Closed-Circuit Hydraulic Cooling Without a Charge Pump
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Solution Overview
Problem
The hydraulic driving apparatus requires a charge pump to return operating oil to the circuit, increasing the number of parts and cost, and results in significant energy loss when the actuator is in a stop state.
Innovation Solution
A liquid-pressure driving system that forms a closed circuit with a liquid-pressure actuator, using a liquid-pressure pump, pressurizing mechanisms, a low pressure selector valve, a restrictor mechanism, a cooler apparatus, and a pressure liquid returning mechanism to cool the operating oil without a sub pump, allowing continuous flow through the cooler and return of cooled oil to the circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a charge pump is used to return operating oil to the closed circuit, then the operating oil can be cooled effectively, but the number of parts increases and manufacturing cost increases
Solution Approach 1:
The invention extracts the charge pump from the system and replaces it with a tank that receives operating oil discharged from the main pump. This eliminates the need for a separate sub-pump while maintaining the cooling function through the tank's heat dissipation capability.
Solution Approach 2:
The tank serves multiple functions: it receives discharged operating oil, provides cooling through heat dissipation, and returns cooled oil to the closed circuit. This multi-functional design replaces the need for a dedicated charge pump system.
2Temperature
If a charge pump is used to return operating oil to the closed circuit, then the operating oil can be cooled effectively, but manufacturing cost increases
Solution Approach 1:
The invention removes the charge pump component from the system, thereby reducing manufacturing costs associated with purchasing, installing, and maintaining this sub-pump while achieving the same cooling effect through the tank.
Solution Approach 2:
The invention uses a simple tank structure instead of a complex charge pump mechanism. The tank is a simpler, more cost-effective component that achieves the required cooling function without the high manufacturing costs of a dedicated sub-pump system.
3Stability of the object's composition
If the charge pump ejects operating oil to the tank when the actuator is in a stop state, then the closed circuit is maintained, but energy loss increases significantly
Solution Approach 1:
The invention implements periodic action by having the main pump discharge operating oil to the tank only when needed (when temperature exceeds the threshold), rather than continuously ejecting oil through a charge pump. This reduces energy loss while maintaining closed circuit stability.
Solution Approach 2:
The system uses its own main pump to discharge operating oil to the tank for cooling, rather than requiring a separate charge pump to perform this function. This self-service approach reduces energy consumption by utilizing the existing pump's discharge capability.
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 eliminates the need for a sub pump, reducing the number of parts and manufacturing costs, while effectively cooling the operating oil and preventing temperature increases in the closed circuit.
Implementation Method 1
a cooler apparatus interposed on the cooling passage so as to be located downstream of the restrictor mechanism, the cooler apparatus being configured to cool the operating liquid flowing through the cooling passage
Data Source
AI summary
A liquid-pressure driving system includes: a pump connected to an actuator through two pressure liquid passages; pressurizing mechanisms interposed on the passages and applying pressure to the operating oil returning from the actuator; a low pressure selector valve connected to parts of the passages and introducing to a cooling passage the operating liquid having lower pressure between the operating liquids flowing through the two pressure liquid passages; a restrictor mechanism interposed on the cooling passage; a cooler apparatus interposed on the cooling passage downstream of the restrictor mechanism, the cooler apparatus cooling the operating liquid flowing through the cooling passage; and a pressure liquid returning mechanism connected to parts of the two pressure liquid passages, each of the parts being at one side of the corresponding pressurizing mechanism close to the pump, the pressure liquid returning mechanism returning the cooled operating liquid to the two pressure liquid passages.