Extendable Ventilation System Circuit for Single-Switch Safety Control
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Solution Overview
Problem
Existing extendable ventilation systems for household appliances, such as lift table ventilation systems, are complex and costly due to the separate design of safety circuits from the motor control, requiring microcontrollers and additional software, which increases the risk of injury and operational complexity.
Innovation Solution
A circuit that uses a single switch to control the lift motor, selecting between two current paths for extending and retracting the ventilation system, with a delay circuit and position limit switches to ensure safe operation without the need for microcontrollers or additional software, utilizing passive components like diodes and relays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate safety circuits with microcontrollers are used to control the lift motor, then safety protection is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the safety circuit functions directly into the motor control circuitry. The control unit integrates both motor control and safety monitoring functions, eliminating the need for separate safety circuits with microcontrollers. This merging approach maintains comprehensive safety protection while significantly reducing device complexity and cost.
Solution Approach 2:
The control unit monitors its own operation and automatically detects unsafe conditions (such as obstacles during retraction). The system self-terminates the retraction sequence when safety criteria are not met, without requiring external safety circuits. This self-service approach maintains reliability while simplifying the overall system architecture.
2Ease of operation
If a single switch controls both extension and retraction of the ventilation system, then ease of operation is improved, but the risk of injury increases
Solution Approach 1:
The control unit continuously monitors the position of the ventilation system and the state of safety criteria during operation. When a single switch is actuated, the system feedback-detects whether extension or retraction is commanded, checks safety conditions in real-time, and automatically terminates the sequence if unsafe. This feedback mechanism enables simple single-switch operation while preventing injury through automatic safety intervention.
Solution Approach 2:
The control unit preliminarily checks safety criteria before executing retraction commands. If safety conditions are not met (such as detecting an obstacle or improper positioning), the system preemptively prevents the harmful action by terminating the retraction sequence before it can cause injury. This preliminary anti-action allows single-switch operation while blocking harmful outcomes in advance.
3Measurement precision
If microcontrollers and software are used to control the ventilation system, then control precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive microcontrollers with more economical control components such as relays, contactors, or simple programmable logic controllers. These alternative components achieve sufficient control precision for the application while being significantly cheaper and easier to manufacture. The control logic is implemented through hardware circuits or simple programming rather than complex microcontroller software.
Solution Approach 2:
The patent substitutes complex electronic control systems (microcontrollers with software) with simpler electro-mechanical control components. Relays and contactors provide the necessary control precision through their inherent mechanical switching characteristics, eliminating the need for expensive microcontrollers and associated software development, testing, and maintenance costs.
Data Source
Figure 1
AI summary
The ventilation system has a main unit hat is provided with a stroke motor (101) and a semiconductor switch (S1). The primary operation of semiconductor switch is performed based on movement of stroke motor along the predetermined direction. The secondary operation of semiconductor switch is performed based on movement of stroke motor in direction opposite to the predetermined direction. The main unit is provided with a delay circuit. An independent claim is included for a method for operating extensible ventilation system.