Vibration Actuator Positioning Member Stiffness
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Solution Overview
Problem
Existing vibration-type actuators face challenges in achieving high driving accuracy and durability, especially under conditions of repeated rapid acceleration and deceleration or excessive load, due to limitations in the stiffness of the positioning and holding members.
Innovation Solution
The vibration-type actuator design includes a vibrating body with elastic grooves and projecting portions, supported by a contact body and positioning and holding members with interposing and mounting portions, where the positioning and holding members are mounted on a supporting member with a clearance, allowing for increased stiffness and durability through adjustable positioning and reduced stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of interposing portions is made smaller to fit into spaces between comb teeth, then the positioning and holding member can be reliably inserted, but the stiffness of the interposing portion decreases
Solution Approach 1:
The positioning and holding member is divided into multiple interposing portions that are separately insertable into spaces between comb teeth. Each interposing portion can be independently optimized for both fit and stiffness, resolving the contradiction between reliable insertion and structural strength.
Solution Approach 2:
Different regions of the positioning and holding member have different properties: the interposing portions have dimensions optimized for fitting into spaces (smaller width), while the connecting portions have increased thickness to provide structural stiffness. This local differentiation allows each part to fulfill its specific function optimally.
2Duration of action of stationary object
If the positioning and holding member is made more rigid to increase stiffness, then durability improves, but the ability to accommodate manufacturing tolerances and reduce stress concentrations decreases
Solution Approach 1:
The thickness parameter of the connecting portions is increased to provide stiffness while maintaining overall flexibility. This parameter optimization allows the structure to withstand loads and maintain durability without becoming overly rigid, thus accommodating manufacturing tolerances and reducing stress concentrations.
Solution Approach 2:
The positioning and holding member combines regions of different structural properties: thinner interposing portions for flexibility and fit, and thicker connecting portions for stiffness and durability. This composite structure achieves both durability and reliability under varying operational conditions.
3Productivity
If the vibration-type actuator is driven under excessive load or repeated rapid acceleration, then high performance is achieved, but damage and stress concentrations occur in the positioning and holding member
Solution Approach 1:
The positioning and holding member is designed with built-in stress distribution features through its varying thickness structure. The thicker connecting portions act as cushioning elements that preemptively absorb and distribute stresses before they can concentrate and cause damage during high-load operation.
Solution Approach 2:
The thickness parameters of different portions are optimized to withstand excessive loads and repeated acceleration. The connecting portions have increased thickness to provide the necessary strength and stress resistance, allowing the actuator to maintain high performance without suffering damage.
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 design enhances the actuator's ability to maintain high driving accuracy and durability by allowing for wider interposing portions and increased stiffness, reducing the risk of damage and stress concentrations, even under high torque and load conditions.
Implementation Method 1
an electromechanical transducer that is mounted on the elastic body
Implementation Method 2
exciting progressive vibration waves in the vibrating body to cause the vibrating body to apply frictional driving force
Implementation Method 3
the vibrating body is not rotatable with respect to the pan unit
Data Source
AI summary
A vibration-type actuator, which achieves high accuracy and durability, includes a vibrating body, a contact body, a supporting member, and at least one positioning and holding member. The vibrating body includes an elastic body with grooves and projecting portions alternately formed in a direction of relative movement of the vibrating body and the contact body, and further includes an electromechanical transducer mounted on the elastic body. The at least one positioning and holding member restrains movement of the vibrating body with respect to the supporting member in the relative movement direction, and includes an interposing portion interposed between a plurality of the projecting portions and a mounting portion mounted on the supporting member. The supporting member includes a receiving portion onto which the mounting portion is mounted with a clearance formed between the mounting portion and the receiving portion in the relative movement direction.