Segmented Pinion Gear Transmission for Electric Pruning Tool
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Solution Overview
Problem
Traditional electric pruning instruments are heavy, bulky, and prone to damage due to cantilevered conical pinion gears, which makes them difficult to handle and less effective for cutting thicker branches, and their lead batteries contribute to energy waste and discomfort for operators.
Innovation Solution
An electric cutting instrument with a conical pinion gear supported at both ends to reduce flexion loads, combined with a lightweight lithium rechargeable battery, allowing for a more compact and ergonomic design that maintains high cutting torque without the risk of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conical pinion gear is used to transmit high torque for cutting thick branches, then the cutting power is improved, but the pinion gear becomes oversized and heavy
Solution Approach 1:
The pinion gear is divided into two separate components: a driving pinion gear connected to the motor shaft and a driven pinion gear connected to the curved rack. This segmentation allows each gear to be smaller and lighter while maintaining the same torque transmission capability, as the torque is distributed across two meshing gears rather than requiring one large cantilevered gear.
Solution Approach 2:
A second pinion gear acts as an intermediary between the motor shaft and the curved rack. This intermediate gear transfers the rotational motion and torque from the driving pinion to the rack, enabling the system to achieve high cutting power without requiring an oversized single pinion gear.
2Device complexity
If a conical pinion gear is supported only at one end to maintain simplicity, then the device complexity is reduced, but the pinion gear is prone to damage under high torque
Solution Approach 1:
The single cantilevered pinion gear is segmented into two supported gears. The driven pinion gear is supported at both ends by bearing assemblies, eliminating the cantilevered configuration and distributing the mechanical loads, which significantly improves reliability under high torque conditions.
Solution Approach 2:
The second pinion gear serves as a mediator that changes the load path. By introducing this intermediate gear, the system transforms the single-point support structure into a distributed support structure, where loads are shared across two gears with proper bearing support.
3Use of energy by moving object
If lead batteries are used to power the motor, then the energy supply is sufficient, but the battery weight and size increase
Solution Approach 1:
The battery technology parameter is changed from lead-acid chemistry to lithium-ion chemistry. This parameter change maintains sufficient energy supply capacity while dramatically reducing both weight and volume, as lithium-ion batteries have higher energy density than lead-acid batteries.
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 efficient cutting of thicker branches with reduced weight and size, enhancing user handling and reducing energy consumption through the use of a rechargeable battery, while maintaining high cutting performance.
Implementation Method 1
motor means housed in said grip body and operatively connected to an electric energy supply means
Implementation Method 2
a pinion gear having a first end and a second end opposite to the first end; a rack, that is adapted to mesh with said pinion gear
Data Source
Figure 1~3
Figure 4
Figure 5~6
AI summary
Cutting instrument (1) of electric type, in particular for pruning branches (60), comprising a grip body (25) at which an user can grip the instrument (1) and a push button (26) to start the rotation of a cutting blade (2) about a rotation axis (102). The cutting blade (2) can rotate about its rotation axis (102) for moving from a distant position to an approached position, or vice-versa, with respect to a fixed counter-blade (3). The cutting blade (2) is connected to the shaft (11) of an electric motor (10) by a mechanical transmission comprising essentially a conical pinion gear (20) and a curved rack (15). The conical pinion gear (20), at a first end (21), has a recess (22) in which a shaft (11) of the motor (10) is inserted. This way, when the motor (10) is operated the conical pinion gear (20) rotates integrally to the shaft (11) about a rotation axis (101). The pinion gear (20), at a second end (23) opposite to first end (21), has a protrusion (24) that is adapted to be put in a recess, or bush, (34) that is made in the mounting body (30).