US 2026/0200522 A1Published application

A Steering System and a Method of Controlling a Steering System

AssigneeAGCO International GmbH

InventorsGabriel Reitemann, Stefan Prestel, Benjamin Frommelt

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Abstract

An electro-hydraulic steering system comprises a hydraulic steering actuator and a hydro-mechanical steering unit for actuating the hydraulic steering actuator in response to a steering demand. An electronically controllable steering supply valve arrangement is able to supply fluid to the actuator independently of or in combination with hydro-mechanical steering unit. The hydro-mechanical steering unit is specified to provide a maximum volume flow rate of fluid to the actuator which is above that required to provide an emergency steering function but is less than that required for full steering functionality under normal operating conditions. In normal use, the steering supply valve arrangement is used to amplify the fluid flow from the hydro-mechanical steering unit to ensure full steering capability. In an emergency steering situation, the hydro-mechanical steering unit is able to provide sufficient fluid flow to maintain a limited steering capability.

Claims15

Dependent claims

An electro-hydraulic steering system for a vehicle comprising:

a hydraulic steering actuator for turning a steered wheel through a rotation angle;
a fluid supply arrangement including a source of pressurized fluid and a tank;
a working port arrangement having two working ports fluidly connected with the hydraulic steering actuator;
a hydro-mechanical steering unit fluidly connected between the fluid supply arrangement and the working port arrangement and configured to connect one of the working ports with the source of pressurized fluid and the other with the tank in dependence on a steering demand;
an electronically controllable steering supply valve arrangement fluidly connected with the source of pressurized fluid, the tank and the working ports;
a controller operatively connected with the electronically controllable steering supply valve arrangement;
wherein the hydro-mechanical steering unit is calibrated/specified to provide a maximum volume flow rate of fluid to said one of the working ports which is below a first threshold value and above a second threshold value, the controller configured to provide a control output to the electronically controllable steering supply valve arrangement to supply pressurized fluid to said one of the working ports in addition to fluid supplied by the hydro-mechanical steering unit in order to raise the volume flow rate of fluid provided to said one of the working ports above the second threshold value as required to meet a steering demand, the electronically controllable steering supply valve arrangement being capable of raising the volume flow rate of fluid provided to said one of the working ports up to the first threshold value.

4 more elements

A method of operating an electro-hydraulic steering system, the system comprising:

a hydraulic steering actuator for turning a steered wheel through a rotation angle;
a fluid supply arrangement including a source of pressurized fluid and a tank;
a working port arrangement having two working ports fluidly connected with the hydraulic steering actuator;
a hydro-mechanical steering unit fluidly connected between the fluid supply arrangement and the working port arrangement and configured to connect one of the working ports with the source of pressurized fluid and the other with the tank in dependence on a steering demand;
an electronically controllable steering supply valve arrangement fluidly connected with the source of pressurized fluid, the tank and the working ports;
a controller connected with the electronically controllable steering supply valve arrangement;
wherein the hydro-mechanical steering unit is calibrated/specified to provide a maximum volume flow rate of fluid to said one of the working ports which is below a first threshold value and above a second threshold value;
the method comprising actuating the electronically controllable steering supply valve arrangement to supply pressurized fluid to said one of the working ports in addition to fluid supplied by the hydro-mechanical steering unit in order to raise the volume flow rate of fluid provided to said one of the working ports above the second threshold value as required to meet a steering demand, the electronically controllable steering supply valve arrangement being capable of raising the volume flow rate of fluid provided to said one of the working ports up to the first threshold value.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/865,533Filed 5 Apr 2023
Priority: GB 2207466.020 May 2022
Published: 16 Jul 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

B62D 5/093
Characterised by means for actuating valves: telemotor driven by steering wheel movement
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 5/32
Safety devices, e.g. alternate emergency power supply or transmission means to ensure steering upon failure of the primary steering means: for…
B62D 6/008
Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits: control of…