Combined fixed and variable displacement pump system

• US 4,050,478 A
• Filed: 05/04/1976
• Issued: 09/27/1977
• Est. Priority Date: 04/23/1975
• Status: Expired due to Term

• Current Assignee: Komatsu Dresser Company E Sunnyside 7TH St Libertyville IL A General Partnership Under The Uniform Partnership Act of The State of de
• Original Assignee: International Harvester Co. (CNH Industrial N.V.)
• Inventors: Lech, Richard J., Virtue, Eugene P.
• Primary Examiner(s): Freeh, William L.
• Application Number:
  US05/683,124
• Time in Patent Office: 511 Days
• Field of Search: 137/102, 137/625.66, 137/625.69
• US Class Current: 137/625.66
• CPC Class Codes: F04B 49/007 Installations or systems with two or more pumps or pump cylinders, wherein the flow-path through the stages can be changed, e.g. from series to parallel centrifugal pumps F04D15/0072
• CPC Class Codes: F04B 49/08 Regulating by delivery pressure
• CPC Class Codes: F04B 49/24 Bypassing
• CPC Class Codes: Y10T 137/8663 Fluid motor
• CPC Class Codes: Y10T 137/8671 With annular passage [e.g., spool]

Abstract

A hydraulic pump arrangement and control circuit for supplying fluid at high volume and a high pressure to a work circuit. The system utilizes a fixed displacement pump, a variable displcement pump, a dual pressure compensator, and an unloading valve working together to provide high pressure fluid delivery while reducing the horsepower requirements of the fixed displacement pump and the variable displacement pump. High flow is provided through the utilization of the combined pumps and high pressure is attained through the unloading of the fixed displacement pump through the unloading valve and destroking of the variable displacement pump in response to signals provided by the dual pressure compensator.

Claims

1.

A pressure responsive fluid compensator for metering fluid flow between a source of fluid and a pressure responsive actuator, the pressure responsive fluid compensator responsive to one or more than one fluid pressure input source comprising:

a housing having a plurality of ports including a first inlet port, a second inlet port, a first outlet port, and a second outlet port;

the housing also provided with a bore therethrough having several concentric diameters;

s spool alignment collar having an aperture therethrough carried in one of said concentric diameters;

a spool slidably carried in said bore of said housing, said spool equipped with a first end slidably carried in said spool alignment collar, a second end and a land between said first and said second ends having a diameter greater than the diameter of said first end of said spool, said spool further having a core portion on which said first end, said land and said second end are formed, an arcuate portion at the end of said second end portion of said spool, said land having a circumferential groove formed therein, and an internal passage open at each end thereof between said circumferential groove of said land and said arcuate portion at the second end of said spool;

a biasing assembly carried in said housing urging said spool to its normal position in said bore of said housing whereby said land of said spool prevents fluid flow from said second inlet port to said first inlet port;

a first chamber formed in the housing accommodating said first end of said spool, said first chamber accessed only through said first inlet port;

a second chamber formed in said housing, said second chamber accessed only through said second inlet port when said land of said spool is urged to its normal position.

2.

A pressure responsive fluid compensator for metering fluid flow between a source of fluid and a pressure responsive actuator, the pressure responsive fluid compensator responsive to one or more than one fluid pressure input source comprising:

a housing having a plurality of ports including a first inlet port, a second inlet port, a first outlet port, and a second outlet port;

the housing also provided with a bore therethrough having several concentric diameters;

a spool alignment collar having an aperture therethrough carried in one of said concentric diameters;

a spool slidably carried in said bore of said housing, said spool equipped with a first end slidably carried in said spool alignment collar, a second end and a land between said first and said second ends having a diameter greater than the diameter of said first end of said spool;

a biasing assembly carried in said housing urging said spool to its normal position in said bore of said housing, including a pressure plate having an aperture therethrough coincidental to the minor axis thereof, an arcuate concave spool receiver on the innermost surface of said pressure plate, and an outermost surface, a coil spring seated on the outermost surface of said pressure plate, a retainer plate seated against the coil spring retaining said coil spring between said retainer plate and said pressure plate, and a retainer plate adjustment screw carried in said bore of said housing maintaining said retaining plate in contact with said coil spring, whereby said land of said spool prevents fluid flow from said second inlet port to said first inlet port;

a first chamber formed in the housing accommodating said first end of said spool, said first chamber accessed only through said first inlet port;

a second chamber formed in said housing, said second chamber accessed only through said second inlet port when said land of said spool is urged to its normal position.

3. A Pressure responsive fluid compensator for metering fluid flow between a source of fluid and a pressure responsive actuator, the pressure responsive fluid compensator responsive to one or more than one fluid pressure input source comprising:

a housing having a plurality of ports including a first inlet port, a second inlet port, a first outlet port, and a second outlet port;

the housing also provided with a bore therethrough having several concentric diameters;

a spool alignment collar, having an aperture therethrough carried in one of said concentric diameters;

a spool slidably carried in said bore of said housing, said spool formed on a core portion on which a first end is slidably carried in said aperture of said alignment collar, a land having a circumferential groove and a second end having an arcuate portion are formed;

the spool equipped with an internal passage open from said groove of said land to said arcuate portion of said second end;

a biasing assembly carried in said housing urging said spool to its normal position, said biasing assembly including pressure plate having an aperture therethrough for alignment with said internal passage of said spool, a coil spring, a retainer plate and a retainer plate adjustment screw;

a first chamber formed in the housing, said first chamber accessed only through said first inlet port and accommodating said first end of said spool;

a second chamber formed in said housing, said second chamber accessed only through said second inlet port when said land of said spool is urged to its normal position.