Excavator Hydraulic Flow Control for Fast Bucket Response
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Solution Overview
Problem
Conventional hydraulic circuit systems in work machines, such as hydraulic excavators, experience deteriorated responsiveness and reduced work efficiency when the operation lever's operation amount changes frequently in a short period, leading to delayed bucket response and decreased accuracy during actions like gravel spreading.
Innovation Solution
A work machine equipped with a hydraulic pump, multijoint front work implement, directional control valves, operation devices, operation amount sensors, and a controller that can switch between a normal mode and a responsiveness priority mode to manage the flow restriction of the directional control valves, ensuring optimal fluid flow based on detected operation amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the delivery flow rate of the hydraulic pump is reduced to enhance fuel efficiency, then energy consumption is improved, but the responsiveness of the hydraulic actuator deteriorates when the operation lever changes frequently
Solution Approach 1:
The flow restriction device dynamically adjusts the opening area of the meter-in throttle based on the operation state of the operation lever. When the operation lever is operated (detected by operation amount sensor), the controller increases the opening area to improve responsiveness. When the operation lever is not operated, the controller maintains a smaller opening area to preserve fuel efficiency. This dynamic adjustment resolves the contradiction between energy efficiency and responsiveness.
Solution Approach 2:
The system changes the flow rate parameter of the hydraulic pump by controlling the opening area of the meter-in throttle. The controller modifies this parameter in real-time based on operation lever position, allowing the system to switch between fuel-efficient mode (smaller opening area) and responsive mode (larger opening area), thereby resolving the contradiction between these two opposing requirements.
2Use of energy by moving object
If the opening area of the meter-in throttle is reduced to maintain fuel efficiency, then energy consumption is improved, but the bucket speed decreases making it impossible to appropriately spread gravel
Solution Approach 1:
The opening area of the meter-in throttle is dynamically adjusted based on real-time detection of operation lever position. During gravel spreading operations when the operation lever is actively moved, the system increases the opening area to maintain bucket speed and productivity. During idle periods, the system reduces the opening area to preserve fuel efficiency, thus resolving the contradiction between these two parameters.
Solution Approach 2:
The system performs preliminary detection of the operation lever position and proactively adjusts the meter-in throttle opening area before the hydraulic actuator needs to respond. This ensures that when the operator moves the operation lever for gravel spreading, the flow restriction is already reduced, allowing the bucket to maintain appropriate speed without delay.
3Force
If the supply flow rate to the bucket directional control valve is restricted to enable simultaneous movement of boom and bucket, then the ability to move boom at high load pressure is improved, but the responsiveness during frequent operation changes deteriorates
Solution Approach 1:
The meter-in throttle opening area is dynamically controlled based on operation lever detection. When the operation lever is moved (indicating need for responsiveness), the controller increases the opening area to improve bucket responsiveness. When the operation lever is stationary and simultaneous movement is needed, the controller maintains a smaller opening area to preserve boom load pressure capability, thus resolving the contradiction.
Solution Approach 2:
The system changes the flow rate parameter by adjusting the meter-in throttle opening area based on real-time operation state. This parameter change allows the system to switch between maintaining high boom load pressure (smaller opening area) and achieving high responsiveness (larger opening area), resolving the technical contradiction between these two requirements.
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
Enhances responsiveness and maintains work efficiency by allowing the hydraulic actuator to respond quickly to frequent operation lever changes, preventing declines in work accuracy and efficiency during operations requiring rapid adjustments.
Implementation Method 1
a hydraulic pump driven by a prime mover; a plurality of hydraulic actuators each driven by pressurized fluid delivered from the hydraulic pump
Implementation Method 2
a plurality of hydraulic actuators each driven by pressurized fluid delivered from the hydraulic pump and driving each of the plurality of driven members
Implementation Method 3
a flow restriction device that can restrict a flow rate of pressurized fluid in at least one of a meter-in passage and a meter-out passage of one of the directional control valves
Data Source
AI summary
A work machine includes directional control valves 43 and 44 each controlling a direction and a flow rate of a pressurized fluid supplied to each a boom cylinder 32 and a bucket cylinder 36; operation amount sensors 51a, 52a, and 52b detecting operation amounts of operation devices 51 and 52; a variable flow control valve 45 that can restrict the flow rate of the pressurized fluid in a meter-in passage of the directional control valve 44 related to the bucket cylinder 36; and a controller 60 controlling the variable flow control valve on the basis of the detection results by the operation amounts from the operation amount sensors, and the controller changes over an action mode to any one of a normal mode for restricting the flow rate of the pressurized fluid by the variable flow control valve and a responsiveness priority mode for not restricting the flow rate of the pressurized fluid by the variable flow control valve in response to the detection results of the operation amounts of the plurality of operation devices. It is thereby possible to enhance responsiveness in an action that requires responsiveness such as an action in which an operation amount of an operation lever frequently changes in a short period of time and to suppress a decline in work efficiency.