However, when the electric motor inertia is bigger than the strain inertia, the engine will require more power than is otherwise necessary for this application. This improves costs since it requires paying more for a motor that’s bigger than necessary, and since the increased power usage requires higher working costs. The solution is to use a gearhead to complement the inertia of the electric motor to the inertia of the load.
Recall that inertia is a way of measuring an object’s level of resistance to improve in its movement and is a function of the object’s mass and shape. The higher an object’s inertia, the more torque is needed to accelerate or decelerate the thing. This implies that when the load inertia is much larger than the electric motor inertia, sometimes it could cause extreme overshoot or enhance settling times. Both conditions can decrease production line throughput.
Inertia Matching: Today’s servo motors are producing more torque relative to frame size. That’s because of dense copper windings, lightweight materials, and high-energy magnets. This creates greater inertial mismatches between servo motors and the loads they want to move. Utilizing a gearhead to raised match the inertia of the motor to the inertia of the load allows for using a smaller motor and results in a far more responsive system that’s easier to tune. Again, this is attained through the gearhead’s ratio, where in fact the reflected inertia of the load to the motor is decreased by 1/ratio^2.
As servo technology has evolved, with manufacturers making smaller, yet better motors, gearheads are becoming increasingly essential partners in motion control. Finding the ideal pairing must take into account many engineering considerations.
So how does a gearhead go about providing the power required by today’s more demanding applications? Well, that all goes back to the fundamentals of gears and their capability to change the magnitude or direction of an applied power.
The gears and number of teeth on each gear create a ratio. If a motor can generate 20 in-pounds. of torque, and a 10:1 ratio gearhead is attached to its result, the resulting torque will be near to 200 in-lbs. With the ongoing emphasis on developing smaller footprints for motors and the gear that they drive, the ability to pair a smaller engine with a gearhead to achieve the desired torque result is invaluable.
A motor could be rated at 2,000 rpm, however your application may just require 50 rpm. Trying to run the motor at 50 rpm might not be optimal predicated on the following;
If you are working at a very low speed, such as for example 50 rpm, as well as your motor feedback resolution is not high enough, the update price of the electronic drive could cause a velocity ripple in the application form. For instance, with a motor feedback resolution of 1 1,000 counts/rev you have a precision gearbox measurable count at every 0.357 degree of shaft rotation. If the electronic drive you are using to control the motor includes a velocity loop of 0.125 milliseconds, it will look for that measurable count at every 0.0375 degree of shaft rotation at 50 rpm (300 deg/sec). When it does not observe that count it will speed up the engine rotation to find it. At the swiftness that it finds another measurable count the rpm will become too fast for the application and the drive will sluggish the motor rpm back down to 50 rpm and the whole process starts all over again. This constant increase and decrease in rpm is exactly what will trigger velocity ripple in an application.
A servo motor operating at low rpm operates inefficiently. Eddy currents are loops of electric current that are induced within the engine during operation. The eddy currents actually produce a drag push within the engine and will have a greater negative impact on motor efficiency at lower rpms.
An off-the-shelf motor’s parameters may not be ideally suitable for run at a minimal rpm. When a credit card applicatoin runs the aforementioned electric motor at 50 rpm, essentially it isn’t using all of its obtainable rpm. Because the voltage continuous (V/Krpm) of the electric motor is set for a higher rpm, the torque continuous (Nm/amp), which is directly linked to it-is lower than it requires to be. Because of this the application needs more current to drive it than if the application had a motor particularly created for 50 rpm.
A gearheads ratio reduces the engine rpm, which explains why gearheads are occasionally called gear reducers. Using a gearhead with a 40:1 ratio, the motor rpm at the input of the gearhead will end up being 2,000 rpm and the rpm at the output of the gearhead will be 50 rpm. Working the engine at the bigger rpm will enable you to prevent the worries mentioned in bullets 1 and 2. For bullet 3, it allows the look to use much less torque and current from the engine predicated on the mechanical benefit of the gearhead.