Getting Rid of the Belt in a Clothes Dryer Driving the Drum Directly

This application covers a laundry treatment apparatus, meaning a washer, dryer or combined machine, with a drive arrangement that removes the belt and pulley used in conventional heat pump dryers. The applicant is LG Electronics, the South Korean appliance manufacturer.

The Problem

Heat pump dryers have become the efficient option in laundry, using a refrigeration cycle to dehumidify and reheat circulating air rather than heating fresh air and dumping it. The specification describes the standard architecture: a cabinet, a rotating drum, a circulation flow channel carrying air out of the drum and back, a heat pump in that channel condensing moisture from the air and reheating it, and a pump moving the condensate to a storage tank.

The drive train is where the compromise sits. The motor is mounted to the bottom surface of the cabinet, or to a base fixed there, underneath the drum. That placement keeps the cabinet floor from deforming when the motor vibrates or when the machine takes a knock. But it means the motor shaft is not parallel with the drum’s rotation axis, so extra components are needed to get the rotation where it belongs: a shaft driven by the motor, a small pulley on that shaft, and a belt running from the pulley around the outside of the drum.

The large ratio between drum diameter and pulley diameter conveniently removes any need for a reduction gearbox. It also creates the flaw. When the motor accelerates quickly, the belt slips on the drum or the pulley. The machine must therefore limit rotational acceleration to a level low enough that slipping does not occur, which the specification calls a fundamental limit: the motor has to accelerate and decelerate slowly whenever the drum is turned.

What This Invention Does

The disclosure restructures the drive so the belt and pulley are not required, along with the supporting arrangements inside the cabinet that a repositioned motor implies. Removing the belt removes the slip constraint, and removing that constraint lets the drum accelerate and decelerate as quickly as the control strategy wants.

Fast, controlled changes in drum speed are not a trivial gain in a dryer. Tumbling behaviour, which determines how evenly laundry is exposed to the drying air, depends on how the drum speeds up, slows down and reverses. Belt driven machines run a narrower repertoire of motions than their motors could otherwise produce. A machine that can change speed sharply can shake out tangled loads, redistribute items that have balled together, and vary the tumble pattern through the cycle.

The remaining claims address what changes structurally when the motor moves: how the drive is supported, how vibration is handled without relying on a cabinet floor mounting, and how the drive coexists with the circulation channel, heat pump and condensate handling that occupy the space beneath and behind the drum.

Key Features

• Belt free drum drive. The pulley and belt arrangement of conventional heat pump dryers is eliminated.
• No slip acceleration limit. Removing the belt removes the constraint that forced slow motor acceleration and deceleration.
• Heat pump circulation retained. The apparatus keeps the circulation flow channel and heat pump that recover heat and condense moisture.
• Condensate handling. Water condensed by the heat pump is collected and moved to a storage tank.
• Revised vibration support. The structure accommodates motor vibration without depending on cabinet floor mounting for stiffness.
• Wider tumbling repertoire. Faster speed changes allow drum motions that a belt drive cannot deliver.

Who Is Behind It

The applicant is LG Electronics Inc., headquartered in Seoul and one of the largest home appliance manufacturers in the world, with a substantial washing machine and dryer business including direct drive washing machines it has marketed for years. The named inventors are Yeonju Lee, Jongmin Lee, Minji Kim, Woonje Choe and Taewoong Kim. The application is a divisional of Australian application 2022333753, and the background section cites Korean Patent Application Publication 10-2019-0121656 as the reference dryer structure.

Why It Matters

Direct drive is a familiar story in washing machines, where LG made it a marketing point some time ago, but dryers held onto belts longer. The reason is layout. A dryer’s under-drum space is contested territory: the heat pump, the circulation ducting, the condensate pump and the water tank all want to be there, and a motor placed on the drum axis has to fit around them.

The efficiency argument for heat pump dryers has strengthened as energy labelling tightens across markets including Australia, and manufacturers have responded by shifting their premium ranges to heat pump models. Once a machine costs more, the mechanical compromises inside it get more attention, and a drive train that limits how the drum can move is a visible constraint on what the control software can achieve.

The broader point is that fewer transmission components generally means less to wear, less noise and less that can slip. Whether the tumbling improvements are perceptible to a household is harder to say than whether a belt is present, but the direction of travel in appliance engineering has been consistently towards driving things directly.

Related Concepts

• Clothes dryer – the appliance category this apparatus belongs to.
• Heat pump – the efficient drying cycle the machine is built around.
• Direct drive mechanism – the drive approach that removes the belt and pulley.
• Belt drive) – the conventional transmission whose slip limits acceleration.
• Energy Rating Australia – the labelling scheme that pushes appliance efficiency in this market.
• Electric motor – the component whose placement drives the whole redesign.

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AU 2026202076 was published in the Australian Official Journal of Patents on 16 April 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.