Hydraulic Swing Control Valve for Hybrid Excavator
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Solution Overview
Problem
In hybrid construction machines with both hydraulic and electric motors for swing structures, the simultaneous operation of these motors leads to increased hydraulic fluid flow to the hydraulic swing motor under low load, reducing operator manipulability and causing unintentional acceleration of the swing structure during boom raising operations, especially during cargo lifting tasks.
Innovation Solution
The implementation of a directional control valve system that prevents the hydraulic fluid from flowing into the hydraulic swing motor during combined swing and boom raising operations, using a regulating device to control the flow of hydraulic fluid and prevent unintended acceleration, thereby maintaining high manipulability during these operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the hydraulic pump supplies hydraulic fluid to both the hydraulic swing motor and another hydraulic actuator simultaneously, then the hydraulic system can perform combined operations, but more hydraulic fluid flows to the actuator under low load pressure causing the swing structure to accelerate unintentionally
Solution Approach 1:
The hydraulic system is segmented into two independent control paths: one for the hydraulic swing motor and another for the other hydraulic actuator. Each path has its own directional control valve, allowing independent control of hydraulic fluid flow to each actuator, thereby preventing unintended acceleration during combined operations
Solution Approach 2:
A regulating device is introduced as an intermediary between the swing operating device and the directional control valve for meter-in control. This regulating device prevents switching operation of the directional control valve when the other hydraulic actuator is operating, thereby preventing unintended swing acceleration while maintaining the ability to perform combined operations
2Power
If the boom cylinder exerts higher load during swing boom raising operation, then the hydraulic pump pressure rises to lift the cargo, but high-pressure hydraulic fluid is forced into the hydraulic swing motor causing unintentional acceleration
Solution Approach 1:
The disturbing factor (high-pressure hydraulic fluid flow to the swing motor) is extracted and blocked by the regulating device. When boom raising operation is detected, the regulating device prevents the directional control valve for meter-in control from switching, thereby blocking the path for high-pressure hydraulic fluid to enter the hydraulic swing motor and cause unintended acceleration
Solution Approach 2:
The regulating device performs preliminary anti-action by preventing the switching operation of the directional control valve before high-pressure hydraulic fluid can be forced into the hydraulic swing motor. This preemptive measure eliminates the harmful effect of unintended swing acceleration during swing boom raising operations
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 high operator manipulability during combined swing operations by preventing unintended acceleration of the swing structure, allowing for precise control and accurate positioning of lifted cargo, and maintains similar manipulability to solo swing operations.
Implementation Method 1
a hydraulic pump (1) delivering hydraulic fluid; a hydraulic swing motor (3) driven by the hydraulic fluid from the hydraulic pump (1)
Implementation Method 2
an electric swing motor (14) driven by an output shaft of the speed reduction mechanism (59)
Implementation Method 3
high-pressure hydraulic fluid flows into (i.e., is forced into) the hydraulic swing motor (3) under the lower load
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An object of the present invention is to provide a hybrid construction machine having a hydraulic motor (3) and an electric motor (14) as driving sources for a swing structure (50), the hybrid construction machine being configured to provide the operator with high manipulability during combined swing operation. This invention provides a hybrid construction machine including a swing structure (50), a hydraulic pump (1), a hydraulic swing motor (3) driving the swing structure (50) using hydraulic fluid from the hydraulic pump (1), an electric swing motor (14) driving the swing structure (50) in conjunction with the hydraulic swing motor (3), a boom cylinder (16) operated simultaneously with the swing structure (50) at times and driven by the hydraulic fluid from the hydraulic pump (1), a first directional control valve (28) controlling flow of the hydraulic fluid supplied from the hydraulic pump (1) to the hydraulic swing motor (3), a second directional control valve (29) controlling the flow of the hydraulic fluid returning from the hydraulic swing motor (3), and a controller (13) and solenoid pressure reducing valves which prevent operation of the second directional control valve (29) when the boom cylinder (16) is operated simultaneously with the swing structure (50).