Harvesters – Motorized harvester – With condition-responsive operation
Patent
1998-10-05
2000-07-11
Will, Thomas B.
Harvesters
Motorized harvester
With condition-responsive operation
56DIG11, 172 7, 60413, 91390, 91173, 92 63, 92134, A01D 7528
Patent
active
060855010
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the adjustment of the lightening of a working unit of a machine, which working unit is carried by a carrying structure in such a way as to rest on the ground during work and be held away from the said ground when work is interrupted or during transport, it being possible for the said unit to be lowered so as to be brought to rest on the ground or to be raised so as to be brought away from the said ground by means of at least one hydraulic-energy converter fed by an oil-supply source through a hydraulic circuit.
By way of entirely non-limiting example, such machines may be encountered in the field of agriculture, civil engineering works, the upkeep of roads and verges, etc.
2. Discussion of the Background
The amount by which the working unit of such a machine is lightened is generally of great importance as regards the quality of the work done. Excessive lightening does not allow the working unit to remain continuously in contact with the ground. This will lead to uneven work. Insufficient lightening, on the other hand, in some cases increases the risk of clogging, increases the power that needs to be developed to move the working unit, and increases wear.
In the field of mowers, for example, it is known practice for the harvesting mechanism (working unit) to be lightened by means of a lightening device comprising at least one elastically deformable member, the action of which can be adjusted by means of an adjusting device coupled to the said elastically deformable member.
As elastically deformable members, it is known practice to use mechanical tension springs (GB 2 053 645 A), mechanical compression springs, torsion bars, deformable cushions filled with air (EP 0 570 315 A1) or nitrogen-filled accumulators combined with hydraulic rams (EP 0 149 870 A1).
The lightening provided by these elastically deformable members is generally adjusted manually and requires a number of tests, with work being interrupted, and this may lead to time being lost especially since, as the initial adjustment is carried out when the working unit is clean, there is the risk that it will soon become inappropriate during work as a result of a build-up of earth, for example.
Various solutions have already been proposed to facilitate this adjustment.
Described in document HP 0 149 870 A1 is a solution which consists in constantly measuring the pressure with which the working unit of a machine rests on the ground. The working unit is provided with a runner which is connected to it so that it can pivot. A piston and cylinder sensor is fitted between the said runner and the chassis of the working unit. A conversion device converts the pressure in the piston and cylinder sensor into an electrical signal which controls an electric motor. This electric motor drives a pinion which meshes with a rack actuating the rod of a compensation ram equipped with gas accumulators. This compensation ram is in communication with hydraulic rams fitted between the chassis of the working unit and the arms of the wheels via which the working unit runs along the ground.
When the pressure in the piston and cylinder sensor increases following an increase in weight of the working unit, the electrical signal created actuates the electric motor in a direction such that the pressure in the compensating ram and the hydraulic rams increases. This correction takes place entirely automatically until the correct pressure is achieved.
Described in document WO 86/00002 is a solution which consists also in measuring the pressure with which the cutting head (working unit) of a harvesting machine rests on the ground. The cutting head of this harvesting machine is carried by a chassis coupled to a tractor and comprising two wheels by means of which it runs along the ground. Each wheel is connected in a pivoting fashion to a corresponding side wall of the chassis by means of a wheel arm. A hydraulic ram associated with a hydropneumatic accumulator is fitted between each wheel arm and the
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Ermacora Rino
Guesdon Alain
Walch Martin
Wattron Bernard
Wilhelm Joel
Kuhn S.A.
Mammen Nathan
Will Thomas B.
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