Tachograph Paper Box Unit Locking Mechanism
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Solution Overview
Problem
Existing tachographs face issues with the paper box unit detaching during vibrations, causing damage and rattling noises, and lack effective splash water protection due to structural play and tolerance-related issues.
Innovation Solution
The paper box unit is mechanically locked in its operating position with elastic locking arms and a seal to prevent unintentional release, and an elastic seal is used to prevent moisture ingress and dampen vibrations, while a transport roller and thermal print head ensure secure positioning and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the paper box unit is designed with inherent play for easy insertion and removal, then ease of operation is improved, but the paper box unit becomes unstable and produces rattling noises during vehicle operation
Solution Approach 1:
The locking arm is designed as an elastic component that can dynamically change its position. During insertion, the locking arm deflects to accommodate the paper box unit. Once locked, it maintains a stable engaged position with the locking stop, preventing rattling while allowing easy insertion and removal when deliberately actuated.
Solution Approach 2:
The locking mechanism is segmented into distinct functional elements: the locking arm with locking hook, the locking stop, and the elastic deflection zone. This segmentation allows each element to perform its specific function - the locking hook engages the stop for stability, while the elastic portion allows for easy insertion and deliberate unlocking.
2Reliability
If the paper box unit is securely locked to prevent unintentional release during vibrations, then reliability is improved, but the complexity of the locking mechanism increases
Solution Approach 1:
The locking mechanism is designed to be self-latching once engaged. The elastic locking arm automatically engages with the locking stop when the paper box unit is inserted, providing reliable locking without requiring additional actuators or complex control systems. The mechanism locks itself through the natural engagement geometry.
Solution Approach 2:
The elastic locking arm acts as an intermediary element between the paper box unit and the housing. It provides the necessary mechanical connection for reliable locking while absorbing vibrations and tolerances through its elasticity, simplifying the overall design by eliminating the need for rigid precision-machined connections.
3Device complexity
If the locking hooks are positioned close to the paper box front for compact design, then device complexity is reduced, but sufficient space for arranging locking elements cannot be ensured
Solution Approach 1:
The locking mechanism utilizes the depth dimension of the paper box unit rather than only the lateral dimensions. The locking arm extends forward from the side wall, and the locking hook engages with the locking stop in the insertion direction. This dimensional approach allows compact lateral packaging while providing sufficient engagement length for reliable locking.
4Ease of manufacture
If the paper box cover is designed without handles for cleaner appearance, then ease of manufacture is improved, but the ability to pull the paper box unit out of the receiving chute is reduced
Solution Approach 1:
The paper box cover itself serves as the handling element. The flat front surface and sides of the cover provide sufficient surface area for direct grasping and pulling. No additional handles are needed - the cover structure itself enables easy manual removal when the locking mechanism is actuated.
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 securely maintains the paper box unit in place, preventing accidental detachment and rattling, while providing splash water protection and ensuring easy refilling without handles, enhancing operational safety and reliability.
Implementation Method 1
an elastic seal is used to prevent moisture ingress and dampen vibrations
Implementation Method 2
the locking arms can be elastically deflected transversely to the insertion direction into deflection recesses
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a tachograph with a printing device and a paper box unit 10, which has a paper box 25 for receiving a printing material roll 26 and which can be inserted and locked into a receiving shaft 2 of a housing 1 in the insertion direction 14 and can be moved out of a rectangular or square opening 6 of the receiving shaft 2 for refilling a printing material roll 26, with a paper box cover 18 of the paper box unit 10, by which, in the operating position of the paper box unit 10 inserted into the receiving shaft 2, the opening 6 of the receiving shaft 2 can be closed, forming a plane with the front of the housing 1. The paper box cover 18 is pivotably mounted on the paper box unit 10 about a pivot axis 19 extending transversely to the insertion direction 14 from the operating position of the paper box unit 10 into an opening position inclined to the plane of the front of the housing 1.The paper box cover 18 has an opening pressure surface 20 and a closing pressure surface 30 on its outer side at a radial distance from the pivot axis 19. One or more locking hooks 23 extending in the insertion direction 14 are arranged on the paper box cover 18. In the operating position of the paper box unit 10, these hooks engage locking stops 11 arranged on the housing 1 and can be pivoted from their locked position (engaging the locking stop 11) to an unlocked position (not engaging the locking stop 11) by pivoting the paper box cover 18 into the open position.