Power Train Clutch Nesting for Weight Reduction
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Solution Overview
Problem
The existing power train configurations, such as those described in Japanese Patent Laying-Open No. 2011-106611, face challenges in reducing size and weight due to the large diameter of the hydraulic clutch mechanism, which hinders further miniaturization and weight reduction.
Innovation Solution
The power train design incorporates a hydraulic motor, a motor housing, a rotatable housing, a bearing, a first planetary gear reducer, a second planetary gear reducer, and a clutch, where the clutch is positioned on the radially inner side relative to the bearing, overlapping with the first planetary gear reducer in the axial direction, and is disposed closer to the hydraulic motor, allowing for a reduced clutch diameter and eliminating the need for a clutch housing, thus minimizing size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hydraulic clutch mechanism is used, then the power train can achieve reliable torque control and clutch engagement, but the clutch diameter becomes large, increasing the overall size and weight of the power train
Solution Approach 1:
The clutch is positioned on the radially inner side relative to the bearing, allowing it to be nested within the radial space already occupied by the bearing assembly. This nested arrangement enables the clutch to utilize the central radial space of the power train, significantly reducing the overall external diameter and weight while maintaining reliable torque control functionality
Solution Approach 2:
The clutch is arranged in the radial dimension rather than extending the external diameter, and overlaps with the first planetary gear reducer in the axial dimension. This dimensional repositioning allows the clutch to occupy unused radial space without increasing the power train's external footprint, achieving both reliability and weight reduction
2Reliability
If a conventional hydraulic clutch mechanism is used, then the power train can achieve reliable torque control, but the clutch diameter becomes large, increasing the external dimension in the radial direction
Solution Approach 1:
The clutch is nested within the radial space defined by the bearing assembly, utilizing the central radial area that would otherwise be empty space. This nesting approach allows the clutch to achieve reliable torque control while keeping the power train's external radial dimension minimized
Solution Approach 2:
The clutch is positioned on the radially inner side relative to the bearing, and the bearing is selected with sufficient radial width to accommodate the clutch within its radial envelope. This preliminary spatial arrangement ensures that the clutch can perform reliable torque control without increasing the power train's external radial area
3Weight of moving object
If the clutch is positioned on the radially inner side relative to the bearing, then the power train size and weight are reduced, but the spatial arrangement becomes more complex
Solution Approach 1:
The clutch overlaps with the first planetary gear reducer in the axial direction, merging the spatial occupancy of two components. This merging allows the clutch to be positioned on the radially inner side without requiring additional axial space, reducing overall power train compactness while maintaining simple spatial relationships
4Area of stationary object
If the clutch diameter is reduced, then the power train external dimension in the radial direction is reduced, but the clutch may interfere with the hydraulic motor body
Solution Approach 1:
The clutch inner diameter is specifically designed to be smaller than the maximum diameter of the hydraulic motor body, creating a local quality difference that prevents interference. This localized dimensional specification ensures the clutch can be positioned on the radially inner side without contacting the hydraulic motor, maintaining both compact size and proper component clearance
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 achieves a significant reduction in size and weight of the power train, enhancing its structural efficiency and power transfer capabilities while maintaining a simple and robust structure.
Implementation Method 1
a bearing which rotatably supports the rotatable housing relative to the motor housing
Implementation Method 2
a first planetary gear reducer which includes a first sun gear to which a torque is input from the hydraulic motor, a plurality of first planetary gears engaged with the first sun gear, a first carrier rotatably supporting the plurality of first planetary gears, and a first ring gear provided in the rotatable housing, the first ring gear being engaged with the plurality of first planetary gears
Implementation Method 3
The clutch permits or prohibits rotation of the second carrier about the center of rotation of the output shaft
Data Source
AI summary
A power train is provided having a reduced size and weight. A hydraulic motor includes a rotatable output shaft. Wheel bearings rotatably support a rotatable housing relative to a motor housing. A hydraulic clutch mechanism permits or prohibits rotation of a second carrier of a second planetary gear reducer about the center of rotation of the output shaft. The hydraulic clutch mechanism is disposed on the radially inner side relative to the wheel bearings.