C-Shaped Spring Mitigating Starting Shock in Electric Disc Grinders
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Solution Overview
Problem
Conventional electric tools experience unstable mitigation of starting shock due to the inability of torque transmission members to undergo elastic deformation in the diameter enlarging direction, leading to durability issues and suboptimal user experience.
Innovation Solution
A C-shaped torque transmission member with an inclined abutment surface allows for radial sliding and elastic deformation, combined with a guide member made of synthetic resin for low friction, stabilizing the position and improving sliding properties, thereby effectively mitigating starting shock while maintaining durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the end portions of the torque transmission member and abutment surfaces of the rotary members contact in a face-to-face contact state, then the structure is simple, but the torque transmission member does not easily undergo elastic deformation, making it difficult to mitigate starting shock
Solution Approach 1:
The abutment surface is designed with a curved inclined surface instead of a flat face-to-face contact surface. This curvature enables the torque transmission member to slide radially during elastic deformation, allowing the C-shaped member to expand and contract smoothly while transmitting torque, thereby resolving the contradiction between structural simplicity and starting shock mitigation capability
Solution Approach 2:
The contact interface parameters are changed by introducing an inclined surface with specific geometry. This parameter change allows the contact surface to transition from rigid face-to-face contact to sliding contact that accommodates radial elastic deformation, enabling both structural simplicity and reliable starting shock mitigation
2Strength
If the radial clearance is reduced to prevent excessive elastic deformation, then the durability of the torque transmission member is improved, but the starting shock mitigating effect is impaired
Solution Approach 1:
The radial clearance parameter is optimized to a specific range that allows sufficient elastic deformation for starting shock mitigation while preventing excessive deformation that would compromise durability. This parameter optimization resolves the contradiction between durability and starting shock mitigation by finding the optimal balance point
Solution Approach 2:
The radial clearance is set to provide partial elastic deformation capability - enough to mitigate starting shock effectively, but controlled to prevent excessive deformation. This partial action approach allows the system to achieve the necessary shock mitigation while maintaining component durability
3Stability of the object's composition
If a guide member is added to stabilize the position of the torque transmission member, then the position stability is improved, but the device complexity increases
Solution Approach 1:
A guide member in the form of a thin-walled cylindrical shell is introduced to stabilize the torque transmission member. This thin-film structure provides positional stability through its geometric constraints while minimizing the addition of material and complexity to the overall transmission system
Solution Approach 2:
The guide member acts as an intermediary component between the torque transmission member and the housing. It provides positional stability by guiding the torque transmission member without requiring complex coupling mechanisms, thereby adding minimal complexity while achieving the desired stability
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 enables stable mitigation of starting shock in electric tools, enhancing durability and user experience by allowing controlled elastic deformation and preventing excessive wear, while maintaining the effectiveness of the torque transmission.
Implementation Method 1
a C-shaped torque transmission member capable of radial elastic deformation is provided between two rotary members in a torque transmission system
Implementation Method 2
because of the abutment surface formed as an inclined surface, the end portion of the torque transmission member slides radially on the abutment surface
Implementation Method 3
the guide member is made of a synthetic resin member having a low friction property, so that it is possible to improve the sliding property for sliding contact of the torque transmission member with the guide member
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Providing an electric tool capable of mitigating the starting shock in a stable manner. In an electric disc grinder, there is provided, between a driven gear (26) and a spindle (30) in a torque transmission system, a C-shaped spring member (44) capable of elastic deformation in a diameter enlarging direction. With respect to the rotating direction, the spring member (44) is engaged with a driving protrusion (48) of the driven gear (26) and a driven protrusion (50) of a joint sleeve (42) of the spindle (30); when transmitting the rotation of the driven gear (26) to the spindle (30), the spring member undergoes elastic deformation in the diameter enlarging direction depending on the driven side load, thereby mitigating the starting shock. An abutment surface (50a) of the driven protrusion (50) is formed as an inclined surface causing an end portion of the spring member (44) contacting with the abutment surface (50a) to slide radially outwards. As a result, the spring member (44) can easily undergo elastic deformation in the diameter enlarging direction.