SU1569733A1 - Apparatus for checking speedometers - Google Patents

Abstract

The invention relates to the field of measurement technology, namely to devices for calibrating measuring instruments for the path traveled and the speed of the vehicle. The aim of the invention is to improve the accuracy and speed of calibration of speedometers. The device consists of an electric motor, a photoelectric sensor, a pulse generator, a switch of operating modes, two digital blocks: calculating the distance traveled and calculating the speed and indicators. In this device, verification of the speedometer for the distance traveled and speed is performed simultaneously. There is also a control mode of the device. 3 il.

Description

The device relates to the field of measurement technology, namely, devices for calibration of measuring instruments for the path traveled and vehicle speed.

The aim of the invention is to improve the accuracy and speed of checking speedometers for speed and distance traveled.

Figure 1 presents the scheme of the device; Fig. 2 is a diagram of the speed detection unit; FIG. 3 is a diagram of the unit for determining the distance traveled.

The motor shaft 1, whose rotational speed is controlled by the control unit 2, has a photodiode converter 3 attached to it, the output of which is connected to the first inputs of the speed determining unit 4 and the distance traveled 5, the second inputs of which are connected to the Reset terminal, third

the inputs of blocks 4 and 5 are connected to the first output of the pulse generator 6, the second output of the latter is connected to the fourth input of the speed determining unit 4, and the third output to the first contact of the operating mode switch 7, the second contact of the switch 7 is connected to the + U power supply, and the third - with the cathode of the emitting diode of the photovoltaic converter 3, the fifth input of the unit for determining the speed is connected to the Start terminal.

The scheme of the speed determination unit 4 (Fig. 2) consists of control triggers 8-10, control logic circuits AND 11-13, OR 14-16, which are used to set the modes for measuring time intervals between two serif pulses and calculate the corresponding reference speed, counter 17, in which there is

about 50 1

CO SO

accumulation of the number of pulses corresponding to the time interval between two serif pulses, subtracting counters 18 and 19, and a binary decimal counter 20, which together form a divisor with a preset, a binary decimal counter 21, which records the result of the speed calculation, and an indicator 22, which indicates the result in decimal form.

The circuit for determining the distance traveled 5 contains an AND 23 circuit, a trigger 24, a binary-decimal counter 25, an indicator 26, a subtractive counter 27 with a preset, and an OR circuit 28 and multiplies the number of shaft revolutions by a factor Ks corresponding to the value of the distance traveled at one full turn speedometer shaft.

The principle of operation of the calibration scheme for the path traveled is as follows. Each class of speedometers has its own coefficient K, which exactly corresponds to the distance traveled at one turn of the speedometer shaft. If we accurately record the speed of the shaft of the speedometer, which is achieved by using a slotted disk fixed to the speedometer (motor) and a photodiode sensor that produces a servo pulse when the slot passes past the photocamera, then we can calculate the exact value of the distance S, corresponding to full speed shaft speedometer according to the formula

S pk

S

This value of the traversed path is exemplary and a comparison with the indication of a calibrated speedometer can be judged on its suitability.

The principle of operation of the speed calibration scheme is as follows. From the time of one complete revolution of the speedometer shaft, corresponding to the time between two adjacent serif pulses, it is possible to accurately determine the speed of movement with the coefficient of speed Kv 60-Kv known for a certain type of speedometer

Ofcp

 oSp

U (Gl - the speed that should

show the perfect speedometer;

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C - the time of one is full about the shaft rotation spi / home gra.

According to the testimony of the speed of the checked speedometer and the calculated exemplary speed value, it is possible to judge the suitability of the speedometer.

The speedometer calibration scheme for the path traveled works as follows. To start the engine, a rotatable speedometer is inserted into a special socket (with a nozzle on the engine shaft) and its indication is filled on the scale of the distance traveled. The initial setup signal of the WELL will nullify the block and enter the binary code of the path traveled, reduced by one least significant bit. After starting the engine 1, the servo pulses are output from the output of the photodiode converter 3 at each revolution of the motor shaft (speedometer), and the output of the unit is recorded by the amount of the path traveled.

The speedometer calibration scheme for speed (FIG. 2) works as follows. The initial setup signal NU through the circuits OR 14 and 15, the triggers 8-10 are reset to the state O, the binary decimal counters 21 and 20 are wrapped, the speedometer’s speed factor in the binary code is inserted into the subtracting counter 18, all the triggers of the accumulating counter 17 are set to single state. I

After the start signal

trigger 10 is cocked into a single state and from the single arm will give resolution to the AND I1 circuit, after which the first received serif pulse through the AND 11 circuit will pass to the counting input of trigger 8, which will be cocked, and the signal from the single arm will allow the passage of pulses with a frequency fc through the circuit AND 13 to the counter 17. The pulses to the counter 17 are passed until a second serif pulse arrives, i.e. until the speedometer shaft makes one full revolution, the second serif pulse will reset trigger 8, this closes the AND 13 circuit and the passage of filling pulses to counter 17 stops, by which time the number of pulses received by counter 17 is proportional to the time of full speedometer shaft rotation. After the return of the trigger 8 to the state O signal from a single arm

will trigger the trigger 9 into the unit state and with the falling edge of the same signal through the circuit OR 16 the code located in the meter 17 will be fixed in the meter 19. The signal from the zero arm of the trigger 9 closes the circuit 11 and blocks the subsequent passage of the serif to the the trigger counting input 8. The signals from the single arms of the three heres 9 and 10, which are in the cocked state, will open the circuit 12 for passing the filling high frequency pulses fe to the subtractive inputs of the counters 19 and 20. The pulses at the input of the counter 19 will begin to decrease its contents are up to e the overflow, the pulse of which writes the unit to counter 21 and again through the scheme OR 16 rewrites the contents of counter 17 to counters 19, this continues until the pulses passed through counter 20 do not overflow the counter 18. Pulse from the overflow output of counter 18 through the OR 15 circuit will again restore the K Y values in binary code in counter 18, reset trigger 10, and circuits AND 11 and 12 will close, after which the status of circuit elements will remain unchanged, and the value of counter 21 will be displayed on the indicator. By coincidence of the readings of the indicator and the calibrated speedometer, it is possible to judge the suitability of the speedometer.

If you wish to repeat the speedometer's calibration in terms of speed, you need to send a triggering pulse to the Start terminal, after which the verification process is repeated. The speedometer's calibration scheme for speed can work in the mode of non-periodic calibration, if a periodic pulse signal is sent to the Start terminal, but the signal period should not be less than the time of one calibration cycle.

The counter size 17 and the frequency are selected from the overflow condition of the counter 17 at the smallest number of shaft revolutions fc / m: 2h-I,

where fc is the frequency of the filling pulses; ha - the number of revolutions of the shaft

five

0

five

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five

The result is the more accurate the higher the bit. The bitness of the counters 21 and 20 is determined from the conditions for checking the maximum speed and the need for a certain number of decimal places. The latter is determined by the counter size 20. For a correct calculation of the reference speed using the estimated time of one revolution G, using the number of pulses at one revolution of the shaft, the coefficient that is entered into the counter 18 is calculated by the formula

Ku Kv-60-fc ...

When the filling frequency is constant, fc, and for a certain class of speedometers, the coefficient K v is constant.

In the verification mode of the device using the switch 7, the third output of the generator 6 is connected to the emitter of the photodiode converter 3. In this mode, the motor 1 does not rotate and the disk is set so that the portion of the emitter-photodetector is transparent. The output of the photoconverter simulates serif pulses with a frequency corresponding to the actual number of revolutions of the speedometer shaft, and the speedometer readings should be in the range of 20-120 km / h.

Claims (1)

Invention Formula A device for calibrating speedometers containing a motor, an engine control unit, a photodiode transducer mounted on an engine shaft, an amplifier shaper, characterized in that, in order to improve the accuracy and speed of calibration of speedometers and the distance traveled, a pulse generator, an operation mode switch, a distance calculation module with the first indicator, the first, second and third scheme I, the first, are entered into it, the second and third OR scheme, summing counter, the first and second subtractive counter with preset, the first and second binary-decimal counter, the second indicator, the first, second and speedometer on the smallest third triggers, while the output is the speed of the receiver; n is the counter size 17. The width of the counter 18 selects, from the accuracy condition of the result, the formatter reamer is connected to the first input of the path calculation unit with the first input of the third circuit And, the first output of the formformer generator is connected to the first path the input of the path calculation unit with the first input of the third circuit I, the first output of the pulse generator. FIG. I