Electro-Hydraulic Control Circuit for Low-Energy Pressure Readiness
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Solution Overview
Problem
Electrified work vehicles face energy inefficiency due to the continuous operation of electric motors to maintain hydraulic circuit pressurization, even when the control lever is released, leading to unnecessary electricity consumption and potential uncontrolled behavior of hydraulic organs.
Innovation Solution
Incorporating an overpressure valve and pressure sensor in the hydraulic circuit to manage pressure thresholds, allowing the electric motor to deactivate when the control lever is released, ensuring minimal pressure for solenoid valve actuation and reducing non-continuous activations, thus conserving energy and maintaining controlled behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor is continuously operated to maintain hydraulic circuit pressurization, then the hydraulic circuit remains pressurized and ready for operation, but electricity consumption increases significantly
Solution Approach 1:
The electric motor operates periodically rather than continuously. It runs intermittently to recharge the hydraulic accumulator, maintaining system pressure readiness without continuous power consumption. The control unit monitors pressure levels and activates the motor only when the accumulator requires recharging.
Solution Approach 2:
A hydraulic accumulator is introduced as an intermediary energy storage device between the electric motor and the hydraulic circuit. The accumulator stores hydraulic energy when the motor is active and releases it when the motor is inactive, decoupling the motor operation from continuous circuit pressurization.
2Use of energy by moving object
If the electric motor is deactivated to save energy, then electricity consumption decreases, but the hydraulic circuit becomes depressurized causing uncontrolled behavior of hydraulic organs
Solution Approach 1:
The hydraulic accumulator is pre-charged and maintains a baseline pressure in the hydraulic circuit before any operation occurs. This preliminary pressurization ensures that when the electric motor is deactivated, the circuit remains pressurized through the stored energy in the accumulator, preventing uncontrolled hydraulic organ behavior.
Solution Approach 2:
The accumulator acts as a cushion that compensates for pressure drops when the motor is off. It provides a buffer of stored hydraulic energy that maintains system pressure and prevents sudden, uncontrolled movements of hydraulic organs during motor deactivation transitions.
3Productivity
If a fixed displacement hydraulic pump is used, then the hydraulic circuit can maintain constant flow, but the electric motor must run at minimum speed continuously consuming unnecessary electricity
Solution Approach 1:
The system transitions from a static, continuous motor operation with fixed displacement pump to a dynamic, intermittent motor operation. The control unit dynamically adjusts motor activation based on actual hydraulic demand and accumulator charge level, allowing the fixed displacement pump to operate only when needed rather than continuously.
Solution Approach 2:
The system recovers and stores hydraulic energy in the accumulator during periods of high demand or low electrical cost, then discards the need for continuous motor operation by relying on stored energy. This allows the fixed displacement pump to be intermittently operated while maintaining overall system productivity.
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
This solution achieves significant energy savings by minimizing electric motor activity while maintaining hydraulic circuit pressurization and preventing uncontrolled behavior, ensuring efficient operation of electrified work vehicles.
Implementation Method 1
an overpressure valve arranged on the neutral line of the directional open center electro-valve, which connects the electro-valve with the hydraulic oil recovery tank, configured to open when a first predetermined pressure threshold is exceeded
Implementation Method 2
divide the hydraulic oil fluid pumped by the hydraulic pump into a first flow destined for one of the hydraulic actuator chambers, while the second, remaining flow is sent to a collection tank
Implementation Method 3
a fixed displacement hydraulic pump fed by an electric motor in rotation
Data Source
Figure 1
Figure 2
AI summary
Electro-hydraulic circuit (HC) comprising a fixed displacement hydraulic pump (P) and an electric motor (M) arranged to drive the hydraulic pump in rotation, a recovery tank (T) arranged to collect hydraulic oil, an actuator (BUCKET , BOOM, AUX) hydraulic arranged to move a work member (B, T) and be powered by the electro-hydraulic circuit, an directional open center electro-valve (VI, V2, V3) operatively interposed between said hydraulic pump and said actuator and defining a rest condition in which it isolates the hydraulic actuator by connecting the hydraulic pump with the recovery tank, and an overpressure valve (SV) interposed between the electro-hydraulic valve and the recovery tank and configured for open when a first predetermined pressure threshold is exceeded. The electric motor (M) is configured to deactivate when the electro-valve is in rest condition. In addition, a pressure sensor (PS) is associated with a portion of the circuit between the hydraulic pump and the electro-valve to keep the aforementioned portion of the hydraulic circuit pressurized.