Variable speed drive system for a system for a rotor assembly of a grain threshing mechanism

A grain threshing mechanism including a power source having a preselected rotational speed, a concave assembly and a device operably connecting the concave assembly in driven communication with the power source for rotation thereby, a rotor assembly positioned for independent rotation within the concave assembly, and a drive system connecting the rotor assembly in driven communication with the power source for rotation thereby, the drive system including the transmission and a planetary gear set, the transmission being operable for selecting at least one predetermined rotational speed range for the rotor assembly and the planetary gear set being operable for varying the rotational speed of the rotor assembly within the at least one predetermined rotational speed range.

TECHNICAL FIELD 
The present invention relates generally to drive systems for grain 
threshing mechanisms and more particularly to a drive system for a rotor 
assembly of a rotating concave grain threshing system which is operable to 
vary rotor assembly speeds throughout one or more selectable speed ranges. 
BACKGROUND ART 
In farming, an incentive exists to improve harvest efficiency. The overall 
effectiveness of agricultural harvest machinery is dependent upon a 
combination of its design, reliability, and operating conditions. The 
primary functional objective of harvesting equipment such as combines is 
to collect the crop in the minimum amount of time with the least losses 
and product damage and the lowest capital and operating costs. However, 
the combine encounters a wide range of harvesting situations and crops. 
Because of these factors and the potential return obtainable for 
performance improvements, development of a more effective drive system for 
the grain threshing mechanism of the combine is desirable. 
One known development in grain threshing systems is the rotating concave 
threshing mechanism which utilizes a rotor assembly positioned within a 
rotating concave assembly, each driven independently and rotatable in a 
selected direction one relative to the other. This improved mechanism has 
increased the productivity and efficiency of threshing grains, but, owing 
to its construction, is susceptible to stalling when encountering physical 
properties of the material entering the mechanism which tend to overload 
the system. 
Physical properties which can generate stalling of the threshing system 
when encountered at normal operating speeds of the system, are for 
example, intermittent high density of the crop, scattered patches of weeds 
having exceedingly high moisture content, crops which have been broken 
down by high winds, hail, and rain, and solid articles such as rocks and 
wood that are delivered to the threshing system when attempting to harvest 
such "downed" crops. 
Previously used methods of preventing stalling or plugging the threshing 
mechanism are, for example, slowing down the feed rate of material 
delivered to the threshing mechanism by slowing down the feeder chain, 
adjusting the forward speed of the combine, and reversing rotational 
direction of the rotating concave assembly to clear plugs. These methods 
have been found to be relatively ineffective in maintaining productivity 
and efficiency. 
One characteristic of the rotating concave threshing mechanism is the 
rotating speeds required for the rotor assembly. Generally, only a few 
speeds are required and it is known to employ multi-ratio transmissions in 
rotor assembly drive systems to provide selectability of predetermined 
rotor assembly speeds. However, for a more productive and efficient 
operation, it is desirable to have still greater flexibility in speed 
selection. Some known threshing systems provide an infinitely variable 
speed capability. Infinitely variable speed drive systems, however, tend 
to be bulky, complex, have short component life, and are expensive. 
Thus, what is needed is a drive system for the rotor assembly of a combine 
threshing mechanism that provides the capability to selectably drive the 
rotor assembly within several distinct speed ranges. 
The present invention is directed to overcome one or more of the problems 
as set forth above. 
DISCLOSURE OF THE INVENTION 
In one aspect of the invention, a grain threshing mechanism as disclosed 
including a power source having a preselected rotational speed, a concave 
assembly and means operably connecting the concave assembly in driven 
communication with the power source for rotation thereby, a rotor assembly 
positioned for independent rotation within the concave assembly, and a 
drive system connecting the rotor assembly in driven communication with 
the power source for rotation thereby, the drive system including the 
transmission and a planetary gear set, the transmission being operable for 
selecting at least one predetermined rotational speed range for the rotor 
assembly and the planetary gear set being operable for varying the 
rotational speed of the rotor assembly within the at least one 
predetermined rotational speed range.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring to FIGS. 1 and 2, a combine 10 of this invention has a header 12 
for receiving cut crops which have been cut by a sickle 14. The cut crops 
(not shown) fall into the header 12 and are transported by an auger 16, a 
portion of which is shown, or other means for moving the cut crops through 
a discharge port 18 into a crop feeding apparatus or feederhouse 20 
located beneath a operator compartment 22 in a conventional manner. The 
feederhouse 20 transports the cut crops from the header 12 into a rotating 
concave threshing mechanism 24. 
The rotating concave threshing mechanism 24 includes a rotor assembly 26 
positioned within a concave assembly 28 with cut crop passing from the 
feederhouse 20 into an annulus 30 between the rotor assembly 26 and the 
concave assembly 28. 
A drive system 32 is connected to and associated with the concave threshing 
mechanism 24 for rotating the concave threshing mechanism 24 during the 
threshing operation. As will be discussed hereinafter in reference to FIG. 
2, rotor assembly 26 and concave assembly 28 are connected independently 
in driven communication to a power source, which in this case is an engine 
34 having a preselected rotational speed such that rotor assembly 26 and 
concave assembly 28 are rotatable in a desired direction one relative to 
the other. Engine 34, in this example, is a diesel engine having a 
preselected rotational speed of approximately 2200 revolutions per minute 
(RPM) referred to herein as the engine operating speed. 
Briefly discussing the driving connection of engine 34 to concave assembly 
28, referring first to FIG. 2, engine 34 is connected in driving 
communication to a clutch 36 which in turn is connected in driving 
communication to a first drive shaft 38, clutch 36 being engageable to 
transfer motive power from engine 34 to first drive shaft 38 in the 
conventional manner. A drive gear 40 is mounted on first drive shaft 38 
for rotation therewith and is meshed in driving communication with a drive 
gear 42 mounted on a second drive shaft 44 for rotation therewith. Second 
drive shaft 44, in turn, is connected in driving communication to a 
hydrostatic transmission 46 (FIG. 1). Referring to FIG. 1, hydrostatic 
transmission 46 is connected in driving communication to a third drive 
shaft 48 having a first pulley 50 mounted thereto for rotation therewith. 
A second pulley 52 extends around the outer periphery of concave assembly 
28 and an endless belt 54 encircles the first pulley 50 and second pulley 
52. In operation, with clutch 36 engaged, engine 34 rotates first drive 
shaft 38 and drive gear 40, which in turn rotate drive gear 42 and second 
drive shaft 44 to provide power to hydrostatic transmission 46. In turn, 
hydrostatic transmission 46 is operable to rotate third drive shaft 48, 
first pulley 50 and second pulley 52 to thereby rotate concave assembly 
28. It is recognized that other types of variable speed drives could be 
used to drive the third drive shaft 48. For example, the drive could also 
be electric or friction drives. 
Referring again to FIG. 2, the portion of drive system 32 for driving rotor 
assembly 26 includes a planetary gear system 56 connected in driven 
communication to first drive shaft 38, and a transmission 58 connected in 
driven communication with planetary gear system 56. Planetary gear system 
56 includes a ring gear 60 connected in driven communication with first 
drive shaft 38, a sun gear 62, and planet gears 64 meshed with both ring 
gear 60 and sun gear 62. Planet gears 64 are mounted for rotation on a 
carrier 66. Sun gear 62 is mounted on one end of a fourth drive shaft 68 
for rotation therewith, the opposite end of fourth drive shaft 68 being 
connected in driven communication to a hydraulic motor 70 powered by a 
hydraulic pump or other suitable device (not shown). Hydraulic motor 70 is 
operator controlled using conventional means (also not shown) located in 
operator compartment 22. Fourth drive shaft 68 in turn is mounted for 
independent rotation in a central passage 72 extending through an input 
shaft 74 of transmission 58. Input shaft 74, in turn, is mounted in driven 
communication to carrier 66 of planetary gear system 56. It is recognized 
that the drive and driven connections of the planetary gear set 56 could 
be changed. For example, the input shaft 38 could be connected to the 
carrier 66 and the input shaft 74 connected to the ring gear 60. It is 
recognized that an electric or friction drive could replace the hydraulic 
motor 70. 
Transmission 58 is a manual transmission of conventional construction and 
operation having three selectable operating ratios and including a first 
input gear 76, a second input gear 78 and a third input gear 80 mounted on 
input shaft 74 for rotation therewith and selectably engageable 
respectively with a first output gear 82, a second output gear 84, and a 
third output gear 86, output gears 82, 84, and 86, each being mounted on 
an output shaft 88 for rotation therewith. Referring back to FIG. 1, 
shifting between the gears of transmission 58 is accomplished in the 
conventional manner using a simple ratio selector mechanism 90 which is 
operator controlled using conventional means (not shown) located in 
operator compartment 22. Output shaft 88 of transmission 58 is coupled in 
driving communication with a fifth drive shaft 92 by a coupler 94, and 
rotor assembly 26 is mounted on fifth drive shaft 92 for driven rotation 
therewith by output shaft 88. 
In operation, driving engagement of first gear 76 with first output gear 82 
as shown provides about a 4.2 to 1 ratio of rotational speed between input 
shaft 74 and output shaft 88, such that, if the input shaft rotational 
speed equals the engine operating speed of about 2200 RPM, output shaft 
rotational speed and correspondingly the rotational speed of rotor 
assembly 26, will be about 500 RPM, which has been found to be a desirable 
speed for threshing large grains such as corn and soy beans. 
With second gear 78 drivingly engaged with second output gear 84 (not 
shown), a ratio of about 2.8 to 1 between the rotational speed of input 
shaft 74 and output shaft 88 and consequently rotor assembly 26 is 
achieved. With input shaft 74 rotating at the engine operating speed of 
2200 RPM, the rotor assembly 26 will rotate at approximately 750 RPM, 
which has been found to be desirable for threshing intermediate size 
grains such as wheat, flax, milo and oats. 
Then, with third gear 80 drivingly engaged with third output gear 86 
(again, not shown), a ratio of about 2.1 to 1 between the rotational speed 
of input shaft 74 and output shaft 88 is achieved, which, with input shaft 
74 rotating at the engine operating speed of 2200 RPM, means that the 
output shaft 88 and rotor assembly 26 would rotate at about 1000 RPM, 
which is a desirable speed for threshing small grains such as rape, grass 
and clover. 
In operation, it is generally desirable to maintain engine 34 operating at 
the preselected rotational speed of about 2200 RPM for maintaining 
constant power to hydrostatic transmission 46 which powers concave 
assembly 28 and other devices receiving power from second drive shaft 44, 
while, at the same time, it is desirable to vary the rotational speed of 
rotor assembly 26 for accommodating different harvesting situations such 
as different crop densities, moisture contents and crop damage to maintain 
harvesting productivity and efficiency at desired levels. In this regard, 
it has been found that the capability to vary the rotational speed of 
rotor assembly 26 by about plus or minus 10% from the 500 RPM, 750 RPM and 
1000 RPM speeds discussed above is sufficient variability to maintain most 
desired harvesting productivity and efficiency levels. This can be 
achieved using planetary gear system 56 which is operable to vary the 
rotational speed of input shaft 74 relative to engine rotational speed 
under the control of hydraulic motor 70. That is, hydraulic motor 70 is 
operable to rotate the fourth drive shaft 68 and sun gear 62 to cause 
input shaft 74 of transmission 58 to rotate either faster or slower 
relative to first drive shaft 38, depending on the direction of rotation 
of fourth drive shaft 68 and sun gear 62. In this regard, rotating fourth 
drive shaft 68 and sun gear 62 in the same direction as input shaft 74 has 
the effect of increasing the rotational speed of carrier 66 and input 
shaft 74, thereby proportionally increasing the rotational speed of output 
shaft 88, fifth drive shaft 92 and rotor assembly 26. Conversely, rotating 
fourth drive shaft 68 and sun gear 62 in the opposite direction with 
respect to first drive shaft 38 has the effect of slowing down the 
rotation of carrier 66, input shaft 74 and correspondingly output shaft 
88, fifth drive shaft 92 and rotor assembly 26. 
Industrial Applicability 
The variable speed drive system for a rotary assembly of a grain threshing 
mechanism according to the present invention provides a simple, reliable 
apparatus for maintaining operability and efficiency of a grain threshing 
system under changing conditions such as when harvesting intermittently 
high density crops; when harvesting crops containing scattered patches of 
weeds with high moisture content; and when harvesting downed crops such 
that solid articles are delivered to the threshing system. 
Additionally, the present variable speed drive system can utilize a wide 
variety of transmission constructions in addition to the three ratio 
manual transmission discussed above, including manual transmissions having 
a lesser or a greater number of gear ratios, different gear ratios, and 
also power transmissions. Still further, while the present drive system 
provides a variability of about plus or minus 10%, other variable ranges 
can be selected and utilized with equal utility. 
Other aspects, objects, and advantages of this invention can be obtained 
from a study of the drawings, the disclosure, and the appended claims.