Brake-by-wire brake disc temperature acquisition system and method

Abstract

The invention relates to a brake-by-wire brake disc temperature acquisition system and method. The system comprises a thermocouple, a differential amplification module, a cold junction compensation module and a buffer circuit module. The cold junction compensation module is a standard amplifier, and the gain multiple of the standard amplifier is the ratio of the unit scale value of the thermocouple to the drift value of the thermocouple; a common K-type thermocouple can generate drift of 40.6 [mu] V / C, and a standard reading scale is 10mV / C. Therefore, the cold junction compensation module with the standard gain multiple of 10mV / 40.6 mu V is arranged, so that the drift of 40.6 mu V / C generated by the cold junction compensation module is converted into standard 10mV / C; when the output of the cold junction compensation module is the temperature difference between the environment temperature and the standard 0 DEG C, namely the cold end temperature of the thermocouple, a 10mV / C calibration voltage is provided; the temperature of the thermocouple can be collected and compensated, so that the temperature calculation error of the brake disc is reduced, and the real-time detection performance is improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle brake-by-wire technology, specifically to a brake disc temperature acquisition system and method for brake-by-wire. Background Technology

[0002] Electromechanical (EMB) braking can cause brake disc temperatures to become excessively high during frequent braking, especially in scenarios involving long downhill slopes and frequent, prolonged braking. This can easily lead to brake disc material fatigue, resulting in a significant decrease in braking performance and even brake system failure. Therefore, brake disc temperature acquisition and calculation are crucial for braking systems. Traditional braking systems estimate brake disc temperature using physical models, which suffers from large errors and poor real-time performance. This can negatively impact braking control under certain operating conditions. Summary of the Invention

[0003] To address the technical problems of large errors and poor real-time performance in existing technologies that use physical models to estimate brake disc temperature, this invention provides a brake disc temperature acquisition system and method for brake-by-wire systems.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A brake disc temperature acquisition system for brake-by-wire includes a thermocouple, a differential amplifier module, a cold junction compensation module, and a buffer circuit module; the cold junction compensation module is a standard amplifier, and the gain of the standard amplifier is the ratio of the unit scale value of the thermocouple to the drift value of the thermocouple. The positive output terminal of the thermocouple is connected to the non-inverting input terminal of the differential amplifier module, and the negative output terminal of the thermocouple is connected to the inverting input terminal of the differential amplifier module. Both the non-inverting and inverting input terminals of the differential amplifier module are connected to a bias voltage. The power supply terminal of the cold junction compensation module is connected to the power supply voltage. The input terminal of the cold junction compensation module is connected to the negative terminal of the thermocouple output. The output terminal of the cold junction compensation module is connected to the non-inverting input terminal of the buffer circuit module. The output terminal of the buffer circuit module is connected to the inverting input terminal of the buffer circuit module, the reference voltage input terminal of the differential amplifier module, and the output terminal of the differential amplifier module, respectively. The output terminal of the differential amplifier module outputs the brake disc temperature signal.

[0005] The beneficial effects of this invention are as follows: Commonly used K-type thermocouples exhibit a drift of 40.6 μV / ºC, while the standard reading scale is 10 mV / ºC. Therefore, by setting a cold junction compensation module with a standard gain of 10 mV / 40.6 μV, the 40.6 μV / ºC drift generated by the cold junction compensation module is converted into the standard 10 mV / ºC. When the cold junction compensation module outputs the temperature difference between the ambient temperature and the standard 0°C, i.e., the cold junction temperature of the thermocouple, a calibration voltage of 10 mV / ºC is provided. This achieves temperature acquisition compensation for the thermocouple, reducing the temperature calculation error of the brake disc and improving real-time detection performance.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, it also includes a bias voltage module, the input terminal of which is connected to the power supply voltage, and the output terminal of which is connected to the non-inverting input terminal and the inverting input terminal of the differential amplifier module, respectively; the output terminal of the bias voltage module outputs the bias voltage.

[0008] Furthermore, the bias voltage module includes a first resistor, a second resistor, a third resistor, and a fourth resistor; one end of the second resistor is connected to the power supply voltage, the other end of the second resistor is connected to one end of the first resistor, the other end of the first resistor is grounded, one end of the third resistor is connected to one end of the first resistor, and the other end of the third resistor is connected to the non-inverting input terminal of the differential amplifier module; one end of the fourth resistor is connected to one end of the first resistor, and the other end of the fourth resistor is connected to the inverting input terminal of the differential amplifier module; the resistance value of the third resistor is equal to the resistance value of the fourth resistor.

[0009] Furthermore, it also includes an input filtering module, which includes a non-inverting input filtering unit and an inverting input filtering unit. One end of the non-inverting input filtering unit is connected to the non-inverting input terminal of the differential amplifier module, and one end of the inverting input filtering unit is connected to the inverting input terminal of the differential amplifier module. The other ends of the non-inverting input filtering unit and the other end of the inverting input filtering unit are both grounded.

[0010] Furthermore, the differential amplifier module includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and a differential operational amplifier, wherein the differential operational amplifier is an LTC2053 thermocouple amplifier; The non-inverting input of the differential operational amplifier is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the positive output terminal of the thermocouple; the inverting input of the differential operational amplifier is connected to one end of the seventh resistor, and the other end of the seventh resistor is connected to the negative output terminal of the thermocouple. The output terminal of the differential operational amplifier is connected to one end of the sixth resistor and one end of the eighth resistor, respectively. The other end of the eighth resistor is connected to one end of the ninth resistor and the gain setting terminal of the differential operational amplifier, respectively. The other end of the ninth resistor is connected to one end of the tenth resistor, respectively. The output terminal of the buffer circuit module is connected to the reference voltage input terminal of the differential operational amplifier and the other end of the tenth resistor, respectively. The other end of the sixth resistor outputs the brake disc temperature signal.

[0011] Furthermore, the differential amplifier module also includes a differential output filter unit, one end of which is connected to the output terminal of the differential operational amplifier, and the other end of which is grounded.

[0012] Furthermore, the cold junction compensation module is an LTC1025 thermocouple cold junction compensation integrated circuit.

[0013] Furthermore, a cold junction compensation power supply filter unit is connected to the cold junction compensation module; one end of the cold junction compensation power supply filter unit is connected to the power supply terminal of the cold junction compensation module, and the other end of the cold junction compensation power supply filter unit is grounded.

[0014] Furthermore, the buffer circuit module includes a buffer and an eleventh resistor. The non-inverting input terminal of the buffer is connected to the output terminal of the cold junction compensation module, and the output terminal of the buffer is connected to the inverting input terminal of the buffer, the reference voltage input terminal of the differential amplifier module, and the output terminal of the differential amplifier module, respectively.

[0015] To address the aforementioned technical problems, this invention also provides a method for acquiring the temperature of a brake disc controlled by wire. The specific technical details are as follows: A method for acquiring the temperature of a brake disc controlled by wire, comprising the following steps: Thermocouples are used to collect the brake disc temperature to output an initial signal; The initial signal is differentially amplified using a differential amplifier module to output the brake disc temperature signal. Attached Figure Description

[0016] Figure 1 This is a circuit diagram of a brake disc temperature acquisition system according to an embodiment of the present invention; Figure 2 This is a structural block diagram of the brake-by-wire system in an embodiment of the present invention; Figure 3 This is a schematic diagram of the brake-by-wire system in an embodiment of the present invention.

[0017] The attached diagram lists the components represented by each number as follows: 1. Thermocouple; 2. Bias voltage module; 3. Differential amplifier module; 4. Input filter module; 5. Cold junction compensation module; 6. Buffer circuit module; 7. Non-inverting input filter unit; 8. Inverting input filter unit; 9. Differential output filter unit; 10. First friction plate; 11. Brake disc; 12. Second friction plate; 13. Temperature acquisition point; 14. Caliper bracket; 15. Connector; 16. Sensor signal line; 17. Wiring harness; 18. Signal processing device; 19. EMB processor; 20. EMB controller. Detailed Implementation

[0018] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0019] like Figure 1 As shown, this embodiment provides a brake disc temperature acquisition system for brake-by-wire control, including a thermocouple 1, a differential amplifier module 3, a cold junction compensation module 5, and a buffer circuit module 6; the cold junction compensation module 5 is a standard amplifier, and the gain of the standard amplifier is the ratio of the unit scale value of the thermocouple 1 to the drift value of the thermocouple 1; the cold junction compensation module 5 is an LTC1025 thermocouple cold junction compensation integrated circuit.

[0020] The positive terminal of the output of thermocouple 1 is connected to the non-inverting input terminal of the differential amplifier module 3, and the negative terminal of the output of thermocouple 1 is connected to the inverting input terminal of the differential amplifier module 3. Both the non-inverting input terminal and the inverting input terminal of the differential amplifier module 3 are connected to a bias voltage. The power supply terminal of the cold junction compensation module 5 is connected to the power supply voltage. The input terminal of the cold junction compensation module 5 is connected to the negative terminal of the output terminal of the thermocouple 1. The output terminal of the cold junction compensation module 5 is connected to the non-inverting input terminal of the buffer circuit module 6. The output terminal of the buffer circuit module 6 is connected to the inverting input terminal of the buffer circuit module 6, the reference voltage input terminal of the differential amplifier module 3, and the output terminal of the differential amplifier module 3. The output terminal of the differential amplifier module 3 outputs the brake disc temperature signal.

[0021] Commonly used K-type thermocouples exhibit a drift of 40.6 μV / ºC, while the standard reading scale is 10 mV / ºC. Therefore, a cold junction compensation module 5 with a standard gain of 10 mV / 40.6 μV (246) is used to convert the 40.6 μV / ºC drift into the standard 10 mV / ºC. The output of the cold junction compensation module 5 is the temperature difference between the ambient temperature and the standard 0°C, i.e., the cold junction temperature of the thermocouple, thus providing a calibration voltage of 10 mV / ºC. This achieves temperature acquisition compensation for the thermocouple, reducing temperature calculation errors in the brake disc and improving real-time detection performance.

[0022] In some embodiments, the bias voltage is provided by the bias voltage module 2, the input terminal of the bias voltage module 2 is connected to the power supply voltage, and the output terminal of the bias voltage module 2 is connected to the non-inverting input terminal and the inverting input terminal of the differential amplifier module 3 respectively; the output terminal of the bias voltage module 2 outputs the bias voltage.

[0023] The bias voltage module 2 includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. One end of the second resistor R1 is connected to the power supply voltage, and the other end of the second resistor R1 is connected to one end of the first resistor R1, with the other end of the first resistor R1 grounded. One end of the third resistor R3 is connected to one end of the first resistor R1, and the other end of the third resistor R3 is connected to the non-inverting input terminal of the differential amplifier module 3. One end of the fourth resistor R4 is connected to one end of the first resistor R1, and the other end of the fourth resistor R4 is connected to the inverting input terminal of the differential amplifier module 3. The resistance value of the third resistor R3 is equal to the resistance value of the fourth resistor R4. The first resistor R1 and the second resistor R2 are voltage divider resistors that provide a bias voltage of VCC / 2 to the system. The third resistor R3 and the fourth resistor R4 are pull-up resistors that provide high impedance bias for the thermocouple signal, maximizing the anti-interference capability of the working mode.

[0024] In some embodiments, the bias voltage module 2 further includes an input filtering module 4, which includes a non-inverting input filtering unit 7 and an inverting input filtering unit 8. One end of the non-inverting input filtering unit 7 is connected to the non-inverting input terminal of the differential amplifier module 3, and one end of the inverting input filtering unit 8 is connected to the inverting input terminal of the differential amplifier module 3. The other ends of both the non-inverting input filtering unit 7 and the inverting input filtering unit 8 are grounded. The non-inverting input filtering unit 7 uses a third capacitor C3, and the inverting input filtering unit 8 uses a fourth capacitor C4; C3 and C4 are common-mode filtering capacitors for thermocouple signals, used to eliminate common-mode interference.

[0025] In some embodiments, the differential amplifier module 3 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, and a differential operational amplifier U1, wherein the differential operational amplifier U1 is an LTC2053 thermocouple amplifier; The non-inverting input of the differential operational amplifier U1 is connected to one end of the fifth resistor R5, and the other end of the fifth resistor R5 is connected to the positive output terminal of the thermocouple 1; the inverting input of the differential operational amplifier U1 is connected to one end of the seventh resistor R7, and the other end of the seventh resistor R7 is connected to the negative output terminal of the thermocouple 1. The output terminal of the differential operational amplifier U1 is connected to one end of the sixth resistor R6 and one end of the eighth resistor R8, respectively. The other end of the eighth resistor R8 is connected to one end of the ninth resistor R9 and the gain setting terminal of the differential operational amplifier U1, respectively. The other end of the ninth resistor R9 is connected to one end of the tenth resistor R10, and the output terminal of the buffer circuit module 6 is connected to the reference voltage input terminal of the differential operational amplifier U1 and the other end of the tenth resistor R10, respectively. The other end of the sixth resistor R6 outputs the brake disc temperature signal.

[0026] The differential amplifier module 3 further includes a differential output filter unit 9. One end of the differential output filter unit 9 is connected to the output terminal of the differential operational amplifier U1, and the other end of the differential output filter unit 9 is grounded. The output filter unit 9 uses a second capacitor C2.

[0027] The eighth resistor R8 and the tenth resistor R10 form the proportional amplifier feedback circuit of the operational amplifier, with an amplification factor of 1 + R8 / R10; the fifth resistor R5 and the seventh resistor R7 are the input resistors of the differential operational amplifier. The sixth resistor R6 is the output resistor of the differential operational amplifier.

[0028] Commonly used type K thermocouples exhibit a drift of 40.6 μV / ºC, while the standard reading scale is 10 mV / ºC. Therefore, a standard amplifier with a standard gain of 10 mV / 40.6 μV is required. The U3 module circuit converts the 40.6 μV / ºC drift of the type K thermocouple into the standard 10 mV / ºC. That is, the VO output of the standard gain circuit chip U3 is the temperature difference between the ambient temperature where the standard gain circuit chip U3 is located and the standard 0°C, i.e., the cold junction temperature of the thermocouple, providing a calibration voltage V0 of 10 mV / ºC. Therefore, the relationship between the cold junction temperature T0 at the standard gain circuit chip U3 and the voltage VO is: .

[0029] Based on the Seebeck effect, an electromotive force V1 is generated according to the potential difference between V+ and V- at the temperature of the acquisition point. The differential operational amplifier acquires and amplifies the voltage of V1 to obtain V2. Therefore, the output voltage of the entire temperature acquisition system can be obtained as V = V0 + V2. From the output voltage of the temperature acquisition system, we can know the relationship between the temperature and voltage at the acquisition point.

[0030] Since U2 is a buffer, we can obtain VREF = VO; based on the relationship of the differential operational amplifier U1, we can obtain: ; From the above formula, we can derive the electromotive force output by the thermocouple. ; In this invention, the design value of the eighth resistor R8 is 99K, and the design value of the tenth resistor R10 is 1K; thus, ; Assume the EMB system's processor acquires an output voltage V of 750mV and a VREF voltage of 250mV. Then the electromotive force output by the thermocouple is (750mV – 250mV) / 100 = 5mV. Referring to Table 1, the calibration table for nickel-chromium / nickel-silicon thermocouples (Type K), 5mV falls between 4.919 and 5.327, indicating the temperature at the acquisition point is approximately between 120℃ and 130℃. Since the temperature gradient in the calibration table is 10 degrees Celsius, to accurately calculate the acquisition point temperature, the middle of the gradient can be considered a linear region, and a linear function y = (y2 - y1) / (x2 - x1)*(x - x1) + y1 can be inserted.

[0031] We know that y2 is 130℃, y1 is 120℃, x2 is 5.327mV, x1 is 4.919mV, and x is the currently acquired and calculated voltage value of 5mV. Therefore, we can calculate that y is 121.985℃. Since the 750mV voltage output acquired by the temperature acquisition system corresponds to 121.985 degrees Celsius, we can conclude that this is accurate. Table 1. Calibration Table for Nickel-Chromium / Nickel-Silicon Thermocouples (Type K) Through the above process, the EMB braking system can combine the temperature at the acquisition point with the diffusion temperature of the brake disc, and provide a basis for the control of the braking system, providing a safety basis for braking under special working conditions.

[0032] The cold junction compensation module 5 includes a standard gain circuit chip U3, on which a cold junction compensation power supply filter unit is connected. One end of the cold junction compensation power supply filter unit is connected to the power supply terminal of the cold junction compensation module 5, and the other end is grounded. The cold junction compensation power supply filter unit uses a fifth capacitor C5.

[0033] The buffer circuit module 6 includes a buffer U2 and an eleventh resistor R11. The non-inverting input of the buffer U2 is connected to the output of the cold junction compensation module 5. The output of the buffer U2 is connected to the inverting input of the buffer U2, the reference voltage input of the differential amplifier module 3, and the output of the differential amplifier module 3. The buffer U2 is a zero-drift operational amplifier of model LTC2050. The first capacitor C1, the fifth capacitor C5, and the second capacitor C2 are bypass filter capacitors to reduce power supply interference between chips.

[0034] like Figure 2 and Figure 3As shown, in the EMB system wheel-side actuator, the brake disc 11 is located between the first friction plate 10 and the second friction plate 12, and the temperature acquisition point 13 is located on the brake disc 11 to collect the temperature at the temperature acquisition point 13 on the brake disc 11 using a thermocouple; the first friction plate 10 and the second friction plate 12 are mounted on the caliper bracket 14; the two ends of the wiring harness 17 are connected to the EMB system wheel-side actuator and the EMB controller 20 respectively via connectors 15; the sensor signal line 16 is located inside the wiring harness 17, and the thermocouple 1 is connected to the signal processing device 18 via the sensor signal line 16. The signal processing device 18 is connected to the EMB processor 19 in the EMB controller 20; the signal processing device 18 includes the aforementioned bias voltage module 2, differential amplifier module 3, input filter module 4, cold junction compensation module 5, and buffer circuit module 6.

[0035] In other embodiments, a method for acquiring the temperature of a brake disc controlled by wire is also provided, including the following steps: Thermocouple 1 is used to collect the brake disc temperature to output an initial signal; The initial signal is differentially amplified using differential amplifier module 3 to output the brake disc temperature signal.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A brake disc temperature acquisition system for brake-by-wire, characterized in that, It includes a thermocouple (1), a differential amplifier module (3), a cold junction compensation module (5), and a buffer circuit module (6); the cold junction compensation module (5) is a standard amplifier, and the gain of the standard amplifier is the ratio of the unit scale value of the thermocouple (1) to the drift value of the thermocouple (1); The positive output terminal of the thermocouple (1) is connected to the non-inverting input terminal of the differential amplifier module (3), and the negative output terminal of the thermocouple (1) is connected to the inverting input terminal of the differential amplifier module (3). Both the non-inverting input terminal and the inverting input terminal of the differential amplifier module (3) are connected to a bias voltage. The power supply terminal of the cold junction compensation module (5) is connected to the power supply voltage. The input terminal of the cold junction compensation module (5) is connected to the negative terminal of the output terminal of the thermocouple (1). The output terminal of the cold junction compensation module (5) is connected to the non-inverting input terminal of the buffer circuit module (6). The output terminal of the buffer circuit module (6) is connected to the inverting input terminal of the buffer circuit module (6), the reference voltage input terminal of the differential amplifier module (3), and the output terminal of the differential amplifier module (3). The output terminal of the differential amplifier module (3) outputs the brake disc temperature signal.

2. The brake disc temperature acquisition system according to claim 1, characterized in that, It also includes a bias voltage module (2), the input terminal of which is connected to the power supply voltage, and the output terminal of the bias voltage module (2) is connected to the non-inverting input terminal and the inverting input terminal of the differential amplifier module (3) respectively; the output terminal of the bias voltage module (2) outputs the bias voltage.

3. The brake disc temperature acquisition system according to claim 2, characterized in that, The bias voltage module (2) includes a first resistor (R1), a second resistor (R1), a third resistor (R3), and a fourth resistor (R4); one end of the second resistor (R1) is connected to the power supply voltage, the other end of the second resistor (R1) is connected to one end of the first resistor (R1), the other end of the first resistor (R1) is grounded, one end of the third resistor (R3) is connected to one end of the first resistor (R1), and the other end of the third resistor (R3) is connected to the non-inverting input terminal of the differential amplifier module (3); one end of the fourth resistor (R4) is connected to one end of the first resistor (R1), and the other end of the fourth resistor (R4) is connected to the inverting input terminal of the differential amplifier module (3); the resistance value of the third resistor (R3) is equal to the resistance value of the fourth resistor (R4).

4. The brake disc temperature acquisition system for brake-by-wire as described in claim 1, characterized in that, It also includes an input filtering module (4), which includes an in-phase input filtering unit (7) and an in-phase input filtering unit (8). One end of the in-phase input filtering unit (7) is connected to the in-phase input terminal of the differential amplifier module (3), and one end of the in-phase input filtering unit (8) is connected to the in-phase input terminal of the differential amplifier module (3). The other ends of the in-phase input filtering unit (7) and the other ends of the in-phase input filtering unit (8) are both grounded.

5. The brake disc temperature acquisition system according to claim 1, characterized in that, The differential amplifier module (3) includes a fifth resistor (R5), a sixth resistor (R6), a seventh resistor (R7), an eighth resistor (R8), a ninth resistor (R9), a tenth resistor (R10), and a differential operational amplifier (U1), wherein the differential operational amplifier (U1) is an LTC2053 thermocouple amplifier; The non-inverting input of the differential operational amplifier (U1) is connected to one end of the fifth resistor (R5), and the other end of the fifth resistor (R5) is connected to the positive output terminal of the thermocouple (1); the inverting input of the differential operational amplifier (U1) is connected to one end of the seventh resistor (R7), and the other end of the seventh resistor (R7) is connected to the negative output terminal of the thermocouple (1). The output terminal of the differential operational amplifier (U1) is connected to one end of the sixth resistor (R6) and one end of the eighth resistor (R8). The other end of the eighth resistor (R8) is connected to one end of the ninth resistor (R9) and the gain setting terminal of the differential operational amplifier (U1). The other end of the ninth resistor (R9) is connected to one end of the tenth resistor (R10). The output terminal of the buffer circuit module (6) is connected to the reference voltage input terminal of the differential operational amplifier (U1) and the other end of the tenth resistor (R10). The other end of the sixth resistor (R6) outputs the brake disc temperature signal.

6. The brake disc temperature acquisition system according to claim 5, characterized in that, The differential amplifier module (3) further includes a differential output filter unit (9), one end of which is connected to the output terminal of the differential operational amplifier (U1), and the other end of which is grounded.

7. The brake disc temperature acquisition system for brake-by-wire as described in claim 1, characterized in that, The cold junction compensation module (5) is an LTC1025 thermocouple cold junction compensation integrated circuit.

8. The brake disc temperature acquisition system according to claim 7, characterized in that, The cold junction compensation module (5) is connected to a cold junction compensation power supply filter unit; one end of the cold junction compensation power supply filter unit is connected to the power supply terminal of the cold junction compensation module (5), and the other end of the cold junction compensation power supply filter unit is grounded.

9. The brake disc temperature acquisition system for brake-by-wire according to claim 1, characterized in that, The buffer circuit module (6) includes a buffer (U2) and an eleventh resistor (R11). The non-inverting input terminal of the buffer (U2) is connected to the output terminal of the cold junction compensation module (5). The output terminal of the buffer (U2) is connected to the inverting input terminal of the buffer (U2), the reference voltage input terminal of the differential amplifier module (3), and the output terminal of the differential amplifier module (3).

10. A method for acquiring the temperature of a brake disc under a brake-by-wire system as described in any one of claims 1 to 9, characterized in that, Including steps such as: Thermocouple (1) is used to collect the brake disc temperature to output an initial signal; The initial signal is differentially amplified using the differential amplifier module (3) to output the brake disc temperature signal.

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