AGRICULTURAL IMPLEMENT WITH POWER INPUT HAVING CONTINUOUSLY VARIABLE TRANSMISSION

A crop baler has a plunger reciprocable through compression and retraction strokes for compressing charges of crop material into bales within the baler. The crop baler also includes a rotatable flywheel operably coupled with the plunger for transferring kinetic energy to the plunger during reciprocation of the plunger. An output shaft is operably coupled with the flywheel for rotating the flywheel and driving the plunger through its compression and retraction strokes and an input shaft is adapted to be coupled with a power takeoff shaft of a towing tractor for receiving driving power from the tractor. The crop baler also includes a continuously variable transmission operably coupled between the input and output shafts for adjusting the ratio of the angular velocities of the shafts in response to changes in the angular velocity of the flywheel while maintaining the input shaft at a substantially constant angular velocity.

Corresponding reference characters indicate corresponding parts throughout the views of the drawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A mobile baler10may advantageously comprise a Large Rectangular Baler of the type manufactured and sold for many years by AGCO Corporation of Duluth, Georgia under the HESSTON and MASSEY-FERGUSON brand names, for example. Balers of this type are generally disclosed in U.S. Pat. Nos. 5,226,356; 5,540,144; and 7,448,196, for example, which patents are hereby incorporated by reference in their entireties into the present specification for a further understanding of the nature and operation of the baler10.

For purposes of the present invention, suffice it to point out that baler10includes a wheeled chassis having a forwardly projecting tongue12that adapts the baler to be hitched to a towing tractor14for traversing a field having windrowed crop materials lying thereon. A pickup16lifts such materials off the ground as the baler advances and, in cooperation with other mechanism not shown, delivers the materials in successive charges to packaging apparatus within the baler for forming the materials into large “rectangular” bales that issue from the open, but constricted, rear end18of the baler. Among other things, the packaging apparatus includes a reciprocating plunger20that operates within a baling chamber of the machine to compact successively introduced charges of crop materials rearwardly against previously compacted materials to build a bale and incrementally push it toward and through the open rear end18of the baler.

Power for operating plunger20is obtained from an engine22of the tractor14via a PTO shaft24. A drive train on baler10for transmitting power from tractor engine22to plunger20is broadly denoted by the numeral26and connects at its forward end to PTO shaft24for receiving operating power therefrom. Drive train26includes, in relevant part, a continuously variable transmission28, an input shaft30operably coupled at its front end to PTO shaft24and at its rear end to transmission28, an output shaft32operably coupled at its front end to transmission28, and a large, heavy flywheel34operably coupled to the rear end of output shaft32and rotated thereby. Drive train26further includes a gear box36that receives rotational input from flywheel34, a pair of output cranks38(only one being shown) on opposite sides of gear box36, and a pair of pitman rods40(only one being shown) connected at their front ends with cranks38. Pitman rods40are operably coupled at their rear ends with plunger20.

Although continuously variable transmission28may take a variety of different forms without departing from the principles of the present invention, one suitable transmission is a toroidal type continuously variable transmission available from CVT Corporation of Sainte-Julie (QC) Canada. In addition to various mechanical components, transmission28also includes a control system that includes a suitable programmable controller42that renders transmission28capable of very quickly adjusting the ratio of the angular velocities of input and output shafts30,32to maintain a substantially constant angular velocity on the input shaft30and PTO shaft24notwithstanding fluctuations in the angular velocity of the flywheel34due to loading. Controller42may be software, hardware, and/or firmware and configured to determine and regulate the ratio of the velocities of input and output shafts30,32. Preferably, controller42is located on baler10but could comprise part of a unit mounted on tractor14having a display and an operator interface.

A number of suitable sensors, such as a flywheel speed sensor44, an engine speed sensor46, and an engine power sensor48are provided for inputting information into controller42for use in determining the appropriate relative velocities of input shaft30and output shaft32. Controller42receives the input signals, quickly processes the information to determine the appropriate shaft ratios, and quickly outputs appropriate commands for adjusting the angular velocity of output shaft32while maintaining the velocity of input shaft30substantially constant.

It will be appreciated that as a result of having the continuously variable transmission28installed in drive train26between tractor PTO shaft24and flywheel34, nearly constant tractor engine speed and power can be realized while providing variable speed output to flywheel34. Transmission28is able to overspeed flywheel34during the plunger retraction stroke to store additional energy for the next compression stroke. By quickly adjusting the output velocity of transmission28while maintaining the input velocity substantially constant, cyclic loading of the tractor engine and related components can be significantly reduced, and the flywheel's top speed and corresponding peak energy are limited by the tractor engine's maximum power, not its top speed.

The foregoing has broadly outlined some of the more pertinent aspects and features of the present invention. These should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Other beneficial results can be obtained by applying the disclosed information in a different manner or by modifying the disclosed embodiments. Accordingly, other aspects and a more comprehensive understanding of the invention may be obtained by referring to the detailed description of the exemplary embodiments taken in conjunction with the accompanying drawings.