Hydraulic Excavator Pump Control for Cylinder Operation During Travel
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In construction machines, the combination of a closed-circuit pump and an open-circuit pump for driving a single-rod hydraulic cylinder during travel operations impairs travel operability due to the diversion of open-circuit pumps from travel hydraulic motors, leading to reduced traveling speed.
Innovation Solution
A construction machine configuration where a closed-circuit pump exclusively drives the single-rod hydraulic cylinder during travel operations, ensuring the open-circuit pumps are dedicated to driving the travel hydraulic motors, with a controller managing flow rates and valve operations to maintain optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If open-circuit pumps are used to drive both the single-rod hydraulic cylinder and the travel hydraulic motor during travel operations, then the hydraulic cylinder can be driven, but the traveling speed is largely lowered and travel operability is impaired
Solution Approach 1:
The patent divides the hydraulic pump system into two separate functional segments: open-circuit pumps dedicated exclusively to travel hydraulic motors, and closed-circuit pumps dedicated to single-rod hydraulic cylinders. This segmentation prevents resource contention and ensures that travel operations receive dedicated pump capacity, maintaining travel speed while enabling hydraulic cylinder operation during movement.
Solution Approach 2:
The patent introduces a closed-circuit pump as an intermediary system to handle hydraulic cylinder operations during travel. This intermediary closed-circuit system acts as a buffer that handles cylinder actuation demands without interfering with the open-circuit travel system, thereby preventing speed reduction while maintaining operational versatility.
2Ease of operation
If a single-rod hydraulic cylinder is driven by a combination of closed-circuit pump and open-circuit pump, then favorable operability can be obtained, but the open-circuit pump is diverted from driving the travel hydraulic motor, reducing travel speed
Solution Approach 1:
The patent segments the pump control system into dedicated open-circuit pump control for travel operations and closed-circuit pump control for hydraulic cylinder operations. This segmentation allows each pump type to operate independently at optimal performance levels, with open-circuit pumps maintaining full capacity for travel while closed-circuit pumps handle cylinder actuation, thus preserving both operability and travel speed.
Solution Approach 2:
The patent implements dynamic parameter changes in pump delivery flow rates based on operational mode. The controller adjusts the closed-circuit pump's delivery flow rate to match the hydraulic cylinder's requirements while ensuring the open-circuit pump maintains sufficient flow rate for travel hydraulic motors, optimizing both operability and travel speed through real-time parameter adaptation.
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 prevents a decrease in travel speed and maintains operability by ensuring the open-circuit pumps are solely used for travel, while the closed-circuit pump handles the hydraulic cylinder's operation, thus enhancing overall travel performance.
Implementation Method 1
a closed-circuit pump (7) connected through a closed circuit to the single-rod hydraulic cylinder (13), a cap-side flow path (41) connecting a delivery port on one side of the closed-circuit pump (7) to a cap-side chamber (13a) of the single-rod hydraulic cylinder (13), and a rod-side flow path (42) connecting a delivery port on the other side of the closed-circuit pump (7) to a rod-side chamber (13b) of the single-rod hydraulic cylinder (13)
Implementation Method 2
an open-circuit pump (8, 9), a travel flow rate control valve (17a, 17b) that controls flow rate supplied from the open-circuit pump (8, 9) to the travel hydraulic motor (16a, 16b)
Data Source
AI summary
Provided is a construction machine in which travel operability is not impaired when a combined operation is performed in which a single-rod hydraulic cylinder is driven during a travel operation. A hydraulic excavator includes a controller that controls the delivery direction and delivery flow rate of a closed-circuit pump, opens and closes a travel switching valve and an assist switching valve, and controls the delivery flow rate of the open-circuit pump, according to a travel operation lever and a work operation lever. The controller holds the assist switching valve in a closed position irrespective of whether or not the work operation lever is operated in a case where the travel operation lever is operated.