Hydraulic Pump Selector Layout for Stable Attachment Operation
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Solution Overview
Problem
In hydraulic drive systems for work machines like hydraulic excavators, the operation of special attachments is hindered by insufficient or unstable hydraulic fluid supply due to shared fluid sources with permanently installed actuators, leading to suboptimal combined operation performance.
Innovation Solution
The system incorporates multiple hydraulic pumps and directional control valves, along with a selector valve that allows the special attachment's hydraulic actuator to draw from an independent fluid source, ensuring stable and sufficient fluid supply by switching between primary and additional hydraulic pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional hydraulic actuators are connected to auxiliary directional control valves that share hydraulic fluid sources with permanently installed actuators, then the special attachment can be operated in combination with other work elements, but the hydraulic fluid supply to the additional actuators becomes insufficient or unstable due to mutual interference from operation load pressures
Solution Approach 1:
The hydraulic drive system is segmented into multiple independent hydraulic circuits, each with its own hydraulic pump. Permanently installed actuators are supplied by first and second hydraulic pumps, while additional actuators for special attachments are supplied by a third hydraulic pump. This segmentation ensures that each circuit operates independently without mutual interference from operation load pressures, resolving the contradiction between combined operation capability and hydraulic fluid supply stability.
2Device complexity
If multiple hydraulic actuators share common hydraulic fluid sources, then the system structure remains simple, but the operability of special attachments deteriorates when combined operation is performed
Solution Approach 1:
The hydraulic system is divided into separate circuits with dedicated pumps for different actuator groups. The third hydraulic pump is exclusively dedicated to supplying additional actuators for special attachments, while first and second pumps supply permanently installed actuators. This segmentation improves special attachment operability during combined operations without significantly complicating the overall system structure, as each circuit remains independent and manageable.
3Productivity
If hydraulic pumps supply fluid to multiple actuators simultaneously, then the system can perform multiple operations, but the hydraulic fluid is preferentially supplied to actuators other than additional actuators, reducing the amount of fluid available to special attachments
Solution Approach 1:
The hydraulic system is segmented into independent supply circuits, with the third hydraulic pump exclusively dedicated to additional actuators. This ensures that the quantity of hydraulic fluid supplied to special attachments is not reduced by preferential supply to other actuators, as each circuit operates independently with its own fluid source.
Solution Approach 2:
Each hydraulic pump serves its designated actuators independently without relying on shared resources. The third hydraulic pump self-serves the additional actuators, ensuring they receive sufficient hydraulic fluid regardless of the operational state of other actuators in the system.
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 enhances the operability of special attachments by providing a dedicated and stable hydraulic fluid source, independent of other actuators' operation loads, thereby improving combined operation performance.
Implementation Method 1
a plurality of hydraulic actuators that drive work elements such as a boom and an arm; a plurality of hydraulic pumps as hydraulic fluid sources that supply a hydraulic fluid to those hydraulic actuators
Data Source
AI summary
A hydraulic drive system includes a swing directional control valve 81 and a third boom directional control valve 82 that are connected to a third hydraulic pump 33. Furthermore, the hydraulic drive system includes: a second auxiliary directional control valve 84 that is connected to the third hydraulic pump 33, and is connectable with a second special hydraulic actuator 64 for driving special attachments; and a first selector valve 96 that is connected to the third hydraulic pump 33 upstream of the second auxiliary directional control valve 84, and is connectable with an additional hydraulic pump 97. The first selector valve 96 switches the hydraulic fluid source of the second special hydraulic actuator 64 connected to the second auxiliary directional control valve 84 at least between the third hydraulic pump 33 and the additional hydraulic pump 97. Operability for combined operation of a special attachment can be improved in the hydraulic drive system equipped in advance with an auxiliary directional control valve that is connectable with an additional hydraulic actuator for driving the special attachment.