CA1141627A

CA1141627A - Hydraulic system for harvesting machines

Info

Publication number: CA1141627A
Application number: CA000327680A
Authority: CA
Inventors: Norman G. Stroup; Eugene J. Krukow
Original assignee: Individual
Current assignee: Case LLC
Priority date: 1978-09-05
Filing date: 1979-05-15
Publication date: 1983-02-22
Also published as: UST986004I4

Abstract

IMPROVED HYDRAULIC SYSTEM FOR HARVESTING MACHINES

ABSTRACT OF THE DISCLOSURE
An open center hydraulic system in which a pair of flow divider valves is connected in series with the system's hydraulic pump to create a parasitic pressure upstream of these flow valves and the feeder and separator cluthces are controlled remotely by simple solenoid actuated two-position valves. The cylinders actuating the clutches are of sufficient size upon application of the minimum parasitic pressure to hold the clutches in a given position so that no center neutral position is necessary on the two-position valves.

Description

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IMPROVED HYDRAULIC SYSTEM _OR HARVESTING MACIIINES

BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a hydraulic 5 circuit for a harvesting machine generally, and more speciEically to an open center type hydraulic system for a harvesting machine with a simplified control for the feeder and separator mechanisms in such machines.
In a harvesting machine, e.g. a combine, having 10 a feeder mechanism and separator mechanism, there is need to provide the operator with the ability to independently engage and disengage the mechanisms. Obviously, the controls for such engagement and disengagement must be located in the operator's compartment in close proximity 15 to the operator. For hydraulic actuation of these mech-anisms, the prior art has either located a valve bank near the operator's compartment, which undesirably moves a heat source in close proximity thereto, or extended mechanical linkages and/or cables between the operator's compartment 20 and a valve bank located remote therefrom.
With open center hydraulic systems, the pressure in the system will drop to that level determined by the friction losses between the pump outlet and the reservoir and all valves in the system are in their center neutral 25 position. In the prior art, this has necessitated em-ploying three-position valves with a center neutral position that hydraulically locks the cylinders controlled by the valves, which valves are expensive.
The present invention seeks to provide a hydraulic 30 syst~m capable oi permitting in~epend~n~ =tuation F eedqr ;27 and separator mechanisms on a harvesting machine which is simple, inexpensive and permits the location of a valve bank remote from the operator's compartment without the necessity of employing complicated mechanical linkages and/or cables between the operator's compartment and the valve bank.
Further, this invention seeks to provide such a hydraulic system wherein the separator and feeder mechanisms may be controlled by simple two-position valves.
In one broad aspect, the invention pertains to a harvesting machine having an open center hydraulic system including a pump, a feeder clutch and separator clutch.
The improvement relates to flow divider valve means connected in series with the pump to create a parasitic pressure up-stream of the valve means, with a pair of two-position valves communicating with the parasitic pressure. A double acting cylinder communicates with each of the two-position valves and is connected respectively to the feeder and separator clutches.
Bias means urge each of the two-position valves toward a dis-engage position to cause each of the cylinders to disengage the ~ associated clutch. Solenoid means on each of the two-pos:ition valves are capable, when energized, of positioning the associa~ed two-position valve to cause the associated cylinder to engage the clutc}l to which it is connected.
These and other aspects and many of the intended ~5 advantages of the present invention will become more readily apparent upon a perusal of the following descrip-tion and the accompanying drawing, wherein the sole figure is a hydraulic schematic of a hydraulic circuit employing the present invention.

3~ DESCRIPTION OF A PREFERRED EMBODIMENT
ReEerring now to the drawing, there is shown a pump 10, which may be of the fixed displacement type, which draws hydraulic fluid from the reservoir 12 through a conduit 14. The pump 10 discharges fluid under pressure through conduit 16 which communicates with a valve block, indicated generally at 18. The valve block contains a system relief valve 20 which normally is biased to preclude communication between the conduit 16 and reservoir 12 through conduit 22, but which will open to permit communi-`I ~

cation between conduit 16 and conduit 22 upon reachillg a predetermined maximum system pressure, such as 1750 ps:i..
Downstream of the relief valve 20 is a flow divider 24, which preferably is a priority type flow divider which is pressure compensated. The priority flow is directed to conduit 26 while the excess flow from flow divider 24 is directed into conduit 28 leading to header lift control valve 30.
A pair of single acting header lift cylinders 32 and 34 communicate with the valve 30 through conduit 36. Pilo-t operated valve 38 is positioned in the conduit 36 -to function as a load check valve, which precludes -the drop-ping or leak down of the cylinders 32 and 34 under the load of the header itself without the necessity of relying upon those tolerances within the spool of header lift valve 30. As shown in the drawing, the valve 30 is in its center neutral position and the load check valve 38 would be maintaining the cylinders 32 and 34 in their given position against the force of gravity acting on the header itself. When the spool of valve 30 is shifted to the right conduit 28 is connected with conduit 36 and the cylinders 32 and 34 would be extended to raise the header.
When the spool of valve 30 is shifted to the left, conduit 36 is connected with conduit 40 which leads to the reser-voir 12 permitting the exhaust of hydraulic fluid from -the ~5 head end of cylinders 32 and 34 thereby permitting -the header to be lowered. An adjustable orifice contained internally of the valve 30 permits an adjustment of the maximum drop rate permitted by the header.
A second relief valve 42 communicates with the conduit 26 and is connected with the reservoir 12 through conduits 44, 40 and 22. ~he second relief valve 42 is set to connect with the reservoir at a predetermined pressure which is slightly below the predetermined pressure setting for relief valve 20, e.g. 1600 psi. A second flow divider valve ~16, which preferably is of the priority type and pressure compensated, communicates with the priority flow from flow divider valve 24 in conduit 26. The priority out-let fl~l from flow ~ivide.r valve 46 is into conduit 48 and leads to a hydrostatic steering circuit, indicated generally `';~

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-- (l at 50. Since the hydrostatic steering circuit 50 is old and well known in the art, a detailed description of its operation is not necessary. The excess flow from flow divider valve 46 is directed into conduit 52 which leads to t~e valve bank indicated generally at 54. The valve bank 54 contains a pair of three-position, open center valve spools 56 and 58. The two valves 56 and 58 are connected in series with the spool 56 being upstream of the spool 58. The valve 56 controls flow to and from the unloading auger swing cylinder 60, which is a double acting cylinder connected with the valve 56 through conduits 62 and 64.
Pilot operated load check valves 66 and 68 are lnterposed in the conduits 62 and 64 respectively in order to maintain the position of the unloading auger swing cylinder when the valve 56 is in its center or neutral position. A
conduit 70 leads from the valve 56 to the valve 58 which latter valve controls the reel lift cylinders 72 and 74, cylinder 72 being a master cylinder and cylinder 74 being a slave cylinder. The arrangement of the master and slave cylinders on a reel lift is old and well known in the art and any detailed description thereof is not necessary herein. The head end of master cylinder 72 communicates with the valve 58 through conduit 76. A pilot operated check valve 78 is interposed in conduit 76 to function as a load check valve in the usual and well known manner.
While the cylinders 72 and 74 are single acting cylinders which would normally require only a three-port valve rather than a four-port valve, as valve 58 is illustrated to be, it is frequently more economical to use a valve which is already available and identical to other valves in a given valve bank, such as valve bank 54, and hence the drawing illustrates an unused pilot-operated, load check valve 80 with its associated porting which is plugged at 82 to render it ineffective.
A conduit 84 communicates with conduit 16 and connects with a two-position, four-port valve 86 which is moved to the position shown in drawing by spring 88 and is .

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moved to the left against the bias of spring 88 by ener-gizing solenoid 90. A double acting cylinder 92 communicates with the valve 86 through conduits 94 and 96 which connect with the head end and rod end respectively of the cylinder 5 92. A return conduit 98 connects between the valve 86 and reservoir 12. The piston rod 100 of cylinder 92 is connected to engage and disengage a separator clutch not shown. Such clutch is engaged when the cylinder rod 100 is retracted and is disengaged when the rod 100 is extended.
10 The separator clutch may in practice be a simple belt tightener of the type old and well known in the art. A
conduit 102 also connects with the conduit 16 and with a valve 104, which is also of the four-port, two-position type~ The valve 104 is biased to the position shown in 15 the drawing by means of spring 106 and is moved to the left by energizing solenoid 108. Conduits 110 and 112 communicate respectively with the rod end and head end of a double acting cylinder 114. The cylinder 114 has its rod 116 connected with the feeder clutch, which clutch may in practice be a simple belt tightener of the type known in the art. The feeder clutch is engaged when the rod 116 is extended and is disengaged when the rod 116 is retracted.
Both the feeder clutch and separator clutch are engaged when the solenoids 108 and 90 respectively are energized. The energizing of solenoid 108 is accomplished by closing switch 118 which connects with electrical source 119. The solenoid 90 is similarly energized by the closing of switch 120 which provides a connection between the solenoid 90 and the electrical source 119.
It will be seen from the foregoing, that the two priority flow dividers 24 and 46 connected in series create a back pressure or parasitic pressure in the conduit 16. This pressure is communicated through conduit 84 to the separator clutch cylinder 92, which cylinder is posi-tioned in either its retracted or extended position depending upon whether solenoid 90 is energized or not. That is, if the solenoid 90 is not energized, i.e. switch 120 is open, ~o .. . .. . . ~ . . .

as shown in the drawing, the spring 88 will bias the valve 86 to the position shown and the separator clutch cylinder 92 will be extended because of the pressure present in conduit 94, while conduit 96 will be connected with the reservoir 12 through conduit 98, causing the separator clutch connected with the rod 100 to be disengaged.
Closing of the switch 120 will energize the solenoid 90 which will shift the valve 86 against the bias of spring 88 to the left. Thus positioned, conduit 84 will be in communication with conduit 96 introducing the parasitic pressure from conduit 16 to the rod end of separator clutch cylinder 92 while simultaneously connec-ting conduit 94 to the reservoir 12 through conduit 98. The rod 100 will therefor be retracted causing engagement of the separator clutch.
A similar action occurs with respect to the feeder clutch cylinder 114. With the solenoid 108 not energized, the spring 106 will urge the spool 104 to the right connecting the conduit 102 with conduit 110, thereby introducing the parasitic pressure from conduit 16 into the rod end of the cylinder 114 causing the rod 116 to be retracted. Simultaneously the head end of the cylinder 114 will be connected with the reservoir 12 through conduits 112 and 113. Under such conditions the feeder clutch will be disengaged thereby interrupting any drive to the feeder mechanism. When the switch 118 is closed solenoid 108 will be energized causing the valve 104 to be shiEted to the left. In this position conduit 102 will be connected with conduit 112 directing the parasitic pressure in conduit 16 to the head end of cylinder 114 while simul-taneously connecting conduit 110 with the reservoir 12 through conduit 113. Tne introduction of the parasitic pressure in the head end of cylinder 114 will cause the rod 116 to be extended and thereby engage the feeder clutch.
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While a preferred embodiment of the present invention has been disclosed herein, it will be appreciated that various changes and modifications may be made therein without departing from the spirit of the invention as defined by the scope of the appended claims.

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Claims

What is claimed is:

1. In a harvesting machine having an open center hydraulic system including a pump, a feeder clutch and separator clutch, the improvement comprising:
flow divider valve means connected in series with said pump to create a parasitic pressure upstream of said valve means;
a pair of two-position valves communicating with said parasitic pressure;
a double acting cylinder communicating with each of said two-position valves and connected respectively to said feeder and separator clutches;
bias means urging each of said two-position valves toward a disengage position to cause each of said cylinders to disengage the associated clutch;
solenoid means on each of said two-position valves and capable, when energized, of positioning the associated two-position valve to cause the associated cylinder to engage the clutch to which it is connected.

2. In a combine having an open center hydraulic circuit including a pump, and a feeder clutch, the improve-ment comprising:
flow divider valve means connected in series with, and downstream of, said pump to create a parasitic pressure upstream of said flow divider valve means;
a feeder clutch cylinder carried by said combine and connected to engage and disengage said feeder clutch;
a first valve connected to receive said parasitic pressure and movable between an engage position, wherein said parasitic pressure is directed to said feeder clutch cylinder to engage said feeder clutch, and a disengage position, wherein said parasitic pressure is directed to said feeder clutch cylinder to disengage said feeder clutch;
first bias means for urging said first valve to its disengage position; and first solenoid means connected to said first valve for moving the latter to its engage position when said solenoid means is energized.

3. The invention according to Claim 2, and further comprising:
a separator clutch carried by said combine;
a separator clutch cylinder connected to engage and disengage said separator clutch;
a second valve connected to receive said parasitic pressure and movable between an engage position, wherein said parasitic pressure is directed to said separator clutch cylinder to engage said separator clutch, and a disengage position, wherein said parasitic pressure is directed to said separator clutch cylinder to disengage said feeder clutch;
second bias means for urging said second valve to its disengage position; and second solenoid means connected to said second valve for moving the latter to its engage position when said solenoid in energized.