TRACTOR AND IMPLEMENT HYDRAULIC CONTROL SYSTEM

• US 3,561,541 A
• Filed: 09/21/1967
• Issued: 02/09/1971
• Est. Priority Date: 09/21/1967
• Status: Expired due to Term

• Current Assignee: Roger W. Woelfel
• Original Assignee: Roger W. Woelfel
• Inventors: Woelfel, Roger W.
• Application Number:
  US04/669,497
• Time in Patent Office: 1,237 Days
• US Class Current: 172/260.5
• CPC Class Codes: A01B 61/046 the device including an energy accumulator for restoring the tool to its working position

Abstract

Disclosed herein are hydraulic circuits for controlling hydraulic cylinders utilized on agricultural implements to afford tripping and resetting of the earth working tools. The circuits are provided with means for maintaining suitable working pressures in the cylinders. In one embodiment an adjustable pressure responsive electrical switch is used. In another embodiment an adjustable pressure responsive unloading valve is provided. Check valves in the circuits seal the desired pressure in the hydraulic cylinders and pressure relief valves permit discharge of fluid from the cylinders into a reservoir as the working tools trip. The circuits also include fluid accumulators which can be selectively connected to function as shock absorbers to absorb surges in pressure or disconnected to increase the resistance of the circuit to tripping of the working tools.

Claims

1. The combination of a tractor having fluid pumping means and a fluid reservoir in communication with said pumping means, and an implement carryinG an earth working tool with a hydraulic cylinder connected to said implement and said working tool to afford tripping of said working tool from its operative position upon increase in the draft pressure and to afford resetting of the tool upon decrease in the draft pressure on the tool, a hydraulic circuit including fluid passage means connecting said fluid pumping means to said hydraulic cylinder, adjustable pressure responsive valve means in said fluid passage between said pump and said cylinder for controlling fluid flow through said passage to maintain a selected working pressure in said hydraulic cylinder, said valve means closing said passage to prevent flow from said pump to said cylinder when said selected working pressure is attained in said cylinder, and pressure relief valve means communicating with said fluid reservoir to afford fluid flow into said reservoir and tripping of said working tool as the pressure in said hydraulic cylinder increases and attains a predetermined level upon tripping of said working tool, one-way valve means having an intake side and a discharge side located in said fluid passage means between said pumping means and said hydraulic cylinder, said valve means permitting fluid flow from said pumping means to said hydraulic cylinder but preventing flow from said hydraulic cylinder to said fluid pumping means and wherein said pressure relief valve means communicates with said fluid passage between said one-way valve means and said hydraulic cylinder, and whereby said pressure responsive valve means restores the selected working pressure in said hydraulic cylinder upon loss of fluid to said reservoir through said pressure relief valve means.

2. The combination of a tractor having fluid pumping means and a fluid reservoir in communication with said pumping means, and an implement carrying an earth working tool with a hydraulic cylinder on said implement and connected to said working tool to afford tripping of said working tool upon increase in the draft pressure and resetting of the tool upon decrease in the draft pressure on the tool, a hydraulic circuit including fluid passage means connecting said fluid pumping means to said hydraulic cylinder, said means responsive to pressure in said fluid passage for controlling fluid flow and maintaining the preselected working pressure in said hydraulic cylinders comprises a solenoid operated valve in said fluid passage means, said valve being biased to a normally closed position, an adjustable pressure responsive electrical switch having a pilot conduit in communication with said fluid passage means and an electrical circuit connected to said switch to energize said solenoid and open said valve means as said switch closes responsive to a drop of pressure in said fluid passage means below a preselected level and whereby as said working pressure in said hydraulic cylinder is restored to said preselected level, said pressure responsive electrical switch will open and deenergize said solenoid, and pressure relief valve means connected to said fluid passage means, said pressure relief valve means communicating with said fluid reservoir to afford fluid flow into said reservoir and tripping of said working tool as the pressure in said hydraulic cylinder increases and attains a predetermined level upon tripping of said working tool.

3. The combination of a tractor having fluid pumping means and a fluid reservoir in communication with said pumping means, and an implement carrying an earth working tool with a hydraulic cylinder on said implement and connected to said working tool to afford tripping of said working tool upon increase in the draft pressure and resetting of the tool upon decrease in the draft pressure on said tool, a hydraulic circuit including fluid passage means connecting said fluid pumping means to said hydraulic cylinder, one-way valve means in said fluid passage means, a pressure responsive unloading valve having inlet, outlet and pilot ports, a conduit connecting said fluid passAge means with said inlet of said unloading valve, a bypass conduit connecting said outlet of said unloading valve with said fluid reservoir, a pilot conduit connecting said pilot port with said fluid passage means on the discharge side of said one-way valve means and said unloading valve being in a normally closed position until the pressure in said fluid passage means attains the selected working pressure and opens said unloading valve thereby providing fluid communication between said inlet and outlet of said unloading valve and fluid communication between said fluid passage means and said fluid reservoir for continuous flow therethrough to bypass said hydraulic cylinder.

4. The combination of a tractor having fluid pumping means and a fluid reservoir in communication with said pumping means, and an implement carrying an earth working tool with a hydraulic cylinder on said implement and connected to said working tool to afford tripping of said working tool upon increase in the draft pressure and resetting of the tool upon decrease in the draft pressure on the tool, a hydraulic circuit including fluid passage means connecting said fluid pumping means to said hydraulic cylinder, means responsive to pressure in said fluid passage for controlling fluid flow through said passage to maintain a selected working pressure in said hydraulic cylinder, and pressure relief valve means connected to said fluid passage means, said pressure relief valve means communicating with said fluid reservoir to afford fluid flow into said reservoir and tripping of said working tool as the pressure in said hydraulic cylinder increases and attains a predetermined level upon tripping of said working tool, and whereby said means responsive to said pressure in said fluid passage will restore the selected working pressure in said hydraulic cylinder upon loss of fluid to said reservoir, one-way valve means having an intake side and a discharge side located in said fluid passage means between said pumping means and said hydraulic cylinder, said valve means permitting fluid flow from said pumping means to said hydraulic cylinder but preventing flow from said hydraulic cylinder to said fluid pumping means and wherein said pressure relief valve means communicates with said fluid passage between said one-way valve means and said hydraulic cylinder, fluid accumulator means and a first conduit connecting said fluid accumulator means to said fluid passage means on the intake side of said one-way valve means and a second conduit connecting said fluid accumulator to the discharge side of said one-way valve means, first valve means in said first conduit, second valve means in said second conduit, and means for selectively opening and closing said first and second valve means.

5. The device of claim 4 wherein said first valve is biased to a normally closed position and said second valve is biased to a normally open position and said means for selectively opening and closing said first and second valve means includes solenoid coils for actuating said valves and a circuit with switch means for energizing said solenoid coils to open said first valve and close said second valve.

6. In combination, a tractor having fluid pumping means a fluid reservoir in communication with said pumping means, an implement having a hydraulic cylinder connected to a working tool carried by said implement, said hydraulic cylinder affording tripping to an inoperative position and resetting of said working tool to an operative position, fluid passage means connecting said fluid pumping means with said hydraulic cylinder on said implement, fluid flow restrictor means in said fluid passage between said pump and said cylinder to afford greater resistance to fluid flow from said pump to said cylinder than to fluid flow from said cylinder to retard movement of said working tool to its operative position from its tripped position, and pressure relief valve means connected to and in communication with said fluid passage means and said reservoir, sAid pressure relief valve means affording communication of said fluid passage with said reservoir when said pressure in said hydraulic cylinder attains a predetermined level to afford tripping of said working tool to an inoperative position.

7. The combination of a tractor having fluid pumping means and a fluid reservoir in communication with said pumping means, and an implement carrying an earth working tool with a hydraulic cylinder connected to said implement and said working tool to afford tripping of said working tool from its operative position upon increase in the draft pressure and to afford resetting of the tool upon decrease in the draft pressure on the tool, a hydraulic circuit including fluid passage means connecting said fluid pumping means to said hydraulic cylinder, fluid flow restrictor means in said fluid passage means adjacent said hydraulic cylinder, said fluid restrictor means affording greater resistance to flow toward said hydraulic cylinder than from said cylinder to minimize loading forces acting on said hydraulic cylinder and said working tool when said working tool is returned from the tripped position to the operative position.

8. The combination of a tractor having fluid pumping means and a fluid reservoir in communication with said pumping means, and an implement carrying an earth working tool with a hydraulic cylinder connected to said implement and said working tool to afford tripping of said working tool from its operative position upon increase in the draft pressure and to afford resetting of the tool upon decrease in the draft pressure on the tool, a hydraulic circuit including fluid passage means connecting said fluid pumping means to said hydraulic cylinder, said hydraulic cylinder having an air inlet and fluid restrictor means connected to said inlet to afford greater resistance to air flow from said hydraulic cylinder than into said cylinder to minimize loading forces acting on said hydraulic cylinder and said working tool when said working tool is returned to the operative position from the tripped position.

9. In the combination of a tractor having fluid pumping means and an implement having a frame with earth working tools, and means for connecting said earth working tools to said frame, and a hydraulic circuit including hydraulic cylinders on said implement, said cylinders being connected to said working tools to afford tripping of said working tools upon increase in pressure on said working tools and resetting of the tools to their operative position upon decrease in the pressure on said tools, the improvement comprising fluid flow restrictor means in said hydraulic circuit, said fluid flow restrictor means affording greater resistance to fluid flow into said hydraulic cylinder than from said cylinder to retard movement of said working tools to their operative position from a tripped position.

10. The combination of claim 9 wherein said hydraulic circuit includes a manifold line and passage means connecting said manifold line to each of said hydraulic cylinders and wherein said fluid flow restrictor means is in each of said passage means connecting said manifold to each of said cylinders, said flow restrictor means preventing a surge of pressure in said cylinders upon sequential tripping of said working tools to prevent rapid return of said tripped working tools to their operative position.

11. The combination of an agricultural implement having a frame and a plurality of working tools, means connecting said working tools to said frame to afford tripping of the working tools upon encountering an obstacle, hydraulic cylinders, each of said hydraulic cylinders having one end connected to the working tool and the other end connected to said frame, a manifold line adapted to be connected to a hydraulic circuit on a tractor, means for connecting said manifold line to each of said hydraulic cylinders, and fluid restrictor means in said means connecting said manifold to each of said cylinders, said restrictor means affording tripping of the working tool at a first rate to clear the obstacle and affording resetting of said working tool to its operative position at a second rate, said second rate being lower than said first rate to minimize shock loads on said working tool and said frame.

12. The combination of fluid pumping means and an agricultural implement comprising a frame, a plurality of working tools pivotally connected to said frame for movement between an earth engaging position and a retracted tripped position, a hydraulic cylinder connected to each of said working tools and to said frame, a fluid passage connected to said fluid pumping means and to said hydraulic cylinders to afford fluid communication between said pumping means and said cylinders, each of said cylinders having flow restrictor means for affording substantially free fluid flow from each of said cylinders upon tripping of said working tools and a limited rate of flow into said cylinders whereby the flow restrictor means prevents a sudden rise in pressure in one of said cylinders upon tripping of other of said working tools.

13. The device of claim 12, including means responsive to pressure in said fluid passage for controlling fluid flow through said passage to said cylinders to maintain a selected working pressure in said hydraulic cylinders and to restore the selected working pressure upon tripping of said tools.