QC T 556-2023 English Version Foreign Language Version Translated Version Temperature measurement method and thermocouple installation requirements for automobile brakes.
QCT 556-2023 English version Foreign language version Translated version.
QC 556-2023 English version Foreign language version Translated version.
1 range. This document specifies the terms and definitions of temperature measurement of automobile brakes, measuring devices, thermocouple installations, and measurement methods for infrared thermometer installations.
This document is applicable to the temperature measurement during the test of automobile brakes,2 normative reference document.
The content of the following documents constitutes an essential provision of this document by means of normative references in the text. Of these, only the version corresponding to that date applies to this document: the latest version of the undated reference (including all change orders) applies to this document.
GB T5620 Road Vehicles, Automobiles and Trailer Brake Noun Terms and Definitions.
gb/t16839.1Thermocouples Part 1: Electromotive Force Specifications and Tolerances.
GB T30429 Industrial Thermocouple.
JB T 5582 Technical Specifications for Industrial Armoured Thermocouples.
3Terms and Definitions.
gb/t16839.1 and GB T5620 and the following terms and definitions apply to this document.
Contact thermometry
Temperature measurement method for temperature detection element to contact with the measured object and achieve thermal equilibrium Note: Commonly used contact temperature measurement methods include thermocouple temperature measurement method, resistance temperature measurement method, etc.
Non-contact thermometry
A temperature measurement method in which the temperature detection element does not come into contact with the object to be measured.
Note: Commonly used non-contact temperature measurement methods include radiation temperature measurement, spectral temperature measurement, etc.
Service flat. embedded thermocouple
A thermocouple embedded inside the object to be measured at the measuring end.
Rubber thermocouple
Thermocouple in which the measuring end is always in contact with the surface of the object to be measured, 4 measuring devices.
4.1. Measuring device for contact thermometry.
4.1.1. The contact temperature measuring device shall meet the following requirements: a) The electromotive force specification and tolerance of the thermocouple selected according to the temperature range and environmental conditions shall conform to GB T168391; b) The embedded thermocouple shall comply with the provisions of GB T30429, and the requirements of the veneer thermocouple can refer to JB T 55824.1.2. See Appendix A for the structural types of commonly used thermocouples.
4.2. The measuring device of the non-contact thermometer: The non-contact thermometer (infrared thermometer) shall meet the following requirements:
a) It can continuously record the temperature of the measured object
b) Prevent dust, smoke, etc. from contaminating the lens:
c) Able to withstand an ambient temperature of not less than 70°C.
4.3 Display and recording device.
The device for displaying and recording the dynamic temperature of the brake shall meet the following requirements:
a) With self-calibration (automatic compensation) function:
b) The indication error should be less than 3% of the measured value;
c) The dynamic response time should not be greater than 02s。
5 Thermocouple Installation.
5.1 Embedded thermocouples.
5.1.1 Installation on the brake lining assembly.
5.1.1.1. For the brake shoe assembly, the installation position of the thermocouple measuring end should be located near the maximum stress point of the brake lining of the shoe assembly, and when there are ribs, heat sinks, grooves or rivet holes, it should deviate by more than 5mm.
5.1.1.2 For pad assemblies, the mounting position of the thermocouple measuring end should be located in the center of the length and width of the brake lining. When the brake lining is grooved, it should be adjusted to the edge of the groove 7 along the center of the friction trajectory on the working face5mm or more; When it is necessary to measure the temperature of the brake lining in contact with the piston and cannot be arranged according to the above requirements, it should be adjusted to the edge of the diameter of the piston and the lining assembly along the center of the friction trajectory on the working face.
5.1.1.3. Process the 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, should not be loosened, and the distance from the measuring end to the friction surface (1+0.)2)mm。See Figures 1 and 2 for details.
5.1.2 Installation on the brake drum (disc).
5.1.2.1 For brake drums, the thermocouple measuring end should be installed in the center of the width 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 measuring end should be located at the effective friction radius of the brake disc, and avoid structures such as ventilation ribs (ventilated discs), heat dissipation holes, surface grooves, etc.
5.1.2.3. Process the 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, should not be loose, and the distance from the thermocouple measuring end to the friction surface is (04±0.1)mm。Among them, the solid disc with thin disc thickness can also be processed through hole in the center of the thickness direction (the aperture is determined according to the outer diameter of the thermocouple measuring end), and the thermocouple measuring end is fixed in the disc body, and the relative position is the effective friction radius of the brake disc. See Figure 3 for details.
5.1.3. Installation at the time of brake fluid temperature measurement.
5.1.3.1 The thermocouple measuring end is mounted on the bleed screw of the brake wheel cylinder.
5.1.3.2. Along the axis line of the vent screw drain hole, process the through hole (the hole diameter is determined according to the outer diameter of the thermocouple measuring end, and the size gap is matched), bury the thermocouple measuring end into the hole, and weld it with the gas release screw with silver soldering or solder welding, and the sealing cone should not be damaged, see Figure 4. During the test, the pressure drop within 30s should not be greater than 055MPa, the test pressure is 1 of the maximum working pressure of the brake wheel cylinder2 times.
5.2 Veneer thermocouples.
5.2.1 The installation position of the thermocouple measuring end on the brake drum is shown in Figure 5
5.2.2 The mounting position of the thermocouple measuring end on the brake disc is shown in Figure 6.
5.2.3. After the position of the measuring end of the thermocouple is determined, the mounting bracket should be tightened, and the position of the measuring end should not be changed during the test. After installation, the following requirements should be met:
a) During installation, the contact pressure between the measuring end of the thermocouple and the surface of the measured object should not exceed 1N;
Under normal temperature conditions, when simulating the idling condition of vehicle speed (50+3) kmh or rotation speed (660+10) r min, the temperature rise generated by the thermal b) galvanic couple itself within 1 min does not exceed 5.
6. Infrared thermometer installation.
The installation steps for the temperature measurement of the brake disc are as follows:
a) Ensure that the outer circumferential surface of the brake disc provides the same emissivity as the infrared measurement system, and spray a black non-reflective paint with a heat-resistant temperature exceeding the maximum temperature achieved in the test, depending on the situation.
According to the field of view of the infrared thermometer (the ratio of distance to photoelectric size), the distance and angle between the lens and the measured object are adjusted. b) Horizontal or overhead view with the axis of the brake disc being measured.
Adjust the measuring point according to the thickness of the brake disc, so that the light spot completely falls on the circumference of the outer diameter of the brake disc, and avoid the structure of ventilation ribs, dynamic balance c) calibration process gap, etc. Targets can be aimed with the help of optical aiming techniques such as rifled sights, lookers, lens sights, beam markers, etc. The position of the measuring end of the infrared thermometer is shown in Figure 7, and the position of the measuring end should not be changed during the test. In general, when using this method, it is recommended to confirm the difference between the infrared temperature measurement reading and the temperature measurement of the embedded thermocouple.
7 Measurement Methods.
7.1 Preparation for measurement.
7.1.1 Contact thermometry.
7.1.1.1. According to the specific installation environment conditions and test conditions during the automobile brake test, combined with the temperature control requirements and the degree of damage to the measured object, select the appropriate temperature measurement method and measuring device, and install the measuring device according to the requirements of Chapter 5. 7.1.1.2 Connect the temperature measuring instrument. Depending on the length of the connection distance, the thermocouple can be connected with an appropriate extension wire or compensation wire, and the reference end of the thermocouple can be placed in a freezing point, thermostat or a more stable room temperature as required.
7.1.1.3 If a man-type thermocouple is used on the brake drum (disc), it needs to be connected to a collector ring (slip ring) or telemetry system to transfer the signal from the rotating part to the stationary part.
7.1.1.4 When the compensation wire needs to be used, attention should be paid to the matching of the compensation wire and the thermocouple material. 7.1.2 Non-contact thermometry.
7.1.2.1. According to the specific installation environment conditions and test conditions during the automobile brake test, the measuring device shall be installed according to the requirements of Chapter 6.
7.1.2.2 Connect the temperature measuring instrument. Adjust the cable according to the length of the connection distance.
7.1.3. Before measuring, calibrate the measuring device (including display and recording device) used.
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 change of the measured object during braking, and if necessary, record the temperature change within a certain period of time after the brake drum (disc) stops rotating.
7.2.2 Temperature measurement of brake fluid.
Turn on the recording instrument, record the change in the temperature of the brake fluid during the test, and continue to record continuously after the test (brake action is released) until the temperature begins to drop significantly.
Appendix A Informational).
Commonly used thermocouples.
a.1 Embedded thermocouples.
The structure and size of the measuring end are shown in Figure a1. The length of the lead wire is customized according to the need.
a.2 Veneer thermocouples.
The structure of the measuring end of the needle thermocouple is shown in Figure A2。The structure of the measuring end of the sliding shoe type thermocouple is shown in Figure a3。The structure of the measuring end of the thin-slice thermocouple is shown in Figure a4。