A MACHINE OF THE CENTRIFUGAL SPREADER TYPE FOR SPREADING GRANULAR AND POWDERY MATERIAL

Abstract: In a machine of the centrifugal spreader type for spread­ ing granular and powdery material, said machine having a hopper (5) for the material with a bottom (6) with an outlet opening (7), through which the material flows down­ wards on the rotating spreading disc (13), and in which the flow-through area of the opening (7) can be varied by means of two rotatably adjustable dosing plates (8,9), the framing edges (11,12) respectively of which limit the effective flow-through area in the opening (7), the new feature is that the adjustment mechanism (21-33) for the dosing plates (8,9) is so arranged, that not only is the angular distance (16) between the framing edges (11,12) varied, but also the angular position of the bisecting line (17) between the framing edges. In this manner, a substantially constant distribution pattern is achieved irrespective of the amount of material being spread per unit time.

Description: The present invention relates to a machine of the kind set forth in the preamble of claim 1. A machine of this kind is known from the German published specification No. DE-A-1,924,631. In this known machine, separate adjusting means are provided for mutually independent adjustment of the relative angular position of the two dosing plates and of the angular position of the two dosing plates as a whole relative to the machine frame, thus making it possible to change the size and position of the outlet opening independently of each other. Further, the framing edges in the dosing plates in this known machine are in the form of non-radial angled lines with a view to keeping the distribution pattern constant with varying size of the outlet opening. This arrangement does, however, suffer from two significant disadvantages, viz. a) that the separate adjusting means entail a risk of incorrect adjustment being made by less skilled operators, and b) that the use of non-radial framing edges makes the machine less adaptable to use with materials with different grain sizes, because the non-radial orientation of the framing edges causes the distance between opposing framing edges to be small, especially when the outlet opening is set to be small. It is the object of the present invention to provide a machine of the kind initially referred to, in which the disadvantages referred to above are avoided, and this object is achieved with a machine, which according to the present invention further exhibits the features set forth in the characterizing clause of claim 1. In this arrangement, an interdependent and simultaneous change of the magnitude and the angular position of the outlet opening is exploited to achieve a substantially constant distribution pattern, irrespective of whether the flow-through area of the outlet opening is large or small, so that a relatively large variation in the flow-through area of the outlet opening is accompanied by a relatively small variation in the angular position of the opening, exactly what is needed to compensate for that influence on the distribution pattern, which experience has shown that a change in the flow-through area will cause. By using radial framing edges, the disadvantages mentioned above in connection with non-radial edges are avoided. In order to achieve the desired interdependence between the effective magnitude and the angular position of the outlet opening, the adjustment mechanism may be arranged in any manner suitable for this purpose, e.g. also with devices including curved tracks or cams, but in practice it has proved expedient to use a mechanism consisting of arms and link rods in the same manner as in the known machine referred to above. A corresponding embodiment of the machine according to the present invention is thus of the kind set forth in the preamble of claim 2, and according to the present invention this machine also exhibits the features set forth in the characterizing clause of claim 2. In this manner it is possible to achieve the mutually opposite movements of the two dosing plates without the use of special mechanisms to reverse the movement. In addition, this embodiment provides a clear and simple construction, in which there is no risk of making wrong connections between the link rods, the dosing plates and the arms, such as after repair or maintenance work. The present invention will now be explained in more detail with reference to the exemplary embodiment of a machine according to the invention shown on the drawing, in which Figure 1 shows the machine seen from the right-hand side relative to the forward direction of motion, Figure 2 shows the machine of Figure 1 seen from above, and Figures 3a-c are partial views of the left-hand half of Figure 2 and show three different possible adjustments of the dosing plates. The exemplary embodiment shown on the drawing of a machine of the centrifugal spreader type according to the present invention comprises a chassis 1, that in a manner known per se by means of coupling members 2 and 3 may be supported on corresponding coupling members on a tractor (not shown), with which the machine is to be driven during use, the tractor then moving the machine in the direction of motion indicated with an arrow 4. In the chassis 1 there are suspended side-by-side two generally funnel-shaped hoppers 5, in the bottom 6 of each of which there is formed an outlet opening 7 shaped like a sector of an annulus. The effective flow-through area in the outlet opening 7 is determined by two dosing plates 8 and 9, in a manner not shown in detail supported for rotational adjustment about a vertical axis 10 extending through the hopper bottom 6, all in such a manner, that the dosing plates 8 and 9 are constantly being pressed against or held in a short distance from the lower side of the bottom 6, whilst their radially extending framing edges 11 and 12 extend beyond the radially extending edges of the outlet opening 7 and thus limit the effective flow-through area of this opening. Below the bottom 6 of each hopper 5 there is in a manner known per se situated a spreading disc 13 adapted to be rotated about the vertical axis 10 in the direction shown by an arrow 14 in Figure 2 by drive means 15 not shown in detail. In this manner, granular or powdery material (not shown) falling from the hopper 5 through the outlet opening 7 down onto the spreading disc 13 will in manner known per se be thrown out sideways and hence be spread out on the field. The amount of material being spread per unit of time depends amongst other factors on the effective flow-through area in the outlet opening 7, i.e. of the angular distance 16, cf. Figure 3, between the framing edges 11 and 12 on the dosing plates 8 and 9 respectively. The manner, in which the material is distributed on the field during the spreading operation, depends amongst other factors on the angular position of the bisecting line 17, in Figure 3 indicated by an angle 18 between the bisecting line 17 and a line 19 extending transversely to the direction of motion 4. Experience has shown that if the angle 18 is held constant and the angular distance 16 between the framing edges 11 and 12 is varied, not only is the amount of material being spread per unit time changed, but also the distribution of this material. In order to maintain the pattern of distribution constant to the greatest possible extent, independently of the amount of material per unit time, the machine is therefore arranged in such a manner, that the angular distance 16 and the angle 18 are varied simultaneously, and in the exemplary embodiment shown this is achieved by using adjustment means to be described in more detail below. To make it possible to adjust the dosing plates 8 and 9, each of them has an adjustment lug 21 and 22 respectively. The adjustment means further comprise two link rods 23 and 24 respectively, at their rear ends being connected to the adjustment lugs 21 and 22 and with their forward ends to a long arm 25 and a short arm 26 respectively, said arms being rigidly secured to a horizontally extending adjustment shaft 27, which is rotatably supported in a number of bearing lugs 28 on the chassis 1. On the adjustment shaft 27 there is further secured an adjustment arm 29, being connected through a link rod 30 to a further adjustment arm 31 on a short shaft 32 extending parallel to the adjustment shaft 27 and carrying an adjustment handle 33, the position of which may be read on a scale 34. In the position of the adjustment handle 33 shown in Figures 1 and 2 and in the position of the dosing plates 8 and 9 shown in Figure 2, there is an angular distance 16 as shown in Figure 3b between the framing edges 11 and 12 respectively of the dosing plates. If the adjustment handle 33 is moved forward, i.e. in the same direction as the arrow 4 shown in Figure 2, then the short shaft 32 and hence the adjustment shaft 27 will rotate clockwise as shown in Figure 1, for which reason the long arm 25 and the short arm 26 by means of the link rods 23 and 24 respectively will move the adjustment lugs 21 and 22 respectively on the dosing plates 8 and 9 respectively towards the rear, e.g. to the position shown in Figure 3a. Correspondingly, by moving the adjustment handle 33 in the opposite direction, it is possible to move the dosing plates 8 and 9 to the position shown in Figure 3c, in which the distance 16 is equal to zero, i.e. that the flow-through area of the outlet opening is equal to zero. As may be seen from Figures 3a-c adjustment of the adjustment handle will not only cause the angular distance 16 between the framing edges 11 and 12 to be changed, but will also produce a slight rotation of the bisecting line 17 about the vertical axis 10, i.e. a change of the angle 18 from the value - not necessarily its maximum value - shown in Figure 3a, through the intermediate value shown in Figure 3b to the minimum value shown in Figure 3c, at which the outlet opening 7 is closed. Experience has shown that by a suitable adjustment of the length ratio between the long arm 25 and the short 26 it is possible to achieve that the distribution of the material being spread remains essentially constant, irrespective of whether the angular distance 16 between the framing edges 11 and 12 is large or small. In the exemplary embodiment shown, the adjustment means comprise a long arm 25 and a short arm 26 having a fixed length ratio to each other, but it lies within the scope of the present invention to arrange both these two arms and the link rods 23 and 24 to be adjustable in length. Neither is the present invention limited to the use of arms (levers) and link rods to transmit the adjustment movements from the adjustment handle 33 to the dosing plates 8 and 9, as it is also possible to use means comprising curved tracks or cams to transmit the adjustment movements, provided, of course, that the criteria for the mutual dependence between the opening angle 16 and the angular position of the bisection line 17 are met. In Figure 2 the axis of rotation for the adjustment shaft 27 bears the reference number 35.

Claims: A machine of the centrifugal spreader type for spreading granular and powdery material and of the kind comprising a machine chassis (1) with a) at least one container (5) for the material to be spread, said container having b) a bottom (6) with at least one outlet opening (7), adjacent to which there are situated c) two dosing plates (8,9) supported for rotational adjustment about a substantially vertical axis (10), said dosing plates having framing edges (11,12) and depending on the adjustment of the dosing plates covering a greater or lesser part of the outlet opening (7) from each side of the latter, d) under each container (5) a spreading disc (13) being rotatably supported about said axis (10) and adapted whilst rotating to throw the material flowing out through the outlet opening (7) radially outwards, and e) an adjustment mechanism (21-33) connected to the dosing plates (8,9) of each container (5), said mechanism being adapted to rotate the dosing plates relative to each other and to the outlet opening (7), such that the framing edges are moved in a positive interdependence, characterized in that the framing edges (11,12) of the dosing plates (8, 9) extend substantially radially relative to the axis (10); and that said mechanism (21-33) is arranged to turn the radial centre line (17) of the angular distance (16) between the framing edges (11,12) about the axis (10) simultaneously with a change in the angular distance (16), and hence the effective flow-through area of the opening (7), between the framing edges (11,12), such that dosing plates (8,9) move to an unequal degree in mutually opposite directions. A machine according to claim 1 and of the kind, in which the adjustment mechanism (21-33) comprises two rigidly interconnected arms (25,26) being supported for rotation about a common, substantially horizontal axis (35), said arms (25, 26) through link rods (23,24) further being connected to an eccentric linkage member (21,22) on each of the two dosing plates (8,9) belonging to each container (5), characterized in that the two linkage members (21,22) on the dosing plates, as well as the link rods (23,24) and arms (25,26) of unequal length connected thereto, are placed on opposite sides of a plane extending through the first-mentioned substantially vertical axis (10) and transverse to the last-mentioned, substantially horizontal axis (35).

Inventors: NIELSEN, THORKILD
Applicants: A.P. LAURSEN A/S
Application year: 1989
Main classification: A01C17
IPC codes: A01C17