Hydraulic Steering With Closed Circuit and Two-Way Electric Pump
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Solution Overview
Problem
Conventional hydraulic steering systems face high energy consumption due to open-center circuits and the need for booster pumps, leading to inefficiencies and energy waste, especially when no hydraulic actuation is required.
Innovation Solution
A closed hydraulic circuit using a single electric two-way flow pump pressurizes both supply and return lines with a check valve group and hydraulic accumulator, eliminating the need for a booster pump and optimizing pressure control with a pressure sensor and anti-shock valves to minimize energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an open-center hydraulic circuit is used, then the system can operate with simple circuit design, but high power is consumed due to continuous oil flow through the system
Solution Approach 1:
The patent replaces the conventional mechanical open-center hydraulic circuit with a closed hydraulic circuit that uses an electro-actuated pump. This substitution eliminates the need for continuous oil circulation through a mechanical pump, allowing the system to operate with minimal or zero flow when steering is not required, thereby dramatically reducing power consumption while maintaining circuit simplicity through electronic control.
2Loss of energy
If a closed hydraulic circuit is used, then energy efficiency is improved, but margin pressure and stand-by pressure are higher leading to energy consumption
Solution Approach 1:
The patent implements a dynamic closed hydraulic circuit where the electro-actuated pump can vary its operation based on system needs. The pump operates at high pressure only when hydraulic actuation is required, and can be deactivated or operate at minimal flow during stand-by conditions. This dynamic operation allows the system to maintain the energy efficiency benefits of a closed circuit while eliminating constant pressure-related energy consumption.
Solution Approach 2:
The system dynamically changes operating parameters including pressure and flow rate based on steering requirements. During normal operation, the circuit maintains closed-loop efficiency with optimized pressure levels. During stand-by conditions, the system transitions to zero or minimal flow mode, effectively changing the pressure parameter from constant high pressure to variable pressure that approaches zero when not in use, thereby eliminating stand-by energy consumption.
3Ease of operation
If an electro-actuated hydraulic pump is used, then steering control is improved, but large consumption of electrical energy occurs in open-center circuits
Solution Approach 1:
The patent replaces the conventional mechanical pump-driven open-center system with an electro-actuated pump in a closed hydraulic circuit. This substitution enables precise electronic control of hydraulic flow and pressure, improving steering control responsiveness and accuracy. Simultaneously, because the electro-actuated pump only operates when steering input is detected, electrical energy consumption is dramatically reduced compared to systems requiring continuous pump operation.
Solution Approach 2:
The electro-actuated pump operates periodically based on steering requirements rather than continuously. The control system activates the pump only when steering input is detected, and deactivates it during stand-by conditions. This periodic operation pattern maintains excellent steering control when needed while minimizing electrical energy consumption during normal vehicle operation without steering inputs.
4Reliability
If a booster pump is used in closed hydraulic circuits, then volumetric losses are compensated and pressurization is ensured, but constant energy consumption occurs even when no hydraulic actuation is carried out
Solution Approach 1:
The patent implements a self-regulating closed hydraulic circuit where the electro-actuated pump serves multiple functions. The same pump that provides hydraulic actuation also compensates for volumetric losses and maintains circuit pressurization when needed. The pump's control system automatically detects when pressurization is required and activates the pump accordingly, eliminating the need for a separate booster pump that would consume energy continuously regardless of actual system needs.
Solution Approach 2:
The electro-actuated pump is designed to perform multiple functions within the closed hydraulic circuit: it provides hydraulic actuation during steering operations, compensates for volumetric losses in the system, and maintains minimum circuit pressurization when required. This multi-functionality eliminates the need for a dedicated booster pump, reducing component count and eliminating constant energy consumption associated with separate pressurization systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves significant energy savings by only consuming electricity when necessary, reducing heat dissipation and component losses, while maintaining efficient steering control.
Implementation Method 1
a single electric two-way flow pump, without implementing any boost pump
Implementation Method 2
The circuit includes a check valve group arranged in a bridge
Implementation Method 3
The valve group is connected to a hydraulic accumulator to pressurize it independently of the direction of operation of the electric pump
Implementation Method 4
a pressure limiting group to keep the low pressure line pressurized
Data Source
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AI summary
Hydraulic steering system comprising an electric pump (2, 3) with two-way flow and at least one actuator cylinder (4) powered by said electric pump via a closed hydraulic circuit (1) comprising at least a first supply line (L1) and a second supply line (L2) and in which said circuit includes mutual connection means (12, 12', 13, 13', 14, 15) between said first and second lines arranged so that when the electric pump is operational by pressurizing one of said first and second supply lines at a first pressure value, said connection means are configured to pressurize the other line at a second established pressure value, lower than said first pressure value.