Intelligent Motion Systems MDriveAC manual Chain Drive

Chain Drive

In a system with a chain drive, the following must be considered:

the weight and size of drive sprocket and any attaching hub

the weight and size of the driven sprocket and shaft

the weight of the chain

the weight of any material or parts being moved

Weight of

chain

Weight and size of drive

sprocket and hub

Weight and size of driven sprocket,

shaft and any material or parts being moved

Figure B.6: Chain Drive System Inertia Considerations

Once the system inertia (JL) has been calculated in oz-in-sec2, it can be matched to the motor inertia. To match the system inertia to the motor inertia, divide the system inertia by the square of the gearbox ratio. The result is called Reflected Inertia or (Jref).

Jref = JL ⎟ Ζ2

Where:

JL = System Inertia in oz-in-sec2

Jref = Reflected Inertia in oz-in-sec2

Z = Gearbox Ratio

The ideal situation would be to have a 1:1 system inertia to motor inertia ratio. This will yield the best positioning and accuracy. The reflected inertia (Jref) must not exceed 10 times the motor inertia.

Your system may require a reflected inertia ratio as close to 1:1 as possible. To achieve the 1:1 ratio, you must calculate an Optimal Gearbox Ratio (Zopt) which would be the square root of JL divided by the desired Jref. In this case since you want the system inertia to match the motor inertia with a 1:1 ratio, Jref would be equal to the motor inertia.

Zopt = JL ⎟ Jref

Where:

Zopt = Optimal Gearbox Ratio

JL = System Inertia in oz-in-sec2

Jref = Desired Reflected Inertia in oz-in-sec2(Motor Inertia)

Appendices A-13