Earth working – Mast type hitch – Hitch quadrilateral modified during lift
Reexamination Certificate
2000-10-10
2001-11-27
Novosad, Christopher J. (Department: 3671)
Earth working
Mast type hitch
Hitch quadrilateral modified during lift
C280S456100, C280S477000, C280S482000
Reexamination Certificate
active
06321851
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a hitch mechanism for coupling implements to a utility vehicle.
There are various known hitch or implement coupling mechanisms for coupling an agricultural implement to an agricultural vehicle. One such hitch is the conventional three-point implement hitch, as it is defined by standards ISO 730 or DIN 9674. However, an implement cannot be steered with a conventional three-point hitch. There are guidance mechanisms, such as the Acura Trak from Senco Marketing, which can steer an attached implement, but these mechanisms do not permit a pure lateral shifting of an attached implement. U.S. Pat. No. 5,697,454 shows a mechanism which is pivoted about a vertical pin and which therefore does not permit sideways shifting. Furthermore, there are row guidance mechanisms such as, for example, the “Navigator” from the HR Manufacturing Company, which permit a sideways shifting, but do not provide any implement steering capability.
U.S. Pat. No. 3,432,184 describes a tractor implement hitch which has a triangular plate to which a triangular implement coupling plate can be fastened. Seven variable length actuators extend between the tractor frame and the plate, and have first ends connected to four connecting joints on the tractor frame. Two generally horizontal upper actuators are oriented in a V-shaped pattern with respect to each other and converge with their second ends at an upper joint of the plate. Two generally horizontal lower actuators are oriented parallel to each other and have second ends coupled to lower connecting points on the plate. Two inclined lifting actuators are oriented parallel to each other. They have first ends coupled to the first ends of the upper actuators and have second ends coupled with the second ends of the lower actuators. A lower stabilizing actuator is coupled between the first end of one lower actuator and the second end of the other lower actuator. This hitch is intended to permit rapid and simple attachment of an implements without requiring a precise alignment of the tractor to the implement. The actuators are also used to raise and lower the implement during operation. However, the functions of this hitch are limited. For example, with this hitch an implement cannot be shifted or steered sideways.
“Kinematik und Robotik”, by Manfred Husty, Adolf Karger, Hans Sachs, and Waldemar Steinhilper, published in 1997 by x. Springer-Verlag, pages 491-524, describes a mechanism which includes six variable length links coupled between a pair of triangular plates. In this mechanism the links form closed kinematic chains, wherein pairs of the links are connected to a common base or body. A similar mechanism has also been used to support and move a tractor cab in an off-road vehicle simulator, as described by Duncan and Wegscheid in “Off-Road Vehicle Simulation for Human Factors Research”, ASAE Paper No. 82-1610 (1982). However, these references do not show such a mechanism in use as a vehicle-implement hitch.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide a vehicle-implement hitch mechanism which permits a sideways steering function and a sideways shifting of the implement.
A further object of the invention is to provide such a hitch mechanism which reduces sideways forces transmitted from the implement to the vehicle during operation.
A further object of the invention is to provide such a hitch mechanism which accommodates motions with six degrees of freedom.
A further object of the invention is to provide such a hitch mechanism which enables easy coupling of implements.
These and other objects are achieved by the present invention, wherein a hitch mechanism for an agricultural tractor includes three pairs of links arranged in closed kinematic chains in such a way that an implement coupling frame can be moved with six degrees of freedom. A first end of each link is pivotally coupled to the vehicle body, and a second end of each link is pivotally coupled to the coupling frame. The links are loaded only in compression and tension, and not in bending. Preferably, the links are arranged in the form of a hexapod, such as described in German patent 197 20 049, or as described in ASAE Paper No. 82-1610 (1982).
The first ends of the links are connected to the vehicle in three pairs, each pair positioned near to corner points of a triangle. The second ends of the links are connected to a triangular implement coupler frame in three different pairs, each pair being positioned near to corner points of the frame. Ideally, two links would converge precisely in each of the corner points, where the two links include a relatively large angle towards each other, so that the forces transmitted by the links can be well controlled. However, such a common connecting joint of two links is difficult to design. For this and other reasons, it is advantageous that the link ends be arranged merely in the vicinity of the particular theoretical corner point of the triangle, so that the actual connecting joints of two links are located not exactly but only approximately at the corner points of the triangle.
This hitch can be mounted on the rear or the front of a utility vehicle, and with variable length links the coupling frame is movable with in six degrees of freedom (three rotations, three translations). With six degrees of freedom, various functions can be performed, which a known three-point hitches cannot perform. To provide a known three-point hitch with such additional functions would require additional mechanical repositioning arrangements or additional hydraulic cylinders had to be provided (for example, hydraulic upper steering arms, hydraulic lifting strut, hydraulic side stabilizers and others), but without the versatility of the present invention.
The length of the links can be selected largely independent of one another. The relationship of the lengths to each other can be adjusted as desired by an appropriate control. By an appropriate adjustment of each of the lengths of the links of this hitch mechanism, an implement can be shifted vertically, laterally and in the longitudinal direction of the vehicle. The implement may also be rotated about an axis transverse to the vehicle or about a vertical axis. The implement can also be rotated with respect to the utility vehicle about a longitudinal axis of the vehicle. With this hitch the implement may steered sideways or shifted sideways. Thus, in addition to providing the functions of a conventional three-point implement hitch (raising and lowering of an implement), this hitch mechanism also makes possible an easy coupling of implements to the utility vehicle, without the need for moving the entire vehicle or the implement. It is also possible by varying the lengths of the links to change the spacing between the rear (or the front) of the utility vehicle and the coupling frame, in addition to a height adjustment and a sideways adjustment. By the application of various couplers, implements may be coupled to the coupling frame. Thus, an automatic coupling and uncoupling of implements becomes possible when the vehicle is stopped.
Further, an implement can be steered and shifted sideways during its operation in order to reduce transmission of side forces to the tractor. By optimizing the side forces the maneuverability and the steerability of the complete system (tractor and implement) can be improved.
The angle between the longitudinal axis of the vehicle and that of the implement (as well as that between the implement and the ground) can be adjusted as desired. In particular, the adjustment angle between the implement and the ground can be readjusted independently of the lifting height, or it can be retained as constant over a large range of lifting heights.
With this hitch the implement may be pivoted during travel. The implement can also be shifted sideways, for example, in order to shift the center of gravity of the entire system toward the slope while operating on a slope. A reduction of the turning radius and an improvement in the maneuverabilit
Bernhardt Gerd
Fedotov Sergiy
Weiss Heinz
Wünsche Mario
Deere & Company
Novosad Christopher J.
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