Conveyor Oven Load-Based Speed Control Without a Gearbox
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Solution Overview
Problem
Conveyorized ovens with radiant heating face issues of load dependency, inconsistent cooking results, and motor torque challenges due to gearbox requirements, along with sensitivity to voltage fluctuations and processing time variations.
Innovation Solution
A conveyor oven system utilizing a stepper motor with sinusoidal current control, where the motor speed is adjusted based on load variance by monitoring power consumption, eliminating the need for a gearbox and ensuring consistent cooking through precise temperature and speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a gearbox is used to provide sufficient torque for the conveyor motor, then the motor can operate at low rotational speeds, but the device becomes expensive and complex
Solution Approach 1:
The patent replaces the mechanical gearbox system with an electronic control system that drives a motor directly. The controller adjusts motor speed electronically to provide variable torque output, eliminating the need for mechanical gear components while achieving the same functional result of providing sufficient torque at low rotational speeds.
Solution Approach 2:
The patent changes the operating parameters of the motor by using electronic speed control to vary the motor's rotational speed and torque output dynamically. This allows the motor to operate efficiently across different load conditions without requiring a fixed-ratio gearbox, thereby reducing mechanical complexity while maintaining adequate torque.
2Manufacturing precision
If the conveyor speed is adjusted based on oven temperature sensor information, then cooking uniformity can be improved, but the processing time increases significantly
Solution Approach 1:
The patent implements preliminary action by using multiple temperature sensors positioned throughout the oven chamber to detect temperature variations before they significantly affect cooking uniformity. The controller proactively adjusts conveyor speed based on these early temperature readings, preventing cooking defects rather than reacting to them after they occur, thereby reducing processing time while maintaining uniformity.
Solution Approach 2:
The patent employs feedback control by continuously monitoring temperature at multiple locations and adjusting conveyor speed in real-time based on temperature deviations from the setpoint. This closed-loop control system maintains cooking uniformity while minimizing processing time by making precise, timely adjustments rather than conservative, delayed changes.
3Manufacturing precision
If multiple temperature sensors are used to monitor cooking uniformity, then cooking precision can be improved, but the system complexity and cost increase
Solution Approach 1:
The patent applies segmentation by dividing the oven chamber into multiple monitoring zones with strategically positioned temperature sensors. Each sensor monitors a specific region, and the controller processes these segmented measurements to determine overall cooking uniformity. This segmented approach provides comprehensive monitoring while keeping the sensor count manageable and the system complexity reduced compared to continuous monitoring.
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 consistent cooking results independent of load factors and appliance age, minimizes cooking variations, and eliminates the need for a gearbox, ensuring efficient and uniform processing times while maintaining temperature control.
Implementation Method 1
A stepper motor is coupled to the drive wheel. A controller is coupled to drive the stepper motor
Implementation Method 2
A heater is disposed in the oven compartment to provide heat to cook food products disposed on the conveyor belt
Data Source
AI summary
A conveyorized oven that provides uniform cooking with control of the heater and/or the conveyor belt speed. The oven includes a controller that monitors power consumption of the heater and uses the power consumption to control the heater and/or the speed of the motor that drives the conveyor belt. The power consumption is monitored by counting the on time cycles of a switch that connects and disconnects the heater to a power main. Changes in the power consumption due to changes in loading are used by the controller to reduce recovery times of the oven temperature to a set temperature by controlling the heater and/or the motor. By using a stepper motor, there is no need for a gear box.