Gear Adjustment Mechanism for Lawnmower Cutting Height
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Solution Overview
Problem
Existing self-propelled lawnmowers require time-consuming adjustments for cutting height, as the operation involves a screw or spindle with a large displacement, which is inefficient.
Innovation Solution
A working device with a gear connection between the actuating element and the structural unit, allowing for quick and easy adjustment through a rotational movement conversion, utilizing a guide device with inclined guides to prevent self-locking and enable precise positioning with less than one revolution of the operating element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a screw or spindle with large pitch is used for height adjustment, then the adjustment range is sufficient, but the adjustment operation becomes time-consuming
Solution Approach 1:
The patent replaces the traditional screw or spindle mechanism with a rack and pinion gear system. The pinion gear engages with the rack to convert rotational movement of the control element into linear movement of the cutting unit, eliminating the need for large-displacement screw threads while achieving quick adjustment through simple rotation.
Solution Approach 2:
The patent changes the adjustment mechanism from a large-pitch screw thread to a gear system with specific tooth pitch and radius. By modifying the gear parameters (tooth count, module, pinion radius), the system achieves rapid adjustment with less than one full revolution of the control element, fundamentally changing the adjustment characteristic from slow to fast.
2Productivity
If a gear connection is used for quick adjustment, then the adjustment speed increases, but self-locking may occur causing adjustment difficulties
Solution Approach 1:
The patent incorporates a spring element that applies a separating force between the pinion gear and the rack. This dynamic mechanism prevents the gear teeth from locking together during adjustment, allowing smooth rotational movement of the control element while maintaining positive engagement for precise positioning. The spring ensures continuous separation that prevents self-locking.
3Ease of operation
If the operating element rotates less than one revolution for adjustment, then the operation becomes simpler, but the adjustment range may be limited
Solution Approach 1:
The patent combines multiple design elements: a pinion gear with optimized tooth count, a rack with appropriate length, and a control element with detent positions. This composite mechanism allows the control element to rotate less than one revolution (typically 1/3 to 1/2 revolution) while still achieving the full adjustment range through the lever arm effect and multiple detent positions that provide discrete height settings.
4Reliability
If a positive connection is used to secure the operating element, then the fixation becomes secure, but the device complexity increases
Solution Approach 1:
The patent employs a spring-loaded detent mechanism that automatically engages with notches on the rack to secure the cutting unit at predetermined heights. The spring provides automatic latching without requiring additional locking components or complex mechanisms. The system self-secures at each adjustment position, eliminating the need for manual locking operations or complex fixation devices.
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 rapid and intuitive adjustment of the structural unit, such as cutting height, with low frictional forces, ensuring easy operation and secure fixation in multiple positions without the need for external stops, enhancing user experience and operational efficiency.
Implementation Method 1
a spring (25) which acts with a separating force on the pinion (12) and the rack (11)
Implementation Method 2
the actuating element (11) is in operative connection with the structural unit (60) via a gear connection, by which the actuating movement of the actuating element (11) can be translated into the actuating movement of the structural unit (60)
Implementation Method 3
utilizing a guide device with inclined guides to prevent self-locking and enable precise positioning
Data Source
Figure 1~4
Figure 5~7
Figure 8~9
AI summary
The machine i.e. lawn mover (1), has a housing (2), and a component (60) comprising a drive motor (3) and a tool rotated around a rotational axis (9). An adjusting device adjusts position of the component opposite to the housing. An operating element (10) rotates the adjusting device around a rotational axis (28). The device has an adjusting element (11) that stays in connection with the operating element over a gear box connection. The device has a guiding device for converting rotating movement of the adjusting element into movement of the component in the direction of the former axis.