Motorized Pruner Weight Layout for Lower Rotational Inertia
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Solution Overview
Problem
Existing pruners have unreasonable tool dimensions, weight distributions, and handle configurations, leading to discomfort and unsafe operation due to high moment of inertia during use.
Innovation Solution
A pruner design with a balanced weight distribution and ergonomic handle configuration, including a motor-driven working assembly, where the center of gravity is positioned relative to user grips and the motor, and a compact structure to minimize moment of inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pruner has a relatively large dimension and heavy weight to effectively trim branches, then the cutting capability is improved, but the moment of inertia increases making it uncomfortable and unsafe to operate
Solution Approach 1:
The pruner is divided into distinct functional modules: a handle assembly with ergonomic grips, a motor assembly with integrated control, and a working assembly with cutting members. This segmentation allows each component to be optimized independently - the handle provides ergonomic support while the motor and working assembly deliver cutting power, reducing the moment of inertia during rotation.
Solution Approach 2:
The patent repositions the motor assembly along the longitudinal axis of the handle, specifically at a distance of 50-150mm from the proximal end. This dimensional repositioning shifts the center of gravity to an optimal location that reduces rotational inertia while maintaining cutting effectiveness, transforming the weight distribution from a problematic concentrated mass to an optimized distributed system.
2Productivity
If the pruner uses a motor-driven working assembly to enhance cutting power, then the productivity is improved, but the weight and dimension increase leading to high moment of inertia
Solution Approach 1:
The motor assembly is merged with the handle structure, where the motor housing forms an integral part of the handle body. The control unit is integrated into the motor assembly, and the battery pack is positioned within the handle's internal cavity. This merging eliminates separate mounting structures and reduces overall weight while maintaining the motor-driven cutting capability.
Solution Approach 2:
The patent optimizes the motor power parameters to match the specific cutting requirements, using a motor with power between 50-200W. The working assembly parameters are also optimized with cutting member dimensions and configurations tailored to the application, ensuring high productivity without excessive weight - the motor and working assembly total weight is controlled to minimize moment of inertia while delivering sufficient cutting power.
3Ease of operation
If the pruner has an optimized center of gravity position to reduce moment of inertia, then the ease of operation is improved, but the structural complexity increases
Solution Approach 1:
The pruner employs asymmetric weight distribution with the motor assembly positioned at a specific distance (50-150mm) from the proximal end of the handle, creating an intentional asymmetric center of gravity. The handle itself features asymmetric grip design with a first grip and second grip positioned at different locations. This controlled asymmetry reduces moment of inertia during rotation while the integration of these asymmetric features into the overall structure avoids adding significant complexity.
Data Source
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AI summary
Provided is a pruner. The pruner includes: a body connected to an energy device; and a motor configured to drive a working assembly to move. The body includes: a first grip for a user to hold; and an accommodation portion for accommodating at least part of the motor. The motor has the center of gravity of the motor. The working assembly includes a first working member and a second working member, and the plane that is located at the center of the first working member and the second working member and is substantially parallel to the extension direction of the first working member and the extension direction of the second working member is defined as a center plane. The distance between the center plane and the center of gravity of the motor in an up and down direction is greater than or equal to 0 mm and less than or equal to 40 mm. This pruner is comfortable and safe to use.