| High-torque motor -> Monitor Keywords |
|
|
 
High-torque motorHigh-torque motor description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080203841, High-torque motor. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION
This is a divisional application of pending patent application Ser. No. 11/033,368 filed Jan. 10, 2005. BACKGROUNDThis application relates generally to motors. The teachings are considered particularly applicable in the field of robotics and active orthotics. Motors are used in a wide variety of applications. In many applications, including robotics and active orthotics, it may be useful to imitate characteristics similar to human muscles. Such characteristics include, for example, the ability to deliver high torque at a relatively low speed, and to allow free-movement when power is removed, thereby allowing a limb to swing freely during portions of the movement cycle. With a standard DC motor, torque varies directly in proportion to the motor current. This relationship is expressed as a torque constant, KT, which may be in N-m per amp. The same constant relates voltage to rotation speed. In SI units, KV=KT, which may be in Volts/rad/s. A DC motor is normally designed with a single torque constant. This means the motor operating at a fixed power input cannot dynamically trade off speed for torque. Accordingly, manufacturers typically sell families of motors with different motor constants depending on whether the application needs high torque (high KT) or high speed (low KV). This is a significant drawback for applications that require relatively fast, low torque operations as well as slower, high torque example, imitate the modes of operation of human muscles, which allow the same arm to swat a fly (fast, low torque) and to lift a heavy weight (slow, high torque). Standard electric motors typically operate at thousands of RPMs, and the range of typical motor constants does not extend down to the point where standard motors can deliver extremely high torque at low speed. In order to provide this capability, a reduction gear must be added to convert the motor's high speed and low torque into the desired low speed and high torque. Current reduction gearing techniques include spur gears, worm gears, pulleys and harmonic drive gears. All of these techniques decrease efficiency and have other undesirable characteristics including the addition of cost, weight, volume, and noise. Also, when an output shaft is driven through a high gear ratio, it is difficult to turn the output shaft when the motor is not powered. The absence of an unpowered free-movement mode is a significant disadvantage in some applications. Most motors are also inefficient when moving slowly while holding tension against an external load. In order for a slowly moving motor to hold its current position, significant current must be applied to the motor windings and this current results in large power dissipation even though no work is being performed on the output load. A mechanical reduction gear, such as a worm gear, can avoid this power loss when moving slowly, but this type of gearing also makes the free movement mode impossible. SUMMARYA technique for dynamically and efficiently delivering, alternatively, high torque or high speed involves providing multiple brakes along a flexible moving element called a flexor. In different embodiments, the flexor may include, for example, a long strip with load connected at one end to form a linear actuator, a belt coupled to an output gear coupled to the load, or a disk that is flexed around its periphery and coupled to an output shaft at its center. The brakes may be arranged in pairs along the length of a linear or belted motor or around the circumference of a rotary motor. Between each pair of brakes (“Brake 1” and “Brake 2”) is a driver which, in an embodiment, acts primarily at right angles to the flexor to cause the flexor to bend or otherwise deflect. The driver may include a linear actuator, a motor with cam, a motor with offset rollers, a piezoelectric bender, or other technology that delivers a force to bend the flexor. A first step of operation involves activating both Brake 1 and the driver. The activation of the driver then bends the flexor and causes the part of the flexor near Brake 2 to move a small distance toward Brake 1. A second step involves activating Brake 2, and a third step involves releasing Brake 1 and deactivating the driver. During the third step, the flexor may be restored to its unbent position. The cycle then repeats with the first step to impart a repetitive linear or rotary motion to the flexor. The amount of movement of load during each activation of the driver may be associated with the distance between the brakes and the amount of deflection of the flexor. When the deflection imparted by the driver is small compared to the distance between the brakes, the mechanical advantage is large, and a relatively weak driver force can move the free portion of the flexor a small distance against a strong load force resisting the movement. In this situation, the driver has a mechanical advantage against the load because the load is pulling at nearly right angles to the driving force. As the driver deflection distance increases, the driving force vector rotates and the component of the driving force vector opposing the load force increases, thereby decreasing the mechanical advantage. The mechanical advantage is approximately determined by the formula:
Mechanical_Advantage
=
1
Thank you for viewing the High-torque motor patent info. IP-related news and info Results in 0.07387 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
How KEYWORD MONITOR works... a FREE service from FreshPatents