Power-Split Worm-Wheel Transmission With Axially Floating Worm Shaft
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Solution Overview
Problem
Existing worm gear designs for high-power applications are bulky and inefficient due to high torque loads, limiting the development of compact gearboxes.
Innovation Solution
A worm gear design with a sliding coupling and floating bearing support for the worm shaft, allowing axial displacement and power splitting, combined with a backlash-fixing device for zero axial play, and a single-piece gearbox housing for enhanced torque transmission and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the worm shaft is rigidly coupled to the drive shaft, then torque transmission is stable, but the gearbox becomes bulky and cannot accommodate thermal expansion
Solution Approach 1:
The coupling between the drive shaft and worm shaft is designed as a sliding coupling that allows axial movement while maintaining rotational connection. This dynamic coupling enables the worm shaft to move axially in response to thermal expansion and manufacturing tolerances, preventing binding and maintaining reliable torque transmission without requiring excessive clearance or larger housing dimensions.
2Manufacturing precision
If two bearings are provided for the worm shaft, then positioning precision is improved, but friction and complexity increase
Solution Approach 1:
The invention extracts the positioning function from a second bearing and transfers it to the sliding coupling. The sliding coupling provides axial positioning through its sliding surface while allowing free rotation, thereby eliminating the need for a second bearing and reducing friction losses while maintaining adequate positioning precision for the worm shaft.
Solution Approach 2:
The sliding coupling acts as an intermediary element between the drive shaft and worm shaft, providing both torque transmission and axial positioning functions. This intermediary component resolves the conflict between positioning precision and friction by using a sliding surface that maintains positional control with minimal rotational friction.
3Stability of the object's composition
If the worm shaft is supported at both ends, then stability is improved, but axial displacement capability is reduced
Solution Approach 1:
The worm shaft support system is designed with dynamic characteristics, providing rigid support in the radial direction for stability while allowing controlled axial movement through the sliding coupling. This dynamic support arrangement enables the shaft to adapt to thermal expansion and assembly variations while maintaining operational stability.
Data Source
Figure 1~5
Figure 6a~7
Figure 8~10
AI summary
A worm gear comprising a worm stage (2) and a spur gear stage (4) in a gearbox housing, wherein the worm stage (2) has a worm shaft (20) with two opposing worm teeth (23, 24) and at least two transversely arranged intermediate shafts (31, 32). The spur gear stage comprises a pinion (41, 42) on each of the intermediate shafts and a common output gear (43) with which the pinions mesh. The worm shaft has a coupling (85) for a drive shaft (50) at one end near the drive. According to the invention, the coupling is designed as a sliding coupling (8) to accommodate the drive shaft in a rotationally fixed but axially displaceable manner. The worm shaft is supported only at one end in the gearbox housing (10) by means of a bearing (6) at the end furthest from the drive. The drive-side end of the worm shaft is arranged "freely" in the gearbox housing, so that the worm shaft is axially displaceable.This allows for self-adjusting axial centering of the worm shaft. The result is an efficient and robust power split, which, together with the common output gear, forms a compact, high-torque gearbox.