Closed-Loop Hydraulic Flushing With Actively Controlled Discharge Flow
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Solution Overview
Problem
Existing hydraulic systems in mining vehicles face inefficiencies in energy usage and unsatisfactory controllability during flushing of closed loop hydraulic circuits.
Innovation Solution
A mining vehicle equipped with a hydraulic system featuring a closed loop circuit and an actively controlled by-pass flow system, which includes a feed arrangement for adding fresh hydraulic fluid and a discharge arrangement for removing used fluid, both controlled by a dedicated control unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate flushing pump is used to produce flushing fluid flow, then the closed loop hydraulic circuit can be flushed, but energy efficiency deteriorates and system complexity increases
Solution Approach 1:
The main hydraulic pump is made to serve dual functions: driving the hydraulic actuator during normal operation and producing flushing fluid flow when needed. The pump can operate in different modes (actuator drive mode and flushing mode) by controlling the directional control valve to route fluid differently, eliminating the need for a dedicated flushing pump and reducing overall system energy consumption.
Solution Approach 2:
The flushing system components (flushing pump, directional control valve, flow control valve) are merged with the existing hydraulic system components. The main hydraulic pump serves as the flushing pump, the directional control valve integrates flushing flow control with actuator control, and the flow control valve is used for both actuator speed control and flushing flow regulation, thereby simplifying the system structure.
2Reliability
If a separate flushing pump with separate control valve is used, then flushing can be performed, but controllability of flushing becomes unsatisfactory
Solution Approach 1:
The directional control valve integrates two functions: controlling hydraulic fluid flow to the actuator during normal operation and directing flushing fluid flow through the closed loop circuit during flushing. This unified control mechanism improves controllability by using a single valve system for both operations, eliminating the need for separate control mechanisms.
Solution Approach 2:
The flow control valve is designed to dynamically adjust the flushing fluid flow rate based on system conditions and flushing requirements. The valve can be positioned to control both the magnitude and direction of fluid flow, enabling flexible and precise control of the flushing process while maintaining system versatility.
3Reliability
If flushing system components are added to the hydraulic system, then the closed loop circuit can be flushed, but device complexity increases
Solution Approach 1:
Existing hydraulic system components are made multi-functional to avoid adding separate flushing-specific components. The main hydraulic pump drives both the actuator and produces flushing flow; the directional control valve routes fluid for both actuator control and flushing; the flow control valve regulates both actuator speed and flushing flow rate. This approach maintains flushing capability while minimizing system complexity.
Solution Approach 2:
The flushing system is merged with the existing hydraulic system by integrating flushing flow production, direction control, and flow regulation functions into the existing pump and valve components. This consolidation eliminates the need for separate flushing pump and control valve, thereby reducing overall system complexity while preserving flushing functionality.
Data Source
Figure 1~2
Figure 3
AI summary
A hydraulic system, mining vehicle, and method for flushing a closed loop hydraulic circuit. The hydraulic system (HS) provides at least one closed hydraulic circuit (CL) comprising a hydraulic pump, a motor and one or more hydraulic actuators. The hydraulic system further comprises a flushing system for discharging and feeding a limited amount of hydraulic fluid for flushing the closed loop hydraulic circuit. There is discharge valve (DV) which is actively controlled by means of a control unit (CU) so that fluid flow through the valve is selectively controlled.