EP0892152B1 - Heating or cooling device for a carter with circular section - Google Patents

Description

The invention relates to a device for crankcase cooling or heating circular.

The desire to increase yields engines is general today. In aeronautics, one way to do this is to reduce as much as possible clearances between the rotor and the stator, especially at the free ends of the blades rotors of the rotor and the bearing surfaces of the casing which face each other. We have already devised means to achieve this, in particular by varying the diameter of the casing. The the most common method is to impose thermal expansion or contraction in blowing on its outer surface, opposite the vein gas flow, gas taken from other parts machine and at the desired temperature to heat or cool the housing as appropriate.

It is however fundamental to obtain a high temperature uniformity over the entire surface of the housing. A device already used consists of have two networks of semicircular tubes around of the casing, each of the networks therefore extending over a half circumference of the housing and being powered by a conduit, which is connected to a distributor box connected to each of the pipes in the network, in the middle of their length. The gas therefore disperses in the tubes of the network by traversing them towards their ends at from the middle, and leaves them by borrowing orifices directed towards the housing. This construction explains that these tubes are called "necklaces of shower ". Such a device is described in document EP-A-541,325.

If such a device actually ensures a gas blowing almost uniformly distributed over the entire outer surface of the housing, it fails yet to impose a uniform diameter on it because we finds that the gas heats up during the journey in tubes and can therefore give off more heat by arriving at the ends of the tubes only near the housings distributors; the casing, more and more heated in moving away from the generators located in front of the distributor boxes, therefore takes an ovoid shape whose largest diameter is located at the generators for connecting tube networks. The device subject of the invention has the function of ensuring a heating, or on the contrary cooling, much more uniform of a section housing circular. Like the known device, it includes a gas distribution network in distributors connecting to networks of tubes surrounding the casing on respective parts of the circumferences; at place where a distributor is connected in the middle of tube networks, two distributors are arranged at ends of the networks, each of these two distributors connecting to a respective group of tubes of the considered network: the gas flows through the two groups of tubes in opposite directions, which balances heat gain around the circumference, each generator of the casing being subjected to a double gas blowing, the first of which originates from one of the network tube groups, is hotter as the other, from the other group, is fresher.

So we find twice as many distributors than tube networks, each pair of consecutive arrays of tubes with two adjacent distributors. It is advantageous, in such circumstances, to lead to a single gas distribution pipe in both distributors of these pairs at a time, provided to ensure an adequate connection of these distributors, which may be subject to displacement of nature unpredictable due to original deformation thermal. We suggest connecting them with a cuff comprising two ends in portion of open sphere and by sliding support in sockets delimiting the distributors and provided with stops for the cuff.

Finally, the conduits opening into a pair of distributors are connected to a duct link occupying half of their section and extending to at least one of the sockets in passing through a stop surface of said socket. This last duct slightly penetrates into the duct more distribution network, therefore recovers the half the bit rate that comes out and transmits that half of flow to the distributor located beyond the socket liaison; the other half of the gas flow comes out of distribution duct around the connecting duct and enters the other distributor. The connecting duct having a section half as small as that of the duct distribution, to which it is connected with play, completes the system, the aim of which is to equalize heating or cooling.

A possible improvement consists in provide the device with a flow control valve heating or cooling gas, which is controlled by a calculator or by plan function reached by the machine. In the case mainly envisaged a blowing of fresh gas on the crankcase, it it is particularly advantageous to reduce the gas flow blown during start-up: if a large flow is delivered from this moment, while the machine is still cold, the housing heats up much more slowly as the rotor and its blades, whose ends expand to the point of rubbing against the inner wall of the housing. This wall is normally filled with a layer of soft material, called abradable, which erodes under the effect of friction and prevents damage to the rotor blades, but play reappearing between them and the abradable layer now eroded is increased when the housing is heated and expanded in turn. It is therefore a question of avoiding this result.

• la figure 1 est une vue générale du dispositif,
• la figure 2 est une coupe des réseaux de tubes illustrant leur mode de fabrication et leur emplacement,
• la figure 3 est une représentation à plat du dispositif, explicative de son fonctionnement,
• et la figure 4 illustre le mode de liaison des boítiers distributeurs.

The invention will now be described in more detail with the aid of the following figures, which are annexed by way of illustration and not limitation:

• FIG. 1 is a general view of the device,
• FIG. 2 is a section of the tube networks illustrating their method of manufacture and their location,
• FIG. 3 is a flat representation of the device, explaining its operation,
• and Figure 4 illustrates the connection mode of the distributor boxes.

The device, illustrated as a whole at Figure 1, has substantially the shape of a crown that we have to imagine placed around a housing cylindrical or conical shown elsewhere. This crown consists essentially of three networks of tubes 1, identical and each extending over a third of the circumference of the housing thus forming an almost entirely continuous surface. Each of the tube networks 1 includes six parallel tubes 2 and as an extension from one network to another and is completed by two distributor boxes 3 to which branch their tubes 2, which gives three pairs distributor boxes 3 adjacent to the limits of the three tube networks 1. The housings distributors 3 and the tubes 2 are supplied with gas heating or cooling by a network of conduits first comprising a single conduit 4 which is splits into a first conduit 5 which goes towards a first pair of distributor boxes 3, at the top in the figure, and in a second conduit 6 which itself splits into two conduits, one of which extends over 7 the lower right of the figure and supplies a second pair of enclosures dispensers 3 at this location, while the other is not visible in the figure but extends behind one of the tube networks 1 to connect to the third pair of distributor boxes 3, also invisible but located behind the lower left of the Fig. The ducts are chosen so that the three pairs of distributors 3 are supplied by equal gas flows at the same temperature: the lengths of conduit to travel to reach each pair of cases are all equal, the single duct 4 dividing at the junction of two networks of tubes 1, and the conduit 6 in the middle of one of these two networks of tubes 1; the conduit 5 extends over about a third of the circumference of the housing, and the duct 6 on a sixth in circumference, as well as the two conduits in which it splits.

Figure 2 shows that the tube networks 1 are composed of two corrugated sheets 8 returned and joined so that their corrugations 9 are opposite and come face to face to form the tubes 2. The corrugated sheets 8 have flat portions 10 adjoining corrugations 9, in contact when the 8 sheets are assembled and riveted or united by a other way. The tubes 2 are provided with orifices 11 directed to casing 12 to project gas there heating or cooling. This gas builds up in an annular chamber 13 delimited by the casing 12 and tube networks 1 but can escape from it by additional orifices 14 formed through of the adjoining portions 10. The hooks 15 of the housing 12, i.e. the ribs circulars to which we hang the sectors rings carrying the fixed vanes and the bearings 16 with an abradable layer which surrounds the blades mobile 17 of the rotor. As these hooks 15 are the portions of the casing 12 which directly determine the games at the tip of the blades, it is useful that the tubes 2 and their blowing orifices 11 are each located at face of one of them.

Figure 3 shows that the gas distribution each lead into one of the distributor boxes 3 adjacent pairs mentioned above and their content is spreading first in this distributor box 3 before a half goes into the other distributor box 3 in passing through a cuff 17 which joins them. The six tubes 2 of the networks of tubes 1 are alternately connected to one of the opposite 3 distributor boxes and located at the ends of these networks, so that the gas flows through three of tubes 2 in one direction and in the other three tubes 2 in the direction opposite: the gas heats up in tubes 2 as in the anterior device and therefore exits through the orifices 11 at increasing temperatures away from distributor boxes, but if we consider a generator of the casing 12, it receives gas from three tubes 2 having traveled a relatively long way and gas from three tubes 2 having traveled a path relatively short, i.e. both gas strongly heated and weakly heated gas and therefore a practically uniform quantity of heat: the object of the invention is thus achieved.

It remains to describe how the connection between the adjacent 3 distributor boxes supplied by the same conduit. If we come back temporarily in Figure 1, we see that the housings distributors 3 have protrusions 18 to the exterior and in extension, and that the conduits feed such as 5 and 7 end up in the alignment of these protrusions 18 and penetrate into one of them. As seen in Figure 4, the protrusions 18 each contain a socket 19 which partially delimits them, the sockets 19 being facing facing and connected by one of the cuffs 17; the cuff 17 is terminated by two spherical portions 20, open at their opposite ends 21 and which are able to roll and slide on the internal surface of sockets 19. Tube networks 1 and sockets 19 can therefore move mutually without producing more than a rotation or a sliding movement of the cuff 17 in sockets 19, and without sealing and even less the connection between distributor boxes 3 is broken. The cuff 17 must obviously be inserted sufficiently into the sockets 19 so that its extraction is impossible even if the networks of tubes 1 deviate; through elsewhere, the sockets 19 are provided with surfaces stop 22 which surround the cuff 17 and him prohibit moving indefinitely in the same direction, because it would come up against them. The surfaces stop 22 include a central opening 23 for allow the entry of gas into the boxes distributors 3. A connecting tube 24 is welded to one of these openings 23, and the other of the openings is free. The connecting tube 24 is connected to the conduit power supply such as 5 occupying only the half of its section, which guarantees the passage of the half of the gas flow in the distributor box 3 opposite, on the left in the figure, by the connecting tube 24, while the other half of the flow stops against the sleeve 19 and is forced back into the tubes 2 of the distributor 3 on the right. According to one last improvement, gas flow can be controlled by a progressive opening valve 25, controlled by a computer 26 depending on the speed reached, for adjust the gas flow rate supplied to the device and therefore the expansion undergone by the casing 12. The computer 26 can be informed by speed sensors, temperature, pressure, etc. who measure quantities present in the machine, and it uses these measurements using empirically established tables or formulas. We finally figured point 27 of sampling gas through the supply line 4; it's about usually from a point in the gas flow stream of the machine, from which part of the flow is withdrawn, in a manner widely known in the art.

Three networks of tubes 1 have been depicted; a different number of networks, spanning corresponding fractions of the housing circumference 12, remains possible; the tubes are shorter if the networks are numerous, which limits the path of gases and therefore their heating, but the characteristics of the invention precisely overcomes the consequences of this warming up, so it is no need to split the device a lot.

The invention will especially find utility on turbomachine turbines, where the hotter gases that elsewhere make it more necessary.

Claims (4)

1. Device for heating or cooling a circular casing (12) comprising networks (1) of tubes (2) surrounding the casing on respective circumference parts and comprising gas inlet manifolds (3) connected to the tubes (2) and gas outlet orifices (11) directed towards the casing, on the tubes, and a network (4, 5, 6) for distributing gas to the manifolds, in which the networks (1) of tubes are located between two of the manifolds (3), each of the said two manifolds being connected to a respective group of the tubes of the said network, and the network for distributing gas comprises pipes (5, 6) each opening into a pair of manifolds, characterized in that the manifolds of the pair are adjacent, associated with different networks of tubes and connected by a cuff (17) comprising two ends (20) in the shape of portions of spheres which are open and bear with sliding in sockets (19) delimiting the housings and provided with end stops (22) for the cuff (17) and in that the pipes (5, 6) opening into a pair of manifolds (3) are joined end-to-end to a pipe (24) occupying half of their cross section and extending as far as at least one of the sockets (19) passing through a stop surface (22) of the said socket (19).
2. Device according to Claim 1, characterized in that each of the networks of tubes is made up of two corrugated plates (8) which are assembled at portions (10) mid-way between corrugations (9), the tubes (2) being formed by the corrugations (9), and the parts mid-way between comprising orifices (14) for removing the gas.
3. Device according to Claim 1, characterized in that there are three of the networks of tubes (1).
4. Device according to Claim 1, characterized in that the gas distribution network (4, 5, 6) comprises a gradually opening valve (25) controlled by a computer (26).

Images