Ovoid spur-planetary gearbox for swimming pool filtration valves

The manufacturer's Blue Lagoon and XClear brand of water treatment equipment sells into the consumer swimming pool, pond and spa markets where competitive pricing, dependability and operational simplicity are key selling factors. The new Tri-Matic water recycling system includes automatic backwash as well as exposing the rinse water to a powerful bacteria eradicating UV-C lamp. The innovative design has very low filtration resistance, allowing low-pressure and low-energy consumption pumps to be used.

Van Erp International had looked at various industrial valve and process control suppliers for the actuators but found that cost and complexity were barriers for the newly planned range. As a key supplier for other Blue Lagoon and XClear products including geared motors for peristaltic dosing pumps, Rotalink worked closely on the new valves with engineers at Van Erp International - closely following the pool equipment innovators philosophy of involving its suppliers in novel design and large scale production techniques.

The automatic backwash system comprises 2- and 3-way motorised automatic actuator valves arranged around the pool filter system that are controlled via a dedicated touchscreen computer. The user simply programs the backwash cycle frequency and the valves are sequenced - reversing the water direction as required for the filtration, backwash and rinse phases of the process. In operation, an open loop control using limit switches combines with the Rotalink reversible AC synchronous motor and high ratio ovoid gearbox, where the fixed speed at the output shaft is timed through the opening or closing phases of the valve. Should the valve be restricted by any sort of blockage, resulting in a timeout, an alarm and backup process is called into action and executed by the program.

The choice of the Rotalink Type 230 ovoid gearbox has special significance for the application: the 230 is a part of a wide range that combines both spur and planetary gear trains in a very compact pressed steel gearbox case with 4-point mounting. This technology facilitates a much higher torque-to-size factor than conventional ovoid gearboxes with spur gears and 2-point mounting, and also allows a significantly higher gear ratio to be used. The benefits of this elevated gearbox performance for the Blue Lagoon Tri-Matic backwash application include the advantage of a very compact PVC moulded valve housing that suits the restricted areas available in typical pool pump cabinets. In addition, the output torque available (up to 5Nm at low speeds) combined with the rigidity of the 4-point mounting increases the valves' ability to clear debris by pushing solid material through the valve more effectively. Also derived from the 230's torque output, the resulting torque reserve - being much higher than required for simply positioning the valve - provides the basis for high levels of reliability and long working life.

Concurrent product development process

As with past projects, Van Erp International and Rotalink worked closely as partners from the initial design brief through to volume production. Various motor-gearbox combinations were evaluated in a concurrent product development process that saw Rotalink test complete valves at its UK manufacturing plant. This process helped Van Erp International to reduce overall development timescales and achieve the fast time-to-market it requires to maintain a leading position in a very competitive business to consumer marketplace.

The Type 230 ovoid gearbox is part of a wide range of in-house designed and manufactured miniature gearboxes that include spur, combined spur-planetary and planetary gear systems in a choice of steel, polymer and ultra-polymer gear materials. Additional design options include nylon or ball-type bearings with standard and customised shafts, mechanical mountings and electrical connections. To learn more about motors and gearboxes from Rotalink, please visit www.rotalink.com.