Harvesters – Motorized harvester – Having driven means for handling or treating crop
Reexamination Certificate
2003-03-04
2004-08-24
Will, Thomas B. (Department: 3671)
Harvesters
Motorized harvester
Having driven means for handling or treating crop
Reexamination Certificate
active
06779326
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a spring system for the upper feeder rollers in forage harvesters; in particular in a feeder device for a self-propelled forage harvester.
BACKGROUND OF THE INVENTION
Spring systems are encountered in feeder systems for forage harvesters, which in the predominant number today are equipped with two lower feeder rollers carried in bearing point fixed in the feeder casing and two upper feeder rollers working together with these. The upper feeder rollers designated in the following as prepressing rollers, are carried in bearing points in the feeder casing so that their height can be altered, in order to be able to move upwards on the drawing in of harvested crop. In doing so the spring system has the task of applying a defined roll force to the prepressing rollers and to the pressing rollers, so that in conjunction with the lower feeder rollers they can on the one hand compress the crop on being drawn in and on the other hand with the aid of this roll force make possible at all the drawing-in of the crop and its transport to the cylinder chopper.
Because of the increase in performance of forage harvesters required in recent years, ever higher demands are made upon their feeder equipment, which has led on the one hand to ever wider feeder devices and higher lift heights of the prepressing roller and of the pressing roller and to a further increase in the feeding speed of the crop. These higher demands can then be fulfilled only if through the spring system the roll forces exerted by the prepressing roller and the pressing roller on the crop are at least so great that the crop cannot be pulled in from the chopper cylinder. But on the other hand they must not be so great that not just any greater accumulation of crop leads to blockages in the feeder device. The roll forces must increase significantly with growing layer thickness of the crop as a result of friction of the crop on the sidewalls of the feeder device. In the region of smaller layer thickness on the other hand, they must be kept small so that particularly in the case of the maize harvest the grains are not knocked out of the cob by too high roll forces which in the case of large chopped lengths has a particularly negative effect. Finally it is still to be pointed out that the roll forces are applied not only by the spring system, but also by the forces of reaction from the driving moment of the prepressing rollers and the pressing rollers, upon which the roller weights and frictional forces are dependent when raising and lowering them. The greater proportion comes, however, from the spring system, followed by the forces of reaction. The remaining quantities are practically negligible.
For the fulfilment of these requirements already multitudes of spring systems have become known. One of them is to be seen in the Prospectus of the German firm CLAAS for the forage harvester series “Jaguar 880 to 820” with the note “11/20 (Rihn) German 70/CVG 1106.1”. Here on the shafts of the prepressing roller and of the pressing roller, on the right side viewed in the direction of travel of the forage harvester, a gearbox is placed, which is equipped at the front with a console, on which two tension springs placed inside each other engage. Their point of suspension lies plainly in front of the shaft of the prepressing roller. A single further tension spring engages from below on the gearbox about in the centre between the prepressing roller and the pressing roller. On the other hand the arrangement of the tension springs is similar, only for reasons of space they are located somewhat further up, and instead of engaging with the gearbox the tension springs engage with the oscillating crank between the prepressing roller and the pressing roller. For damping unwanted oscillations two shock absorbers are fixed on both sides of the spring system.
A disadvantage with this system is that the differences in the roll forces for a thin and a thick layer of crop are not great enough, so that either with a roll force which is set too small the crop is conveyed ever worse with increasing thickness of the layer, or in the converse case the grains are knocked out of the cobs already before the chopper cylinder. Through the described position of the attachment points of the tension springs, on the one hand it is to be criticised that with every movement of the prepressing roller the magnitude of the roll force of the pressing roller changes and the converse, because of which both roll forces are undefined. On the other hand this attachment leads to an oscillating motion of the prepressing roller and the pressing roller about the point of attachment of the tension springs, so that the aforementioned shock absorber would be necessary, which represents a cost-increasing factor. Finally with these spring systems there is yet another disadvantage, that the tension springs and the lower stops of the prepressing roller and the pressing roller lie in a zone very much endangered by dirt, so that the tension springs can no longer return to their initial lengths and on the lower stops an interfering quantity of crop collects. The consequence of this is a restricted output of the crop with a small layer thickness.
A second variant embodiment for a spring system on a feeder device for forage harvesters was made known with EP 0 797 914 B1 and as an amplification of this in the prospectus belonging to this forage harvester with the note “62027/D00—Printed in Italy—12/96”, in which likewise as with CLAAS on the shafts of the prepressing roller and the pressing roller a gearbox is put on. Almost centrally on the gearbox or on the oscillating crank between the prepressing roller and the pressing roller on the left side there is a pivot point, to which is attached an upwards projecting connecting rod, the upper end of which is likewise joined articulated with a swivelling lever, the other end of which ends in a bearing point attached to the casing of the feeder device. In a forwards projecting connecting bracket on the connecting rod a tension spring is suspended by its upper end and is fixed with its lower end to the front on the easing of the feeder device. As this spring system exhibits the same disadvantages as afore-described one, to avoid repetition reference will be made at this point only to this one.
A third possibility for the design of a spring system for the upper feeder rollers is expounded in EP 1 151 658 A1. The only difference from the two previously described ones consists in that instead of two upper feeder rollers three are employed here. As the coupling of the two tension springs on each side is in principle executed the same as for the two previously described spring systems; the same disadvantages apply here too.
In the prospectus of the German firm MENGELE with the note “WA FITZEK/1/94—10” a self-propelled forage harvester of the type “MAMMUT” with a feeder device and spring system for the upper feeder rollers is depicted. Here the roll force acting on the prepressing roller is produced by two tension springs, and that for the pressing roller is produced by a tension spring one on each side. Although here the directions of pull of the tension springs in the lowest position of the prepressing roller and of the pressing roller appear at first glance to be somewhat more favourable than in the three previously described spring systems, it is nevertheless to be criticised, that with the differently large excursions the position of the tension is so far removed from the shafts of the rollers, that every movement of the prepressing roller changes the magnitude of the roll force of the pressing roller and vice versa. In the same way the disadvantage remains of the too small difference in the roll forces for a thin and a thick layer of crop. Also the soiling of the tension springs and of the lower stops is unavoidable here, so that also the disadvantages associated with this exist.
Finally, reference would be made to the feeder device with upper feeder rollers and a spring system in accordance with DE-OS 26 09 27
Depestel Bernard E. D.
Desnijder Dirk J.
Möller Ralf
Teetaert Pierre E.
New Holland North America Inc.
Stader John William
Torres Alicia
Webb Collin A.
Will Thomas B.
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