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issue: October 2004 APPLIANCE Magazine Part 2: Motors & Air-Moving Devices

Part 2: Motors and Air-Moving Devices
Moving the Industry Forward


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by Jill Russell, Assistant Editor

A segment of the appliance industry that has previously experienced gradual achievements in design innovation, today’s motor industry is gearing up towards new ideas and practices for its customers.

According to research by the Freedonia Group, Inc., fractional horsepower motor demand—the motors typically associated with appliance use—will increase 4.3 percent annually through 2006 to total U.S. $6.7 billion. Additionally, the research group says that motor demand for appliances and consumer durables will grow the fastest out of all industry segments, including heating and cooling and automotive applications.

 

Introducing a new automated epoxy unbalance correction system, Schenck Trebel Corporation (Deer Park, NY, U.S.) says its testing system provides the exact amount of material required to provide fast and accurate motor correction.

The equipment transmits the magnitude and angular position of unbalance to a correction station, where the rotor is then indexed to the correction position. A resin material is then applied to the rotor in accuracy of a few milligrams, where UV light is then used to harden the added material in 3 to 5 sec. The company says the system can be integrated into semi- or fully automatic balancing machines and is customizable.

By 2006, fractional horsepower demand in the appliance and consumer durable market will rise at an annual rate of 5.4 percent through 2006, reaching $930 million. Additionally, a.c. motor demand is expected to dominate the motor segment, growing 3.5 percent per year through 2006 to total $3.6 billion.

Despite the highly anticipated growth rates of a.c. motors, several motor suppliers say they feel differently. Due to their high efficiency capabilities, wide range of application, and reasonable low cost, motor suppliers are anticipating a higher demand for d.c. motors. “To offer more alternatives to our customers,” says Andrew Lee C.K., Sales and Marketing manager, Chiaphua Components Ltd. (Hong Kong, China), “we have already developed several series of brushless d.c. (BLDC) motors, which are applicable for air-moving devices, medical equipment, and health care products.”

 
Chiaphua Components Limited (Hong Kong, China) produces a variety of a.c. and d.c. motors. The supplier conducts its own initial testing at an in-house laboratory to ensure its products meet increasing OEM demands for quiet motors and consistent quality performance.

Another Hong Kong-based motor supplier, Gold Tuning Trading Co., Ltd. (Hong Kong, China) agrees that the appliance industry will see a movement toward the integration of d.c. motors into appliance applications. “We foresee that d.c. motors will play a bigger role shortly because household appliances are becoming more portable than ever, many of which are evolving toward wireless and energy-saving features,” notes Benjamin Kwok, group manger.

In light of what motor suppliers are saying the next move in motor-type will be, they do agree that the motor industry is finally changing. From design innovation to noise reduction and greater efficiency, these critical components are moving the appliance industry into the future.

Customization is Key

Motor suppliers agree that the first step in creating a successful product is focusing on specific customer needs. “It’s a collaborative process,” Roger Dickson, chairman and CEO of Torrington Research (Torrington, CT, U.S.) tells APPLIANCE. “The customer certainly drives the design.” The company says that in the beginning stages of working with a customer, it meets to discuss product expectations, end applications, and project goals. Together, the companies gather their ideas and establish the basis of the project. “When we get done with this process, we have a product that goes beyond statistics and metrics,” Mr. Dickson says. “That’s what is interesting about this [process]. The customer gets a whole lot more than what they may have anticipated in the beginning.”

For example, in one customer application, Torrington designed a new BLDC motor that exceeded expectations that incorporated microprocessor (MCU) controls and combined components into a housing that actually reduced the number of components within the motor. The new motor features a sensorless sine-wave drive and slotless design, both said to improve the motor’s performance. Due to the design of the motor, which combines components and integrates them into the housing, Torrington was able to eliminate the need to include sensors and was also able to reduce the noise of the device by devising a slotless design. The end result, according to the supplier, gave its customer a lighter, cost-effective solution that worked more efficiently than traditional d.c. motors, all the while reducing the number of parts.

Germany-based ebm-papst Landshut GmbH, previously known as MVL Motoren Ventilatoren Lanshut GmbH, also worked closely with an appliance customer to provide multiple solutions that meet demands. According to Stefan Brandal, sales director, this process was used with German appliance maker BSH Bosch und Siemens Hausgeräte GmbH during development of its new Intercooker 3 oven. Mr. Brandl says ebm-papst developed a hot-air convection, single cooling fan for BSH’s low-end models, and a combination fan for the company’s premium models, which included an additional radial fan. According to the supplier, its different versions of the fan allowed it to adjust the blowers to the specific requirements of the customer.

In its single fan model, a simple crossflow blower is featured, which cools the outside of the oven and the electronic parts. In the combination fan, a crossflow blower cools the oven by pulling the hot air from inside the oven and blowing it out, which the supplier says can sometimes result in high speeds and noise. To overcome this problem, ebm-papst says the combination fan cools the oven case using an axial fan on the top of the product while extracting steam through the oven cavity by use of a radial blower. The benefit, according to Mr. Brandl, is the use of one blower to achieve two different functions. “Cost reduction compared to the current range was our goal, which we have achieved with innovative designs and system integration,” he tells APPLIANCE.

Other suppliers are also offering flexible solutions that can be tailored to meet specific OEM needs, allowing them to integrate the solutions into virtually any appliance application. Control Resources (Littleton, MA, U.S.) recently announced the introduction of its a.c. to d.c. fan speed controller, which combines an a.c. to d.c. power supply and a d.c. fan control. The company says its speed-controlled fan uses 40 to 60 percent less power compared to similar a.c. fans and controls speed more accurately, as its voltage vs. flow curve is more linear than a typical d.c. fan. Controlling 24- or 48-V d.c fans up to 4-A, the variable fan speed can be based on temperature or a control signal input.

 
Torrington Research (Torrington, CT, U.S.) engineers redesigned a fan system to integrate the blower, motor, control, and other end-unit elements, significantly simplifying the design. The original design (left) required 120 parts. The redesigned assembly (right) uses only 24 parts—improving size, weight, efficiency, and costs.

Constant Considerations

Although motor suppliers are working with OEMs in the initial design phase to produce customized motor solutions, there are always issues such as heat and noise that motor suppliers are working to eliminate. “There is one essential problem,” Marcel P. Hofsaess, manager of Germany-based ellipson electric GmbH, tells APPLIANCE, “an effective system for protecting electro motors for use in the household industry against overheating.” Consequently, the supplier says it has been investigating the use of thermal cutoffs to help prevent heat problems in electro motors and drives. The supplier says that depending on the type of application, it has developed three main types of cutoff systems: the first being sensitive to undefined currents and temperatures, the second being sensitive to defined currents, and the last being sensitive to defined temperatures only. According to Mr. Hofsaess, the most reliable and durable thermal cutoffs are those which are sensitive to temperatures only. However, these types of cutoffs have previously been known to react to the prevailing ambient temperature in the device and tend to switch before the ideal set temperature is achieved. Additionally, temperature-sensitive cutoffs have had limited range and low production counts due to limited manufacturing capabilities.

According to ellipson, those problems have been eliminated due to a new thermal cutoff design featuring a universal connection. The new design features round cells, which, the company says, are fully functional as half-finished products and can be manufactured according to a wide range of variants. “The innovations could be achieved as a result of a unique bi-metal process which dispenses with the need to subsequently select and adjust the end product,” Mr. Hofsaess explains. “This has made it possible to reduce temperature drifts and switching point tolerances by over half compared with typical market values.”

 
Briggs & Stratton Commercial Power (Milwaukee, WI, U.S.) announced its Etek Brushless Motor System that utilizes axial-gap motor design and a programmable electronic motor controller to offer increased power and reduced noise. Producing up to 15 hp, the axial design features Neodymium Iron Boron magnets in a disc rotor arrangement and a sealed aluminum housing said to be ideal for commercial equipment and floor care applications.

In response to high demands for a non-self resetting motor heat protection device, Texas Instruments (Dallas, TX, U.S.) developed its motor protector for both 120- and 230-V a.c. applications, including washing machine, vacuum cleaner, and lawn mower motors. The 3MP self-hold device consists of a bimetallic disc welded into a metal housing with an integrated terminal covered by a plate and heater to increase the device’s sensitivity. The supplier says the protector is actuated by passing current and heat. When the disc reaches its pre-set temperature, the electrical circuit is interrupted and contacts will remain open until the user switches them off. Once switched, the protector cools down and resets the contacts automatically. The company says that under locked rotor conditions, the device can provide accurate trip times.

The ever-present issue of noise reduction also continues to be a request from OEMs that motor suppliers are still working to achieve. Traditionally, noise reduction focused on the fan, fan blade, or fan wheel, as designers knew that most noise was created from the air-moving component. However, much of the noise associated with the blower has been eliminated, and motor manufacturers are now working to reduce the noise associated with the actual motor. “We have sciences in that area [blowers] that reduce acoustic noise quite a bit,” confirms Mr. Dickson from Torrington. “In fact, we’ve reduced noise so much so, we are now hearing noise from the motor, and we’re down to a point where motor noise, all of a sudden, has become an issue.”

Mr. Dickson says that implementing a higher-efficiency fan can reduce the problem. “If you run a fan at a lower speed, it’s going to make less noise,” he explains. “If you can run a fan at a lower speed, and still get the same performance, then you have a lower noise solution for your customer.”

 

A.O. Smith Electrical Products Company (Tipp City, OH, U.S.) says its new Gemini™ “comfort speed” motor has improved system efficiency and quiet operation, even at low speeds.

The company says the motor design mounts two separate rotors and stators on the same shaft in the same main frame. According to the supplier, customers can control high and low speed operations, as each motor is designed with multiple taps.

The electronic technology found in d.c. motors from the drive is also helping suppliers offer near noiseless motors. “Audible motor noise is a very complicated issue, as it is related to the motor structure,” explains Mr. Lee of Chiaphua Components. “The structure of the BLDC motor is different from the brushed d.c. motors, as its basic operation is controlled by electronic circuits. As a result, BLDC motors are quieter and have a longer life than the traditional brushed d.c. motors.” The company also says it consults motor and noise experts before finalizing its designs. “We have an acoustic room to measure the noise level of motors before they are released to market,” Mr. Lee says. “[We are currently] designing some kinds of electronic circuits to control the basic operation of motors and our BLDC motor. In order to meet noise considerations in appliances, our experienced engineers would suggest our customers replace the brushed d.c. motors with BLDC models.”

Motor supplier Ametek (Paoli, PA, U.S.) recently reduced the noise level of its Advantek™ line of vacuum cleaner motors while simultaneously improving the motor’s airflow and overall efficiency. In redesigning the motors, the supplier’s engineers focused on the carbon brush system of the motor and its air-handling diffuser. According to the company, in conventional vacuum motor models, the carbon brush system is generally mounted top-side up on the motor’s rotating armature, which allows adequate cooling airflow and temperature regulation. In an effort to obtain maximum cooling airflow efficiency, Ametek engineers designed the armature support and carbon brush system to hang upside down in the motor. This, the company says, enabled the coolest air to be directed to the critical motor parts, reducing parasitic high temperatures and improving brush and motor life.

“ Through unconventional thinking, we discovered that by redesigning this motor basically upside down from previous designs, we were able to get considerably more running hours for the same amount of material, without sacrificing performance quality,” says Jim Shawcross, vice president of Engineering for Ametek’s Global Floor Care Motors Division. “We also dramatically reduced noise levels.”

Ametek also focused on redesigning its air diffuser to help eliminate unwanted noise. The air diffuser is responsible for pumping air through the vacuum cleaner system. By reconfiguring the fan-blade arrangement and port placement within the blades of the air diffuser, the supplier was able to reduce the noise level. Using a rapid injection molding software and technology, the motor manufacturer was able to build prototypes, make design changes, and conduct testing of its newly designed motor, saving 6 to 8 weeks of development time.

 

According to supplier Maxon Precision Motors, Inc. (Burlingame, CA, U.S.), its new EPOS 24/5 controller is capable of position, velocity, and current mode functions and can be used in small brush or brushless motors. Requiring a supply voltage of 11 to 24 V d.c., the controller is reportedly capable of a 5-A maximum continuous current and 10-A peak current. The company says the controller’s efficiency is up to 90 percent.

Meddling with Materials

One factor that is also helping to further the motor design process is the use of new materials. Some suppliers are using materials traditionally not associated with the motor industry—the largest contributor being plastic. “Plastic is increasing in many components,” says Mr. Lee of Chiaphua Components. “It is malleable, lighter, and less expensive than steel.”

With the use of plastics, Torrington is actually integrating the outer panel materials into the motor components to help decrease the overall size and weight of the motor while decreasing the overall number of components used to manufacture its motors. The company’s new BLDC motor integrates the motor’s fan and blower into the same housing as the customer’s product. By using an injection-molding process, the company is able to integrate a motor rotor component into a fan blade. The process helps the company produce a single main component to hold the individual components. “In a Torrington motor, without the rest of the product, all we have is a handful of components,” explains Patrick Sandefur, vice president of Marketing and Sales. “By taking those components and integrating them into the housing of the blower and the fan, you reduce the overall size of the product, and you also reduce cost because now no separate handling, assembly, and material costs are associated with a separate motor and its components.”

Torrington says that the new injection-molding process has also helped it to reduce the amount of metal materials being used in its designs. “The lamination still has to be a metal material, but we are using far less of it,” Mr. Dickson tells APPLIANCE. “I think it’s a very efficient use of materials and certainly [the industry will] see more plastics.”

 

The new brushless d.c. gear motor from Merkle-Korff Industries, Inc. (Northbrook, IL, U.S.) reportedly offers high efficiency and extended life to a variety of applications, including business appliances and commercial restaurant equipment. Up to 300 in per lb of output torque is available over a variable speed range of 1 to 30 rpm. Optional features include customized output shafts, integral controls, programmable dynamic braking for back drive resistance, mounting options, and custom speed profiles.

Demanding Elements

One design element that remains of utmost importance is motor quality. “Quality demands are becoming more and more stringent,” says Heiner Frick, director of Sales and Marketing for Kautt & Bux GmbH (Herrenberg, Germany). “Key figures are having no rejected products, continuous reduction of ppm, and official certification is a must.” One way motor suppliers are ensuring they meet demands is with the help of certification and rating programs that not only rate a motor’s quality, but also its overall efficiency.

Bill Gentes, director of Membership and Communications for the Air Movement and Control Association International, Inc. (AMCA) agrees that quality performance and efficiency are two of the main demands in the industry. “OEMs are demanding greater efficiencies and greater energy savings,” he says. “What we’re seeing is that the end-user is demanding that products be efficient and energy-conserving and do what the company claims they will do.” The association says the increased demand for quality is driving the demand for its Certified Ratings Program, which helps to assure that the published ratings of air-movement and air-control devices are reliable and accurate by a standardized method.

 

Sanyo’s d.c. Micro Motor Division (Bensenville, IL, U.S.) has introduced the 12GN Series, a line of 12-mm geared d.c. micro motors said to be ideal for small appliance applications. Measuring 12-mm by 10-mm by 29-mm from terminal to shaft-tip, operation is reportedly quiet due to the close tolerance precision of the shaft rotation.

Fasco (St. Clair, MO, U.S.) says it is consistently receiving new quality demands from customers. To help achieve the requirements, the supplier says it has initiated lean manufacturing and Six Sigma practices and design for manufacturing and assembly. “Fasco engineering strives to provide the most efficient product by matching the highest efficiency motor operating point with the appliance operating point,” says Mike Garrett, advanced gas technology engineer for Fasco. In fact, the supplier internally tests its motors to ensure quality and efficient motors. “Most of the testing is conducted in an automatic test cell that records the test data,” Mr. Garrett explains. “The test cells are programmed to provide the operator with the indication that the test was completed successfully or not.”

Increasing the efficiency of its motor is exactly what GE Industrial Systems achieved with the introduction of its ECM 58 Series fan and motor system and ECM 84 Series motor, which reportedly deliver up to 300-percent energy savings in commercial refrigeration applications. Designed to replace shaded-pole and permanent split-capacitor motors, the new series features a PMDC design. The 58 Series features a smaller fan-tip clearance of its shroud and fan which, according to the company, helps it operate at 20- to 25- percent system efficiency compared to the 5- to 10-percent efficiency of shaded-pole motors. GE says the 84 Series, suitable or applications up to 90 W, is more efficient than a permanent split-capacitor motor by up to 40 percent and a shaded-pole motor by 70 percent. The motors also feature programmable microprocessor controls for customized preferences and ensure efficiency by adjusting torque to maintain programmed speed set points.

Motor drive supplier ABB Inc. is also working to ensure its drives meet standards. In order to help appliance makers meet ASHRAE’s 90.1 Standard, ABB says its drives can be customized to meet needs of single-motor HVAC application requirements. The standard mandates energy-efficiency standards for pumps in HVAC applications flow rates by as much as 50 percent of design rates. ABB’s drives convert a.c. power to d.c. and then invert the d.c. power back to an adjustable a.c. output to a motor. The company says the drives can be installed out-of-box or can be ordered and manufactured as a customized unit, tailored to the design specifications of the application, helping to optimize performance.

Other motor suppliers say the Environmental Management System (EMS) helps to achieve environmental demands as well. “It aims at providing the highest quality of products and services to customers while at the same time committing to environmental requirements,” Mr. Lee of Chiaphua tells APPLIANCE.

 
Adding to its hybrid motor line, Haydon Switch & Instrument, Inc. (Waterbury, CT, U.S.) introduced a new high-force size 14 non-captive linear actuator said to help achieve precise positioning and rapid motion. The company says this design is suited for long linear travel requirements, such as medical equipment, as the lead screw is secured at both ends and the motor translates along the screw. The actuator features thermoplastics in the rotor drive nut and a stainless steel Acme lead screw.

Motor suppliers are working toward producing efficient, reliable, and customized options that satisfy an increasing list of demands from appliance producers. As more applications are tailored to include specific demands in the design phase, suppliers speculate a movement toward d.c. motors that can give apppliance OEMs exactly what they want. Mr. Lee adds: “As customers tend to have a higher demand over motor performance, we believe motors will be smaller in size, but more energy efficient and electronic-orientated in the future.”

 

issue: October 2004 APPLIANCE Magazine
Part 2: Motors and Air-Moving Devices

Click for the online Part 2 Table of Contents.

 

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