Planetary Carrier Radial Guidance for Output Shaft Stability
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Solution Overview
Problem
Existing electric hand tools, such as drill/drivers, face issues with the drill spindle tilting during operation due to inadequate mounting, which requires increased axial length for stability and results in additional space requirements for radial and axial bearing of the output spindle.
Innovation Solution
The output shaft is radially mounted in the transmission housing via a roller or ball bearing, with the planetary carrier absorbing radial forces and being coaxially arranged with the output-side planet carrier, ensuring stable radial guidance and preventing tilting, while a clamping locking mechanism and two-shift planetary gear stages enhance stability and shifting comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output shaft is mounted with both axial and radial bearings at two points close together, then the mounting structure is compact, but the drill spindle tilts during drilling operation
Solution Approach 1:
The patent transitions from a two-point bearing arrangement to a continuous radial guidance arrangement. The output shaft is guided radially along its entire length by the planetary carrier's inner bore, transforming discrete point support into continuous dimensional support, which prevents tilting without increasing axial length.
Solution Approach 2:
The planetary carrier serves as an intermediary component that provides radial guidance to the output shaft. By incorporating the inner bore in the planetary carrier, the patent introduces a mediating structure that enables precise radial positioning and stabilizes the output shaft during operation.
2Reliability
If the overall axial length is increased to stabilize the drilling spindle, then the tilting is prevented, but additional space is required for axial and radial bearing
Solution Approach 1:
The patent merges the radial bearing function into the planetary carrier structure itself. The inner bore of the planetary carrier simultaneously serves as the radial guidance path for the output shaft and as part of the planetary gear mechanism, eliminating the need for separate axial and radial bearing arrangements.
Solution Approach 2:
The planetary carrier is designed with multi-functionality: it not only transmits torque from the planets to the output shaft but also provides radial guidance through its inner bore. This universal component performs multiple functions within the same structural element, avoiding additional space requirements.
3Length of moving object
If the output shaft is radially mounted via bearing with planetary carrier absorbing radial forces, then the axial length is kept short, but the concentricity and stability must be ensured
Solution Approach 1:
The planetary carrier's inner bore is pre-formed with precise concentricity requirements during manufacturing. By establishing the radial guidance path in advance through precision machining of the inner bore, the patent ensures concentricity without requiring additional adjustment mechanisms or longer assembly procedures.
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 a short overall axial length while ensuring the output shaft's stability and preventing tilting, ensuring precise concentricity and reducing the risk of the clamping lock jamming, thus providing a stable and efficient operation for electric hand tools.
Implementation Method 1
The radial mounting of the output-side planetary carrier can take place via a roller bearing, in particular via a roller or ball bearing
Implementation Method 2
The radial mounting of the output-side planetary carrier can take place via a roller bearing, in particular via a roller or ball bearing
Data Source
Figure 1
AI summary
The invention relates to an electric handheld power tool, in particular a power screwdriver, comprising a gearbox (12) and a drive shaft (32), which is driven by a drive motor and is connected to a driven shaft (44) by means of an engaging and disengaging planetary gear mechanism (14), wherein the planetary gear mechanism (14) comprises a planet carrier (24) on the driven side, wherein an end (58) of the driven shaft (44) on the drive side is led through the planet carrier (24) on the driven side and the planet carrier (24) on the driven side is radially mounted in the gearbox (12).