Hydraulic System Independent Circuit Control for Dozer Straightness
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Solution Overview
Problem
Hydraulic systems for working machines with track devices and dozer devices face issues with straightness and turning performance when the dozer device is operated while the machine is running, due to the reliance on a single hydraulic pump configuration that leads to poor independence between left and right track operations.
Innovation Solution
A hydraulic system with two independent hydraulic-fluid discharge ports, where the track drive motors and dozer cylinder are driven by separate hydraulic fluid sources, allowing independent control of each track control valve and dozer control valve, and incorporating pressure compensation valves to manage flow rates based on actuator loads, ensuring consistent performance during dozer operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hydraulic pump configuration is used to supply hydraulic fluid to both track drive motors and dozer cylinder, then the system structure is simplified, but the independence between left and right track operations deteriorates, causing poor straightness and turning performance when dozer device is operated simultaneously
Solution Approach 1:
The hydraulic pump is divided into two independent discharge ports (first discharge port and second discharge port), each capable of independently supplying hydraulic fluid to different actuators. This segmentation allows the left track drive motor to receive fluid from one port while the right track drive motor receives fluid from the other port, maintaining operational independence even when the dozer cylinder is activated.
Solution Approach 2:
The dozer control valve is extracted from the common hydraulic circuit and provided with a dedicated hydraulic fluid supply path from the hydraulic pump. This separation ensures that dozer operations do not interfere with track drive motor operations, as each has its own independent fluid supply channel.
2Ease of operation
If hydraulic fluid from a single pump is supplied to multiple actuators concurrently, then the system is easier to control, but the flow rate distribution becomes unstable, affecting turning performance and straightness
Solution Approach 1:
Each discharge port of the hydraulic pump is equipped with independent flow control capabilities, allowing the flow rate to each track drive motor to be controlled independently of the other. This local quality control ensures that even when the dozer cylinder is operating, the flow rates to the left and right track drive motors remain stable and can be precisely adjusted for accurate straightness and turning performance.
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 ensures straightness and improved turning performance by maintaining independent circuit control, even when the dozer device is in operation, by evenly distributing hydraulic fluid from both discharge ports to the dozer control valves and track control valves, thus preventing excessive fluid flow to the dozer cylinder and ensuring adequate flow rates to the track drive motors.
Implementation Method 1
a first pump whose discharge flow rate can be controlled; a second pump whose discharge flow rate can be controlled; a third pump whose discharge flow rate is not controlled
Implementation Method 2
Each of the boom control valve, the arm control valve, the bucket control valve, and the swing control valve includes a direction switching valve for switching the direction of the hydraulic fluid with respect to a corresponding hydraulic actuator to be controlled, and in addition, includes a pressure compensation valve configured to adjust, when more than one of the hydraulic actuators under control of these control valves are concurrently operated, the loads among the concurrently operated hydraulic actuators
Implementation Method 3
The track body includes a pair of left and right crawler track devices which are driven by a track drive motor
Data Source
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AI summary
A pair of dozer control valves (V3,V6) concurrently operable; a pilot pressure valve (V14) switchable between an independent position (27) where, when only track devices (5) are operated, discharged fluid from one hydraulic-fluid discharge port (P1) is independently supplied to one track control valve and one dozer control valve, and discharged fluid from the other hydraulic-fluid discharge port (P2) is independently supplied to the other track control valve and the other dozer control valve, and a merging position (28) where, when the other control valves are operated, discharged fluid from the one hydraulic-fluid discharge port and from the other hydraulic-fluid discharge port are merged and supplied to the control valves (V1 to 10) ; and pressure compensation valves (V11) in the control valves and for distributing hydraulic fluid at flow rates based on extent of actuation of the other control valves operated, irrespective of the magnitude of the loads.