and in which:

• Figure 1 is a partial, schematic cross section of an engine structure according to the present invention;
• Figure 2 is a section of Figure 1 along line II-II;
• Figure 3 is a section of Figure 1 along line III-III;
• Figure 4 is an enlarged detail of a part of Figure 3.

[0012] According to the accompanying drawings, the numeral 1 indicates an internal combustion engine block from which the end of a crankshaft 2 protrudes, the latter having keyed to it a first cup-shaped gear wheel 3, that is to say, a gear wheel whose teeth 4 lie in a plane that is axially offset with respect to the wheel hub 5 (see Figure 2) in such a way as to create the space necessary for the ideal positioning of an oil seal 40 without increasing the overall dimensions of the gear.

[0013] With reference to Figure 3, the first gear wheel 3 (not illustrated in this Figure) meshes with a second gear wheel 6 keyed to the shaft 7 of a rotor 8 of a suction unit 9 designed to generate a vacuum, for example for the brake system of a motor vehicle. The suction unit 9 is mounted inside a first box-shaped element 11, located in a first hollow 10, preferably blind, made in the engine block 1.

[0014] The end wall 12 of the first hollow 10 is used as a reference for locating the box-shaped element 11 in which the suction unit 9 is fitted. In this way, the clearance between the rotor 8 of the suction unit and the end wall 12 of the first hollow 10 is reduced to a minimum, depending solely on the tolerances T of the first box-shaped element 11 and that of the rotor 8 (since the first box-shaped element 11 is always in contact with the end wall 12 of the hollow 10, as can be seen in Figure 4). The first gear wheel 3 also meshes with a third gear wheel 13 (see Figure 2) keyed to the shaft 14 of the rotor 19 of a lubricating pump 15. The cup shape of the first gear wheel 3, besides providing space for fitting the oil seal 40, makes it possible to drive the second gear wheel 6 and the third gear wheel 13 even if the teeth of these wheels lie in a plane that is quite far away from the outer surface of the engine block 1.

[0015] The pump 15 is mounted inside a second box-shaped element 17 located in a second blind hollow 16 made in the engine block 1.

[0016] The end wall 18 of the second hollow 16 is used as a reference for locating the box-shaped element 17 in which the pump 15 is fitted. Thus, as for the unit described above, the clearance between the rotor 19 of the pump 15 and the end wall 18 of the second hollow 16 is reduced to a minimum, depending, in this case too, solely on the tolerances between the depth of the second box-shaped element 17 and that of the rotor 19.

[0017] The second box-shaped element 17 comprises a cover 21 that protrudes from said second hollow 16 and that has made in it a first chamber 22 into which the supply duct 23 of the pump 15 leads, in the direction of the arrows F (a part of the supply duct is illustrated in Figures 1 and 2) and a second chamber 24 from which the delivery duct 25 of the pump 15 branches (the connecting port of the delivery duct is illustrated in Figure 1).

[0018] It should be noticed that the first chamber 22 and the second chamber 24 are made around the bearing S of a shaft which mounts the third gear wheel 13 and have the same width as the bearing so as not to increase the overall dimensions of the unit.

[0019] Looking in more detail, the supply duct 23 and the delivery duct 25 of the engine block 1 communicate with the cover 21 of the box-shaped element 17 through corresponding connecting ducts 23' and 25' (partly illustrated in Figure 1) which lie mainly on the outside of the engine block 1, thus eliminating the need to make the ducts entirely in the engine block 1 using complicated and costly processes. The connecting ducts 23' and 25' connect with corresponding ports (not illustrated) made in the engine block 1 and which, after the second box-shaped element 17 has been fitted, lead into the corresponding first and second chambers 22 and 24 in the second box shaped element 17 itself.

[0020] In other terms, the engine block 1 has made in it the first and second hollows 12 and 16 to house the corresponding box shaped elements 11 and 17 each of which has its own fluid supply and delivery ducts. For example (see Figures 1 and 3), the suction unit 9 is supplied with oil from the engine sump (not illustrated) so that the rotor 8 can be lubricated through a first duct 41 that leads into the area labelled 41' in Figure 3. As it rotates, the rotor 8 creates a vacuum in a second suction duct 42 which communicates with the related service tank. The delivery of the rotor 8, which consists of air mixed with oil, is in turn supplied to a third duct 43 made in the front wall of the first box-shaped element 11 and from here, the mixture is fed back into the engine sump and recycled.

[0021] The three ducts 41, 42 and 43 of the suction unit 9 are made in and lie entirely inside the engine block 1 which, once these elements have been assembled, is closed by a simple guard, labelled C in the accompanying drawings, without necessitating special machine processes or sealing elements and thereby also reducing the axial dimensions of the engine block 1 as a whole.

[0022] As shown in Figure 1, located between the supply duct 23 and the delivery duct 25 of the pump 15, there is a pressure regulating valve 26 fitted in a bypass duct 27.

[0023] The valve 26 is designed to enable a part of the fluid delivered by the pump 15 to the delivery duct 25 to be diverted directly into the supply duct 23 through the bypass duct 27 when the delivery pressure of the pump 15 exceeds a preset value.

[0024] The regulating valve 26 consists of a shutter element 30, preferably cylindrical, fitted in a first section 28 of the bypass duct 27. At a first end of it, the shutter element 30 communicates with the delivery duct 25 of the pump 15 and, close to a second end, it has a plurality of radial holes 31. The second end of the cylindrical element 30 has a shutting element 32 pushed by a spring 33 that is preloaded by a preset, adjustable value, the spring having one end resting against the shutting element 32 and the other end resting against a stop element 34. The spring 33 and the shutting element 32 are positioned inside a second section 29 of the bypass duct that is larger in diameter than the first section 28 and that communicates with the suction duct 23 of the pump 15.

[0025] When the pressure of the fluid in the delivery duct 25 of the pump 15 exceeds a preset value depending on the preload value of the spring 33, the force exerted by the fluid under pressure on the shutting element 32 exceeds the force exerted on it by the spring 33 and pushes the cylindrical element 30 further into the second section 29 of the bypass duct 27 so as to allow a part of the fluid delivered by the pump 15 to flow into the second section 29 (see Figures 1 and 2) of the bypass duct 27 and, from there, into the suction duct 23 and then into the above mentioned first chamber 22.

[0026] This prevents the pressure in the delivery duct 25 of the pump 15, and therefore in the lubricating system supplied by the pump, from reaching excessive, dangerous values.

[0027] The invention described can be subject to modifications and variations without thereby departing from the scope of the inventive concept. Moreover, all the details of the invention may be substituted by technically equivalent elements.

Claims

1. An engine structure comprising an engine block (1), a crankshaft (2) having keyed to it at least one first gear wheel (3), auxiliary means comprising means (9) for creating suction and means (15) for distributing lubricating fluid under pressure, the first gear wheel (3) meshes with a second gear wheel (6) that directly drives said means (9) and with a third gear wheel (13) that drives the means (15) for distributing fluid under pressure, said structure being characterized in that the first means (9) are means for continuously generating a vacuum in a chamber connected to the auxiliary services which require negative pressure for their operation and are mounted inside a first box-shaped element (11) located in a hollow (10) of the engine block (1), an end wall (12) of the hollow (10) being used as a reference for locating the box-shaped element (11) in the hollow (10).

2. The engine structure according to claim 1, characterized in that the engine block (1) has a further hollow (16) designed to house the the means (15) for distributing fluid under pressure.

3. The engine structure according to claim 1 or 2 characterized in that the means (15) for distributing lubricating fluid under pressure are connected to a supply duct (23) and to a delivery duct (25) for said lubricating fluid, at least one of which lies mainly outside the engine block (1).

4. The engine structure according to any of the preceding claims, characterized in that the means (9) for generating a vacuum are connected to suction ducts (41, 42) and delivery ducts (25, 43) extending mainly outside the engine block (1).

5. The engine structure according to to any of the preceding claims 1 or 2, characterized in that said first gear wheel (3) is a cup gear designed to provide a space where a seal ring (40) for the lubricating fluid of the engine block (1) can be housed.

6. The engine structure according to any of the preceeding claims 2 to 5 characterized in that the means (15) for distributing lubricating fluid under pressure are mounted inside a second box-shaped element (17) located in the second hollow (16), an end wall (18) of the second hollow (16) being used as a reference for locating the box-shaped element (17) in the hollow (16).

7. The engine structure according to claims 3 or 4 characterized in that the means (15) for distributing lubricating fluid under pressure are equipped with a cover (21) that protrudes from the engine block (1) and that has made in it a first chamber (22) into which the supply duct (23) leads, and a second chamber (24) from which the delivery duct (25) branches; said first and second chambers (22, 24) being made around the bearing (S) of a shaft which mounts the third gear wheel (13) and have the same width as the bearing.

8. The engine structure according to claim 7 where the supply duct (23) and the delivery duct (25) lead into an area, through corresponding ports close to the distributing means (15), characterized in that said supply duct and said delivery duct communicate with the corresponding first and second chambers (22, 24) through connecting ducts (23', 25') lying on the outside of the engine block (1) and leading into corresponding ports made in the engine block (1) and connected in turn to the first and second chambers (22, 24) when the distributing means (15) are assembled.

9. The engine structure according to claim 7 characterized in that the supply duct (23) and the delivery duct (25) are connected to each other through a bypass duct (27) regulated by a valve (26).

10. The engine structure according to claim 9 characterized in that the bypass duct (27) comprises a first section (28), that communicates with the delivery duct (25), and a second, consecutive section (29), that communicates with the suction duct (23), said second section (29) being larger in diameter than said first section (28).

11. The engine structure according to claim 10 characterized in that the regulating valve (26) comprises a shutter element (30) fitted by sliding into the first section (28) of the bypass duct (27), a first end of said shutter element (30) communicating with the delivery duct (25) and a second end of it having close to it a plurality of radial holes (31).

12. The engine structure according to claim 11 characterized in that the second end of the shutter element (30) has a shutting element (32) acted on by preloaded elastic means (33) one end of which rests against the shutting element (32) and the other end rests against a stop element (34).

13. The engine structure according to claim 12 characterized in that the shutter element (30) slides inside the second section (29) of the bypass duct (27) against the action of the elastic means (33).

Ansprüche

1. Brennkraftmaschinenkonstruktion, enthaltend einen Motorblock (1), eine Kurbelwelle (2) mit wenigstens einem ersten Zahnrad (3) aufgezogen, sowie Hilfsmittel, enthaltend Mittel (9) zum Erzeugen eines Unterdruckes und Mittel (15) zum Verteilen einer unter Druck stehenden Schmierflüssigkeit, wobei das erste Zahnrad (3) in ein zweites Zahnrad (6) greift, das direkt die genannten Mittel (9) antreibt, und in ein drittes Zahnrad (13), das die Mittel (15) zum Verteilen der unter Druck stehenden Schmierflüssigkeit antreibt, wobei die genannte Struktur dadurch gekennzeichnet ist, dass die ersten Mittel (9) Mittel zum kontinuierlichen Erzeugen eines Unterdruckes in einer Kammer sind, die an die Hilfseinrichtungen angeschlossen ist, welche für ihren Betrieb einen Unterdruck erfordern und im Inneren eines ersten, kastenförmigen Elementes (11) montiert sind, angeordnet in einem Hohlraum (10) des Motorblockes (1), wobei eine Endwand (12) des Hohlraumes (10) als Bezugsebene zum Anordnen des kastenförmigen Elementes (11) in dem Hohlraum (10) benutzt wird.

2. Brennkraftmaschinenkonstruktion nach Patentanspruch 1, dadurch gekennzeichnet, dass der Motorblock (1) einen weiteren Hohlraum (16) enthält, dazu bestimmt, die Mittel (15) zum Verteilen der unter Druck stehenden Flüssigkeit aufzunehmen.

3. Brennkraftmaschinenkonstruktion nach Patentanspruch 1 oder 2, dadurch gekennzeichnet, dass die Mittel (15) zum Verteilen der unter Druck stehenden Schmierflüssigkeit an eine Zuführleitung (23) und an eine Ablassleitung (25) für die genannte Schmierflüssigkeit angeschlossen sind, von welchen wenigstens eine vorwiegend ausserhalb des Motorblocks (1) verläuft.

4. Brennkraftmaschinenkonstruktion nach einem beliebigen der vorstehenden Patentansprüche, dadurch gekennzeichnet, dass die Mittel (9) zum Erzeugen eines Unterdruckes an Saugleitungen (41, 42) und Ablassleitungen (25, 43) angeschlossen sind, welche vorwiegend ausserhalb des Motorblocks (1) verlaufen.

5. Brennkraftmaschinenkonstruktion nach einem beliebigen der Patentansprüche 1 oder 2, dadurch gekennzeichnet, dass das genannte erste Zahnrad (3) ein Tellerrad ist, dazu bestimmt, einen Raum zu bilden, in welchen ein Dichtungsring (40) für die Schmierflüssigkeit des Motorblocks (1) eingesetzt werden kann.

6. Brennkraftmaschinenkonstruktion nach einem beliebigen der Patentansprüche von 2 bis 5, dadurch gekennzeichnet, dass die Mittel (15) zum Verteilen der unter Druck stehenden Schmierflüssigkeit im Inneren eines zweiten kastenförmigen Elementes (17) montiert sind, letzteres angeordnet in dem zweiten Hohlraum (16), wobei eine Endwand (18) des zweiten Hohlraumes (16) als Bezugsebene zum Anordnen des kastenförmigen Elementes (17) in dem Hohlraum (16) benutzt wird.

7. Brennkraftmaschinenkonstruktion nach den Patentansprüchen 3 oder 4, dadurch gekennzeichnet, dass die Mittel (15) zum Verteilen der unter Druck stehenden Schmierflüssigkeit mit einem Deckel (21) versehen sind, der von dem Motorblock (1) hervorsteht, und in den eine erste Kammer (22) eingearbeitet ist, in welche die Zuführleitung (23) mündet, sowie eine zweite Kammer (24), von welcher aus die Ablassleitung (25) abzweigt; wobei die genannten ersten und zweiten Kammern (22, 24) um ein Lager (S) einer Welle angeordnet sind, welche das dritte Zahnrad (13) trägt und die gleiche Abmessung wie das Lager aufweist.

8. Brennkraftmaschinenkonstruktion nach Patentanspruch 7, bei welcher die Zuführleitung (23) und die Ablassleitung (25) durch entsprechende Öffnungen in einen Bereich dicht an den Verteilermitteln (15) führen, dadurch gekennzeichnet, dass die genannte Zuführleitung und die genannte Ablassleitung mit den entsprechenden ersten und zweiten Kammern (22, 24) in Verbindung stehen, und zwar durch Verbindungsleitungen (23', 25'), die ausserhalb des Motorblocks (1) verlaufen und in entsprechende, in den Motorblock (1) eingearbeitete Öffnungen führen, welche wiederum mit den ersten und zweiten Kammern (22, 24) in Verbindung stehen, wenn die Verteilermittel (15) montiert sind.

9. Brennkraftmaschinenkonstruktion nach Patentanspruch 7, dadurch gekennzeichnet, dass die genannte Zuführleitung (23) und die genannte Ablassleitung (25) durch eine Umgehungsleitung (27) miteinander verbunden sind, die durch ein Ventil (26) reguliert wird.

10. Brennkraftmaschinenkonstruktion nach Patentanspruch 9, dadurch gekennzeichnet, dass die Umgehungsleitung (27) einen ersten Abschnitt (28) enthält, der mit der Ablassleitung (25) in Verbindung steht, und einen zweiten, anschliessenden Abschnitt (29), der mit der Saugleitung (23) in Verbindung steht, wobei der genannte zweite Abschnitt (29) grösser im Durchmesser ist als der genannte erste Abschnitt (28).

11. Brennkraftmaschinenkonstruktion nach Patentanspruch 10, dadurch gekennzeichnet, dass das Regulierventil (26) ein Verschlusselement (30) enthält, welches durch Gleiten in den ersten Abschnitt (28) der Umgehungsleitung (27) eingesetzt ist, wobei das genannte Verschlusselement (30) mit seinem ersten Ende mit der Ablassleitung (25) verbunden ist und dicht an seinem zweiten Ende eine Anzahl von radialen Bohrungen (31) aufweist.

12. Brennkraftmaschinenkonstruktion nach Patentanspruch 11, dadurch gekennzeichnet, dass das zweite Ende des Verschlusselementes (30) ein Absperrelement (32) aufweist, betätigt durch ein vorgespanntes Federmittel (33), dessen eines Ende an dem Absperrelement (32) und das andere Ende an einem Anschlagelement (34) anliegt.

13. Brennkraftmaschinenkonstruktion nach Patentanspruch 12, dadurch gekennzeichnet, dass das Verschlusselement (30) entgegen der Wirkung des Federmittels (33) im Inneren des zweiten Abschnittes (29) der Umgehungsleitung (27) gleitet.

Revendications

1. Une structure de moteur comprenant un bloc moteur (1), un arbre moteur (2) sur lequel est calée au moins une première roue dentée (3), des moyens auxiliaires comprenant des moyens (9) destinés à générer une dépression et des moyens (15) destinés à distribuer un fluide de lubrification sous pression, la première roue dentée (3) s'engrène dans une deuxième roue dentée (6) qui entraîne directement lesdits moyens (9) et dans une troisième roue dentée (13) qui entraîne lesdits moyens (15) de distribution de fluide sous pression, ladite structure étant caractérisée en ce que lesdits premiers moyens (9) sont des moyens qui génèrent en permanence un vide dans une chambre reliée à des services auxiliaires dont le fonctionnement requiert une pression négative et qui sont montés à l'intérieur d'un premier élément (11) en forme de boîte situé dans une cavité (10) du bloc moteur (1), une paroi d'extrémité (12) de la cavité (10) étant utilisée comme référence pour le positionnement de l'élément-boîte (11) dans cette même cavité (10).

2. La structure de moteur selon la revendication 1, caractérisée en ce que ledit bloc moteur (1) présente une autre cavité (16) destinée à loger lesdits moyens (15) de distribution de fluide sous pression.

3. La structure de moteur selon la revendication 1 ou 2, caractérisée en ce que lesdits moyens (15) de distribution de fluide de lubrification sous pression sont raccordés à un conduit d'admission (23) et à un conduit d'évacuation (25) de ce fluide de lubrification, au moins l'un d'entre eux se trouvant principalement à l'extérieur du bloc moteur (1).

4. La structure de moteur selon l'une quelconque des revendications précédentes, caractérisée en ce que lesdits moyens (9) de génération de vide sont raccordés à des conduits d'aspiration (41, 42) et à des conduits d'évacuation (25, 43) qui s'étendent principalement à l'extérieur du bloc moteur (1).

5. La structure de moteur selon l'une quelconque des revendications précédentes 1 ou 2, caractérisée en ce que ladite première roue dentée (3) est un engrenage à godet destiné à définir un espace dans lequel peut être logée une bague d'étanchéité (40) pour le fluide de lubrification du bloc moteur (1).

6. La structure de moteur selon l'une quelconque des revendications précédentes de 2 à 5, caractérisée en ce que lesdits moyens (15) de distribution de fluide de lubrification sous pression sont montés à l'intérieur d'un deuxième élément (17) en forme de boîte situé dans la deuxième cavité (16) susmentionnée, une paroi d'extrémité (18) de la deuxième cavité (16) étant utilisée comme référence pour le positionnement de l'élément-boîte (17) dans cette même cavité (16).

7. La structure de moteur selon les revendications 3 ou 4, caractérisée en ce que lesdits moyens (15) de distribution de fluide de lubrification sous pression sont équipés d'un couvercle (21) qui dépasse du bloc moteur (1) et dans lequel ont été réalisées une première chambre (22) où débouche le conduit d'admission (23) susmentionné, et une deuxième chambre (24) d'où part le conduit d'évacuation (25) susmentionné ; lesdites première et deuxième chambres (22, 24) étant réalisées autour du support (S) d'un arbre qui supporte la troisième roue dentée (13) et présentant la même largeur que le support en question.

8. La structure de moteur selon la revendication 7 où ledit conduit d'admission (23) et ledit conduit d'évacuation (25) débouchent, à travers des orifices correspondants, dans une zone proche des moyens de distribution (15), caractérisée en ce que ledit conduit d'admission et ledit conduit d'évacuation communiquent avec lesdites première et deuxième chambres (22, 24) correspondantes par l'intermédiaire de conduits de communication (23', 25') situés à l'extérieur du bloc moteur (1), débouchant dans des orifices correspondants réalisés dans ce même bloc moteur (1) et raccordés à leur tour aux première et deuxième chambres (22, 24) lorsque les moyens de distribution (15) sont assemblés.

9. La structure de moteur selon la revendication 7, caractérisée en ce que ledit conduit d'admission (23) et ledit conduit d'évacuation (25) sont raccordés entre eux par l'intermédiaire d'un conduit de dérivation (27) régulé par une vanne (26).

10. La structure de moteur selon la revendication 9, caractérisée en ce que ledit conduit de dérivation (27) comprend une première section (28) qui communique avec le conduit d'évacuation (25), et une deuxième section (29) consécutive qui communique avec le conduit d'aspiration (23), ladite deuxième section (29) ayant un plus grand diamètre que ladite première section (28).

11. La structure de moteur selon la revendication 10, caractérisée en ce que ladite vanne de régulation (26) comprend un élément obturateur (30) monté de manière coulissante dans la première section (28) du conduit de dérivation (27) susmentionné, ledit élément obturateur (30) communiquant à une première extrémité avec ledit conduit d'évacuation (25) et étant pourvu, à proximité d'une deuxième extrémité, d'une pluralité de trous radiaux (31).

12. La structure de moteur selon la revendication 11, caractérisée en ce que ladite deuxième extrémité de l'élément obturateur (30) est pourvue d'un élément d'obturation (32) sur lequel agissent des moyens élastiques (33) préchargés dont une extrémité repose contre l'élément d'obturation (32) lui-même et l'autre extrémité repose contre un élément d'arrêt (34).

13. La structure de moteur selon la revendication 12, caractérisée en ce que ledit élément obturateur (30) coulisse à l'intérieur de la deuxième section (29) du conduit de dérivation (27) contre l'action des moyens élastiques (33) susmentionnés.

Drawing