Self-Propelled Mower Height Detection With Coded Setting Gear
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Solution Overview
Problem
Existing self-propelled work apparatuses lack a simple and precise method to detect and adjust the position of tools relative to the chassis.
Innovation Solution
A detection device is provided with encoding elements on a setting gear and detectors to unambiguously identify the end positions of the tool, using optical detectors or other types like magnetic detectors, and a worm gear driven by an actuating motor to adjust the tool's position, with linear guides and an elastic portion to compensate for manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a detection device with encoding elements and detectors is implemented, then the height position detection precision is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical position detection mechanisms with an optical detection system. Encoding elements (optical codes) are printed on the setting gear, and optical detectors read these codes to determine the height position. This substitution of mechanical detection with optical detection achieves high precision while keeping the overall device relatively simple.
Solution Approach 2:
The patent uses encoding elements that are essentially optical copies or representations of position information. Instead of using complex mechanical encoders, simple optical patterns (encoding elements) are created on the setting gear that replicate position data, which can be easily read by detectors to determine the tool's height position.
2Reliability
If two detectors arranged at predefined spacing are used, then the end position detection reliability is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by having different encoding elements at different positions on the setting gear. The encoding elements are specifically designed with different lengths or patterns at different angular positions, allowing the detectors to distinguish between different end positions based on the local optical characteristics they detect.
Solution Approach 2:
The detection system is segmented into multiple detectors positioned at specific spacings. Each detector reads specific portions of the encoding elements, and by combining the information from multiple detectors, the system reliably determines end positions. This segmentation of the detection function improves reliability while keeping each individual detector simple.
3Loss of time
If the setting gear rotates by less than one full revolution between end positions, then the adjustment time is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates encoding elements directly onto the setting gear during manufacturing, so that the position information is pre-encoded on the component itself. This preliminary encoding allows the system to achieve quick positioning (less than one full revolution) without requiring complex real-time measurements, as the position information is already embedded in the encoding elements.
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
Enables simple and precise detection and adjustment of the tool's height position, minimizing manufacturing tolerances and ensuring accurate positioning through a simple construction.
Implementation Method 1
The at least one first encoding element for the first end position differs here from the at least one second encoding element for the second end position
Implementation Method 2
Other types of detectors, for example magnetic detectors such as Hall sensors which interact with magnets
Implementation Method 3
magnetic detectors such as Hall sensors which interact with magnets
Data Source
AI summary
A self-propelled work apparatus, especially a lawnmower, includes a chassis, at least one tool and a drive motor for driving the tool. The tool is height-adjustable with respect to the chassis. A setting unit is provided to set the relative position of the tool with respect to the chassis. The setting unit includes an actuating motor and a setting gear. The setting gear rotates by less than one full revolution between a first, lower end position of the tool and a second, upper end position of the tool. A detection device is provided to detect the height position of the tool. The detection device includes encoding elements on the setting gear and at least one detector. The at least one first encoding element for the first end position differs from the at least one second encoding element for the second end position.