Hydraulic Drive Device Circuit Switching for Energy Saving
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Solution Overview
Problem
Existing hydraulic drive devices in construction machines face challenges in achieving a high energy saving effect while maintaining a low-cost configuration, as open-circuit systems suffer from energy loss due to throttle elements, and closed-circuit systems require multiple dedicated pumps, increasing costs and complexity.
Innovation Solution
A hydraulic drive device with a combination of closed and open circuits, featuring variable displacement pumps and throttle valves, allows for circuit switching to optimize energy efficiency by using closed circuits for primary actuators and open circuits for secondary actuators, reducing the number of pumps and minimizing throttle valve usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an open-circuit hydraulic drive device is used, then a common hydraulic pump can be used to supply hydraulic oil to multiple hydraulic actuators, but a high energy saving effect is difficult to obtain due to pressure loss caused by throttle elements in control valves
Solution Approach 1:
The hydraulic drive device is divided into multiple independent closed circuits, with each circuit dedicated to a specific hydraulic actuator. This segmentation allows each actuator to have its own dedicated pump, eliminating the need for throttle elements and control valves that cause energy loss in shared open-circuit systems.
Solution Approach 2:
The hydraulic pump is designed with multi-functionality to serve different roles: it can operate as a closed-circuit pump for circulating hydraulic oil within a closed circuit, as a charge pump for supplying hydraulic oil to the closed circuit, and as an open-circuit pump for eliminating area differences in cylinders with rods. This universal design reduces the total number of pumps required while maintaining energy efficiency.
2Loss of energy
If a closed-circuit hydraulic drive device is used, then a high energy saving effect is obtained by eliminating throttle elements, but the number of required hydraulic pumps increases by the number of hydraulic actuators, resulting in increased cost
Solution Approach 1:
The hydraulic pump is designed with multi-functionality to serve different roles: it can operate as a closed-circuit pump for circulating hydraulic oil within a closed circuit, as a charge pump for supplying hydraulic oil to the closed circuit, and as an open-circuit pump for eliminating area differences in cylinders with rods. This universal design reduces the total number of pumps required while maintaining energy efficiency.
Solution Approach 2:
Multiple functions that would traditionally require separate pumps are merged into a single hydraulic pump. The pump can switch between operating modes (closed-circuit mode, charge pump mode, open-circuit mode) to perform multiple tasks, thereby reducing the overall number of pumps needed in the system and lowering costs.
3Loss of energy
If multiple dedicated pumps are used in a closed-circuit system, then each hydraulic actuator can be driven efficiently, but the number of required pumps increases even more due to the need for charge pumps and open-circuit pumps
Solution Approach 1:
The hydraulic pump is designed with multi-functionality to serve different roles: it can operate as a closed-circuit pump for circulating hydraulic oil within a closed circuit, as a charge pump for supplying hydraulic oil to the closed circuit, and as an open-circuit pump for eliminating area differences in cylinders with rods. This universal design reduces the total number of pumps required while maintaining energy efficiency.
Solution Approach 2:
Multiple functions that would traditionally require separate pumps are merged into a single hydraulic pump. The pump can switch between operating modes (closed-circuit mode, charge pump mode, open-circuit mode) to perform multiple tasks, thereby reducing the overall number of pumps needed in the system and lowering costs.
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 configuration achieves a high energy saving effect by minimizing pressure loss and reducing the number of required pumps, thereby lowering costs and improving operational efficiency, especially when primarily driving actuators with higher operational frequencies.
Implementation Method 1
a pump section including at least one hydraulic pump for circulating the hydraulic oil in the closed circuit
Implementation Method 2
a plurality of variable throttle valves provided in the plurality of hydraulic actuators so as to change a flow rate of the hydraulic oil supplied from the hydraulic pump included in the pump section to each of the hydraulic actuators
Data Source
AI summary
Provided is a hydraulic drive device that is provided in a work device and with which it is possible to obtain a high energy-saving effect with a low-cost configuration while being equipped with a plurality of hydraulic actuators. The hydraulic drive device is provided with: first and second actuator groups; closed circuits connected to hydraulic actuators included in the first actuator group; a pump section including closed circuit pumps; open circuits which include a plurality of variable throttle valves for changing the flow rate of working fluid supplied from a hydraulic pump included in the pump section to a hydraulic actuator; and circuit switching sections having a first state in which the closed circuits are opened and the opened circuits are blocked, and a second state in which the closed circuits are blocked and the open circuits are opened.