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issue: October 2003 APPLIANCE Magazine Part 2: Motors & Air-Moving Devices

Motors & Air-Moving Devices
The Art of Providing Savings

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by Peter Simmons, Assistant Editor

Appliance OEMs are continuing to rely on motor and blower manufacturers to provide motor solutions and platforms that will help reduce cost, design-cycle time, and energy usage.

According to Texas Instruments (Houston, TX, U.S.), the TMS320C24x(TM) DSP platform of digital signal controllers provides 40 to 150 MIPS of control-optimized performance and up to 128 K of integrated flash memory for virtually all digital control systems and motor control applications.

Accelerated design strategies. Cost-reduction activities. Energy efficiency demands. Whatever the name used to describe them, these processes are all about one thing: savings of time, money, and energy. Each motor and blower manufacturer has its own approach to meeting the energy, time, and cost saving demands of its customers.

Energy and Money Savings

According to most motor and blower manufacturers, improving the efficiency of appliances is one of their most important and sought after goals. This goal is attained through a variety of different methods, including the use of new technologies and materials.

According to John Filla, director of HAC Marketing for the Air-Moving Motors division of Emerson Motors (St. Louis, MO, U.S.), manufacturers of residential HVAC equipment have traditionally used permanent split-capacitor (PSC) products in order to save energy. "Properly designed PSC motors can achieve 60- to 65-percent efficiency on single-speed applications, and can approach the same efficiency thresholds on the high-speed connection of multi-speed motors, as well," says Mr. Filla. He adds that the multi-speed motors are traditionally applied on furnace and air-handler applications.

"Most equipment manufacturers design their equipment to utilize 3- to 5-speed motors," says Mr. Filla. He explains that most of these motors are designed as 6-pole motors that operate at 1,000 to 1,100 rpm on high speed and down to 600 rpm on the lowest speed. "The discrete speeds are achieved through taps in the motor winding. The challenge is that the efficiency drops off to 30 percent on the lower speeds," Mr. Filla continues. He says that Emerson has begun to explore new options to overcome the efficiency of these motors at lower speeds.

According to Continental Fan Manufacturing, Inc. (Buffalo, NY, U.S.), its XR Motorized Impeller combines the efficiency of a backward-curved airfoil impeller with the advanced technology of an external rotor motor, achieving new standards for air performance and sound levels.

The integration of the motor and impeller minimizes space requirements and reportedly enables precision balancing for vibration-free operation. The company says that with both the motor and the impeller located directly in the air stream, the impeller acts as a rotating heat sink, providing excellent heat dissipation and efficient motor cooling. The fan can be mounted in any orientation for supply or exhaust applications.

"The first option is a brushless permanent magnet (BPM) motor," says Sid Ambort, vice president of Customer Development of Air-Moving Motors for Emerson. "The Emerson product is branded as PerfectSpeed and is part of the Emerson Climate Technologies UltraTech Home Series of products." According to Mr. Ambort, the BPM motor provides efficiencies of 80 percent on high speed and 60 percent on low speed. "This product, even with sophisticated electronics, has proven to be very reliable and provides a great value to the consumer at the extra costs," he says.

The other option that Emerson offers to increase energy efficiency is a variable-frequency controller. The inverter reportedly provides variable frequency and voltage to a PSC motor to provide the necessary speed changes to meet the requirements of the OEM and the consumer. "When [the controller] is applied to a PSC motor designed for compatibility, it offers significant energy savings at the lower speeds," reports Mr. Ambort. "This new product improves the efficiency on the lower speed range of a PSC motor from 30-percent efficiency to 45-percent efficiency, and more importantly, allows the product to reach much lower air flows - at reduced power - for continuous airflow operation. The energy savings at these lower speeds approximates the savings of a BPM motor and control. The efficiency on the highest speed is equivalent to that of a standard PSC motor." According to Mr. Ambort, given the HVAC trend toward continuous air circulation to improve air quality and more uniform temperature distribution, the variable-frequency controller offers a cost-effective solution to variable speed in situations where BPM technology is not essential. "The market for variable-speed products is growing at a rate of 8 to 10 percent per year," adds Mr. Ambort. "This is driven by the demand for energy-saving products, improved indoor air quality, and low noise."

Don Schlump, vice president of Engineering for Fasco Residential and Commercial Products (St. Clair, MO, U.S.), agrees that variable-speed motors have been increasingly used for high-efficiency applications. "The change now underway is to try and simplify these technologies and combine part numbers," says Mr. Schlump. He adds that Fasco's EPC series of motors includes both variable-speed induction and brushless d.c. motor types. "The series allows for fast and easy commissioning of the motor into the unit without the need for programming each part number," Mr. Schlump continues. "For the HVAC air-moving applications, the EPC motor/controller incorporates Fasco's Constant Massflow control algorithm. This feature enables constant mass flow over a wide range of system backpressures, making it suitable for both air distribution and draft inducer applications."

The new 000-0326 high-performance brushless d.c. kit motor from Servo Magnetics, Inc. (Canoga Park, CA, U.S.) is reportedly designed for low-voltage applications where an efficient, high-torque motor is required.

With a 5.38-in diam and 2.4-in length, the motor has an operating voltage of 12 V and is capable of delivering in excess of 1 hp of continuous power, according to the company. The motor is designed for battery operation and boasts a typical efficiency of 90 percent. Electrical and mechanical options include windings for specific power requirements, drive-specific commutation, and custom mounting configurations.

Paul Heitzmann, vice president of Engineering for Morrison Products Inc. of Cleveland, OH, U.S., says that the efficiency of an air-moving system is the result of the combination of everything involved in it. He says different motor designs, how well the motor design fits the application, the rating point at which the motor operates, and how much room is available for the appliance all affect the efficiency of an HVAC appliance. "Everybody wants to make their system smaller for the same capacity, so you're trying to squeeze everything down," Mr. Heitzmann observes. He says decreasing the size of an air-moving system usually results in problems with maintaining the airflow, and requires more power.

"Airflow could be improved quite a bit if the enclosure size could be increased to allow for the optimum blower housing size," Mr. Heitzmann says. "But in this current market, everyone needs a smaller footprint for their appliance." Harry Holmes, Morrison's president, adds, "The fan or blower is relatively efficient, but as you apply it to a system - a furnace or an air-conditioner - that reduces the efficiency substantially. Like everything, there are trade-offs, and you design the air-moving package to meet the system requirements. In order to do that, you have trade-offs between size and efficiency and the goal of the finished unit."

While Morrison Products believes that appliance design can limit the efficiency of a component, ebm-papst Industries of Farmington, CT, U.S. is of the opinion that component design can increase the efficiency of an appliance. Armin Hauer, product manager for ebm-papst, says that brushless d.c. motors are replacing induction motors to increase energy efficiency in appliance applications. "Brushless d.c. motors either operated from a low-voltage d.c. remote switch-mode power supply or from a.c. line voltage provide very high efficiencies at any speed," explains Mr. Hauer. "Induction motors have much lower peak efficiencies and even worse losses when speed-controlled."

According to Mr. Hauer, fan selection is as important to appliance efficiency as motor selection. "There is a trend toward making sure the most efficient fan types are selected for the operating point," he says. "For example, filtration equipment designs are changing from forward-curved blowers to backward-curved impellers that offer higher static efficiencies."

According to Stu Gatley, vice president of Engineering for Jakel, Inc. (Highland, IL, U.S.), both technology usage and new materials can aid in making appliances more efficient. It's not just the use of motors that helps to increase the energy efficiency of a product. "For example, we design cost-effective blower housings that use significantly less motor horsepower than previous models and reduce the overall cost to the consumer," Mr. Gatley tells APPLIANCE.

New Materials

The 3D motorized impeller from ebm-papst Industries, Inc. (Farmington, CT, U.S.) features aerodynamically engineered, 3D, extended metal blades within the impeller powered by energy-efficient, long-life external rotor motors. According to the company, airflow and static pressure performance increase by more than 25 percent compared to standard straight-blade designs. The impeller is available with a brushless d.c. motor or a 230-V a.c. 60-Hz motor. 115-V units are available on request.

In new materials usage, Mr. Gatley says Jakel is using more plastic in its products. "Jakel is using an increased amount of plastics in place of aluminized steel products, specifically in the water heater industry," he reports. "Plastic is a more malleable material, which makes it easier to combine parts, reduce costs, and increase efficiency. Another benefit to using plastic in designs is its noise reduction properties, resulting in a quieter end product."

According to Mr. Hauer of ebm-papst, plastics use in motors and blowers is increasing due to the material's many advantages. "There is a growing integration of functionality in plastic parts," says Mr. Hauer. "For example, single-piece impellers, strain relief for cabling, mounting bosses, bearing towers, and insert molding with metal parts or rubber seals result in improved precision and lower part count." Mr. Hauer says that plastics are even making their way into circuit boards. "Plastic wiring boards with snapped-in motor overload protectors and conductors welded to magnet wire replace traditional printed circuit boards with solder joints," he adds.

Mr. Schlump of Fasco also says that plastics and composites are increasingly being used as structural components for motors and blowers. He maintains that these flexible materials can facilitate efficient and quiet designs while lowering part count to improve reliability and reduce cost. "We are able to incorporate mounting features for the customer that eliminate their requirements for mounting brackets," Mr. Schlump says. "Components made from plastic are lighter than steel and can be balanced in the mold, reducing vibration and noise."

AMETEK Rotron Technical and Industrial Products (Kent, OH, U.S.) has expanded its product offering for variable speed brushless motors, blowers, pumps, and electronic drives to include the latest electronic control technology.

Operating features include reliable low-speed operation, surge protection, and closed loop feedback. According to the company, its new Intelligen Windjammer and Minijammer brushless d.c. blowers incorporate an integrated electronic controller that utilizes digital signal processor (DSP) technology. Jeff Anzevino, senior market manager, says external electronic modules are available, as well as an internal version for motor and pump product lines. Features include over and under voltage protection, short circuit protection, and fault LED indication for easy troubleshooting.

Many manufacturers are using new materials such as plastic to save on energy and cost. However, "We [at Morrison Products] keep up-to-date on plastic technology and composite technology, but we have yet to come close on a cost basis between plastic and commercial-quality steel," says Mr. Holmes. "Someday that might certainly become competitive, but we haven't found that to be the case yet."

Mr. Heitzmann says that some applications in an air-moving device might benefit from the use of plastic. "With plastic, you can produce a better quality airfoil on the blading," he continues. "If the efficiency improvement is significant enough, that might be able to offset the extra cost."

Jim Kirkhoff, sales engineer for Alliance Winding Equipment, Inc. (Ft. Wayne, IN, U.S.), says that many motor manufacturers have either increased the amount of copper inserted into the stator slot (slot fill) or narrowed the opening of the stator slot to meet energy efficiency requirements. "To meet these requirements, Alliance has developed a number of new technologies that allow for high copper slot fill even with a very narrow slot opening," Mr. Kirkhoff reports. "By using multiple servo motor drives instead of simple hydraulic cylinders on the inserter, greater control can be maintained over insertion parameters." Mr. Kirkhoff adds that the new generation of hermetic stators uses variable-speed motor technology. "These stators are a departure from traditional designs since they are typically in-slot wound and require a very high fill of wire within the slot," he says.

Noise Reduction

Reducing noise is a major consideration for appliance OEMs and, therefore, for the motor and blower manufacturers who supply to them. A noisy product is not an attractive product, and noise can sometimes be perceived as an indicator of efficiency problems.

According to Archie Eschborn, vice president of Sales and Marketing for Revcor (Carpentersville, IL, U.S.), the company's Pressure Plus 1, 2, 3(TM) and Smooth Flow(TM) blowers were designed to replace existing induced draft blowers or adapt to new furnace designs.

The Pressure Plus 90 Plus Induced Draft Blower line (seen in photo) reportedly features lower noise, a lower profile, and increased air flow performance within industry standard footprints. The Smooth Flow is a transition-less 80 Plus furnace blower line that features lower noise, a lower profile, and improved laminar airflow compared to current transition-less blowers, according to the company.

"The concept behind the induced draft blower from Revcor will help eliminate the obnoxious start-up noise typically identified with the 80 Plus mid-efficiency furnaces, and will also introduce noise reduction in certain frequencies on the 90 Plus high-efficiency furnaces," says Mr. Eschborn.

Eric Cole, vice president of Engineering, adds, "Our new blower product line has changed many of the industry standards regarding sound in induced draft blowers and the motors that drive them. Our lab is currently in the process of developing new motor drives that will revolutionize the way we look at induced draft blowers today."

According to Mr. Schlump of Fasco, noise reduction is a systems issue, involving motor and blower interaction with the appliance and the installation. "Performance and sound level are tested under all operating conditions, using the actual appliance as a test bed," Mr. Schlump says. With the motor engineers, aerodynamics experts, and application engineers working together, system adjustments can reportedly be made quickly.

Mr. Hauer says that ebm-papst incorporates several features in its motors to decrease noise levels. "For both our a.c. and d.c. blowers, we offer vibration isolation mounting systems integrated into the motor casing in order to reduce structure-borne noise," he explains. "In addition, brushless d.c. motors are available with sophisticated commutation algorithms and skewed stator slots that ensure smooth operation at any rotational speed."

Mr. Gatley of Jakel says that the use of plastics and advanced testing equipment is crucial to noise reduction efforts. "From a design perspective, we continue to address noise considerations by using plastic components to combine parts," he elaborates. Mr. Gatley adds that Jakel has invested in testing facilities to ensure that its products meet its customers' noise level standards. "For example, Jakel uses an on-site Gas Furnace Lab facility that allows us to test any gas appliances up to 400,000 BTU," Mr. Gatley says. "We can also send engineering technicians to test products using the customer's own facilities. This saves the customer time and money in the areas of shipping, testing, and manpower."

Mr. Heitzmann of Morrison says one of the main ways the company has recently helped meet noise considerations in appliances is by installing a free-field sound test chamber at its manufacturing facility. "Of course, this is generally used to evaluate changes that are made to reduce noise levels," Mr. Heitzmann acknowledges. "We also try to assist our customers in avoiding system resonance issues." In the continuing cycle of testing and adjustments, Mr. Heitzmann says that the company's new test chamber can be used to test the blower by itself, or to test the entire end product. "We can use it both for analysis and for comparison ratings," he adds.

According to Pete Pavlick, director of Sales and Marketing for Lamb Electric (Kent, OH, U.S.), noise reduction activities are also very important in vacuum motors for the commercial floor care industry. In part, this emphasis is driven by regulatory requirements in Europe that mandate a reduction of equipment sound levels at the workers' position, and a trend focusing on the improvement of quality of life in the workplace, institutions, and the home. "Vacuum motors have long been a notable source of unpleasant noise levels, restricting the use of vacuum cleaners and floor scrubbers to off-hours," says Mr. Pavlick. He adds that reducing the noise in vacuum motors is a multi-step process, but it has accelerated significantly in the past year.

Mr. Pavlick says that Lamb's Acustek vacuum motor design features a unique exhaust air diffusion system to reduce the working air noise and a patented vent air inlet configuration to reduce noise levels by 6 to 8 dB. Now, however, Lamb is working on providing even more advanced noise control solutions.

"The scope of sound enhancement has taken a new dimension by addressing the sound quality aspects in addition to the noise level," says Mr. Pavlick. "We most often refer to noise levels in decibels that measure the overall sound pressure. This measure lacks the identification of the annoyance levels of various noises." He says that Lamb's most recent sound enhancement technology is focused on reducing noise in frequencies objectionable to the human ear in order to improve the quality of sound.

"Using a measure called Sones, we can measure the perceived noise in a much better way than the sound pressure of decibel rating," explains Mr. Pavlick. Lamb has recently introduced the Acustek + motor design to provide further noise reduction and improved noise quality. The Acustek + uses a ramped radial design vent inlet along with a cupped cooling fan to reduce and improve the sound quality of the motor ventilating system, and a redesigned enhanced axial cooling fan. "This approach further reduces motor noise by 2 to 3 decibel sound pressure levels and reduces Sones by up to 15 decibels," Mr. Pavlick says.

October 2003 Special Product Supplement
Motors & Air-Moving Devices
by Peter Simmons, Assistant Editor

1 - The Art of Providing Savings
2 - Electric Motor Testing on the Production Line
3 - Integrating Brushless D.C. Motors Into Plastic Fans for Efficient, Quiet, and Cost-Effective Appliance Solutions
4 - Design Platforms
5 - Discovering the Use of Tangential Blowers in Low-Noise Applications
6 - Automated and Data-Reliant

7 - Improving IAQ in the Home
8 - Floor Care Appliance Boasts 5,000-HR Life
9 - Getting Pumped Up


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