US 9,744,990 B2Granted

Hydraulic steering system

AssigneeDanfoss Power Solutions ApS

InventorsBendt Porskrog, Casper Mikael Olesen, Abdul Karim Rahimzai

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Abstract

A hydraulic steering system 1 is described comprising a steering unit and a priority valve, said steering unit comprising a working port arrangement having two working ports, a supply port arrangement having a high pressure port and a low pressure port, a load sensing port, a main flow path having a main bleed and a metering device and being arranged between said high pressure port and said working port arrangement, an amplification flow path having an amplification bleed and being arranged between said high pressure port and said working port arrangement, said main bleed and said amplification bleed being controlled together by means of a steering handle and being closed in neutral position of said steering handle, wherein said priority valve comprises a priority outlet connected to said high pressure port of said steering unit, a valve element moveable in a priority direction to connect an inlet of said priority valve to said priority outlet, and a load sensing connection connected to said load sensing port of said steering unit, said priority outlet being connected to said load sensing connection via a priority valve bleed, a pressure at a point downstream said priority bleed acting on said valve element in said priority direction, wherein said load sensing port is connected to said low pressure port via a drain bleed being open in neutral position of said steering handle and closing upon actuation of said steering handle out of said neutral position.

Claims20

Dependent claims

A hydraulic steering system comprising a steering unit and a priority valve,

said steering unit comprising
a working port arrangement (L, R) having two working ports,
a supply port arrangement (P, T) having a high pressure port (P) and a low pressure port (T),
a load sensing port (LS),
a main flow path having a main bleed (A1) and a metering device and being arranged between said high pressure port (P) and said working port arrangement (L, R),
an amplification flow path having an amplification bleed (Au) and being arranged between said high pressure port (P) and said working port arrangement (L, R),
said main bleed (A1) and said amplification bleed (Au) being controlled together by means of a steering handle and being closed in neutral position of said steering handle,
wherein said priority valve comprises
a priority outlet (CF) connected to said high pressure port (P) of said steering unit,
a valve element moveable in a priority direction to connect an inlet (P1) of said priority valve to said priority outlet (CF),
and a load sensing connection (LS1) connected to said load sensing port (LS) of said steering unit,
said priority outlet (CF) being connected to said load sensing connection (LS1) via a priority valve bleed,
a pressure at a point downstream said priority bleed acting on said valve element in said priority direction,
wherein said load sensing port (LS) is connected to said low pressure port (T) via a drain bleed being (Ad) open in neutral position of said steering handle and closing upon actuation of said steering handle out of said neutral position.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/147,358Filed 5 May 2016
Priority: EP 1516757913 May 2015
Published: US 2016/0332662 A117 Nov 2016
Granted: 29 Aug 2017
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

B62D 5/062
Fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle: details, component parts
B62D 5/065
Fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle: characterised by specially adapted means for…
B62D 5/075
Supply of pressurised fluid for steering also supplying other consumers ; control thereof: using priority valves
B62D 5/093
Characterised by means for actuating valves: telemotor driven by steering wheel movement