Door Actuator Brake Circuit Using a Bipolar Transistor Load
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Solution Overview
Problem
Existing brake circuits for door operators with electric motors that operate as generators face limitations in adjusting braking or damping effects, particularly at low speeds and with temperature-dependent diodes, leading to jerky movements and reduced effectiveness at low generator voltages.
Innovation Solution
A brake circuit utilizing a bipolar transistor as a load resistor, coupled with a voltage regulator and a voltage divider, allows for adjustable braking or damping effects even at low speeds and low generator voltages, and includes safety features like Zener diodes to prevent overvoltage damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If diodes connected in series are used as load resistors with switches connected in parallel, then the braking or damping effect can be increased, but the braking effect can only be changed gradually leading to jerky movements
Solution Approach 1:
The patent employs a bipolar transistor instead of discrete diodes and switches, enabling continuous and dynamic adjustment of the braking effect. The transistor's collector-emitter path provides smooth variable resistance control through base voltage modulation, eliminating the jerky movements caused by gradual switching of discrete diode elements.
Solution Approach 2:
The patent replaces the mechanical switching system (discrete diodes with parallel switches) with an electronic field-effect system (bipolar transistor controlled by base voltage). This substitution enables continuous analog control of braking force rather than discrete step-wise adjustment, achieving smooth door movement.
2Reliability
If diodes are used as load resistors, then the braking circuit can be implemented, but diodes are temperature-dependent with regard to their breakdown voltages
Solution Approach 1:
The patent changes the fundamental parameter of the load resistor from temperature-dependent diode breakdown voltage to bipolar transistor collector-emitter resistance controlled by base voltage. This parameter change eliminates temperature dependence because the transistor's resistance is controlled by the voltage applied to the base terminal rather than by temperature-sensitive breakdown characteristics.
3Ease of operation
If a field effect transistor is used in the braking circuit, then the braking effect can be controlled, but the high minimum gate-source voltage limits the range of use at low generator voltages
Solution Approach 1:
The patent uses a bipolar transistor as an alternative electronic component that replicates the switching and resistance control function of the field-effect transistor but with different electrical characteristics. The bipolar transistor requires only a small base-emitter voltage (typically 0.7V) compared to the high gate-source voltage required by field-effect transistors, enabling operation at low generator voltages.
4Adaptability or versatility
If switches are used to change the braking effect, then the braking effect can be adjusted, but the adjustment is gradual and causes undesirable jerky movements
Solution Approach 1:
The patent replaces static discrete switches with a dynamic bipolar transistor that can continuously vary its resistance. The transistor's collector-emitter resistance can be smoothly adjusted by varying the base voltage, providing dynamic and continuous control of the braking effect rather than discrete step-wise adjustment.
Solution Approach 2:
The patent substitutes the mechanical switching system with an electronic field-effect system using a bipolar transistor. This allows for analog continuous control of the braking effect through voltage modulation at the base terminal, eliminating the jerky movements inherent in discrete switch-based adjustment.
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 provides a robust, cost-effective, and safe braking or damping effect across various door movement speeds and voltages, ensuring smooth operation and increased operational safety by maintaining effective braking even at low speeds and reducing the risk of component damage.
Implementation Method 1
When the electric motor is operated as a generator in a first operating direction of the electric motor that is opposite to the direction of movement, the brake circuit is set up to supply its generated energy to a bipolar transistor as a load resistor. The higher this speed, the higher the self-induced or generator-generated voltage.
Implementation Method 2
the brake circuit is set up to supply its generated energy to a bipolar transistor as a load resistor
Data Source
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AI summary
The braking circuit has a bipolar transistor (23) placed adjacent to an electric motor which is generatively operated in closing direction with generatively produced energy as a load resistance. A connecting lead (L4) is coupled to collector terminal (c) of bipolar transistor and to voltage input (21a) of voltage regulator (21). An internal connecting lead (L3) is coupled to emitter (E) of transistor and to reference voltage (21b) through a resistive circuit (120). An independent claim is included for door actuator.