QC/T 556-2023Temperature measurement methods and thermocouple installation requirements for automotive brakes (English PDF)

3.1 Contact thermometry

A temperature measurement method, in which the temperature detection element is in contact with the measured object and reaches thermal equilibrium.

Note: Commonly used contact thermometry includes thermocouple temperature measurement method, resistance temperature measurement method, etc.

3.2 Non-contact thermometry

A temperature measurement method, in which the temperature detection element does not come into contact with the object being measured.

Note: Commonly used non-contact thermometry includes radiation thermometry, spectral thermometry, etc.

3.3 Embedded thermocouple

A thermocouple, whose measuring end is embedded inside the object being measured.

4.1 Measuring device for contact thermometry

4.1.1 Contact temperature measurement devices shall meet the following requirements.

4.1.2 See Appendix A for the structural types of commonly used thermocouples.

4.3 Display and recording device

The device that displays and records the dynamic temperature of the brake shall meet the following requirements.

5.1 Embedded thermocouple

5.1.1 Installation on the brake lining assembly

5.1.1.3 Process a through hole, at the corresponding installation position (the hole diameter is determined according to the outer diameter of the thermocouple measuring end). Fix the thermocouple measuring end in the hole, without looseness. The distance between the measuring end and the friction surface is (1 ± 0.2) mm. See Figure 1 and Figure 2 for details.

5.1.2 Installation on the brake drum (disc)

5.1.2.1 For brake drums, the thermocouple's measuring end shall be installed at the center of the width direction of the friction surface of the brake drum and avoid structures such as heat dissipation ribs.

5.1.2.2 For brake discs, the installation position of the thermocouple's measuring end shall be located at the effective friction radius of the brake disc, meanwhile avoid ventilation ribs (ventilation coils), heat dissipation holes, surface grooves and other structures.

5.1.3 Installation when measuring brake fluid temperature

5.1.3.1 The measuring end of the thermocouple is installed on the bleed screw of the brake wheel cylinder.

5.1.3.2 Process a through hole along the axis of the bleed screw's drain hole (the hole diameter is determined according to the outer diameter of the thermocouple's measuring end; the size clearance fits).

5.2 Rubbing thermocouple

5.2.1 The installation position of the thermocouple's measuring end on the brake drum is shown in Figure 5.

5.2.2 The installation position of the thermocouple's measuring end on the brake disc is shown in Figure 6.

5.2.3 After the position of the thermocouple's measuring end is determined, tighten the mounting bracket. The position of the measuring end shall not be changed during the test. After installation, the following requirements shall be met.

7.1 Measurement preparation

7.1.3 Before measurement, calibrate the measuring device (including display and recording device) used.

7.1.2 Non-contact thermometry

7.1.2.1 According to the specific installation environmental conditions and test conditions during automobile brake testing, install the measuring device according to the requirements of Chapter 6.

7.1.2.2 Connect the temperature measuring instrument. Adjust the connecting wire according to the length of the connection distance.

7.2 Temperature measurement

7.2.1 Temperature measurement of brake lining assembly and brake drum (disc)

Turn on the recording instrument to record the temperature changes of the object being measured during the braking process. If necessary, record the temperature changes within a certain period of time, after the brake drum (disc) stops rotating.