Hydraulic Pump Switching Control for Stable Construction Machine Speed
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Solution Overview
Problem
In construction machines with hydraulic systems, unintentional fine operations of control levers can lead to a decrease in actuator speed and work speed due to pump reconnection issues, causing impaired operability.
Innovation Solution
A construction machine with a controller that adjusts pump displacements and selector valve operations to prevent pump switching between actuators, using composite dead zones and operation amount correction to stabilize actuator speed and prevent sharp increases in speed during composite operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If selector valves are opened and closed to reconnect pumps to different actuators, then operability of the second actuator is ensured, but the speed of the first actuator decreases significantly and workability is impaired
Solution Approach 1:
The controller predicts the demand flow rate of the second actuator in advance and compares it with a threshold before actually switching pump connections. This preliminary check prevents unnecessary or erroneous switch operations that would harm the first actuator's speed, while still allowing legitimate operations of the second actuator.
Solution Approach 2:
The system continuously monitors the operation state of control levers and the demand flow rates of actuators, using this feedback to dynamically control selector valve positions. This closed-loop control ensures that pump connections are maintained or switched only when appropriate, preventing unwanted speed reduction of the first actuator.
2Adaptability or versatility
If pump connection is switched to another actuator, then the other actuator can operate, but work speed decreases due to decrease in actuator speed
Solution Approach 1:
Before switching pump connections to enable another actuator, the controller performs a preliminary assessment by comparing the predicted demand flow rate with a predetermined threshold. This prevents premature or erroneous switching that would reduce work speed, while still enabling necessary operations of other actuators.
Solution Approach 2:
The system dynamically changes the operational parameters (pump connections via selector valves) based on real-time analysis of control lever operations and predicted flow rate demands. This parameter adjustment ensures that switching occurs only when beneficial for overall system productivity.
3Measurement precision
If fine operation of control lever is detected, then pump reconnection occurs, but erroneous operations are triggered by unintentional movements
Solution Approach 1:
The controller uses a threshold-based preliminary filter on the predicted demand flow rate to distinguish between intentional fine operations and unintentional movements. Only when the predicted flow rate exceeds the threshold does the system respond with pump reconnection, thereby preventing erroneous operations triggered by accidental control lever movements.
Solution Approach 2:
The system performs a preliminary calculation of the demand flow rate based on control lever operation amounts before executing pump reconnection. This preliminary action allows the system to anticipate and filter out erroneous operations, ensuring that only legitimate fine operations trigger pump switching.
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
Prevents pump connection switching and maintains stable actuator speed, ensuring consistent work speed and preventing erroneous operations when unintentional control lever movements occur.
Implementation Method 1
a plurality of actuators connected in closed circuits to a plurality of closed circuit pumps
Implementation Method 2
a plurality of regulators that adjusts displacements of the plurality of closed circuit pumps
Implementation Method 3
a plurality of selector valves that are respectively arranged between the plurality of closed circuit pumps and the plurality of actuators, and switch interruption and communication of the respective closed circuits
Data Source
Figure 1
Figure 2~2A4(7)
Figure 3
AI summary
To make it possible to prevent a decrease in work speed due to a decrease in the speed of a given actuator when an operator unintentionally performs a fine operation of the control lever of the other actuator in a state in which the given actuator is driven by the hydraulic fluid delivered from a plurality of pumps, a controller (41) sets, as a composite dead zone line serving as a boundary of a composite dead zone, a composite dead zone line such that as an operation amount in one direction of a control lever (12L) or (13L) of a control lever device (12) or (13) is increased, the width of the composite dead zone corresponding to an operation amount in the other direction of the control lever is widened, and corrects the operation amount in the other direction such that the demanded flow rate of an actuator increases from zero, when the control lever is operated in the other direction in a state in which the operation amount in the one direction of the control lever remains within a range of the composite dead zone, and the operation amount in the other direction exceeds the composite dead zone line.