servo gearhead

However, when the motor inertia is larger than the strain inertia, the motor will need more power than is otherwise necessary for the servo gearhead particular application. This improves costs because it requires paying more for a electric motor that’s larger 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 engine 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 shape. The higher an object’s inertia, the more torque is required to accelerate or decelerate the object. This implies that when the load inertia is much larger than the engine inertia, sometimes it can cause excessive overshoot or increase settling times. Both conditions can decrease production line throughput.

Inertia Matching: Today’s servo motors are producing more torque in accordance with 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 better match the inertia of the motor to the inertia of the strain allows for using a smaller motor and results in a more responsive system that’s easier to tune. Again, this is attained through the gearhead’s ratio, where the reflected inertia of the strain to the engine is decreased by 1/ratio^2.

As servo technology has evolved, with manufacturers making smaller, yet more powerful motors, gearheads are becoming increasingly essential partners in motion control. Finding the optimum pairing must take into account many engineering considerations.
So how does a gearhead start providing the power required by today’s more demanding applications? Well, that goes back again to the fundamentals of gears and their ability to modify the magnitude or path of an applied drive.
The gears and number of teeth on each gear create a ratio. If a 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 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 achieve the desired torque output is invaluable.
A motor could be rated at 2,000 rpm, but 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 running at a very low speed, such as 50 rpm, as well as your motor feedback resolution isn’t high enough, the update rate of the electronic drive could cause a velocity ripple in the application. For example, with a motor feedback resolution of 1 1,000 counts/rev you have a measurable count at every 0.357 degree of shaft rotation. If the electronic drive you are employing to regulate the motor has a velocity loop of 0.125 milliseconds, it will look for that measurable count at every 0.0375 amount of shaft rotation at 50 rpm (300 deg/sec). When it generally does not find that count it will speed up the engine rotation to find it. At the velocity that it finds another measurable count the rpm will end up being too fast for the application form and then the drive will slow the motor rpm back down to 50 rpm and then the complete process starts yet again. This constant increase and decrease in rpm is exactly what will trigger velocity ripple in an application.
A servo motor running at low rpm operates inefficiently. Eddy currents are loops of electrical current that are induced within the electric motor during operation. The eddy currents in fact produce a drag push within the engine and will have a greater negative effect on motor overall performance at lower rpms.
An off-the-shelf motor’s parameters may not be ideally suited to run at a low rpm. When an application runs the aforementioned motor at 50 rpm, essentially it is not using most of its offered rpm. Because the voltage continuous (V/Krpm) of the electric motor is set for a higher rpm, the torque continuous (Nm/amp), which is usually directly linked to it-is lower than it needs to be. As a result the application needs more current to operate a vehicle it than if the application had a motor specifically made for 50 rpm.
A gearheads ratio reduces the engine rpm, which explains why gearheads are occasionally called gear reducers. Utilizing a gearhead with a 40:1 ratio, the electric motor rpm at the input of the gearhead will be 2,000 rpm and the rpm at the result of the gearhead will become 50 rpm. Working the motor at the bigger rpm will enable you to prevent the issues mentioned in bullets 1 and 2. For bullet 3, it enables the look to use less torque and current from the electric motor based on the mechanical advantage of the gearhead.