Swivel Joint Power Feeding With One-Core DC Cable Routing
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Solution Overview
Problem
The use of a rotary transformer in a swivel joint for electric power transmission requires two cables, reducing the swivel joint's strength and hydraulic oil flow path area, leading to potential strength and pressure loss issues.
Innovation Solution
A power feeding unit with a rotary transformer, oscillation circuit, and smoothing circuit is integrated into the swivel joint, using a one-core cable and a hydraulic oil flow path within the shaft, allowing for direct current conversion and minimizing the cable's cross-sectional area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a two-core cable is disposed inside the swivel joint to transmit alternating current from the rotary transformer, then electric power transmission is achieved, but the wall thickness of the swivel joint is reduced and strength decreases
Solution Approach 1:
The patent changes the electrical parameter from alternating current to direct current, enabling the use of a one-core cable instead of a two-core cable. This parameter change resolves the contradiction by reducing cable requirements while maintaining power transmission capability
Solution Approach 2:
The patent extracts the alternating current to direct current conversion function into a separate smoothing circuit, allowing the cable to carry only direct current. This extraction enables the use of a simpler one-core cable configuration, reducing the impact on swivel joint strength
2Use of energy by moving object
If a two-core cable is disposed inside the swivel joint, then electric power transmission is achieved, but the area of the hydraulic oil flow path is reduced leading to increased pressure loss
Solution Approach 1:
By changing the current type from alternating to direct current, the patent reduces the cable cross-sectional area required, thereby increasing the hydraulic oil flow path area and reducing pressure loss
Solution Approach 2:
The patent combines the cable into a single one-core configuration, which occupies less space within the swivel joint, thereby preserving more area for hydraulic oil flow and reducing energy loss
3Ease of manufacture
If a cable hole is newly provided inside the swivel joint, then cable installation is enabled, but the wall thickness of the swivel joint is reduced
Solution Approach 1:
The patent changes the cable configuration from two-core to one-core, reducing the number and size of cable holes needed, thereby minimizing the impact on swivel joint wall thickness and strength
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 maintains the swivel joint's strength and hydraulic oil flow path area, reducing pressure loss and cost while enabling efficient electric power transmission.
Implementation Method 1
an oscillation circuit that is coupled to the upper swing body, converts electric power into an alternating current, and supplies the alternating current to the rotary transformer
Implementation Method 2
a rotary transformer that is coupled to each of an upper swing body and a lower traveling body of the work vehicle
Implementation Method 3
a smoothing circuit that is coupled to the lower traveling body and converts electric power output from the rotary transformer into a direct current
Data Source
AI summary
Provided is a power feeding unit mounted on a swivel joint, the power feeding unit including: a rotary transformer that is coupled to an upper swing body and a lower traveling body of a work vehicle, respectively; an oscillation circuit that is coupled to the upper swing body, converts electric power into an alternating current, and supplies the alternating current to the rotary transformer; and a smoothing circuit that is coupled to the lower traveling body and converts electric power output from the rotary transformer into a direct current, in which an electrode on a negative side of the smoothing circuit is electrically coupled to a housing of the lower traveling body, and an electrode on a positive side of the smoothing circuit is taken out from a lower portion of the swivel joint via a cable inserted through a pipe provided inside the swivel joint along an axial direction.