Rotary charging device for shaft furnace

A rotary charging device for a shaft furnace comprising: a stationary housing (16) and a suspension rotor (22) that is supported so that it can rotate about a substantially vertical axis (A), a charge distributor (28) being pivotally suspended to the suspension rotor (22). Rotary drive means are provided for rotating the suspension rotor about its axis (A) and tilting drive means for pivoting the charge distributor (28) about a substantially horizontal pivoting axis (B), independently from said rotary drive means. The tilting drive means are mounted onto the suspension rotor (22) and rotate therewith; they comprise: an electric tilting motor (MB) is installed inside the main casing (36) and having a substantially horizontal output shaft (52); a tilting input gear (54) driven by the tilting motor output shaft; and a tilting output gear (56) rotationally integral with a suspension arm (34) of said chute distributor (28), said tilting input gear meshing with said tilting output gear.

FIELD OF THE INVENTION

The present invention generally relates to a charging installation for a shaft furnace and in particular to a rotary charging device for distributing charge material in a shaft furnace. More specifically, the invention relates to the type of device that is equipped with a chute for circumferential and radial distribution of the charge material.

BACKGROUND OF THE INVENTION

Rotary charging devices using a chute for circumferential and radial distribution of the charge material have been known for several decades, mainly thanks to the present Applicant who brought the BELL LESS TOP® to industry in the early 1970s.

Such a rotary charging device is e.g. described in U.S. Pat. No. 3,693,812. It comprises a suspension rotor and a chute adjustment rotor that are supported in a stationary housing so as to be rotatable about a substantially vertical rotation axis. The chute is suspended to the suspension rotor so that it rotates with the latter for circumferential distribution of charge material. Furthermore, the chute is suspended to be pivotally adjustable about a substantially horizontal axis for radial distribution of charge material. The suspension rotor and the adjustment rotor are driven by a differential drive unit that is equipped with a main rotation drive, namely an electric motor, and an adjustment drive, namely an electric motor. The latter allows creating differential rotation between the suspension rotor and the adjustment rotor. A pivoting mechanism is provided for angular adjustment of the chute. This mechanism, which is connected to the chute and actuated by the rotor, transforms a variation in angular displacement between the suspension rotor and the adjustment rotor due to differential rotation, into a variation of the pivotal position i.e. the tilt angle of the chute.

The rotary charging device of U.S. Pat. No. 3,693,812 is further equipped with a drive unit for driving the two rotors. This unit is enclosed in a casing arranged on the stationary housing that supports the rotors and the chute. The casing has a primary input shaft; a secondary input shaft; a first output shaft, hereinafter called rotation shaft; and a second output shaft, hereinafter called adjustment shaft. The primary input shaft is driven by the main rotation drive. Inside the casing, a reduction mechanism connects the primary input shaft to the rotation shaft, which extends vertically inside the stationary housing where it is provided with a gearwheel that meshes with a gear ring of the suspension rotor. The adjustment shaft also extends vertically into the stationary housing where it is provided with a gearwheel that meshes with a gear ring of the adjustment rotor. Inside the casing of the drive unit, the rotation shaft and the adjustment shaft are interconnected by means of an epicyclic differential mechanism, i.e. a sun-and-planet gear train. The latter mainly comprises a horizontal annulus (ring gear) that has external teeth meshing with a gearwheel on the rotation shaft; a sun gear that is connected to the secondary input shaft; at least two planet gears that mesh with internal teeth of the annulus and with the sun gear. This sun-and-planet gear train is dimensioned so that the rotation shaft and the adjustment shaft have the same rotational speed imparted by the main rotation drive when the secondary input shaft is stationary, i.e. when the adjustment drive is at stop. The adjustment drive is a reversible drive and connected to the secondary input shaft. By virtue of the differential mechanism, the adjustment drive allows driving the adjustment shaft at a faster and at a lower rotational speed than the rotation shaft to thereby produce a relative i.e. differential rotation between the suspension rotor and the adjustment rotor. The pivoting mechanism transforms such differential rotation into pivoting motion of the chute.

Such rotary charging device with distribution chute has proven very successful in industry and various manufacturers have developed their own versions. In the majority of designs, the drive motors, drive unit, the rotation shaft and adjustment shaft are arranged vertically, generally on the top of the stationary housing. As described above, the rotation drive may be achieved relatively easily by a pinion engaging a ring gear attached to the supporting rotor. The tilting drive is more complex as the torque provided by the vertical electric motor has to be converted in such a way to be able to pivot the distribution chute about the horizontal axis. In this regard, the design of the tilting mechanism has led to many developments, using connecting rods, cables, or hydraulic cylinders and specially designed gears. In particular, the tilting drive unit described above is a key component of the device for distributing charge material. Since it is custom made, it represents a significant part of the total cost of the device. Moreover, in order to ensure continuous operation of the furnace when the drive unit requires servicing or major repair, a complete spare unit is typically kept in stock by the furnace operator.

Over the years, the motivations that lead to the development of new designs where:improving the compactness of the device, in particular for small/medium blast furnace installations;improving the reliability of the rotary and tilting drive mechanisms;facilitating the access to the stationary housing, which may be difficult complicated by the various external casings mounted thereto;reducing the quantity of casing openings (seals, gaskets . . . );improving the reliability of the rotary and tilting drive mechanisms.

In EP 0 863 215 it has been proposed to actuate the chute by means of an electrical motor arranged on the rotating part (suspension rotor) that supports the chute. This solution eliminates the need for a highly developed mechanical gear arrangement for varying the chute inclination. It does however require means for electric energy transfer, from the stationary part to the rotatable part, in order to power the electric motor on the chute-supporting rotor.

The solution provided in EP 0 863 215 seems however unfinished and inappropriate for practical use to face the harsh industrial condition, with substantial dust and heat. The power supply to the tilting drive is another problem, not addressed therein.

BRIEF SUMMARY OF THE INVENTION

The invention provides an alternative design of rotary charging device allowing an easy control of the distribution chute, with simple and robust mechanics.

According to the present invention, a rotary charging device comprises:

a stationary housing for mounting on the throat of the shaft furnace;

a suspension rotor in said stationary housing that is supported so that it can rotate about a substantially vertical axis, said suspension rotor and stationary housing cooperating to form the main casing of said rotary charging device;

a charge distributor pivotally suspended to said suspension rotor;

rotary drive means for rotating the suspension rotor about its axis;

tilting drive means for pivoting said charge distributor about a substantially horizontal pivoting axis, independently from said rotary drive means, wherein:

said tilting drive means are mounted to said suspension rotor so as to rotate therewith, and

a tilting motor, preferably an electric motor, is installed inside the main casing and has a substantially horizontal output shaft, and

a tilting input gear is driven by said tilting motor output shaft, and a tilting output gear is rotationally integral with a suspension arm of the chute distributor, said tilting input gear meshing with said tilting output gear.

The invention hence provides a rotary distribution device for shaft furnaces where the rotational and tiling drives can be separately/independently controlled. It shall be appreciated that the tilting motor with associated driving gearing/means are arranged inside the main housing and carried by the suspension rotor so as to rotate therewith. Depending on the embodiment, the tilting motor can be directly supported by the suspension rotor, or laterally deported to be carried along by the suspension rotor as it rotates, whereby in both cases it is arranged so as to rotate with the suspension rotor.

The present rotary distribution device has many benefits:the tilting and rotary drive means are decoupled/independent, which facilitates the mechanical design of the transmission mechanisms;the horizontal installation of the tilting motor frees up some space in the region above the stationary housing;the tilting motor is arranged inside the main casing and thus protected from the harsh outside environment.

Preferably, the suspension rotor comprises a cylindrical body and a substantially horizontal bottom flange; such configuration is however not limitative and other designs may be used. The tilting drive means may thus be mounted onto and supported by this bottom flange. The installation of the tilting motor (with its output shaft horizontal) on the suspension rotor's bottom flange greatly simplifies the tilting drive mechanism, in particular because it is no longer required to transform the rotation of a vertical shaft into a horizontal movement.

In general, the rotary drive means may comprise a rotary motor, preferably electric motor, which may be mounted outside or inside the stationary housing (with its output shaft vertical or horizontal) and operatively coupled to the suspension rotor by a main transmission. The rotary motor may e.g. be mounted so that its output shaft is substantially vertical and said main transmission comprises a input gear driven by said output shaft and meshing with a toothed ring coaxial with and rotationally integral with said rotary support.

However, as for the tilting motor, the rotary motor is preferably mounted laterally to the stationary housing, preferably inside the main casing, so that its output shaft is substantially horizontal. In such case, the rotary drive means may comprise a main transmission with an input gear driven by the rotary motor's output shaft and meshing with a toothed ring coaxial and rotationally integral with the rotary support. The lateral arrangement of the rotary motor again frees up some space above the rotary distribution device and reduces its height. The overall height of the top charging equipment above the blast furnace is thus reduced, also meaning a reduction of costs. As described below, depending on the embodiment, the overall height of the stationary housing may be reduced by about 1 m, from 1.5 m down to 0.5 m.

In a particularly compact embodiment, the toothed ring of the rotary drive means is fixed to an inferior side of the suspension rotor's bottom flange and the input gear driven by the rotary motor is arranged below the bottom flange so as to mesh with said toothed ring. In such embodiment, the suspension rotor may be rotationally supported by a rolling bearing mounted to the top ring of said shaft furnace, one race of said rolling bearing being fixed to the inferior side of the suspension rotor's bottom flange.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1shows the main elements of a first embodiment of rotary distribution device10for distributing bulk charge material (“burden”) into a shaft furnace, especially onto the stock-line of a blast furnace. As it is known in the art, the device10is part of a top charging installation and is arranged to close the top opening of the reactor, e.g. on the throat12of the blast furnace. The distribution device10is fed with charge material from one or more intermediate storage hoppers (not shown), e.g. according to a configuration as disclosed in WO 2007/082633. InFIG. 1, a funnel14guides the charge material discharged from the hoppers into the rotary distribution device10.

The distribution device10has a fixed structure forming a stationary housing16sealing mounted to the furnace throat12, which includes a fixed external casing18that extends between upper and lower flange structures20a,20b. In the variant ofFIG. 1, the stationary housing16is fixed by its lower flange structure20bto the top ring21of the furnace throat12, which constitutes a machined flange.

Inside the housing16, a suspension rotor, generally identified at22, is rotationally mounted about a substantially vertical rotation axis A that corresponds e.g. to the blast furnace axis. This can be carried out by means of a large-diameter annular rolling bearing24, generally a roller bearing and preferably a slewing bearing, supported by the stationary housing structure16and extending circumferentially about axis A.

The burden material discharged from above the device10and guided by funnel14flows through a central channel26in the device10and arrives at the distribution chute generally identified at28. The inner dimensions of the central channel26generally depend on the cross-section of the suspension rotor22. However, a feeding spout30is preferably arranged inside the suspension rotor22and fixedly mounted to the stationary housing16. The axial extent of the feeding spout30may depend on the design. In the present variant the feeding spout30extends from the top opening32of the device10down to the chute28. Since the feeding spout30is here placed inside rotor22, the cross-section of channel26depends on the feeding spout30.

The distribution chute28is mounted to the suspension rotor22so as to rotate in unison therewith about axis A. The chute28actually comprises a pair of lateral suspension arms34(or trunnions) by means of which it is suspended, in a known manner, to mounting bearings (not shown) in rotor22and that further allow its tilting/pivoting about a horizontal axis B. The chute28being generally installed in the lower region of the feed channel26, the burden material—having entered the distribution device10at its top—falls, through rotor22, into the chute28to be distributed in the furnace.

As it will be understood, the suspension rotor22and the stationary housing16cooperate to form the main casing36of the rotary charging device10and hence define a substantially closed annular chamber surrounding the central feed channel26. In this connection, it may be noticed that in all of the figures the suspension rotor22is shown with dashed lines for the sake of illustration only, it does not imply that it should have some traversing openings in its body/bottom parts. In some cases, the main casing36may comprise one or more inner partition walls extending on whole or part of the circumference, as will be discussed below.

It may be noticed that suspension rotor22comprises a tubular support or body38that is arranged coaxial with the rotation axis A and that actually supports the chute28. The tubular body38extends vertically in the central channel26and is operationally connected and supported by one race of the rolling bearing24, the other race being fixedly attached, in this embodiment, to a fixed annular wall39of structure16. Rotor22advantageously comprises a bottom40formed as an annular flange. The bottom40has a, amongst others, a protective function by forming a kind of screen between the interior of the main casing36and the interior of the furnace. The bottom40of the suspension rotor22extends laterally/radially in close proximity of the bottom flange structure20bof the stationary housing16.

Rotary drive means are provided for rotating the suspension rotor22about its axis A. It comprises an electric motor MR, which is here fixed to the top of the housing16(outside thereof) with its output shaft46vertically arranged. The rotary motor MRis operatively coupled to the suspension rotor22by a main transmission. The main transmission may include an input gear48fixed on the output shaft46that drives a toothed annular ring50surrounding and rotationally integral with the suspension rotor22. Toothed ring50is preferably fixed to the bearing race supporting rotor22.

It shall be appreciated that the device10further comprises tilting drive means, independent from the rotary drive means, mounted to the suspension rotor22in such a way as to rotate therewith. Preferably, the tilting drive means are arranged on the bottom flange40of the rotor22.

The tiling drive means comprise a tilting motor MB, preferably an electric motor, installed in the main casing36and having a substantially horizontal output shaft52. A tilting input gear54is driven by the tilting motor output shaft52, whereas a tilting output gear56is rotationally integral with one pivoting arm34of the chute distributor28, the tilting input gear54meshing with the tilting output gear56. Preferably, the tilting motor output shaft52is substantially parallel to the pivoting axis B and preferably substantially aligned therewith, although not required.

In practice, the input gear54may be a wheel with external toothing while the output gear56may take the form of a concave toothed segment integral with the chute arm34. Input gear54may be directly mounted to the output shaft52of motor MB. However, a reduction gear set60is preferably arranged to operatively couple the motor's output shaft52and the input pinion54, the latter being thus mounted on an intermediate tiling shaft62. Reference sign64indicates one bearing that supports rotating shafts62, but more such bearing may be employed. Although not shown, appropriate equipment may be used to support and fix the above-described main parts of the rotating and tiling drive means.

Preferably, for ease of control, the tiling drive means comprise similar drive means on both sides of the chute28, which rest on the bottom40and rotate therewith.

A partition wall37divides the main chamber36into two concentric, annular sub-chambers361,362.

In use, the distribution chute28can thus be rotated about vertical axis A through actuation of rotary motor MR. The distribution chute is also pivotable about the horizontal axis, for adjusting the tilting angle of the chute and reaching various radiuses. As it will be understood, when the rotary motor MR is actuated, the rotor turns around axis A with the tilting drive means that it carries; the tilting drive means are fixed to the bottom40and there is no relative rotation about axis A between the tilting drive means and rotor22.

The present rotary distribution device10has many benefits:the tilting and rotary drive means are decoupled/independent, which facilitates the mechanical design of the transmission systems;the horizontal installation of the tilting motor MBfrees up some space in the region above the stationary housingthe installation of the tilting motor MBon the suspension rotor's bottom flange40greatly simplifies the tilting drive mechanism, in particular because it is no longer required to transform the rotation of a vertical shaft into a horizontal movement;the tilting motor MBis arranged inside the main casing36and thus protected from the harsh outside environment.

Rotating electric motor MRis fixed and can be easily connected to a power source. The tilting motor MB, which rotates with rotor22, requires appropriate electric supply. Slip rings may be used to transfer power from the fixed housing portion to the rotating bottom. A contact-less solution such as an inductive power supply is however preferred, one for each motor MB. Accordingly, an inductive coupling device may be used, which includes a stationary inductor70fixed to the stationary structure16and a rotary inductor72fixed to the rotor22, e.g. at the periphery of bottom40. The stationary inductor70and the rotary inductor72are separated by a radial gap and configured as rotary transformer for achieving contact-less electric energy transfer from the stationary support16to the rotor22by means of magnetic coupling trough the radial gap for powering tiling motor MBarranged on rotary bottom40and connected to rotary inductor72. Such inductive coupling device are known in the art and have been described e.g. in WO 2008/074596; they will therefore not be further described herein.

Conventionally, the present rotary charging device may be equipped with any appropriate means to prevent the entrance of dust into the main casing36. A nitrogen over-pressure may e.g. be maintained in the main casing36. Seals, e.g. water seals, may also be arranged so as to close the operating gaps between the rotor22and the corresponding regions of the stationary housing16.

FIG. 2shows a second embodiment10′, which differs from that ofFIG. 1by the horizontal mounting of rotary motor MR. Rotary motor MRis fixed with its output shaft substantially horizontal and arranged outside the main casing36. This requires a minor change of the configuration of input gear48, now vertical and ring gear50that has its teeth facing upwards instead of radially.

FIG. 3shows a third embodiment10″, which is similar to that ofFIG. 2in that motor MRis horizontally mounted. Rotary motor MRis thus fixed with its output shaft horizontal, but the motor MRis here arranged inside the main casing36.

The removal of the rotary motor MRfrom the top of the stationary housing16allows reducing the height of the device10and freeing up some space in this region where it is desirable to have access for maintenance on the rotary distribution device10itself (e.g. for chute maintenance/replacement) or on the storage hoppers and associated valves located just above the rotary distribution device10. Moreover, it facilitates the access to motor MR.

Turning now toFIG. 4, a third embodiment of the present device110is shown where the rolling bearing124(slewing ring) is mounted directly on the top ring121(machined flange) of the furnace top cone112. As compared toFIG. 1, same or similar elements are indicated by same reference signs, augmented by100. One race of rolling bearing124is thus fixed to the top ring121, while the other is fixed to the lower surface of bottom140. As in the other embodiments, the tilting drive means are carried by the rotary bottom140and preferably supplied by means of an inductive coupling device with cooperating inductors70,72. The tilting drive means are preferably symmetrically arranged and include a reduction gear set (not shown) coupled to the tilting Motor's output shaft152. The output shaft152is rotationally integral with an input gear154. In this embodiment however, to further reduce the height of the device110above the furnace top cone113, the output gear156connected to the pivoting arm134of the chute128is arranged below the input gear154, in a recess155provided in bottom40. Rotary motor MRis also arranged inside main casing136, preferably with tilting motor MBinside a sub-chamber137delimited by an annular partition wall174extending from the top flange120adown to the level of the tilting shaft152.

One will also notice the peculiar shape of rotor122that, in this variant, has a horizontal wall portion176extending from the feed channel towards the interior of the main casing136. The ring gear150associated with the rotor122is fixed at the outer end of said wall portion176.

The embodiment110′ illustrated inFIG. 5is quite similar to that ofFIG. 4, with a similarly configured suspension rotor122′. The suspension rotor122′ is however suspended by way of a rolling bearing124arranged in the upper part of the device110′, one race being affixed to the upper flange structure120aand the other race being connected to the horizontal wall portion176of suspension rotor122′.

To even further reduce the height of the rotary distribution device and hence of the top charging installation, the rotary motor MRcan be arranged below the tilting motor MB, as shown in the embodiment ofFIG. 6. Same or similar elements are identified by same reference signs, augmented by100with respect toFIG. 4. Here, again, one rolling bearing224only is required, and mounted directly onto the top ring221of the blast furnace top cone212. The suspension rotor222has a short cylindrical body238, as compared toFIG. 1, since room above bottom240is only required for accommodating the tilting drive means and fixing the chute228. As inFIG. 4, the rotary bottom240is directly supported by one race of rolling bearing224, while the cooperating race is fixed to the top ring221. The arrangement of the tilting drive means on the bottom240is also similar toFIG. 4.

A substantial reduction in height is thus provided by the arrangement of the fixed rotary motor MRbelow the tilting motor MB, respectively below the rotary bottom240. In practice, it is considered that a reduction of height of about ⅔ can be achieved, leading to a total height (between lower220band upper220aflanges) of the rotary distribution device of about 0.5 m.

In this variant, toothed ring250is preferably fixed directly to the lower side of bottom240, or on a short spacer sleeve. Motor MRis horizontally arranged and has on its horizontal output shaft246an input gear248meshing with toothed ring250.

FIGS. 7 and 8describe two alternative embodiments where the rolling bearing324(slewing ring) is mounted to the lower flange320bof the stationary housing316. The lower flange320is conventionally fixed to the furnace throat312, e.g. at its top ring321. Identical or similar elements are designated with same reference signs as compared toFIG. 4, augmented by200.

The suspension rotor322is supported by rolling bearing324, one race of which is fixed to the lower side of rotor bottom340, e.g. in the region of its periphery, the other directly to the lower flange320bor optionally via a support member (not shown).

The tilting drive means are mounted to the bottom340of suspension rotor322, however closer to the chute328. The output gear356is located below the tilting input gear354, as in the variant ofFIG. 4but without recess in the bottom340.

The rotation drive means includes its fixed electric motor MRand has an input gear348cooperating with a ring gear350attached to a horizontal wall portion376of rotor of rotor322.

In the embodiment ofFIG. 7, an annular wall portion374is fixed to the upper flange320aof the stationary housing316and divides the main casing336into separate, outer and inner annular chambers. The rotary motor MRis thus arranged in the outer annular sub-chamber and the tilting motor MBin the inner annular chamber.

By contrast, in the embodiment ofFIG. 8presenting a laterally compact solution, both motors MRand MBand located in the main casing336, without sub-division. It may be noticed that in the embodiments ofFIGS. 4 to 8, the tilting output gear156,256or356is shown below the input gear154,254,354in the recessed rotor flange140. But the bottom flange140could also be flat, and the tilting output gear arranged above the input gear, as inFIG. 1.

FIG. 9presents an embodiment rotary distribution device410similar to that ofFIG. 7, where the rolling bearing424is however located in the upper region of the stationary housing416. As compared toFIG. 7, identical or similar elements are indicated by same reference signs, augmented by100. The design of the stationary rotor422and the tilting and rotating drive arrangements are similar toFIG. 7.

Rolling bearing424has one race fixed to the upper flange420aof stationary housing416and the other race fixed to the suspension rotor422, e.g. to the upper wall476.

The embodiment410′ ofFIG. 10differs slightly fromFIG. 9in the tilting drive means, where the output gear456is located above the input gear454.

Turning now toFIG. 11, the configuration is the same is inFIG. 10, but further shows a possible realization of an additional cooling system480. The cooling system comprises a rotary circuit portion482fixed on the suspension rotor422and a stationary circuit portion484fixed to the stationary housing416, here actually to an annular, L-shaped wall portion475. During operation, the rotary circuit portion482rotates with the suspension rotor422, whereas the stationary circuit portion484remains immobile with the housing416. The rotary circuit portion482comprises any suitable heat exchanger, e.g. a heat exchanger comprising several cooling pipe coils486, that are arranged on the suspension rotor422. The coils486are in thermal contact with the rotor's body portion438and its bottom flange440, on the side of the main casing436, in order to cool parts of the charging device410′, which are most exposed to the furnace heat. In addition, the rotary circuit portion482also provides cooling of the drive and gear components arranged in the housing416.

Although not shown inFIG. 11, the rotary circuit portion482may comprise additional cooling pipes/coils, e.g. for cooling the distribution chute428itself, or any other suitable kind of heat exchanger configuration. Cooling systems for rotary distribution devices are well known in the art and will not be further described herein. For further details on cooling system, one may refer to WO 2011/023772, which is herein incorporated by reference. In this connection, the cooling system480is preferably further configured to achieve forced circulation of coolant (e.g. water) from the stationary circuit portion484to the rotary circuit portion482and vice-versa, while the latter portion482rotates relative to the former portion484. To this effect, the cooling system480may include an annular swivel joint488, which fluidically couples both circuit portions482,484. The annular swivel joint488is provided in an upper portion of the stationary housing416, e.g. on the horizontal part of fixed annular wall portion475, other locations being possible. The swivel joint488is of generally annular configuration and arranged coaxially on axis A, e.g. so as to surround the feed channel426.

A last embodiment is illustrated inFIG. 12. The same elements as inFIG. 1are indicated by same reference signs, augmented by500. This embodiment differs in that the tilting Motor MBis radially deported and no longer rests directly on the rotor's bottom flange540. This requires a different configuration of the tilting drive means. Although the tilting motor MBis not installed on the rotor flange540, it is carried along by the rotor522as it rotates. Therefore, the tilting motor MBhas its output shaft552horizontally arranged and supported on a large diameter annular rolling bearing594fixed to the flange structure520b, that allows rotation of motor MBall over the circumference. Tilting Motor MBis preferably arranged behind an intermediate wall595, with an annular slot596for the output shaft552. The motor's torque is transmitted to the tiling shaft562mounted to the rotor bottom540by a transmission mechanism comprising: an intermediate shaft597having an intermediate gear597aand a worm597bfixed thereto. The intermediate gear597ameshes with a drive pinion598mounted to the output shaft594. The worm597bmeshes in turn with a worm wheel599mounted at end of the tilting shaft562. The other end of tilting shaft562carries the input gear554meshing with the output gear556rotationally integral with the chute's suspension arm534.

A few remarks remain to be made regarding all of the above-described embodiments.

For the sake of simplicity and clarity of drawing, most embodiments have been described on the basis of a half-cross sectional view, specifically a section view on the left of axis A. In these half-cross sectional views, only one suspension arm of the distribution chute is shown, with the tiling motor MBand associated transmission. It should however be understood that in practice, the tilting drive means preferably comprise two similar tilting drive means with horizontal tiling motors MBand appropriate transmission connected each to a respective suspension arm of the distribution chute. The use of similar tilting drive means on opposite sides of the distribution chute is shown inFIGS. 1 and 3.

Another common aspect of the various embodiments is the power supply. Preferably, an inductive power supply is used to supply the tilting motors MB. The rotating motor MRbeing fixed, it can simply and efficiently be powered by wire. Nevertheless, when installed inside the main casing, one could also use a non-wired power supply as for the rotating tilting motors MB.

In some of the Figures, both supply possibilities for MRare illustrated; the following notation is used:the wired power supply is designated90,190,290,390;and the inductive power supply is generally indicated192,292,392,492.

Finally, as described with respect toFIG. 1, the present rotary distribution devices may advantageously be equipped with any appropriate means to prevent the entrance of dust into the main casing36, e.g. by means of a nitrogen over-pressure. In addition, seals, e.g. water seals, may be arranged so as to close the operating gaps between the rotor22and the corresponding portions of the stationary housing16.