Load sensitive hydraulic system
AssigneeInternational Harvester Company
InventorHarold R. Orth
Life of this patent
Estimating the term…
Abstract
A load sensitive hydraulic system having a variable displacement pump, a priority dependent work circuit, at least one secondary work circuit, priority means preferencing fluid flow to the priority dependent work circuit over the secondary work circuit, flow and pressure compensating means responsive to requirements of either work circuit for controlling displacement of the variable displacement pump and a relief valve, when overriden, allowing fluid flow to the secondary work circuit.
Claims7
In a variable displacement hydraulic system having a variable displacement pump, a compensating circuit for effecting the displacement of said pump, a priority dependent work circuit, a secondary work circuit having a fluid delivery conduit and a flow compensating priority valve system including an orifice metering flow into said fluid compensating priority valve, a priority spool valve upstream of said orifice which when open allows fluid flow via a discharge passage to said secondary work circuit, an isolator valve downstream of said priority valve and said orifice which when opened allows fluid flow via a passage to said discharge passage and to said secondary work circuit, said flow compensating priority valve further including a relief valve downstream of said priority valve which when opened allows fluid flow to said secondary work circuit.
In a flow compensated hydraulic system having a variable displacement pump, a priority dependent work circuit and a secondary work circuit, a flow compensating priority valve comprising:
- a valve body having a plurality of bores including s first passage and a discharge passage communicating with said first passage therein;
- a priority valve spool carried in the first passage of said valve body having an orifice allowing restricted fluid flow through said priority valve spool integral therewith;
- a priority spool spring urging said priority valve spool to an undisplaced position of repose;
- an isolator valve having an outlet port and a pilot signal port carried in said first passage and an isolator valve spool urged to a position blocking said outlet port by an isolator valve spring;
- a relief valve responsive to pressure in said first passage allowing fluid to flow from said first passage via said discharge passage to said secondary work circuit.
In a flow compensated hydraulic system, having a variable displacement pump, a priority dependent work circuit and a secondary work circuit, a flow compensating priority valve comprising:
- a valve body having a plurality of bores including a first passage and a discharge passage therein;
- a priority valve spool carried in the first passage of said valve body;
- a priority spool spring urging said priority valve spool to an undisplaced position of repose;
- a flow metering orifice integrally formed in said first passage of said valve body;
- an isolator valve having an outlet port for allowing fluid to flow to a secondary work circuit and a pilot signal port carried in said first passage and an isolator valve spool urged to a position blocking said outlet port by an isolator valve spring;
- a relief valve responsive to pressure in said first passage allowing fluid to flow from said first passage via said discharge passage to said secondary work circuit.
Dependencies are inferred from the claim text.