Hydraulic Control Valves With Dummy Load for Stable Actuation Speed
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Solution Overview
Problem
Existing working machines face issues with varying actuation speeds of low-load hydraulic actuators, activation shocks, and increased hydraulic fluid temperature during swiveling, particularly when high-load and low-load actuators are operated together or when the machine body is swiveled.
Innovation Solution
The working machine incorporates a first control valve for high-load actuators with a pressure compensation valve and a second control valve for low-load actuators with a flow-rate prioritizing valve, along with a dummy-load forming unit to stabilize actuation speeds and reduce activation shocks, and a variable relief system to manage hydraulic fluid temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure compensation valve is used to balance loads on hydraulic actuators, then the actuation speed stability improves, but the device complexity increases
Solution Approach 1:
The control valve is divided into multiple independent valve units, each equipped with its own pressure compensation valve. This segmentation allows each actuator to have independent load balancing control, improving actuation speed stability without requiring a complex centralized control system.
Solution Approach 2:
The pressure compensation valve performs preliminary load balancing before hydraulic fluid reaches the actuator. By pre-adjusting the pressure differential across each actuator, the system ensures stable actuation speeds without requiring complex real-time control mechanisms.
2Device complexity
If a constant relief set pressure is used, then the relief valve结构简单, but the activation shock of hydraulic actuator increases
Solution Approach 1:
The relief valve transitions from a static constant pressure design to a dynamic variable pressure design. The relief set pressure is adjusted based on the operation amount of the operation member, allowing the system to maintain simple valve structure while reducing activation shock through adaptive pressure control.
Solution Approach 2:
The relief set pressure parameter is changed dynamically based on operation conditions. When the operation member is sharply operated, the relief set pressure is increased to suppress activation shock, while maintaining a simpler structure compared to complex active control systems.
3Ease of operation
If the machine body is swiveled while a working-tool driving actuator is relieved, then the swivel motor can operate, but the hydraulic fluid temperature increases and components deteriorate
Solution Approach 1:
A dummy load is introduced as an intermediary element during swivel operations. The dummy load, generated by the pressure compensation valve of the swivel control valve, prevents direct relief of the working-tool driving actuator while the machine body is swiveled, thereby preventing excessive hydraulic fluid temperature increase and component deterioration.
4Productivity
If multiple hydraulic actuators are operated simultaneously, then the productivity increases, but the actuation speed of low-load actuators varies
Solution Approach 1:
Each control valve is equipped with a dedicated pressure compensation valve that provides local load balancing for its corresponding actuator. This local quality approach ensures that each actuator maintains consistent actuation speed regardless of the operational state of other actuators, enabling simultaneous multi-actuator operation with improved speed consistency.
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 stabilizes actuation speeds and reduces activation shocks by managing pressure differences and fluid temperature, enhancing the performance and reliability of hydraulic systems in working machines.
Implementation Method 1
a pressure compensation valve that sets a pressure difference between a pressure of a hydraulic fluid that is introduced thereinto and a pressure of a hydraulic fluid output therefrom to be constant
Implementation Method 2
a flow-rate prioritizing valve that prioritizes a flow rate of a hydraulic fluid output to the low-load hydraulic actuator
Implementation Method 3
a relief valve that regulates the pressure of a hydraulic fluid delivered from the pump
Data Source
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AI summary
To suppress a variation in the actuation speed of a low-load hydraulic actuator (MT) whose hydraulic pressure required for actuation thereof is low. A working machine (1) includes: a plurality of hydraulic actuators; a plurality of direction switching valves that are provided so as to correspond to the plurality of hydraulic actuators, respectively, and each of which switches a direction of a hydraulic fluid for a corresponding one of the hydraulic actuators; and a dummy-load forming unit (97) that forms a dummy load in a low-load direction switching valve (DV8) that switches a direction of hydraulic fluid for a low-load hydraulic actuator (MT) whose hydraulic pressure required for actuation thereof is lower than a hydraulic pressure required for actuation of a high-load hydraulic actuator (C3), the low-load hydraulic actuator (MT) and the high-load hydraulic actuator (C3) being included in the plurality of hydraulic actuators, to suppress a variation in an actuation speed of the low-load hydraulic actuator (MT) between a time when the high-load hydraulic actuator (C3) and the low-load hydraulic actuator (MT) are operated in combination and a time when the low-load hydraulic actuator (MT) is operated singly.