Hall Effect Sensor Positioning for Pruning Shear Blade Wear Compensation
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Solution Overview
Problem
Existing pruning shears lack simple and inexpensive means to define blade crossing positions and compensate for wear, as well as automatically identify the type of blade mounted, while existing solutions are either prone to wear or overly expensive due to the use of multiple Hall effect sensors.
Innovation Solution
A positional control device using two Hall effect sensors and magnets, where one sensor provides abscissa and ordinate information through a Cartesian frame, allowing for precise positioning and wear compensation, and a control circuit that measures speed and position to adjust the gear motor, enabling automatic blade type identification and configurable semi-open positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple Hall effect sensors are used to identify intermediate positions, then positioning precision is improved, but device cost increases
Solution Approach 1:
The patent transitions from using multiple sensors arranged along an arc to using a single Hall effect sensor that measures magnetic field components in two dimensions (x and y coordinates). This dimensional approach allows the sensor to determine angular position and radius simultaneously, achieving the same positioning capability with fewer sensors.
Solution Approach 2:
The patent uses the magnetic field distribution pattern as a reference model. By measuring the x and y components of the magnetic field vector and comparing them to the known magnetic field distribution of the permanent magnet, the system can calculate position without requiring physical sensors at every possible position point.
2Ease of operation
If contact-based potentiometric sensors are used, then positioning function is achieved, but reliability deteriorates due to wear
Solution Approach 1:
The patent replaces mechanical contact-based potentiometric sensors with a non-contact magnetic field sensing system using Hall effect sensors. The Hall effect sensor detects the magnetic field generated by a permanent magnet on the movable blade, eliminating mechanical contact and associated wear while maintaining positioning functionality.
3Ease of manufacture
If blade crossing position is fixed, then manufacturing simplicity is maintained, but adaptability deteriorates for wear compensation
Solution Approach 1:
The patent makes the blade crossing position dynamic and adjustable rather than fixed. The system can modify the negative gap value (crossing position) during operation to compensate for blade wear, allowing the same device to adapt to different wear states without requiring physical repositioning or replacement of components.
Solution Approach 2:
The patent changes the parameter of blade crossing position from a fixed mechanical setting to an adjustable control parameter. By modifying the negative gap value in the control system, the device can compensate for wear while maintaining the same physical hardware configuration.
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 precise positioning of blades, compensates for wear, and automatically identifies blade types, improving precision and reducing maintenance costs by using a cost-effective Hall effect sensor arrangement.
Implementation Method 1
a first fixed Hall effect sensor (40), connected to the control circuit (3), fixedly installed with respect to the frame, able to materialize with a straight permanent magnet (41), carried by the movable element (22)
Data Source
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AI summary
The invention relates to a device for controlling the positioning of two elements (22, 23), for example the blades of a cutting tool, in which one (23) of the elements is stationary while the other (22) is mobile and driven by a geared motor member (21), the position of said mobile element being controlled by the position of a trigger (24). The device comprises: a circuit (3) for controlling the geared motor member; a first stationary Hall effect sensor (40) connected to the circuit (3) and, together with a magnet (41) borne by the mobile element, providing a negative or zero clearance positioning of the two elements; and a second Hall effect sensor (42) connected to the control circuit (3) and, together with a magnet borne by the mobile element, providing the maximum clearance positioning of the two elements. The magnet (41) is positioned such that the north-south axis thereof is perpendicular to the trajectory of same and the first sensor is disposed in an area in which the field vector of the magnet has a component perpendicular to said north-south axis, the sensitive face of the first sensor being parallel to the north-south axis of the magnet.