QC/T 727-2017Instruments for automobiles and motorcycles (English PDF)

4.1 General provisions

4.1.2 Normal working environment conditions

Temperature. 18 °C ~ 28 °C; Relative humidity. 45% ~ 75%; Air pressure. 86 kPa ~ 106 kPa.

4.2 Units and divisions

4.2.1 The speed unit of the speedometer is generally expressed in kilometers per hour (km/h). The mileage unit is expressed in kilometers (km). The minimum division of speed shall be not more than 10 km/h. The division of speed shall comply with the requirements of GB 15082.

4.2.6 The unit of the thermometer is generally expressed in degrees Celsius (°C). In principle, it shall not be less than two divisions. lower limit value - intermediate value - upper limit value. It is also possible to use C to indicate the lower limit value of temperature, H to indicate the upper limit value of temperature.

4.2.7 The unit of the pressure gauge is generally expressed in megapascals (MPa). In principle, it is not less than two divisions. the lower limit value - the intermediate value - the upper limit value, wherein the intermediate pressure value is about one-half of the upper limit value of pressure.

4.2.8 The unit of clock is generally expressed in hours (h), minutes (min) and seconds (s).

4.3 Appearance

4.3.1 The protective layer shall be uniform, free from obvious bubbles, spots, rust, falling off, or other defects.

4.4 Indication status

When the signal changes smoothly, the pointer movement shall be smooth and there shall be no jamming.

4.5 Basic error

4.5.1 Under the environmental conditions as specified in 4.1.2, the basic error of the pressure gauge is.

4.6 Pointer's response time (pressure gauge, fuel gauge, thermometer, voltmeter, speedometer, tachometer)

4.6.1 When the pressure gauge is abruptly changed from the upper limit value to the lower limit value, the pointer of the pressure gauge must return to less than 10% of the upper limit value of pressure within 10 s (or 2 min for pressure gauge of the bimetal structure).

4.7 Damping of ammeter's pointer

When the ammeter's pointer moves to the upper limit of the scale, if cutting off the current, the pointer must stop swinging within 3 s.

4.8 Overload (pressure gauge, ammeter)

4.8.1 Mechanical pressure gauges shall be capable of withstanding an overload test of 1.2 times the upper limit pressure of the scale.

4.9 Torque of speedometer of magnetic-induction type

The torque for moving the mechanism of the speedometer of the magnetic-induction type shall not exceed 0.02 N·m.

4.10 Withstanding voltage of insulation

The electrical instrument shall be capable of withstanding a test at the voltage of 50 Hz and an actual sine wave of 550 V for 1 min. The insulation shall not be broken down.

4.13 Resistance to cyclic temperature and humidity change

The instrument shall be subjected to 10 cycles of temperature/humidity combination test at -10 °C ~ 65 °C in accordance with the provisions of GB/T 2423.34. Each cycle is 24 h, the changes in temperature and humidity in each cycle are as shown in Figure 1. The test is performed in a non-working state.

After the test, the instrument shall still comply with the provisions of 4.4 and 4.5.

4.14 Resistance to vibration

The instrument is subjected to a random vibration test in accordance with the requirements as specified in 4.1.2.8 of GB/T 28046.3. During the test and after the test, each part shall not be loose or damaged. During the test, it shall comply with the provisions of 4.4. After the test, it shall comply with the provisions of 4.4 and 4.5.

4.17 Over-voltage of power supply

Electronic and electrical instruments shall be able to withstand a certain value of the overvoltage test of power supply without damage. After the overvoltage test of power supply in accordance with the test parameters as given in Table 6, there shall be free of abnormal changes in all parts, and they shall comply with the provisions of 4.4 and 4.5.

5.1 Test conditions

5.1.1 The indicated value of the instrument shall be checked under the environmental conditions as specified in 4.1.2.

5.1.2 The installation position of the instrument on the test bench shall be the same as the actual installation position in the vehicle used.

5.1.3 The signal sources of the instrument are tested in matching with that of the analog sensor.

5.1.9 The accuracy of the standard thermometer shall not be less than ±1 °C.

5.1.10 The accuracy of the standard clock or clock meter shall not be less than ± 0.5 s/24 h.

5.2 Visual inspection

For visual inspection, it shall provide a uniform illumination of approximately 300 Lx, at the visual distance of 500 mm, use the visual inspection method to perform inspection.

5.3 Test of basic error and indication status

5.3.1 Test of basic error of pressure gauge.

During the test, in the order of decreasing first and then rising, read out the indicated value of the pressure gauge corresponding to the signal source when the nominal value is output at the intermediate pressure value and the upper limit pressure value of the scale.

5.3.4 Test of basic error of tachometer.

The test is performed in a comparison with the calibration console of tachometer, in the order of rising first and then descending. The test is carried out in comparison with the calibration console of tachometer or the standard tachometer, in the order of rising first and then descending, to assess three points about 20%, 60% and 90% of the upper limit.

5.3.8 Test of basic error of block.

The test is performed by the method of comparison with a standard clock for 72 h.

5.3.9 The clause 4.4 shall be checked in this test.

5.4 Test of pointer's response time

5.4.1 Make the pressure gauge stably indicate the upper limit of pressure of the scale, then abruptly change the signal source to the 0 position to output the nominal value. When the pointer points to 10% of the upper limit value of pressure, record the response time of the pointer.

5.5 Damping test of ammeter's pointer

Record the time elapsed when the ammeter's pointer returns from the division line of the upper limit of the scale after cut-off of power to motionless at 0 position. It shall take the average of the time which is measured in three tests.

5.6 Overload test

5.6.1 For the mechanical pressure gauge, it shall apply the pressure 1.2 times the upper limit of pressure on the scale for 1 min. After the test, the pressure gauge shall be placed at the environmental conditions as specified in 4.1.2 for not less than 4 h.

6.1 Qualification documents and markings

The instrument can be exit-factory after passing the inspection, meanwhile it shall be accompanied by the instrument quality certificate or marking.

6.2 Type of inspection

The inspection of the instrument is divided into exit-factory inspection, acceptance inspection and type inspection.

6.3 Exit-factory inspection

The exit-factory inspection items include the appearance, installation dimensions, markings, and basic errors and indication status of the instrument.

6.5 Type inspection

6.5.1 Several cases of type inspection.

In any of the following cases, the manufacturer shall carry out type inspection.

6.5.2 Sampling and grouping.

6.5.2.1 Quantity of samples.

The products for type inspection shall be taken from the same batch of products that have passed the exit-factory inspection, the quantity shall not be less than 12.

6.5.3 Qualification judgment

6.5.3.1 The determination of the inspection results of each indicator of the instrument shall be carried out in accordance with the requirements of this standard or the technical requirements of the instrument's product pattern.

6.5.3.2 The processing of test data shall comply with the provisions of GB/T 8170.

6.5.3.3 The type inspection of the instrument shall all meet the requirements. If there is a nonconformance, it may double the samples (that is, take another 6 samples) to carry out re-inspection for this disqualified item. If there is still nonconformance, this batch of products is judged as disqualified.

6.5.3.4 When the durability test fails, it is not allowed to double the sample for re-inspection, it shall be directly judged as disqualified.

7.1 Marking

7.1.1 Product marking

For each product, it should mark the following items at the obvious part.

7.1.2 Packaging mark

The basic contents of the packaging mark shall include.

7.2 Packaging

7.2.1 Product packaging shall consider the following.

7.2.2 Packaging box

7.2.2.1 The packing box shall be secure, the product shall not move in the box, to avoid damage during transportation.

7.2.2.2 The technical documentation accompanying the product in the packaging box shall include.

7.3 Storage and preservation

The storage and preservation of the product shall comply with the relevant provisions of QC/T 238. The shelf life of the product is usually 2 years (from the date of warehousing-in of the manufacturer). At the end of the shelf life of 2 years, the product shall still comply with the provisions of this standard.