On the other hand, when the engine inertia is larger than the strain inertia, the electric motor will require more power than is otherwise essential for this application. This boosts costs since it requires spending more for a motor that’s bigger than necessary, and because the increased power intake requires higher working costs. The solution is by using a gearhead to complement the inertia of the motor to the inertia of the strain.
Recall that inertia is a measure of an object’s resistance to change in its motion and is a function of the object’s mass and form. The higher an object’s inertia, the more torque is required to accelerate or decelerate the object. This means that when the load inertia is much larger than the motor inertia, sometimes it can cause excessive overshoot or boost settling times. Both circumstances can decrease production collection 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 higher inertial mismatches between servo motors and the loads they are trying to move. Using a gearhead to raised match the inertia of the electric motor to the inertia of the load allows for utilizing a smaller electric motor and results in a far more responsive system that is simpler to tune. Again, this is accomplished through the gearhead’s ratio, where the reflected inertia of the load to the motor is decreased by 1/ratio^2.
As servo technology has evolved, with manufacturers producing smaller, yet better motors, gearheads are becoming increasingly essential partners in motion control. Locating the optimum pairing must take into account many engineering considerations.
So how will a gearhead go about providing the power required by today’s more demanding applications? Well, that goes back again to the basics of gears and their ability to change the magnitude or direction of an applied push.
The gears and number of teeth on each gear create a ratio. If a electric motor can generate 20 in-lbs. of torque, and a 10:1 ratio gearhead is attached to its output, the precision gearbox resulting torque will be close to 200 in-lbs. With the ongoing focus on developing smaller sized footprints for motors and the equipment that they drive, the capability to pair a smaller electric motor with a gearhead to attain the desired torque output is invaluable.
A motor may be rated at 2,000 rpm, but your application may only require 50 rpm. Attempting to perform the motor at 50 rpm might not be optimal based on the following;
If you are running at a very low acceleration, such as 50 rpm, and your motor feedback resolution is not high enough, the update rate of the electronic drive may cause a velocity ripple in the application form. For example, with a motor feedback resolution of just one 1,000 counts/rev you possess a measurable count at every 0.357 degree of shaft rotation. If the digital drive you are using to regulate the motor has a velocity loop of 0.125 milliseconds, it’ll look for that measurable count at every 0.0375 degree of shaft rotation at 50 rpm (300 deg/sec). When it does not discover that count it will speed up the engine rotation to find it. At the acceleration that it finds another measurable count the rpm will become too fast for the application form and then the drive will sluggish the engine rpm back off to 50 rpm and the whole process starts all over again. This continuous increase and reduction in rpm is what will cause velocity ripple within an application.
A servo motor running 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 pressure within the engine and will have a greater negative impact on motor overall performance at lower rpms.
An off-the-shelf motor’s parameters might not be ideally suited to run at a low rpm. When a credit card applicatoin runs the aforementioned motor at 50 rpm, essentially it is not using all of its offered rpm. Because the voltage continuous (V/Krpm) of the electric motor is set for a higher rpm, the torque constant (Nm/amp), which can be directly related to it-is usually lower than it requires to be. Because of this the application needs more current to drive it than if the application had a motor specifically made for 50 rpm.
A gearheads ratio reduces the electric motor rpm, which is why gearheads are occasionally called gear reducers. Utilizing a gearhead with a 40:1 ratio, the engine rpm at the input of the gearhead will become 2,000 rpm and the rpm at the result of the gearhead will become 50 rpm. Operating the motor at the bigger rpm will enable you to prevent the worries mentioned in bullets 1 and 2. For bullet 3, it enables the look to use much less torque and current from the motor based on the mechanical advantage of the gearhead.