Water-Cooled Ring Gear in Speed Reducers for Excavator Heat Control
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Solution Overview
Problem
Existing speed reducers for construction machines, particularly in excavators, face challenges with heating issues due to high-speed rotation of electric motors, which complicates downsizing and installation in dirty environments.
Innovation Solution
A speed reducer design that incorporates a fluid channel within the gear of the speed reducing unit to inhibit heating, allowing for high-speed rotation and downsizing while preventing dirt entry, thus facilitating installation on construction machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air cooling with a fan is used to cool the heated portion, then cooling effect is achieved, but dirt enters the cooling system
Solution Approach 1:
The patent introduces a closed-loop cooling system where the cooling medium (air or liquid) circulates through a sealed path with intake and exhaust ports covered by filters or grilles. The intermediary sealed cooling path prevents direct exposure to the external environment, allowing cooling to occur while blocking dirt from entering the system.
Solution Approach 2:
The patent employs a forced circulation cooling system using fans or pumps to move the cooling medium through a closed loop. The pneumatic/hydraulic system creates controlled airflow or fluid flow through the cooling channels while maintaining a sealed environment that excludes contaminants.
2Volume of moving object
If electric motor rotates at high speed for downsizing, then motor size is reduced, but heating occurs at the first-stage speed reducing unit
Solution Approach 1:
The patent applies forced circulation cooling using fans or pumps to move cooling medium through sealed cooling paths. This active thermal management system removes heat from the speed reducing unit that directly drives the high-speed electric motor, enabling downsizing without overheating problems.
Solution Approach 2:
The patent changes the thermal management approach from passive to active cooling, and potentially from air to liquid cooling, to handle the increased heat loads generated by high-speed operation. This parameter change in the cooling system enables the motor to operate at higher speeds with reduced size.
3Temperature
If open cooling system with fan is used, then cooling is effective, but installation is difficult in dirty environments
Solution Approach 1:
The patent introduces sealed cooling paths with filtered intake and exhaust ports as intermediaries between the cooling system and the external environment. This sealed design with filters allows the system to be installed in dirty construction environments without concern for dirt contamination, significantly improving ease of installation.
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
The fluid-cooled speed reducer effectively manages heat, enabling high-speed operation and downsizing of electric motors, while maintaining cleanliness and simplifying installation on construction machines.
Implementation Method 1
a channel provided in a gear of the at least one speed reducing unit and configured to communicate a fluid
Implementation Method 2
the channel cools the gear, and the speed reducing unit connected directly to a motor shaft can be inhibited from heating
Data Source
AI summary
A speed reducer according to one aspect of the present disclosure includes: speed reducing units for decelerating a rotational driving force of an electric motor and transmitting the decelerated rotational driving force to a rotational driving unit; and a ring gear meshing with a gear decelerated by a speed reducing unit on the electric motor side in a direction of a rotational axis of the electric motor. The ring gear is provided with a water-cooling channel that communicates cooling water. The water-cooling channel includes a first groove having a small depth and a second groove having a larger depth and extends in a C-shape as the ring gear is viewed from the direction of the rotational axis. The ring gear is provided with a motor flange mounted to the electric motor. The motor flange is provided with an inlet port and an outlet port connected to the water-cooling channel.