US 5,619,983 · Granted 1997-04-15

The Smart Oven That Learned to Steam Without Flooding Itself

Imagine an oven that cooks with both dry heat and steam — like a sauna inside your kitchen. The trick? A computer brain that constantly tweaks how much water drips into the heating element, so the oven stays perfectly steamy without drowning your food or cooling itself down by accident.

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The plain-English version

What it protects

The claim covers a combination convection and steam oven where a microprocessor controller actively adjusts the water supply rate to the steam generator based on real-time temperature readings from both the cooking chamber and drain area. What's protected here is the specific method of preventing 'quenching' (sudden temperature drops) while maintaining ideal steam levels by calculating water flow rates dynamically — both during startup and steady-state cooking.

Why it matters

Professional kitchens rely on combination ovens to cook everything from bread to roasted vegetables with precise humidity control. This patent solved a real problem: too much water steam and you cool down the oven; too little and you lose the moist-cooking benefits. By automating the water feed with a smart controller, Middleby Marshall eliminated guesswork and made these ovens more reliable and consistent for commercial operators.

Real-world use

Every time a baker uses a convection steamer oven to bake artisan bread with a crispy crust and soft interior, that oven is likely using this patent's method to automatically balance steam and heat.

Original USPTO abstract

An improved combination convection/steamer oven is provided that is capable of maintaining an optimum steam saturation level without quenching by equipping the steam generating system of the oven with an adjustable water supply source. When the oven is initially being brought up to the preselected cooking temperature, a microprocessor controller uses a stored water flow rate profile to calculate the water flow rate required to prevent quenching yet enable a desirable rate of temperature increase. Once the oven has reached operating temperature, the microprocessor controller analyzes temperatures in a drain channel and the cooking cavity and, based on these parameters, calculates the water flow rate into the steam generating system required to optimize steam saturation in the cooking cavity. The steam generating system also has an improved atomizer including a rotating paddle wheel that is fed water from within by a sprayer fan.

Patent details

Publication number: US 5,619,983
Filing date: 1995-05-05
Grant date: 1997-04-15
Assignee: Middleby Marshall, Inc.
Inventor(s): SMITH; MARK J.
CPC class: F24C15/327

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