Electro-Hydraulic Steering Control System

摘要

A steering control system includes a steering circuit, a primary control circuit and a redundant control circuit. The primary control circuit includes primary proportional control valves, and a primary pilot valve having a thermal bleed of pilot fluid to warm the primary pilot valve when not operating to control the steering circuit. The redundant control circuit includes secondary proportional control valves, and a pressure reducing valve having a thermal bleed orifice allowing fluid flow to warm the pressure reducing valve when not operating to control the steering circuit. The thermal bleeds may also flow past the proportional control valves to raise their temperatures. The circuits of the steering control system are contained in a single valve group housing.

主权项

1. A steering control system for a machine having steering components configured to turn in a first direction and a second direction, a steering actuator operatively coupled to the steering components to turn in the first direction and the second direction, a steering input device, a steering fluid source and a pilot fluid source, the steering control system comprising:
a steering circuit comprising a steering valve in fluid communication with the steering fluid source and movable between a closed position, a first open position wherein the steering valve outputs steering fluid to the steering actuator to cause the steering components to turn in the first direction, and a second open position wherein the steering valve outputs steering fluid to the steering actuator to cause the steering components to turn in the second direction; a primary control circuit in fluid communication with the steering circuit and configured to transmit pilot fluid to the steering valve to cause the steering valve to move between the closed position, the first open position and the second open position, the primary control circuit comprising a primary pilot valve in fluid communication with the pilot fluid source and movable between a closed position that prevents transmission of pilot fluid to the steering circuit and an open position that allows transmission of pilot fluid to the steering circuit, wherein the primary pilot valve includes a primary thermal bleed path allowing pilot fluid to flow through the primary pilot valve and output to a pilot fluid drain line when the primary pilot valve is in the closed position.