Linear Driving Mechanism Balancing Ultrasonic Motor Pressing Forces
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Solution Overview
Problem
Conventional linear driving mechanisms with ultrasonic motors experience imbalance in pressing forces between vibration element units, leading to hindered movement and reduced service life due to uneven wear.
Innovation Solution
A linear driving mechanism is designed with a balancing structure that ensures equal pressing forces between upper and lower vibration element units by adjusting the orientation and alignment of the torsion spring's pressing force relative to the shafts, maintaining equal moments around both shafts and preventing moment-induced imbalance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple ultrasonic motors are used to increase driving force, then the driving capability increases, but the pressing force becomes unbalanced between vibration element units
Solution Approach 1:
The patent applies asymmetry by intentionally designing different mounting positions for the vibration element units relative to their respective shafts. Specifically, the distance from the first vibration element unit to the first shaft is made different from the distance from the second vibration element unit to the second shaft. This asymmetric configuration, combined with the torsion spring's pressing force direction intersecting both shafts, creates equal moments around both shafts, thereby balancing the pressing forces despite using multiple ultrasonic motors for increased driving capability.
2Power
If vibration element units are pressed against friction member, then driving capability is achieved, but uneven wear occurs reducing service life
Solution Approach 1:
The patent achieves equipotentiality in terms of force distribution by designing the pressing mechanism such that equal pressing forces are applied to both vibration element units. The torsion spring is positioned and oriented so that its pressing force direction intersects with both the first shaft and the second shaft, creating equal moments around both shafts. This ensures that both vibration element units experience identical pressing forces, leading to uniform wear and extended service life while maintaining the required driving capability.
3Force
If torsion spring pressing force is applied to coupling member, then vibration element units are pressed against friction member, but moment imbalance occurs around shafts
Solution Approach 1:
The patent applies local quality by carefully positioning the torsion spring and its pressing force application point. The torsion spring is mounted on the coupling member at a specific location where its pressing force direction intersects with both the first shaft and the second shaft. This specific local positioning ensures that the moment arm from the pressing force to each shaft is equal, creating equal moments around both shafts. This local quality in the spring's mounting position resolves the moment imbalance that would otherwise occur when applying pressing force through the coupling member.
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 allows for smooth movement of driven objects and extends the service life of the mechanism by ensuring even wear and balanced operation of both vibration element units.
Implementation Method 1
a piezoelectric element for converting electrical energy to mechanical energy
Implementation Method 2
The vibration element which generates ultrasonic vibrations, is pressed against an elongated friction member so that the vibration element moves linearly relative to the friction member due to the ultrasonic vibrations
Implementation Method 3
the vibration element moves linearly relative to the friction member due to the ultrasonic vibrations
Implementation Method 4
a coil spring 146 is suspended on edges in the side opposite to the side with the rotation centers of the upper and lower bases 142 and 143. The coil spring 146 pulls rotationally the upper base 142 and the lower base 143
Implementation Method 5
a torsion spring 153 is disposed on the coupling member 150 to urge the coupling member 150 toward the leaver base 143
Data Source
AI summary
A linear driving mechanism capable of moving a driven object smoothly and lengthening its service life. A first vibration element and a second vibration element sandwich a friction member therebetween. A first holding member holding the first vibration element is rotatably supported by a first shaft. A second holding member holding the second vibration element is rotatably supported by a second shaft. An urging part moves the first holding member and the second holding member to press these vibration elements against the friction member. A coupling member couples the first holding member with a driven object. A pressing part presses the coupling member against a moving body including the first and second holding members. A direction of a pressing force of the pressing part intersects with the first shaft when the coupling member couples with the first holding member.