Miniature Motors

New engineering designs, and the desire to make smaller, more compact mobile phones, medical devices and other consumer products, is fueling the need for more miniature motors. And the desire for more torque that fits into thinner, smaller and light weight product designs is driving manufacturers of miniature motors to develop smaller and smaller packages. Even though the motor diameters and lengths are measured in millimeters, the power/volume ratio of these products continues to expand.

Innovative new miniature motor products are providing solutions for vibration and suppliers are turning to high energy magnets, winding technologies and automated motor assembly to boost performance. Makers of micro motors face the same issues that limit all motor design efforts and continue to focus on delivering higher power-to-volume ratios, motor efficiency and reliability.

MINIATURE BRUSH AND BRUSHLESS GEAR MOTORS

A line of 16 mm miniature brush and brushless dc gear motors is available from Nidec Copal USA. Three types of gears are provided for office automation, medical and laboratory instrumentation applications.

Planetary resin gears are designed for applications where lower audible noise is a requirement. The HG16-XX-AA brush dc gear motor family offers gear ratios of 30, 60, 120 and 240. Rated gear motor shaft speeds range from 310 down to 55 rpm. New planetary metal gears are for applications with demand high shock loads and high torque. Gear ratios of 60, 120, 240, 300 and 500 are available. Available rated torques range from 4.8 to 27.8 oz-inch with rated shaft speeds varying from 164 to 21 rpm.

Spur gear motors are for applications with moderate loads where cost is a concern. Gear ratios include 30, 60, 120 and 240 for the brushless versions, and 50 and 120.9 for the brush gear motors.

MICRO MOTORS OFFER 3.4 mm HEIGHT FOR VIBRATION APPLICATIONS

Sanyo dc Micro Motor Div. has developed a vibrating micro motor featuring a low profile of just 3.4 mm in a SMD package. The BSY Series dc motor is designed for applications requiring a small footprint on surface mount circuit boards, and is available in an 11 mm length. Applications include mobile phones, consumer medical devices and other small handheld devices, in OEM quantities. Medical and other applications requiring disposable functionality are made possible due to the low unit cost of the motors. The series is suitable for devices weighing approximately 80g or less.

The motor measures 11 mm long, with body 4.4 mm wide x 3.4 mm high off the mounting surface. Typical speed is 14,000 rpm with a counterweight of 1.7 mm radius and 2.8 mm length. Mechanical noise is 45 dB max. Electrical noise is controlled by a ring varistor. Standard operating voltage is 2.7V dc. Load current is approximately 65 mA. Operating temperature range is -20 to +70C.

POWERFUL Ø3MM BRUSHLESS DC MOTORS

MicroMo Electronics is expanding its brushless dc motor product line with a new version of the Smoovy Series 0308…B. The new products use skewed winding, in combination with a rotor made of Neodymium rare-earth magnets, to provide cog-free motion.

The bearing system is composed of jewel bearings and with an external motor-diameter of only 3 mm, a length of 8 mm and a weight of 0.33g, the motor is truly a microdrive. Due to electronic commutation, service life is limited only by the bearings. The motor can achieve a continuous output torque up to 0.014 mNm at speeds up to 15,000 rpm.

Motors can be combined with a gearbox and a linear actuator for a complete miniature dc drive system. The plastic planetary gearhead is available in a 3 mm diameter with various reduction ratios allowing a continuous output torque up to 0.88 mNm and up to 1.32 mNm in intermittent operation.

MICROSTEPPING DRIVER AND NEMA 17 HYBRID MOTOR

The PRO Series NEMA 17 integrated motor/drivers from Nippon Pulse America are intended for machine designs where an incorporated motor/driver helps conserve space. A 42 mm hybrid motor with attached drive electronics yields a compact, RoHS-compliant package.

These hybrid stepper motors are precision designed for medical technologies and semiconductor manufacturing applications. They offer accurate open loop control for high performance positioning applications. Two models, PRO 42AP 1/500 microstepping and PRO 42BP 1/8 microstepping are available.

The integrated driver solution can lower installed costs, provides high torque density and simplifies operation through attached drive electronics. This approach can also remove the need to run motor power management cabling through the machine and may reduce the potential for electrical noise.

These motors are available in case lengths of 40, 48 and 60 mm. Depending on the case length, the PRO Series Size 17 motor can produce maximum holding torques (bipolar) ranging from 300 to 440 mNm.

PIEZOELECTRIC SQUIGGLE MOTOR

Using the company's patented piezoelectric SQUIGGLE motor, a new actuator from New Scale Technologies drops into existing lock assemblies to reduce power and size requirements and to about half the size of existing choices. The SQLM Series Motor Lock Module draws less power than solenoids or stepper motors and allows lock manufacturers to reduce the size and power requirements of their electronic locks.

The actuator assembly contains the piezoelectric motor with optical limit switches in compact polymer housing. In a typical lock application, the tip of the motor screw is used to push a spring-loaded shear pin, which engages the latching mechanism. The motor provides 4 mm of stroke with high force and speed and holds its position with power off. A SQLM lock module includes the actuator and an MC-4012-3.4 driver card, powered by two AA batteries and controlled using TTL control signals.