TECHNOLOGY |
|
|
|
| |
| Carbon and holder selection guide |
The effect of carbon brush spring force And How to select the correct force
| The key function of Carbon brush spring are make carbon brush contact the commutator stably, contact impedance stably, make current stabilization scintilla noise smallest.
The affect of Carbon brush with wrong spring force
．Spring force too strong: carbon brush mechanical wear aggrandizes, carbon brush longevity is short.
．Spring force too weak:
1. Carbon brush electrical wear aggrandizes, carbon brush longevity is short.
2. Spark more bigger, temperature rise higher, result in motor breakdown
3. Noise is bigger, if the motor used in accurate electronic apparatus will result in apparatus mistake action or breakdown..
The factor to decide spring force as following:
． The continuously use time and amperage of Motor.
． The Motor maximum electric current and use time.
． Carbon brush size
． The surround condition of motor. ( like vibration, fixed tight enough,....)
Carbon brush material quality and the clearance with carbon brush holder
How to select correct spring force and make the force constantly is an important factor for accurate motor
．For the above reason, in recently manufacturers that keep ahead in Europe and America all use the constant
force spring to increase carbon brush life and quality..
．Usually, spring force must maintain within 10% tolerance, then the motor can be a good characteristic.
Constant force spring is ideal for use as electric motor brush springs that get follow advantage:
．Long life of carbon brush.
．Low noise.
．Low EMC.
．Small size.
|
| Several kinds of carbon brush holder with constant force spring Especially used in treadmill. |
|
Clearance between carbon and holder
：
(A)Limits and clearance on Brush Dimension.
The following table is approach to IEC & JIS standard.
|
Nominal dimension |
Brush limits |
Brush holder limit |
Clearance between
brush and brush holder |
Upper limit |
Lower limit |
Upper limit |
Lower limit |
Max. |
Min. |
1.6, 2 , 2.5 |
-0.03 |
-0.09 |
+0.05 |
+0.01 |
0.14 |
0.04 |
3.2 |
-0.03 |
-0.09 |
+0.07 |
+0.02 |
0.16 |
0.05 |
4,5 |
-0.11 |
-0.03 |
+0.07 |
+0.02 |
0.18 |
0.05 |
6.3 , 8 , 10 |
-0.11 |
-0.03 |
+0.09 |
+0.03 |
0.20 |
0.06 |
12.5,16 |
-0.13 |
-0.04 |
+0.10 |
+0.03 |
0.23 |
0.07 |
20, 25 |
-0.13 |
-0.04 |
+0.12 |
+0.04 |
0.25 |
0.08 |
32, 40, 50 |
-0.15 |
-0.05 |
+0.15 |
+0.05 |
0.30 |
0.10 |
|
Remark:
1. This table can be used for reference in the material with lower thermal expansion coefficient .
2. If you use the material (ex. Metal graphite,..) with higher thermal expansion coefficient.
Please ask
your supplier whether you have to enlarger the clearance .
(B) the checking key point for motor trouble shoot
1. Check in commutate status: with/without mechanical damage, grooving, bar burning, color of film,
…
etc. (see the tech. sheet lhts-c01)
2. Check in carbon brush status: with/without the brush face burning, discoloration or damage of flexible
…etc. (See the tech sheet lhts-b01)
3. Check the electric current density, and calculate the current density. (See tech. sheet lhcb-m01)
4. Check whether the carbon brush material is right. (See tech. sheet lhcb-m02)
5. Whether the vibration is too strong.
6. If you need more detail information about the motor troubleshooting and the other guide.
Please contact with our technical department . (e-mail:lh@carbon-lh.com) |
|
| |
|
