Patent Publication Number: US-6213275-B1

Title: Device for distributing materials in bulk with a rotary chute having a variable angle of inclination

Description:
The present invention relates to a device for distributing materials in bulk with a rotary chute having a variable angle of inclination. It relates more particularly to a device for distributing materials in bulk comprising a chute, a first rotor with a substantially vertical rotation axis, on which the chute is suspended so that it can pivot about a substantially horizontal pivoting axis, and a second rotor, having a rotation axis substantially coaxial with said first rotor. 
     Such devices for the distribution of materials in bulk are used, for example, in devices for charging shaft furnaces, particularly blast furnaces. The rotary and pivoting chute provides for the distribution of the charge over a charge surface inside the shaft furnace. 
     In the device described in the preamble, the first rotor essentially rotates the chute about a vertical axis. The second rotor interacts with the chute so as to fix its angle of inclination to the vertical. For this purpose, the second rotor is connected to the chute through a pivoting mechanism converting a variation in angular displacement between the two rotors into a variation in the angle of inclination of the chute in its vertical plane of pivoting. 
     Different variants have been proposed for the embodiment of this pivoting mechanism, which generates the torque required to pivot the chute about its horizontal pivoting axis and which transmits this torque to the chute. 
     The patent U.S. Pat. No. 3,766,868 proposes a device of the type described in the preamble in which a linking rod located in the pivoting plane of the chute is coupled at one end to the rear surface of the chute. The other end of this linking rod is guided in a sinusoidal guiding track on the second rotor. 
     The patent U.S. Pat. No. 3,814,403 proposes a device of the type described in the preamble in which the second rotor comprises an annular gear. The latter, through the intermediary of a first pinion, drives a worm which, through the intermediary of a second pinion, acts on a sector gear fixed laterally on to a suspension journal for the chute. 
     The document U.S. Pat. No. 4,368,813 proposes a device of the type described in the preamble in which the rotor also comprises an annular gear. The first rotor carries a worm drive. The input shaft of the latter is provided with a pinion which meshes with the annular gear of said second rotor. The output shaft is parallel to the pivoting axis of the chute and is equipped with a crank. A connecting rod. contained in the pivoting plane of the chute, is coupled at one end to the rear surface of the chute and at the other end to the crank. 
     The document U.S. Pat. No. 4,941,792 proposes two devices of the type described in the preamble. A first embodiment uses a pivoting lever supported by the first rotor so that it can pivot in the pivoting plane of the chute. This pivoting lever is connected to the second rotor by means of a linking rod having ball-and-socket joints. The chute comprises two lateral suspension journals each of which is provided with a crank. A forked linking rod connects the pivoting linking rod to the two cranks on the chute. In the second embodiment the second rotor supports an annular segment gear which cooperates with a sector gear attached to a lateral suspension journal on the chute. 
     The document U.S. Pat. No. 5,002,806 proposes a device of the type described in the preamble in which the second rotor is connected to a crank attached to a lateral suspension journal on the chute using a linking rod having ball-and-socket joints. 
     The objective of the present invention is to propose a simple and compact device making it possible to transmit large pivoting torques to the rotary chute. In conformity with the invention, this objective is achieved by a device according to claim  1 . 
     A device for distributing materials in bulk according to the invention comprises a first rotor and a second rotor having a common substantially vertical rotation axis. Said first rotor carries two suspension bearings, in which a distribution chute is suspended so that it can pivot about a substantially horizontal pivoting axis. The device also comprises a gear transmission, which is also carried by said first rotor. This transmission comprises an input shaft and an output shaft. The input shaft is fitted with a pinion which meshes with an annular gear of said second rotor. The output shaft of the transmission is parallel to the pivoting axis of the chute. According to an important feature of the present invention, the output shaft incorporates two cranks, while the chute is fitted with a pivoting lever at the level of each of its suspension bearings. Each of these two pivoting levers is then connected to one of the two cranks of the gear transmission by means of a connecting rod. A difference between the angular rotational speed of the first rotor and that of the second rotor produces a rotation of the input pinion of the gear transmission about its own axis and hence also a rotation of the two cranks carried by the output shaft of the transmission. These two cranks then symmetrically transmit, through the intermediary of the above-mentioned pair of connecting rods and levers, the pivoting torque to the chute. This makes it possible to transmit large pivoting torques to the rotary chute with a simple and compact device. 
     Such a distribution device will usually comprise a fixed vertical charging duct positioned so as to pour the material in bulk into the chute. Said first rotor then advantageously comprises a vertical suspension sleeve which surrounds the fixed charging duct and is provided at its lower end with a horizontal flange. The latter carries the bearings for the suspension of the chute and the gear transmission on its upper surface. 
     The gear transmission is advantageously symmetrical with respect to a symmetry plane of the two suspension bearings. It comprises a worm drive or an equivalent system of gears having an input shaft and an output shaft perpendicular to each other. The worm drive has the particular advantage that it can easily be designed to be self-locking, so that the torque due to the weight of the chute will not be taken up by the second rotor. 
     When the device according to the invention is installed in a furnace, it will advantageously include a casing provided at its lower end with a fixed screen. This screen is then provided with a circular opening into which a flange of said first rotor is fitted. A gas injection pipe is positioned along said circular opening so as to be able to inject a cooling gas into a hollow space of the flange. A cooling system for the device may also include a cooling circuit positioned in an annular space between said first rotor and the fixed vertical charging duct used to pour the material in bulk into the chute. 
    
    
     Other special features and characteristics of the invention will emerge from the detailed description of an advantageous embodiment, described below as an illustrative example, referring to the appended drawings. These show: 
     FIG.  1 : a vertical cross-section through a device for the distribution of materials in bulk according to the invention; and 
     FIG.  2 : a horizontal cross-section through the line labelled  2 — 2  in FIG.  1 . 
    
    
     The device for distributing materials in bulk  10  shown in the figures is more particularly intended to form part of a feeding device for a shaft furnace, such as a blast furnace, represented schematically by its upper end  12 . 
     The device  10  comprises an outer casing  14 , which is mounted in an impervious manner on the upper end  12  of the shaft furnace. This casing  14  is provided with a fixed charging duct  16 , which is substantially coaxial with the vertical axis  18  of the shaft furnace. In the casing  14 , a first rotor  20  is suspended by means of a first large-diameter roller ring  22 . This first rotor  20  comprises a vertical suspension sleeve  24 , which surrounds the fixed charging duct  16  and is provided, at its lower end, with a horizontal flange  26 . A second large-diameter roller ring  28  is used to suspend the second rotor  30  in the casing  14 . This second rotor  30  surrounds the first rotor  20 , and its rotation axis is coaxial with the rotation axis of the first rotor  20 . 
     The two rotors  20  and  30  are driven in rotation about their common rotation axis by a driving device denoted in general in FIG. 1 by the reference number  32 . It comprises a first pinion  34 , which meshes with an annular gear  36  of the first rotor  20 , and a second pinion  38 , which meshes with an annular gear  40  of the second rotor  30 . With the help of two motors  41  and a differential mechanism  43 , which are installed outside the casing  14 , this driving mechanism  32  is suitable for driving the two rotors  20 ,  30  either with perfectly synchronised rotational speeds or with different rotational speeds. 
     The reference number  42  denotes a chute for the distribution of materials in bulk through the charging duct  16 . This chute  42  is suspended from the first rotor  20  by means of two suspension bearings  44 ,  46  so that it can pivot about a substantially horizontal pivoting axis. The suspension bearings  44 ,  46  are positioned on the flange  26  of the first rotor  20  on either side of its suspension sleeve  24 . At the level of each of its suspension bearings  44 ,  46 , the chute  42  is equipped with a pivoting lever  48 ,  50  protruding upwards with respect to the suspension bearings  44 ,  46 . 
     The reference number  52  denotes in a general way a gear transmission carried by the flange  26  of the first rotor  20 . This transmission  52  comprises an input shaft  54 , which is parallel to the rotation axis of the two rotors  20 ,  30  and which is provided with a pinion  56  which meshes with an annular gear  58  of the second rotor  30 . It also comprises an output shaft  60 , which is itself parallel to the pivoting axis of the chute  42 , and comprises two free ends, each of which is equipped with a crank  64 ,  66 . A worm drive  62  interconnects the input shaft  54  and the output shaft  60 , so as to convert a rotation of the vertical input shaft  54  into a rotation of the horizontal output shaft  60 . Two connecting rods  68 ,  70  connect the two cranks  64 ,  66  symmetrically to the pivoting levers  48 ,  50  of the chute  42 . It follows that a rotation of the input pinion  56  of the gear transmission  52  produces a rotation of the cranks  64 ,  66 , which is converted by the connecting rods  68 ,  70  and the pivoting levers  48 ,  50  into a pivoting of the chute  42 . Now, the input pinion  56  rotates if there is a difference of angular speed between the first rotor  20  and the second rotor  30 . To make the chute  42  pivot from a first inclined position into a second inclined position, it is therefore sufficient to drive the second rotor  30  at an angular speed different from the first rotor  20 . To make the chute rotate with a constant angle of inclination, it is sufficient to drive the second rotor  30  with the same angular speed as the first rotor  20 . It should be appreciated that the device described makes it possible, with a relatively simple and compact equipment, to transmit appreciable pivoting forces to the chute  42 . 
     It remains to indicate a few important details about the protection of the distribution device  10  against the heat prevailing inside the furnace  12 . It should first be noted that the flange  26  of the first rotor  20  is positioned with a small working clearance in a circular opening in a lower screen  72  of the casing  14 . This lower screen  72  is provided with insulation  74  and with a closed cooling circuit  76 . The flange  26  itself is provided on its lower side with insulation  80  which is separated from the upper metallic flange  26  by a hollow space  82  open at the side. This hollow space  82  is cooled by injecting a gas through a circular duct  84 , which is positioned along the edge of the circular opening in the lower screen  72 . The first rotor  20  is advantageously cooled by a cooling circuit  86  positioned in the annular space remaining between the sleeve  24  of the first rotor  20  and the fixed charging duct  16 . The annular space in which the second rotor  30  and the gear transmission  52  are placed is advantageously cooled by injection of a gas.