FR2905730A1 - Gas turbine e.g. petrol engine, fabricating method for e.g. hybrid car, involves assembling vanes of cylindrical bodies and plane ring gears constituting heat resisting steel turbine wheels which are radial centrifugal flow type of wheels - Google Patents

Abstract

The method involves assembling vanes (8) of cylindrical bodies (9, 10) and plane ring gears (13, 14) constituting heat resisting steel turbine wheels (2, 6) which are radial centrifugal flow type of wheels. Each of the turbine wheels of low pressure and high pressure turbo compressors groups of a gas turbine includes a central core and plane peripheral ring gears (11, 12) in which the vanes are implanted, where the two groups respectively include a single stage centrifugal compressor and a centrifugal compressor.

Description

The present invention resides in the implementation of solutions and

  unusual technical means, from which arises a general arrangement of organs particularly favorable to the realization of "mini-combustion Turbo-engines", much less powerful than the current smaller models. The technical sector of the invention is therefore that of the construction of turbo-machines, but according to a mechanical design using machining and assembly means specially adapted for small-scale constructions, of a moderate cost price and sufficient performance to be truly competitive. In the current state of the art, in their terrestrial, aeronautical or marine industrial applications, the power of gas turbines is evaluated in MegaWatt and the smaller ones, which equip helicopters, small turbo-propelled airplanes and generators. for aircraft, develop between 200 and 300 kW: Except the model of 100 kW "OREDON IV", built by TURBOMECA in France, it does not seem to exist much less powerful since the English firm ROVER, after having produced a range from only 44 to 85 kW until around 1980, seems to have definitively given up. This can be explained by the fact that their field of application is more economically covered by reciprocating piston engines produced in mass production for the industry and the automobile. Because the construction of a mini-gas turbine according to the usual technologies and by simple reduction of scale, comes up against technical problems difficult to overcome: Hence a very high cost and a significantly lower yield. There does not seem to be any existing combustion turbine built with centrifugal radial-flow drive wheels, as this method of construction has so far been very rarely used, apparently only for 2 steam turbines: Electra "built around 1900 by the General Electric Company in Nancy, then around 1920, a twin-rotor turbo-alternator for a marine turbo-electric propulsion, built by Ljungstriem for the Ets. Sautter-Harle. The latter, superheated steam, 1000 kW at 3000 rpm, is characterized in that it comprises two coaxial rotors nested face to face and necessarily turning in the opposite direction, the steam path from the center to the periphery through a rather large number of concentric rings of reaction-effect blades, those of one of the two rotors serving as rectifiers of the vapor flow for the other and vice versa. However, the turbo-engine according to the present invention has a similar arrangement because it also has two co-axial rotors arranged face to face: But the similidude stops there, its rotors not being constrained to turn into reverse direction, nor at the same speed, and non-rectifiers of the working gas stream. On the other hand, its advantageous feature consists in the arrangement, within the space available in the hollow of these two wheels, of the gas distributor members at the outlet of the combustion chambers, so as to constitute a set as compact as possible , thus minimizing energy losses. It is thus a very original and novel provision, constituting an innovation.

  The targeted applications are all those where a small turbo-engine of equal power is preferable to a reciprocating engine with pistons, gasoline or diesel, because of its own advantages: - Absence of vibrations, operating noise easier to neutralize by covers, polycombustible and especially all gases, without the need for refrigeration and insensitive to frost, endurance, low maintenance cost, and, above all, emitting much less pollutants to the exhaust: 2905730 - 2 - Because of this advantage , an application envisaged is the generator of future hybrid automobiles, the engine driving the generator of rare models currently marketed still being pistons, for lack of better. Indeed, among other unsuccessful projects to date, we know the experimental electric vehicle "Sensiva", built in 1994 by the Italian engineer Leonardo FIORAVANTI 5, equipped with a combustion turbine of 170 kW ( 232 Ch) classifying it in the category of luxury and prestige cars. However, if it had existed a turbo-engine developing only 1/4 of this power, this project could have been that of a hybrid car of large diffusion, more ecological. Another application is the gas-fired turbo-engine object of the Patent of Invention N 02 14652, which was issued to me on 16/06/2006 (to BECH Jean André, Bopi N 06/24, Publication No. 2,847,620 ), Wherein is described and claimed a mode of construction using existing turbo superchargers, for piston engines: But as this method leads to a relatively heavy and bulky machine, the present invention is advantageously applicable. The technical characteristics peculiar to the invention reside primarily in the machining and assembly modes of the components of centrifugal steel centrifugal impeller wheels, that is to say, where the working gaseous fluid flows radially from the center to the periphery through blades arranged parallel to the axis of rotation, according to the generatrix of a cylinder. Secondly, it allows a general arrangement of the turbo-engine more compact and lightweight, reducing thermal losses by confining the hottest organs between these turbine wheels.

This choice implies giving up the use of existing turbo-compressors, but only with regard to their original turbine (of the so-called "centripetal radial flow" type), with its heavy and too bulky gas casing, and the tree that is inseparable. Thus, only the compressor wheels and their suction-discharge casing, as well as their central bearing body, are conserved and used here, another shaft being made to adapt to it as well as to the new turbine wheel.

The blades of conventional axial turbines are implanted perpendicularly to the axis of rotation, at the periphery of a disc or drum, so that their base and their end have a different peripheral speed: which imposes a warping of dawn, difficult machining and only achievable by special machines. On the other hand, the arrangement parallel to the axis of rotation places the entire blade on the same diameter, hence a peripheral speed equal over its entire length: there is therefore no longer any need to "warp" it, being in this case a solid generated by a rectilinear generator parallel to itself the contour of the transverse profile of the blade, similar to that of a wing. The advantage is easier machining of the blades from "raw" commercial refractory steel, by simple milling or, better, by means of cutting by electro-erosion. This profile of the blade is defined as a function of the relative velocities deduced from the triangles formed by the vectors representing the peripheral speed on the one hand and, on the other hand, that of the fluid at the inlet and the outlet of the nozzle formed between "the intrados" and "the extrados" of 2 consecutive blades. Another advantage is to minimize losses by peripheral leaks whereas, in the case of a very miniaturized realization of a paddle wheel implanted perpendicularly, these leaks become prohibitive because of the impossibility of reducing the games in the same proportions . DESCRIPTION according to boards 1/3 (Fig. 1), 2/3 (Fig. 2 & 3) & 3/3 (Fig. 4, 5, 6 & 7): Figs. 1 & 2 represent the general layout of the machine in longitudinal section by its axis of rotation, according to the vertical plane and the horizontal plane. Fig. 3 is the cross section through the median plane of the turbines.

Figs. 4 & 5 are the longitudinal and transverse sections detailing the turbine wheels and distributor blades with their method of assembly, FIGS. 6 & 7 illustrating the crimping of the blades. The turbo-engine according to the present invention comprises two turbo-compressor units whose turbines are face-to-face, in the same median transverse plane and on the same axis of rotation (FIGS. 1, 2 & 4)). - One is the group "Low-pressure" (or BP), consisting of a single-stage centrifugal compressor (1) 10 sucking the air flow working Cycle. This compressor "BP" is driven by a turbine wheel (2) wedged on the same shaft (3) and which delivers, in addition to this work of compression, the useful driving power expected from the machine. Its rotational speed is constant, but much too high to directly drive a usual electric generator: A speed reducer (4) (Fig.1) is necessary to output at 3000 rpm, for example, and to deliver alternating current to the frequency of 50 hertz. Otherwise, the direct drive requires a special alternator (with permanent magnet inductors to support this high speed of rotation) which in this case delivers a much higher frequency current, an electronic converter then being necessary to make it usable. - The other is the group "High-pressure" (or HP), consisting of a centrifugal compressor (5) with 1 or 2 stages, in series with the previous "BP": So that in total, the machine can have up to 3 successive compression stages. This single or double compressor "HP" is driven by a turbine wheel (6) wedged on the same shaft (7) and which delivers only this work of compression "HP": Indeed this turbo-compressor, not being subject to the motor shaft, is said "Turbo-free", its rotational speed being variable depending on the thermodynamic conditions of the moment, depending on the load of the machine. As already indicated, the turbines (2) & (6) of these two turbo-compressors are of the centrifugal radial flow type, with diameters whose ratio is of the order of 1 to 2, provided with blades in refractory steel, milled or cut by electro-erosion and implanted parallel to the axis of rotation: Thus, with the same blade (8) for the two turbines, the ratio of their number is also of the order of 1 to 2, as well as the passage sections of the fluid evolving in the state where it is at the crossing of each. As detailed in FIG. 4 & 5, these two wheels each consist of a frustoconical body (9) & (10), also made of refractory steel and similar to a very flared funnel whose tip would be the hub with, on the contrary, a plane peripheral ring (11) & (12) carrier of the blades (8). Another planar ring (13) & (14) of the same metal, same diameters and thickness, is intended to contain the centrifugal force at the end of these blades, by means of the same mode of implantation as in the body. Each wheel is thus obtained by assembling its body with its crown, by means of blades (8) used for this purpose, as so many spacers and links. For this purpose, these blades have a cylindrical "foot" (15) at each end, machined in turn in the pre-cut blank by milling or electro-erosion, by means of grip tooling that also allows with a precise length, with the drilling of a centering hole (16) at each end, and the guided drilling of 2 channels (17) & (18) parallel to the axis of the blade, at a definite point, on both sides of the "foot".

2905730 4 Each of these 2 "feet" engages, slightly forced, in as many holes of the body and the crown, also spaced angularly and intended to receive them in a desired number, with an overshoot exceeding slightly the thickness of these 2 rooms. The orientation of the blades to the right or to the left determines the direction of rotation given to the turbine, this position being fixed by a pin 5 passing through the channel (17) located on the axis of rotation side and which engages from and else in the blind hole (19) pierced in the body and its crown at a point on the radius passing through the axis of the feet. The wheel being thus assembled, these 2 feet are definitively "set with cold", (Fig 6 & 7), by means of a special press operating the simultaneous flaring of their centering hole, by means of 2 balls of appropriate diameter placed therein and subjected to exactly the same mechanical pressure. So that riveting does not cause further deformation and therefore, the wheel thus built remains circular and substantially balanced statically and dynamically, the blades having been previously put on the same weight and the rest being entirely machined and homogeneous. This means of assembly is required because the link fixing the blades to the body and to the crown must imperatively be of the same refractory steel. However, solutions bolted out of this metal are excluded because of the difficulty and the cost of executing many threads whose assembly strength could be insufficient, given the importance of the centrifugal force and the alternations of dilations, conducive to loosening. It is much more satisfying and easy to machine the "feet" (15) directly into the metal of the dawn with a generous fillet at birth to avoid breakouts. Nevertheless, it is to be feared that the crimping will be loosened over time: it is therefore planned to pass to the oven of this set crimped to wear it to the "solder blank", in order to perfect the connection by this self-welding, provided that deformations occur. requiring too delicate machining resumptions are avoided. A similar "consolidation" can also be obtained by means of electron beam welding: But this technique is more difficult to implement and surely more expensive. The channel (17) is used to fix the orientation of each blade and its neighbor (18), in addition to reducing it all the way, is intended to cool by circulation (air: For this purpose are In the body and in the crown, there are holes of the same diameter allowing this air to enter and exit on the other side, and a more or less deep conical milling performed in these inputs and outputs allows if necessary, to perfect the static and dynamic balancing of the wheel The passage of the working fluid between two consecutive blades is channeled on each side by the internal faces of the body and the crown, without any other possibility of lateral leakage that bypassing the outer face of the latter.To prevent this leakage, each ring (13) & (14) rotates in housings (20) & (21) of the stator with side and radial play also as possible, these spaces being moreover a dam under pressure, obtained by inje permanent filtration of compressed air taken from the HP flow. This air sampling, which also ensures the cooling of the blades through the internal channel (18), is partially recovered: Having no other outlet than the BP Turbine, it relaxes by yielding the heat taken from HP blades to cool them. Similarly for the one injected identically to the LP turbine: It is found in the working flow which comes out at the end of relaxation and whose residual heat is recoverable in the multitubular heat exchanger Gas / Air (22) (Fig. 2) placed at the exhaust outlet of this Turbine BP to preheat it before admission to the combustion chamber. 2905730 -5- It also results from the shape of these wheels, a hub (23) & (24) relatively far from the part containing the blades: hence a large cylindrical hollow with frustoconical bottom, space here used to house the stationary distributor members (25) & (26) of the two turbines, as well as a manifold (27) which connects them, all being of the same refractory steel, including the assembly bolting (42).

The HP distributor member (25) consists of a certain number of fixed vanes arranged in a circular manner and with a good orientation in order to obtain, at the inlet of the turbine, an almost tangential injection of the hot stream and under high pressure, which arrives via a central duct, the manifold (27). It is carried by this manifold, itself attached to the distributor member (26) of the BP wheel. This BP distributor member (26) also consists of a certain number of fixed vanes (28) maintained and positioned in orientation by the bolting (42) ensuring the tightening of the assembly, between as many dwellings (29). pierced in the inlet face of the header and the same (30) drilled in the ring (31) of the stator of the machine at the outlet of the hot stream from the HP combustion chambers. These blades (28) consist of a cylindrical portion concentrically pierced with a large central duct (32) and décolletée the ends to fit into the housing (29) & (30), these 15 central ducts allowing the passage this hot stream, from the HP combustion chambers, in the manifold (27) and from there to the HP distributor (25). On the back of this cylinder and forming a kind of comma, is grafted an excrescence (33) cut by electro-erosion along 2 circular paths that are tangent to it, the inside being "the intrados" of the dawn, the other his "extrados". So that the nozzle through which the quasi-tangential injection of the gas flow entering through the inside of the wheel BP is constituted by the juxtaposition of "the intrados" and "extrados" of 2 vanes consecutive (28), this flow being laterally contained between the flat faces of the manifold (27) and the ring (31). The annular space between the periphery of the HP turbine and the inlet of these LP injection nozzles may constitute a "warming" or "secondary combustion" chamber (34), insofar as the degree of miniaturization of the machine makes it possible to house additional burners for this purpose in the crown (31) of the stator: Circularly, in a desired number and sufficiently set back from this annular space so that their flame can develop properly therein. the miniaturization comes from the fact that the dimensions of the "heat generating organs" are not reducible below a certain threshold: For burners, besides the space necessary for the intimate mixing of the fuel with the combustion air, the flame It also needs an extra volume to develop and reach its maximum temperature with a very high speed of propagation.A sufficient space is especially necessary for it to be done properly. t the heat transfer between the flame and the working airflow so that, in accordance with the cycle, the cycle heats up as intensively as possible with an excellent heat exchange efficiency. The face of the stator ring (31) in which the housings (30) are drilled is, on this side, that of the fixed assembly (35) in which the "main heat generators" are normally located: burners, either flameless heaters, by catalysis (36) (Fig.l & 2) provided, as previously explained, that their size allows to accommodate them, none of the 2 systems having the advantage on this point: It follows that below a certain dimensional limit, the "heat generating" organs will have to be placed outside the machine, which lends itself easily to its construction. Because instead of going directly to the HP air circular manifold (37) arranged in the portion (35) of the stator, the air flow out of the last HP compression stage can be channeled to this "generator of external heat ", then return into this manifold (37), hot and always under high pressure, to finally relax in the HP turbine through the ducts (32) and the manifold (27).

This "external generator" can then be conceived with a reduced number of powerful burners, or even a single one, of a much better combustion and heat exchange efficiency than many small burners arranged in a ring in the machine, of embodiment more difficult and expensive. Such a derivation of HP air is also provided in the application "turbo-engine gasifier", to send it into the heat exchanger incorporated in its "generator of wood gas" and recover therein content 10 in this gas-fuel produced, which can in this case supply the (or the) burners of this "external generator", with a more powerful propellant capable of injecting it in HP medium instead of BP. And for all other applications, the machine can be designed and built to work with any fuel of petroleum or vegetable, liquid or gaseous origin. As already indicated, the 2 HP and LP turbo-compressors are derived from existing "turbo-chargers", 15 of which are reused only the central bearing body and their centrifugal compressors, almost all designed to rotate in the clockwise direction seen from Aspiration side: Now, the turbines being here face-to-face and each compressor on the opposite side, it follows that, seen from the side "aspiration to the atmosphere" of the compressor BP, the turbine driving the latter must turn in direction clock and the other, HP, in the opposite direction. The abandonment of the original turbine and its inseparable shaft implies, for each of these two turbo-compressors, the creation of a new shaft specially designed to adapt to their new wheel. With regard to the turbocharger HP, called "turbo-free", this specially created shaft (7) (Fig. 1 & 2) can be much longer on the Compressor side, provided however that it is supported at its end by an additional bearing ( 38): So that 2 compressor wheels can be optionally mounted without excessive overhang, of different dimensions depending on the specific volume reached by the air in these successive compressions, the largest being therefore at the entrance , at the repression of the BP Compressor. A two-stage compressor is thus feasible with a modification of the original casing of the smaller wheel, to adapt another and new casing to create for the big wheel, this set being completed by the suction box (39) of the latter, bearing the additional bearing. The advantage of this option is the gain in overall efficiency resulting from the sharp increase in the compression ratio that can be obtained, this increased pressure facilitating further startup: Because this "free" HP turbo-compressor is also responsible for Initially supply the HP combustion chamber (s) during ignition and start operation until the LP drive turbine starts to rotate. For this purpose, the new shaft is extended by another (40) which it can be secured or not by means of a device (41), centrifugal or electromagnetic, driven by the launching device: Which may be a automotive electric starter modified to receive a driving pulley with a "light" toothed belt engaged with a much smaller pulley of this kind (43) wedged on the clutch shaft, the multiplication ratio thus obtained giving this turbo HP compressor the desired rotational speed and high enough to start the machine.

Claims (8)

  : 1) Process for producing miniaturized "turbo-combustion engines" (or gas turbines), based on the use of a particular model of turbine blade (8), with a straight generator and constantly parallel to its main axis, therefore achievable by simple straight milling or cutting by electro-erosion, and from which derives the general arrangement of the machine, the method further characterized by the assembly by means of these blades of the bodies (9) & (10) and crowns (13) & (14) constituting these refractory steel wheels, which are, with this blade model, of the type called "centrifugal radial flow".   2) Method according to claim 1, characterized in that these miniaturized turbo-motors consist of 2 turbo-compressor sets whose turbines are arranged face-to-face in the same median transverse plane and on the same axis of rotation, one being the group "Low-pressure" (BP), consisting of a single-stage centrifugal compressor (1) sucking the atmosphere, the other being the High-pressure group (HP), composed of a centrifugal compressor (5) optionally with 1 or 2 stages in series with the previous BP and whose turbine (2) delivers, in addition to this BP compression work, the useful driving power, while the HP turbo-compressor, not mechanically subject, is "free", these centrifugal compressors with their bearing bodies and some accessories being taken from existing turbo-compressors normally intended for the supercharging of piston engines.   3) Process according to claim 1 & 2, characterized in that each of the turbine wheels (2) & (6) of the LP and HP turbo-compressors is entirely of refractory steel, consisting of a body (9) & (10) ) frustoconical, having a central hub and a flat peripheral ring (11) & (12) where are implanted the vanes (8), which body is assembled with another flat ring (13) & (14) of the same diameter and thickness, according to the same mode of implantation and by means of these same blades, which constitute as many spacers and connections between these 2 crowns, by means of the cylindrical "foot" (15) with the centering hole (16) that each blade comprises at its end, obtained by machining its milled or sintered blank, by means of a special jaw-grip tool, which is, in addition, a drilling guide for positioning channels (17) and cooling the blade (18), parallel and on both sides of the axis pa by the "feet".   4) Method according to claim 3, characterized in that the assembly of the wheel bodies (9) & (10) with their crown (13) & (14) by means of their vanes (8) is permanently cold set at by means of a special press operating by simultaneous flaring of the two centering holes (16) of each blade, by means of 2 balls of appropriate diameter and subjected to the same mechanical pressure force, this riveting of all the blades being able to then be consolidated by self-welding by baking it at the "white-solder" temperature, or by means of electron beam welding.   5) Method according to claim 3, characterized in that the cylindrical hollow with frustoconical bottom or plane of each of the turbine wheels and resulting from their method of construction, is used to accommodate their stationary dispensing members (25) & (26). ) constituted by circular vanes arranged in a circular direction and oriented to obtain an almost tangential injection, as well as a collecting box (27) connecting them, the whole being of the same refractory steel, including the assembly bolts (42) each blade (28) of the dispensing member BP being in the form of a comma pierced with a large central duct (32) concentric with its cylindrical portion and positioned by these bolts (42) ensuring the clamping of all this fixed assembly. 2905730 -E-   6) Process according to claim 5, characterized in that the space between the periphery of the HP turbine and the inlet of these BP injection nozzle (28) can constitute a "heating chamber", by means of the flow additional heat produced for this purpose by a secondary heat generator and arriving there through conduits (34) arranged in this case in the stator (35). 5   7) Method according to claims 1 & 2, characterized in that the "main" and / or "secondary" heat generating members (32) of such gas mirai-turbines, can be: Either burners producing a flame in it burning any fuel, of petroleum, vegetable or other, liquid or gaseous, or flameless heating elements, catalytically burning any of these fuels, all arranged if possible in a ring within the whole fixed (35) or, if it can be, outside the machine and can, in this case, constitute a single heat generator, "main" and / or "secondary".   8) Method according to claim 2, characterized in that the shaft (7) of the HP turbo-compressor is supported at its end by an additional bearing (38) carried by the suction box (39), and extended beyond of this additional bearing by another shaft (40) which it can be secured or not, 15 by means of a clutch device (41), centrifugal or electromagnetic, in order to launch the machine by means of an electric starter and a light belt transmission (43), this HP turbocharger then assuming the role of compressor startup. 20 25 30 35