Hydraulic Travel Motor Control Under Rapid Excavation Load Spikes
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Solution Overview
Problem
In excavation work, the rapid increase in load pressure of a working hydraulic pump can lead to an insufficient reduction in travel driving force due to the time lag in displacement change of the hydraulic motor, resulting in reduced workability and difficulty in lifting the bucket.
Innovation Solution
A travel control apparatus that sets a predetermined maximum load pressure for the bucket cylinder and includes a maximum value control unit to decrease the hydraulic motor's displacement to a minimum limit when the load pressure exceeds a predetermined value, ensuring the travel driving force remains balanced with the lifting force, thereby preventing excessive skidding and improving workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the displacement of the traveling hydraulic motor is controlled to gradually decrease with an increase in the discharge pressure of the working hydraulic pump according to a predetermined characteristic, then the travel driving force is reduced to improve workability, but the displacement change cannot follow the rapid change of working load pressure, resulting in insufficient reduction of travel driving force
Solution Approach 1:
The patent applies dynamics by making the maximum displacement of the hydraulic motor variable rather than fixed. The control device dynamically adjusts the maximum displacement based on real-time working load pressure feedback, allowing the system to adapt to rapidly changing working conditions. This dynamic adjustment ensures that travel driving force is sufficiently reduced even when load pressure changes rapidly, resolving the contradiction between improving workability and maintaining fast response speed.
Solution Approach 2:
The patent implements feedback control by using a pressure sensor to detect the working load pressure in real-time and feeding this information back to the control device. The control device then adjusts the maximum displacement of the hydraulic motor based on this feedback signal. This closed-loop feedback mechanism enables the system to respond quickly to rapid changes in load pressure, ensuring that travel driving force is appropriately reduced to improve workability while maintaining fast response capability.
Data Source
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AI summary
There are provided: a first circuit for traveling HC1, formed through a closed circuit connection of a variable displacement hydraulic pump 2 and a variable displacement hydraulic motor 3, that includes a motor control unit 10, 11 that controls a displacement of the hydraulic motor 3; a second circuit for working HC2 that drives a work hydraulic actuator 114, 115 by pressure oil from a work hydraulic pump 4; and a maximum value control unit 10 that controls a maximum displacement of the hydraulic motor 3 in accordance with load pressure Pf in the second circuit HC2. The maximumvalue control unit 10 decreases the maximum displacement to a minimum limit q1 corresponding to a maximum load pressure Pr in the second circuit when load pressure Pf in the second circuit exceeds a predetermined value Ps.