US 8,668,465 B2Granted

Hydraulic system with supplement pump

AssigneeSauer-Danfoss ApS

InventorsLuke Wadsley, Niall Caldwell

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Abstract

If a hydraulic system has several modes of operation, in particular a mode with a high pressure demand (II) and a mode with a high fluid flow demand (II), the hydraulic fluid pump has to be built with an accordingly high fluid flow output. Such a pump is expensive. Therefore it is suggested, to provide two pumps. I.e. a controllable main pump (2) is provided, which supplies the hydraulic consumer (6) during phases (I) of high pressure demand. During phases (II) of high fluid flow demand, normally, relatively low pressures are sufficient. Therefore, it is suggested to provide a parallel boost pump (9), which supplies the hydraulic consumer (6) in addition to the high pressure pump (2), if a high fluid flow is needed. Excess fluid flow output is avoided by controlling the fluid output flow of main pump 2.

Claims12

Dependent claims

A hydraulic system comprising:

at least one hydraulic main pump driven by a power supply, the at least one hydraulic main pump being a variable displacement pump;
and
at least one hydraulic boost pump selectively driven by said power supply, the at least one hydraulic boost pump being a fixed displacement pump;
wherein the at least one hydraulic main pump and at least one hydraulic boost pump are configured to supply an output fluid flow to at least one hydraulic consumer;
wherein, in a low fluid flow mode, the at least one hydraulic boost pump is not driven by said power supply such that the at least one hydraulic main pump supplies the output fluid flow to the at least one hydraulic consumer;
wherein, in a high fluid flow mode, the at least one hydraulic boost pump is driven by said power supply so that the at least one hydraulic boost pump and the at least one hydraulic main pump supply the output fluid flow to the at least one hydraulic consumer;
wherein the output fluid flow to the at least one hydraulic consumer is higher in the high fluid flow mode than in the low fluid flow mode.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/740,783Filed 29 Oct 2008
Priority: EP 072543301 Nov 2007
Published: US 2010/0322791 A123 Dec 2010
Granted: 11 Mar 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

F04B 1/34
Multi-cylinder machines or pumps characterised by number or arrangement of cylinders: control not provided for in groups F04B1/02, F04B1/03,…
F04B 1/28
Control: of machines or pumps with stationary cylinders
F04B 23/04
Pumping installations or systems: combinations of two or more pumps
F04B 23/06
Combinations of two or more pumps: the pumps being all of reciprocating positive-displacement type