Analysis of Different Technical Paths for Diaphragm Pumps in High-End Rice Cookers Across Various Brands

In high-end rice cookers from different brands, although diaphragm pumps are commonly used, their design purposes and ultimate functions differ significantly, corresponding to distinct technical approaches. The main technical paths can be categorized as follows:

  • Pursuing Extreme Gelatinization through Physical High Pressure.
  • Focusing on Preservation and Pre-treatment in a Vacuum Environment.
  • Utilizing High-Temperature Steam for Final Flavor Enhancement.

Diaphragm Pumps for Pressurization: Enhancing Cooking Temperature and Efficiency.

Example:​ In its pressure IH rice cookers, ZOJIRUSHI​ uses a diaphragm pump (or a small pressurization pump) with the core purpose of actively increasing the internal pot pressure.

  • Working Principle:​ During the "high-heat" cooking phase, the pump draws in external air to raise the pot pressure beforeboiling begins. This elevates the boiling point of water above 100°C (typically reaching 104-107°C).
  • Core Functions: High-Temperature, Efficient Gelatinization:​ At temperatures above standard atmospheric pressure, starch in the rice grains undergoes gelatinization (α-conversion) more rapidly and thoroughly, fully releasing the sweet components of the rice. Promoting Water Penetration:​ Increased pressure helps water penetrate the rice core faster and deeper, allowing even brown rice and multigrain rice to be cooked thoroughly and deliciously without requiring long soaking times. Intelligent Pressure Regulation:​ High-end models (e.g., the "Enbu" series) can intelligently and precisely adjust pressure between 1.0 and 1.3 atmospheres, tailoring the optimal pressure-temperature curve for different rice varieties and desired textures.

In short, ZOJIRUSHI's diaphragm pump acts as a "pressure booster," aiming to physically optimize the rice cooking process by creating a high-temperature, high-pressure environment.


Used for Vacuum Creation: Achieving Preservation and Optimized Soaking.

Example: TOSHIBA​ pioneered the integration of a vacuum pump in rice cookers. The core task of its diaphragm pump is to reduce internal air pressure, creating a vacuum or low-pressure environment.

  • Working Principle:​ Before cooking, the pump evacuates air from the inner pot, reducing the pressure to approximately 0.6 atmospheres.
  • Core Functions: Vacuum Soaking:​ Under low pressure, air is released from the cavities within the rice grains, allowing water to penetrate the core more quickly and uniformly, achieving an ideal 28%-29% moisture content without the need for prolonged soaking. Vacuum Preservation (Core Advantage):​ After cooking, the pump creates a vacuum again during the keep-warm phase, significantly reducing oxygen concentration inside the pot. This effectively inhibits oxidation, preventing the rice from yellowing, drying out, or developing off-flavors. Some models claim to achieve preservation for up to 40 hours, keeping the rice fresh-tasting without refrigeration. Texture Enhancement:​ As the rice absorbs water thoroughly from the inside out, the cooked result is softer and more pleasantly chewy.

Therefore, TOSHIBA's diaphragm pump functions as an "air extractor," primarily serving to optimize pre-treatment before cooking and provide long-lasting preservation after cooking, focusing on chemical and preservation aspects.


Used for Steam Circulation: Achieving High-Temperature Steam Steaming.

In its high-end models (e.g., the SR-SPZ183 series), Panasonic​ employs the diaphragm pump primarily to support its "Steam Delicious Circulation" or "200°C High-Temperature Steam Injection" technology.​ Its core function is to drive the circulation and injection of high-temperature steam.

  • Working Principle:​ The rice cooker features an independent steam generator and circulation channels. The diaphragm pump is likely responsible for actively pumping or circulating​ the generated high-temperature steam (reaching 200°C or even 220°C) within the sealed pot.
  • Core Functions: High-Temperature Steam Steaming:​ In the final stage of cooking, ultra-high-temperature steam is evenly injected onto the surface of the rice. This forms a thin gelatinized layer on the surface, locking in internal moisture and aroma, resulting in rice with enhanced gloss and elasticity. Aiding Thermal Convection:​ Promoting the flow of steam inside the pot, combined with 3D IH heating, ensures more uniform heating, making the rice grains "dance" for thorough cooking. Moisture Retention:​ Steam circulation also helps maintain humidity inside the pot during the keep-warm phase, preventing the rice from drying out too quickly.

Thus, Panasonic's diaphragm pump acts more like a "steam circulation manager," focusing on using high-temperature steam for the final quality enhancement and moisture retention of the rice during specific cooking stages.


NIDEC​ diaphragm pumps are widely used in the rice cooker industry, with main models including 00H220H020​ and 00H220H022.

The core advantages of this pump series are reflected in the following three aspects:

Excellent Reliability:​ Designed for a long service life, capable of sustained and stable operation.

High Consistency:​ Stable performance and uniform quality in mass-produced units.

Outstanding Safety:​ The plastic and rubber materials used in the pump comply with Japanese Food Hygiene Standards, ensuring safety and reliability.