^ Optical line speed code wheel 500 | measuring grating and comprises a circular circuit board ^
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Cars competition control is essential for the vehicle speed, this is particularly true for particular beaconing group H car models. But for four motor car models on H how convenient speed becomes a big problem. In Tweets "
"Cars introduced providers increase HALL sensors on the motor coaxially to obtain the motor speed program, the program can not meet the requirements for accuracy rate. Today, H Cars provider over four transmission lines of the photoelectric encoder 500 samples test to see if meet competition requirements, said to each optical encoder assembly price of 50 yuan.
Celluloid grating
The core of the photoelectric encoder is a rigid transparent plastic (Polycarbonate: polycarbonate) grating 500 weekly printed black lines. A grating with a dedicated reading sensor can be obtained the angle of rotation of the code wheel.
The following figure shows the code wheel shown in the raster pattern loupe. Compared to conventional hollow metal grating disc code, this code wheel through a special process grating is a grating in the center of the radiation distribution on the surface of the transparent polycarbonate sheet characterization, more dense and uniform grating, lower cost.
^ Gratings higher magnification | left panel comprises a supporting board ^
The motor can be fixed to the rotor shaft, the encoder grating stuck on a hollow metal cylinder. In the two side drilled holes for fixing screws, bolts using pin may be locked in the metal cylinder motor output shaft.
Hex bolts may be provided with a metal cylinder shaft fixed to the rotor
The following measurements are supporting the circuit board. Wherein the grating comprises a sensor, it can detect the number of rotation of the grating lines. Orthogonal two pulse outputs, can indicate the direction of rotation of the grating.
Diameter on the circuit board comprises two motor leads welding hole. The circuit board may be directly welded and fixed at the back of the motor stator armature pin.
The circuit board has a six-pin socket, the socket spacing of 2mm. From left to right pin is defined as:
M+，+5V，GND，P1，P2，M-。
Measuring photoelectric encoder circuit board
Pin M +, the voltage applied to the motor drive M-. At + 5V, GND is applied to both ends of the encoder operating voltage. P +, P- output two square waves in quadrature pulse signal.
The encoder will be installed later in the motor housing, a fixing bolt inserted into the first required raster metal cylinder, in which case the bolt screwing operation more convenient. Need to leave a certain margin, not the bolt screwed into the fixing hole too much, otherwise affect the fixed grating.
Measuring grating and then inserted behind the circuit board while the motor rotor shaft. Aspect of the grating is fixed on the rotor shaft, on the one hand the circuit board solder pins inserted into holes of the two motors on the motor leads.
While the measuring grating and the circuit board is fixed to the motor shaft
Two motor leads using the soldering iron, so that we can measure the fixed circuit board.
Note that at this time to maintain the rear end of the circuit board held parallel state with one click.
Motor welding pin, fixing the sensor circuit board
Then use hex drive, fixed grating. When tightening the locking bolt, the need to adjust the vertical position of the grating, it is possible in grating sensor slots in the intermediate position. Grating rotation, not to touch the measuring circuit and the sensor.
Fixed modulation and grating height
If the raster touch during the installation process, there may be some stains on its surface, the grating affect the measurement. Of the grating surface clean with alcohol or other cleaning agents after installation.
Clean up the grating surface
After the installation of the machine will be able to re-install on the car models. However, before mounting the motor, the sensor function is preferably tested to detect speed grating is installed correctly, no other defects.
By definition of the measuring circuit board output pin. Of constant voltage of about 3V is applied to the motor. At this time, the motor rotor can be driven by rotation of the grating. Check that during the rotation of the grating does not touch other obstacles.
The fixed motor function test
Use of two oscilloscope test encoder output signal. They observed waveform parameters, + 5V amplitude similar whether applied. Rising and falling edges of the square wave whether steep. Two square wave pulse signal in phase whether approximately 90 °.
By changing the polarity of the motor driving voltage, observe whether the phase of the pulse signal has two transitions occur.
Motor rotation, two pulse signal oscilloscope display
Motor reverse rotation, two pulse signal oscilloscope display
The plastic grating, low price and high precision, is also more convenient cleaning. However, it does not heat. If long-term when the motor is in overload, or start and stop more frequent case, the motor loss is relatively large, the temperature may be high. Through the grating is transmitted to the rotor shaft, it is possible to deform it to melt.
A glass transition temperature of polycarbonate material is 147 degrees Celsius. Above this temperature, the material softens, and gradually becomes fluid. Under normal circumstances, needs to be below 80 degrees Celsius, the material to be able to resist external forces. It is necessary to keep the motor bearing temperature should not exceed 80 degrees Celsius.
Grating rapidly deform under heat gun
In order to be able to display raster plastic deformation at high temperature, using a hot air gun grating heated. Plastic grating rapid deformation, loss of function.
Hot air is being torn plastic grating ten seconds of silence.
Gratings deformation at elevated temperatures can not be recovered.
After deformation can not respond polycarbonate grating
In addition to the above high temperature is placed in use, the dust is also noted. Since the grating is very precise, so dust particles, dirt easily damage detection grating introduce noise in the output signal.
Thus, after the installation of the grating, but also a need to increase the motor behind the dust cover, the protective grating is not touched during use, or contaminated.
Zhuo teacher can do this set of energy-saving car models, right?
Cars energy group structure before making any decisions need
Answer: Yes, of course.
