Arrangement to control a fluid flow for steering

A hydraulic control unit comprising

• an arrangement for controlling a flow of a fluid in a pressurized state in a fluid circuit which comprises a tank for the fluid, the arrangement, a first and a second pump, a steering cylinder, and a steering unit for controlling operation of the steering cylinder by controlling discharging the fluid from the steering cylinder towards the tank and charging the fluid pressurized by at least one of the first and second pumps to the steering cylinder, the arrangement comprising
• a first flow path including a first inlet for receiving the fluid from the first pump and a flow direction control device arranged and configured to prevent a flow of the fluid to the first inlet in response to a pressure difference across the flow direction control device;
• a second flow path including a second inlet for receiving the fluid from the second pump, and an emergency valve for opening of the second flow path comprising and controlled via a control port;
• a flow connection between the first and the second flow path arranged in accordance with a position of the flow direction control device between the emergency valve and the first inlet;
• and
• a control connection to the control port for controlling the opening of the second flow path in response to a pressure drop in a section of the fluid circuit between the first pump and the flow direction control device,
• wherein the hydraulic control unit further comprises
• the steering unit connected to the arrangement for forming a section of the of the fluid circuit, wherein the steering unit comprises
• a shaft;
• a by-pass valve;
• and
• a metering pump arrangement for providing the controlling of the discharging and charging via the by-pass valve, and comprising a set of two metering pumps connected to the shaft for receiving torque from a steering wheel, wherein the by-pass valve is connected and configured for switching between fluidically connecting the two of the metering pumps in parallel and fluidically connecting input and output sides of one of the two of the metering pumps with each other.

A hydraulic system for a work vehicle, comprising a fluid circuit comprising

• a tank for a fluid being a work fluid;
• first and second pumps for aspirating the fluid from the tank;
• a steering cylinder;
• a section between the first and second pumps and the steering cylinder which is a hydraulic control unit comprising
• an arrangement for controlling a flow of a fluid in a pressurized state in a fluid circuit which comprises a tank for the fluid, the arrangement, a first and a second pump, a steering cylinder, and a steering unit for controlling operation of the steering cylinder by controlling discharging the fluid from the steering cylinder towards the tank and charging the fluid pressurized by at least one of the first and second pumps to the steering cylinder, the arrangement comprising
• a first flow path including a first inlet for receiving the fluid from the first pump and a flow direction control device arranged and configured to prevent a flow of the fluid to the first inlet in response to a pressure difference across the flow direction control device;
• a second flow path including a second inlet for receiving the fluid from the second pump, and an emergency valve for opening of the second flow path comprising and controlled via a control port;
• a flow connection between the first and the second flow path arranged in accordance with a position of the flow direction control device between the emergency valve and the first inlet;
• and
• a control connection to the control port for controlling the opening of the second flow path in response to a pressure drop in a section of the fluid circuit between the first pump and the flow direction control device,
• wherein the hydraulic control unit further comprises
• the steering unit connected to the arrangement for forming a section of the of the fluid circuit, wherein the steering unit comprises
• a shaft;
• a by-pass valve;
• and
• a metering pump arrangement for providing the controlling of the discharging and charging via the by-pass valve, and comprising a set of two metering pumps connected to the shaft for receiving torque from a steering wheel, wherein the by-pass valve is connected and configured for switching between fluidically connecting the two of the metering pumps in parallel and fluidically connecting input and output sides of one of the two of the metering pumps with each other,
• wherein the hydraulic system further comprises a discharge conduit for discharging the fluid from the steering unit of the hydraulic control unit to the tank.

A hydraulic system for a work vehicle, comprising a fluid circuit comprising

• a tank for a fluid being a work fluid;
• first and second pumps for aspirating the fluid from the tank;
• a steering cylinder;
• a section between the first and second pumps and the steering cylinder which is a combination of a steering unit and an arrangement for controlling a flow of a fluid in a pressurized state in a fluid circuit which comprises a tank for the fluid, the arrangement, a first and a second pump, a steering cylinder, and the steering unit for controlling operation of the steering cylinder by controlling discharging the fluid from the steering cylinder towards the tank and charging the fluid pressurized by at least one of the first and second pumps to the steering cylinder, the arrangement comprising
• a first flow path including a first inlet for receiving the fluid from the first pump and a flow direction control device arranged and configured to prevent a flow of the fluid to the first inlet in response to a pressure difference across the flow direction control device;
• a second flow path including a second inlet for receiving the fluid from the second pump, and an emergency valve for opening of the second flow path comprising and controlled via a control port;
• a flow connection between the first and the second flow path arranged in accordance with a position of the flow direction control device between the emergency valve and the first inlet;
• and
• a control connection to the control port for controlling the opening of the second flow path in response to a pressure drop in a section of the fluid circuit between the first pump and the flow direction control device,
• wherein the hydraulic system further comprises a discharge conduit for discharging the fluid from the steering unit of the hydraulic control unit to the tank.