Braking Device for Movable Door Wings Using PWM Field-Effect Transistors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing braking devices for movable door wings lack direction-dependent damping control and achieve insufficient damping power, particularly when closing doors for physically impaired individuals or in sequential door control systems, due to limitations in adjustable impedance and energy dissipation.
Innovation Solution
A braking device featuring anti-serially arranged field-effect transistors and partial braking circuits connected to individual stator coils of a brushless electric motor, allowing for low-impedance short-circuiting and flexible, direction-dependent damping control through pulse width modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a generator-operated electric motor with short-circuitable contact pair is used for damping, then autonomous operation without external power supply is achieved, but the damping power and adjustability are insufficient
Solution Approach 1:
The patent applies dynamics by making the braking impedance adjustable through pulse width modulation (PWM) of the switching element. The duty cycle of the PWM signal dynamically changes the effective resistance in the braking circuit, allowing the damping force to be adapted in real-time based on door position, speed, or desired closing characteristics. This transforms a static braking system into a dynamically controllable one.
Solution Approach 2:
The patent changes the electrical parameter (impedance/resistance) of the braking circuit by using PWM to vary the duty cycle of the switching element. This parameter change allows the same hardware configuration to provide different damping levels, enabling both strong damping (for safety) and adjustable closing times without requiring multiple physical components.
2Object-affected harmful factors
If strong damping is applied to slow door closing for safety, then injury risk is reduced, but the closing time increases excessively
Solution Approach 1:
The patent uses periodic pulse width modulation to apply braking force in controlled intervals rather than continuous application. The PWM switching element rapidly switches on and off, creating periodic braking pulses that provide strong damping when needed while allowing the door to move during off-periods. This enables safe, controlled closing without excessive total closing time.
3Adaptability or versatility
If adjustable damping control is implemented, then closing characteristics can be optimized, but device complexity increases
Solution Approach 1:
The patent makes the switching element serve multiple functions: it acts as both the power switch for the brushless motor and the braking control switch. The same PWM controller that drives the motor also controls the braking impedance by modulating the switch duty cycle. This multi-functionality reduces component count and system complexity while maintaining full adjustability.
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
This configuration enables powerful, flexible, and direction-dependent damping, significantly increasing the closing time of door wings from 20 seconds to 3 minutes, achieving stronger and adjustable damping characteristics.
Implementation Method 1
a generator-operated electric motor with a motor shaft which is rotatable by a movement of the door wing and which expends motion-dependent motor voltage to a contact pair
Implementation Method 2
the contact pair is short-circuitable in order to dampen a movement of the door wing... the generator-operated electric motor generates electrical energy that is consumed by the short-circuiting
Data Source
AI summary
A braking device for a movable door wing comprises an electric motor operated as a generator with a motor shaft which is rotatable by a movement of the door wing and which expends motion-dependent motor voltage at a contact pair, as well as a braking circuit upon which the motor voltage is applied or applicable and via which, the contact pair is short-circuitable in order to dampen a movement of the door wing. It is provided that the braking circuit comprises two anti-serially arranged field-effect transistors wherein their drain terminals are connected each to another contact of the contact pair and wherein their source terminals are connected to each other and preferably also connected to earth or a zero line, so that the contact pair is short-circuited depending on the switching state of the field effect transistors. Alternatively or in addition to such a design of the braking circuit, provision is made that the electric motor is designed as a brushless electric motor with a plurality of stator coils, in each of which an AC voltage is induced as a function of the movement of the door wing, and that one of the AC voltages induced in the stator coils is outputted at the contact pair. The braking circuit comprises a partial braking circuit to which the alternating voltage output on the contact pair is applied or can be applied and via which, the contact pair can be short-circuited.