Earth working – With actuator adapted to lift tool for transport on wheeled...
Reexamination Certificate
2000-02-09
2001-11-20
Batson, Victor (Department: 3671)
Earth working
With actuator adapted to lift tool for transport on wheeled...
Reexamination Certificate
active
06318477
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to agricultural vehicles and implements. More particularly, it relates to agricultural implements having wings pivoted to a frame. Still more particularly, it relates to control systems for controlling the pivotal motion of those wings.
BACKGROUND OF THE INVENTION
Agricultural implements that engage the ground, such as planters, harrows and rakes, are often formed in several laterally disposed sections. These sections are pivotally connected to each other for several reasons. First, and due to the great width of the implement, they cannot be pulled along a road without blocking several lanes of traffic unless they can be folded. Second, and also due to their great width, they cannot follow the ground contours of the field unless some vertical pivoting about a longitudinal axis of each section with respect to its adjacent sections is provided.
Implements formed as a series of laterally disposed, pivotally coupled sections suffer from several problems. First, they are difficult to turn. When traveling on the road, turning is not a serious problem since the wings can be completely pivoted to a position above a center section having a center frame, and the center frame can be supported on two or more support wheels. This arrangement permits easy turning. This folding process takes a great deal of time and thus is impractical to perform when turning at the end of each row in the field. At the end of the day, when the farmer has finished working a field, he can engage hydraulic cylinders that gradually lift the wings into this folded position. This may require releasing or engaging various linkages, making or breaking certain hydraulic connections, and emptying certain of the ground engaging tools on the wings that contain fertilizer, herbicides or seed. In short, converting the vehicle into an easy turning roadable configuration takes many minutes and may require the farmer to leave the cab of the vehicle. In a field of 200 acres, for example, the farmer may have to spend more time turning the vehicle at the ends of rows than he would spend actually working the ground.
A partial solution to the problem of difficult turning is to raise the wings about their pivot points, but only slightly. Typically, the hydraulic cylinders that raise the wings are engaged for a limited amount of time to lift the wings only slightly above the ground. This process can be performed in a matter of a few seconds and does not require the farmer to leave the vehicle. It also does not require the time consuming mechanical and hydraulic manual manipulations of the implement.
A second problem that implements with wings have is difficulty in properly distributing the weight of the implement equally over all the ground contacting tools. The center section of the implement typically includes a variety of additional components such as wheels, hydraulic motors, cylinders, bins, hoppers and towing tongue that are not found on the wing sections. A greater downwardly disposed force is applied by the collective weight of these components to each of the ground engaging tools supported on the center section than to those supported by the wings. As a result, the ground engaging tools supported on the center frame penetrate the ground to a greater extent. The center frame also applies a downwardly disposed force to the pivoted inner ends of the wings that it is connected to. This tends to force the inner ends of the wings downward and tends to allow a resistance of the soil to being penetrated to lift the outer, free, ends of the wings upward. The end result of this weight imbalance, then, is to prevent all the ground engaging tools on the center frame and on the wings from penetrating the ground to an equal depth.
One solution that has been proposed to this weight imbalance or “down pressure” problem is to add springs to the implement coupled between the center frame and the wings that are biased to pull the wings downward with respect to the center frame. In this manner, some of the weight of the center frame will be transferred to the wings and the ground engaging tools on the center frame and the on wings will tend to have a more nearly equal weight distribution.
Providing an implement having spring-based down pressure biasing of implement wings with hydraulic cylinders used to lift the wings slightly during turns in the field is difficult, and requires a complicated arrangement of linkages, cylinders and springs.
It would be beneficial, therefore, to provide an improved agricultural vehicle and implement arrangement with a wing lift and down pressure control. It is an object of this invention to provide such a improved system.
SUMMARY OF THE PRESENT INVENTION
In accordance with the first embodiment of the invention an agricultural implement configured to be towed by an agricultural vehicle is provided having a first frame with a plurality of spaced apart ground engaging tools, a second frame with a second plurality of spaced apart ground engaging tools that is pivotally coupled to the first frame, a first hydraulic cylinder coupled between the first frame and the second frame to pivot the first frame with respect to the second frame about a substantially horizontal axis, and a hydraulic control circuit fluidly coupled to the first hydraulic cylinder and including the pressure regulating valve configured to provide a supply of hydraulic fluid under substantially constant pressure to a first port of the first hydraulic cylinder over a range of pivotal positions of the first frame with respect to the second frame. The implement may also include a hydraulic pump configured to be driven by the agricultural vehicle and fluidly coupled to the pressure regulating valve to supply fluid to the first port of the first hydraulic cylinder at a substantially constant pressure. The hydraulic cylinder may have a first piston and a first piston rod coupled to that piston that extends out of the hydraulic cylinder, the piston and piston rod being movable to a fully extended position, a fully retracted position and an intermediate position between those two positions. The fully extended position defines a first frame raised position which the first frame is pivoted above the second frame. The fully retracted position defines the first frame lowered position in which the first frame is pivoted below the second frame and the intermediate position defines an intermediate frame position in which the first frame is pivoted above the second frame between the first raised and second lowered positions. A first hydraulic fluid port is provided in the hydraulic cylinder to lower the first frame when it is filled with hydraulic fluid. The hydraulic cylinder further has a second piston, and a second hydraulic fluid port that is disposed in the cylinder to raise the first frame when the second port is filled with fluid. This happens by driving the second piston toward the first piston a distance that is sufficient to engage the first piston and drive the first piston to the intermediate position. The hydraulic control circuit may include a first check valve located between the pump and the pressure regulating valve that responds to pressure applied to the second port thereby checking hydraulic fluid flow travelling from the pump to the pressure regulating valve. The hydraulic control circuit valve itself may include a hydraulic reservoir disposed on the implement to supply fluid to an inlet of the hydraulic pump and a second check valve located in the hydraulic line extending between the first port and the hydraulic reservoir to check hydraulic fluid flow from the first port to the reservoir through that line. In operation, increasing the hydraulic pressure applied to the second port preferably opens the second check valve and thereby permits the flow of hydraulic fluid from the first port to the reservoir. This increasing hydraulic pressure may also close the first check valve. The hydraulic control circuit may also have another hydraulic supply line that can be coupled to a hydraulic pump o
Batson Victor
Case Corporation
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