However, when the electric motor inertia is larger than the load inertia, the motor will need 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 precision gearbox increased power usage requires higher operating costs. The solution is to use a gearhead to match the inertia of the motor to the inertia of the strain.
Recall that inertia is a measure of an object’s level of resistance to change in its movement and is a function of the object’s mass and form. The greater an object’s inertia, the more torque is needed to accelerate or decelerate the thing. This implies that when the strain inertia is much bigger than the electric motor inertia, sometimes it could cause extreme overshoot or boost settling times. Both circumstances can decrease production line throughput.
Inertia Matching: Today’s servo motors are generating more torque relative to frame size. That’s because of dense copper windings, light-weight materials, and high-energy magnets. This creates better inertial mismatches between servo motors and the loads they want to move. Using a gearhead to raised match the inertia of the electric motor to the inertia of the strain allows for using a smaller motor and outcomes in a more responsive system that’s simpler to tune. Again, this is attained through the gearhead’s ratio, where in fact the reflected inertia of the load to the electric motor is decreased by 1/ratio^2.
As servo technology has evolved, with manufacturers generating smaller, yet better motors, gearheads are becoming increasingly essential partners in motion control. Locating the optimal pairing must consider many engineering considerations.
So how will a gearhead go about providing the energy required by today’s more demanding applications? Well, that all goes back to the fundamentals of gears and their ability to modify the magnitude or direction of an applied power.
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 mounted on its output, the resulting torque can be near to 200 in-lbs. With the ongoing emphasis on developing smaller sized footprints for motors and the equipment that they drive, the capability to pair a smaller motor with a gearhead to achieve the desired torque output is invaluable.
A motor could be rated at 2,000 rpm, however your application may just require 50 rpm. Attempting to run the motor at 50 rpm may not be optimal based on the following;
If you are operating at an extremely low quickness, such as for example 50 rpm, as well as your motor feedback resolution is not high enough, the update price of the electronic drive may cause a velocity ripple in the application. For instance, with a motor opinions resolution of just one 1,000 counts/rev you possess a measurable count at every 0.357 amount of shaft rotation. If the electronic drive you are using to control the motor has a velocity loop of 0.125 milliseconds, it’ll search for that measurable count at every 0.0375 degree of shaft rotation at 50 rpm (300 deg/sec). When it generally does not find that count it will speed up the electric motor rotation to think it is. At the quickness that it finds the next measurable count the rpm will become too fast for the application form and then the drive will sluggish the electric motor rpm back down to 50 rpm and the whole process starts yet again. This constant increase and reduction in rpm is exactly what will trigger velocity ripple in an application.
A servo motor working at low rpm operates inefficiently. Eddy currents are loops of electrical current that are induced within the electric motor during operation. The eddy currents actually produce a drag force within the engine and will have a larger negative effect on motor performance at lower rpms.
An off-the-shelf motor’s parameters may not be ideally suited to run at a minimal rpm. When a credit card applicatoin runs the aforementioned motor at 50 rpm, essentially it is not using most of its available rpm. Because the voltage continuous (V/Krpm) of the engine is set for an increased rpm, the torque continuous (Nm/amp), which is certainly directly linked to it-is certainly lower than it requires to be. Because of this the application requirements more current to drive it than if the application form had a motor particularly designed for 50 rpm.
A gearheads ratio reduces the electric motor rpm, which explains why gearheads are occasionally called gear reducers. Using a gearhead with a 40:1 ratio, the electric motor rpm at the input of the gearhead will become 2,000 rpm and the rpm at the output of the gearhead will end up being 50 rpm. Operating the electric motor at the bigger rpm will allow you to avoid the problems 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 benefit of the gearhead.