Electric Shaver Gear Mechanism for Angled Head Design
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Solution Overview
Problem
Existing electric shavers face design limitations due to inefficiencies in power transmission, resulting in bulky and misbalanced heads, increased friction, noise, wear, and reduced effectiveness, primarily caused by the mechanical complexity and soft power transmission properties of known gear mechanisms.
Innovation Solution
An electrically driven device with a gear mechanism that includes an intermediate shaft and a crank arm, which converts rotary motion into reciprocating pivoting motion, providing increased dynamical stiffness and allowing for an angled shaver head design without loss of effectiveness, using a scotch yoke mechanism and a pivotable bridge to transmit power efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional gear mechanism with oscillating bridge is used, then the device can transmit power from motor to cutting elements, but the transmission effectiveness is reduced (output deflection/input deflection < 0.9) and dynamical stiffness is low
Solution Approach 1:
The gear mechanism is segmented into distinct functional components: drive pin, crank arm, intermediate shaft, and driven shaft. This segmentation allows each component to be optimized for its specific function, improving overall transmission effectiveness and stiffness.
Solution Approach 2:
An intermediate shaft is introduced as a mediator between the crank arm and driven shaft. This intermediate element enables more efficient power transmission by reducing deflection and improving dynamical stiffness in the transmission path.
2Adaptability or versatility
If the head is arranged angled with respect to the main body, then design flexibility is improved, but friction, noise, and wear increase due to restricted force flow
Solution Approach 1:
The mechanism accommodates angled head arrangements by introducing rotational degrees of freedom through the crank arm and intermediate shaft, allowing power transmission along inclined paths without compromising force flow efficiency.
Solution Approach 2:
The crank arm and intermediate shaft create a dynamic transmission system that can adapt to angled configurations while maintaining efficient force transmission, reducing friction and wear compared to rigid fixed-angle designs.
3Productivity
If the motor is connected directly to the head, then power transmission path is shortened, but the head becomes bulky and misbalanced
Solution Approach 1:
The intermediate shaft and crank arm arrangement allows power transmission along an inclined path, effectively shortening the transmission path while maintaining head compactness and balance through three-dimensional spatial optimization.
4Adaptability or versatility
If the motor is positioned in an inclined position relative to the body, then angled head design is enabled, but the body or handle becomes bulky
Solution Approach 1:
The mechanism uses three-dimensional spatial arrangement of the crank arm and intermediate shaft to enable angled head design without increasing body volume, as the power transmission path is optimized through inclined rotational axes rather than bulkier structural arrangements.
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 solution enhances dynamical stiffness, reduces energy loss, and allows for a more flexible and efficient power transmission system, independent of the motor's position relative to the cutting elements, resulting in a more balanced and effective shaver design with reduced wear and noise.
Implementation Method 1
a crank arm coupled to the drive pin, wherein the crank arm is pivotably mounted in the housing and is coupled to the intermediate shaft thereby converting a rotary motion of the drive shaft into a reciprocating pivoting of the intermediate shaft
Implementation Method 2
a drive pin connected to the drive shaft eccentrically with respect to the rotary axis
Data Source
Figure 1
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AI summary
The invention relates to an electrically driven device comprising a housing (4, 5), an electric motor (1) with a drive shaft (2) having a first rotary axis (I) and a drive pin (3) connected to the drive shaft (2) eccentrically with respect to the rotary axis (I), and a driven shaft (12) mounted in the housing (4, 5) for performing a pivoting. The driven shaft (12) is indirectly coupled to the drive shaft (2) by means of a gear mechanism converting a rotary motion of the drive shaft (2) into a reciprocating pivoting motion of the driven shaft (12). The gear mechanism comprises one intermediate shaft (9, 17, 20) having a second rotary axis (II) extending in the longitudinal direction of the intermediate shaft (9, 17, 20) and at least one crank arm (6, 8, 16) coupled to the drive pin (3). The crank arm (6, 8, 16) is pivotably mounted in the housing (4, 5) and is coupled to the intermediate shaft (9, 17, 20) thereby converting a rotary motion of the drive shaft (2) into a reciprocating pivoting of the intermediate shaft (9, 17, 20) about the second rotary axis (II). The intermediate shaft (9, 17, 20) is coupled to the at least one driven shaft (12) by means of a pivotable bridge (10) such that the intermediate shaft (9, 17, 20) is offset with respect to the at least one driven shaft (12).