Dual-pump, flow-isolated hydraulic circuit for an agricultural tractor
First Claim
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1. A hydraulic circuit for an agricultural tractor including:
- a valve assembly having a manifold block with first and second valves fitted therein;
and wherein the manifold block further includes;
a first feed path connected to the first valve and a second feed path flow-isolated from the first feed path and connected to the second valve;
a first return path connected to the first valve and a second return path flow-isolated from the first return path and connected to the second valve;
and wherein the circuit further includes;
a first pump flowing fluid to the first feed path; and
a second pump flowing fluid to the second feed path;
and wherein;
the first pump is a fixed displacement pump and the second pump is a variable displacement pump; and
the second pump has an inlet and the first and second return paths are connected to the inlet through a common return line.
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Accused Products
Abstract
A hydraulic circuit has first and second pumps coupled to first and second directional valves, each controlling work mechanisms such as a hydraulic cylinder and a hydraulic motor. The directional valves are in a valve assembly having a fluid passage through it. The passage includes first and second input ports and a passage closure intermediate the ports to prevent cross-feeding of the pumps. The first valve is connected to the passage between the first port and the closure and the first pump flows fluid to the first port. Similarly, the second valve is connected to the passage between the second port and the closure and the second pump flows fluid to the second port. In a more-specific embodiment, the second pump is a variable displacement pump and the first pump is a fixed displacement pump also connected to a power steering system through a priority valve. Thus, the first pump flows fluid to the power steering system as well as to the first port.
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Citations
8 Claims
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1. A hydraulic circuit for an agricultural tractor including:
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a valve assembly having a manifold block with first and second valves fitted therein; and wherein the manifold block further includes; a first feed path connected to the first valve and a second feed path flow-isolated from the first feed path and connected to the second valve; a first return path connected to the first valve and a second return path flow-isolated from the first return path and connected to the second valve; and wherein the circuit further includes; a first pump flowing fluid to the first feed path; and a second pump flowing fluid to the second feed path; and wherein; the first pump is a fixed displacement pump and the second pump is a variable displacement pump; and the second pump has an inlet and the first and second return paths are connected to the inlet through a common return line. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In combination, (a) a tractor, (b) a planter towed by the tractor and including a planting mechanism powered by a rotary hydraulic motor and at least one lateral wing extension powered by a hydraulic cylinder, and (c) a hydraulic circuit for the tractor, and wherein the circuit includes:
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a valve assembly having a manifold block with first and second valves fitted therein; and wherein the manifold block further includes; a first feed path connected to the first valve and a second feed path flow-isolated from the first feed path and connected to the second valve; a first return path connected to the first valve and a second return path flow-isolated from the first return path and connected to the second valve; and wherein the circuit further includes; a fixed displacement pump flowing fluid to the first feed path; and a variable displacement pump flowing fluid to the second feed path; and wherein; the first valve is connected to the hydraulic cylinder and the second valve is connected to the motor.
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8. In combination, (a) a tractor, (b) a planter towed by the tractor and including a planting mechanism powered by a rotary hydraulic motor and at least one lateral wing extension powered by a hydraulic cylinder, and (c) a hydraulic circuit for the tractor, and wherein the circuit includes a power steering system and further includes:
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a valve assembly mounted on the tractor and having a manifold block with first and second valves fitted therein; and wherein the manifold block further includes; a first feed path connected to the first valve and a second feed path flow-isolated from the first feed path and connected to the second valve; a first return path connected to the first valve and a second return path flow-isolated from the first return path and connected to the second valve; and wherein the circuit further includes; a fixed displacement pump flowing fluid to the first feed path; and a variable displacement pump flowing fluid to the second feed path; and wherein; the first pump is connected to the power steering system through a priority valve; the first pump flows fluid to the power steering system and to the first feed path; the first valve is connected to the hydraulic cylinder and the second valve is connected to the motor.
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Specification
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Current AssigneeBlue Leaf IP Incorporated (CNH Industrial N.V.), CNH America Llc (CNH Industrial N.V.)
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Original AssigneeCase Corporation (CNH Industrial N.V.)
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InventorsSusag, David E.
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Primary Examiner(s)Novosad, Christopher J.
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Application NumberUS08/980,827Time in Patent Office582 DaysField of Search111/200, 60/422, 60/413US Class Current111/200CPC Class CodesF15B 11/162 for giving priority to part...F15B 11/17 using two or more pumpsF15B 2211/20538 constant capacityF15B 2211/20553 with pilot circuit, e.g. fo...F15B 2211/20576 with multiple pumpsF15B 2211/30535 the pressure compensating v...F15B 2211/3111 the pump port being closed ...F15B 2211/3138 the positions being discreteF15B 2211/325 actuated by an output membe...F15B 2211/6054 using shuttle valvesF15B 2211/7128 the chambers being connecte...F15B 2211/7142 the output members being ar...
