Vehicle brake disc temperature monitoring method and apparatus

Abstract

Regarding vehicle brake disc temperature monitoring units. [Solution] The vehicle brake disc temperature monitoring unit comprises a temperature acquisition module that collects temperature values ​​near the brake disc that change over time during vehicle braking, and a control module that estimates the brake disc temperature using an observation model and a state estimation model based on the temperature values ​​collected by the temperature acquisition module and an estimated actual temperature of the brake disc, and adjusts and controls the braking state of the vehicle brake system via the estimated temperature value and the temperature sensor's detection value. By using a temperature sensor that is non-contact with the brake disc and utilizes the Kalman filtering method, the brake disc temperature is effectively estimated, improving monitoring accuracy and enabling safe and reliable monitoring of the brake system, thereby improving vehicle safety.

Description

Technical Field

[0001] This application relates to a vehicle braking system, and more particularly, to a method and apparatus for monitoring brake disc temperature by indirect measurement using a temperature sensor.

Background Art

[0002] A brake disc is an important component of a vehicle braking system. By regularly checking the condition of the brake disc, the reliability and effectiveness of the braking system can be ensured, and traffic accidents caused by brake failures can be avoided. However, it is usually difficult to test the intuitive braking performance and wear resistance of the brake disc. Therefore, after continuous braking, the temperature of the brake disc is examined, and based on this, in addition to the wear of the brake disc, it is determined whether the braking characteristics of the brake disc have deteriorated, and then the service life and safety of the brake disc are quantified. Regarding the temperature detection process of the brake disc, in the simulation control of experimental vehicles, the brake disc can be directly measured to obtain a specific temperature curve of the brake disc. However, this cannot directly measure the actual temperature of the brake disc during the vehicle driving process because the temperature sensor cannot be directly attached to the brake disc or be in contact with the brake disc, so it is impossible to achieve in mass-produced vehicles. Therefore, non-contact measurement is required.

[0003] In non-contact brake disc temperature measurement, an infrared thermal imaging device is often used to remotely detect the temperature of the brake disc, but its detection accuracy is restricted in many aspects and is not sufficient.

[0004] When attempting to measure brake disc temperature using high-precision wear-resistant thermocouple sensors, attempts have been made to obtain the brake disc temperature using indirect methods. For example, the brake hydraulic pressure or brake current acting on the brake disc is used, and a simulation algorithm is used to obtain an estimated brake disc temperature. However, due to the low correlation between brake pressure or brake current and temperature, unacceptable errors still exist. Furthermore, while placing the temperature sensor in a non-contact manner near the brake disc solves problems that could arise from the temperature sensor contacting the brake disc during such measurement processes, it is necessary to generate software to calculate the brake disc temperature by combining three heat dissipation models: heat conduction, heat convection, and heat radiation. However, ultimately, the temperature difference between the estimated and actual brake disc temperature exceeds 100°C. In the thermal friction coefficient curve at 100°C, the evaluation of μ can differ by as much as twofold.

[0005] Therefore, there is a need for methods and devices that can monitor the temperature of brake discs in a vehicle's braking system relatively accurately and safely. [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of this application is to provide a method and apparatus for monitoring the brake disc temperature in a vehicle's brake system relatively accurately and safely using an indirect temperature sensor. Specifically, a Kalman filter is used to make an optimal estimation of the brake disc temperature using an indirect brake disc temperature sensor. [Means for solving the problem]

[0007] To achieve the above objectives, this application provides a vehicle brake disc temperature monitoring unit comprising: a temperature acquisition module that collects temperature values ​​near the brake disc that change over time during vehicle braking; a temperature estimation module that estimates the temperature of the brake disc by a Kalman filtering process using an observation model and a state estimation model based on the temperature values ​​collected by the temperature acquisition module and an estimate of the actual temperature of the brake disc; and a control module that adjusts and controls the braking state of the vehicle brake system via the estimated temperature values ​​and the detection values ​​of the temperature sensor.

[0008] Optionally, the state estimation model for the estimation module is given by the following equation

number

[0009] Optionally, the observational model of the estimated module is given by the following equation

number

[0010] Optionally, the estimation module is the following predictive update iterative equation.

number

number

[0011] Optionally, the state transition coefficient or function takes into account the following factors, namely, the vehicle's driving position, road conditions, ambient temperature, etc.

[0012] Optionally, the control coefficient takes into account the following factors: the gap between the temperature sensor and the surface of the brake disc, and the heat transfer loss between the brake disc and the temperature sensor.

[0013] This application further relates to a vehicle brake disc temperature monitoring system, the vehicle brake disc temperature monitoring system comprising: a temperature sensor for detecting the temperature of a brake disc in a vehicle brake system; a sensor holder for holding the temperature sensor, the sensor holder holding the temperature sensor with a predetermined gap between it and the surface of the brake disc; and the vehicle brake disc temperature monitoring unit which estimates the temperature observed by the temperature sensor, an estimated value of the actual brake disc temperature, and the optimal estimated value that is closest to the actual brake disc temperature.

[0014] Here, the temperature sensor has a gap of less than a predetermined value between it and the surface of the brake disc.

[0015] The vehicle brake disc temperature monitoring system further includes an information display device that sends a warning to the vehicle control unit when the brake disc temperature exceeds a predetermined value, indicating that a problem may occur with the brake disc.

[0016] The present application further relates to a method for monitoring the temperature of a brake disc of a vehicle, the method being implemented by a vehicle brake disc temperature monitoring unit as described above, the method comprising the following steps: providing a temperature sensor for detecting the temperature of the brake disc, arranging the temperature sensor near the surface of the brake disc with a predetermined gap between the temperature sensor and the surface of the brake disc, using the temperature sensor via a temperature collection module to collect the temperature value near the brake disc as an input value in an observation model, based on the observed value and the estimated value of the temperature of the brake disc, repeatedly estimating the estimated value instant by instant via an estimation module, and performing Kalman filtering on the estimated value and the observed value to obtain an optimal temperature estimated value.

Advantages of the Invention

[0017] By adopting the solution of the present application as described above, it becomes possible to use a temperature sensor that is non-contact with the brake disc and utilizes the Kalman filtering method. Even if it is impossible to directly measure the temperature of the brake disc using a temperature sensor attached to or abutting on the brake disc, the temperature of the brake disc can be effectively estimated, thereby improving the monitoring accuracy and enabling safe and reliable monitoring of the brake system of the vehicle, and thus improving the safety of the vehicle during driving.

Brief Description of the Drawings

[0018] Embodiments of the present application will be described in more detail with reference to the accompanying drawings. [Figure 1] Schematically shows a schematic diagram of a monitoring unit for a brake disc having an indirect temperature sensor according to the present application. [Figure 2] It is a schematic diagram of a temperature sensor used in the monitoring unit according to the present application. [Figure 3A] Shows the state where the temperature sensor is arranged near the brake disc of the test vehicle. [Figure 3B]The temperature sensor indicates that it is at a predetermined distance from the brake disc. [Figure 4] This is a comparison diagram of temperature value curves measured by temperature sensors during the vehicle braking process, under the conditions shown in Figures 3A and 3B, respectively. [Figure 5] This is a schematic calculation block diagram of the temperature estimation module of the brake disc temperature monitoring unit according to this application. [Figure 6] This is a schematic diagram of the temperature monitoring unit according to this application. [Modes for carrying out the invention]

[0019] Preferred embodiments of this application are described below in detail, along with the examples. These embodiments are not intended to limit this application in any way, and it will be understood by those skilled in the art that the features of each embodiment may be combined with one another. The same components are indicated by the same reference numerals in different drawings, and certain components are omitted for simplification, but this does not mean that other components are excluded. It should be understood that the dimensions, proportions, and numbers of components shown in the drawings should not be considered limitations of this application.

[0020] As mentioned earlier, direct detection of brake disc temperature using high-precision wear-resistant thermocouple temperature sensors in test vehicles cannot be applied to mass-produced vehicles. When measuring brake disc temperature to confirm high temperatures on a rotating object, indirect monitoring methods are considered because accurate temperature values ​​on the brake disc cannot be directly obtained. For example, infrared thermal imaging devices are primarily used to detect whether the friction material of the brake disc is suitable. If the brake disc temperature detected by the infrared thermal imaging device rises sharply after continuous braking, it may indicate that the friction material of the brake disc is too soft, which can lead to reduced braking performance. If the trend of temperature change is gradual, it means that the friction material is too hard, which may cause the brake disc to wear out more quickly. At the same time, problems may occur during emergency braking, potentially leading to brake failure. However, infrared thermal imaging devices still have significant measurement errors. Furthermore, there is also a method of calculating brake disc temperature through software simulation, which generates software to calculate brake disc temperature by combining three heat dissipation models: heat conduction, heat convection, and heat radiation. However, such calculations often result in temperature differences of up to 100°C. In temperature friction coefficient curves at 100°C, the evaluation of μ can differ by as much as twofold. As a result, accurate information regarding brake disc temperature cannot be obtained, and high temperatures can damage the brake disc, potentially leading to brake failure.

[0021] With this in mind, this application intends to use a combination of software and hardware, namely an indirect temperature sensor and an optimal iterative estimation method for observed values, to monitor brake disc temperature with relative accuracy.

[0022] Generally, methods for indirectly detecting and estimating brake disc temperature employ Kalman filtering, which acquires instantaneous data related to brake disc temperature estimation, including the current brake disc temperature, vehicle speed, wheel speed, current ambient temperature, and brake pressure during vehicle braking. This data is input into a pre-built brake disc temperature estimation model, which is obtained by calibrating pre-set heating and heat dissipation model coefficients. This method enables highly accurate real-time estimation and prediction of the vehicle's brake disc temperature in the next moment, helping drivers understand the brake disc temperature in the next moment and ensure driving safety.

[0023] Therefore, in this application, for example, a temperature sensor comprising a thermocouple or thermistor is used and fixed at a predetermined distance from the brake disc. The heat source temperature is detected mainly by thermal radiation, and then direct detection errors are compensated for using a Kalman filtering algorithm. The temperature compensation requirements for the brake disc are met by combining software and hardware, and the optimal estimated temperature, which is closest to the actual temperature of the brake disc, can be obtained as accurately as possible.

[0024] Figure 1 shows a schematic diagram of the temperature monitoring unit according to this application mounted on the brake disc of a vehicle brake system. As shown in the figure, the vehicle brake system comprises brake discs 1 located on both sides, and the monitoring unit further comprises a temperature sensor 2 installed near the brake disc 1 and a holder 3 for holding the temperature sensor 2. The temperature sensor 2 is installed so as to be spaced away from the surface of the brake disc 1 by a gap 4. If the gap 4 is too large, the temperature sensing by the temperature sensor 2 will be excessively distorted, thereby rendering the observed value useless as a basis for estimation. On the other hand, if the gap 4 is too small, the placement of the sensor 1 will affect the brake disc 2 when the wheel (not shown) rotates, or the temperature sensor 1 will wear down. In other words, the temperature sensor 2 must always be kept as close as possible to the brake disc 1, but without contact with the brake disc 1.

[0025] Although holder 3 is shown in the figure as a separate component, it may be modified as needed. For example, brake disc 1 has a heat shield, and temperature sensor 2 may be mounted directly on the heat shield by being fixed to the heat shield of brake disc 1, for example, by screw connection or welding. In this case, the heat shield of brake disc 1 itself constitutes the holder for temperature sensor 2.

[0026] Figure 1 also shows the heat transfer from the brake disc 1 to the temperature sensor 2 during braking. For example, arrow 5 shows the process of heat transfer by radiation, arrow 6 shows the process of heat transfer by conduction, and arrow 7 shows the process of heat transfer by convection.

[0027] The equations related to heat transfer are expressed as follows:

number

[0028] These heat transfer processes are taken into account by the deviation or covariance of the temperature values ​​measured by the temperature sensor 2.

[0029] Figure 2 schematically shows the external appearance of the temperature sensor 2 and holder 3, where the temperature sensor 2 may be incorporated into the tip of the holder 3 and has a probe 9 for sensing temperature. The holder 3 also has a data line 8 for transmitting sensor data to an estimation unit (not shown in the figure). The data line 8 may also communicate with the estimation unit via a wireless connection and be configured to accurately repeat the measured temperature data.

[0030] Figures 3A and 3B show the position and state diagrams, respectively, of the temperature sensor 2 when used to detect the temperature on the brake disc of the experimental vehicle. In Figure 3A, the probe 9 of the temperature sensor 2 is in contact with the brake disc 1, while in Figure 3B, the probe 9 of the temperature sensor 2 is separated from the brake disc 1 through a gap.

[0031] Figure 4 shows a graph illustrating the relationship between the actual temperature values ​​measured during real-time detection of the brake disc temperature of the experimental vehicle during braking (Figure 3A) and the indirect temperature values ​​measured using the indirect temperature sensor shown in Figure 3B.

[0032] As can be seen from Figure 4, during the braking process of the brake disc 1, the value measured by the temperature sensor 2 when the probe 9 of the temperature sensor 2 is near the surface of the brake disc 2 is called the reference value, and this is represented by curve a in the figure. The temperature value measured by the temperature sensor 2 when the probe 9 of the temperature sensor 2 is positioned between it and the brake disc with a predetermined gap is called the indirect temperature value, and this is represented by curve b in the figure. Although curves a and b basically follow similar trends of change, it can be seen that there is a difference of more than 100° between the reference value of curve a and the indirect temperature value of curve b, and this difference can be set as a deviation estimate when optimizing the evaluation of the indirect temperature value.

[0033] In this application, the estimation accuracy of the non-contact indirect temperature detection process for brake discs is improved by introducing a Kalman filtering process based on reference values ​​and observed indirect temperatures and performing optimized autoregressive data processing to estimate the optimal value that is closest to the actual temperature of the brake disc surface based on indirect temperature values.

[0034] The brake disc temperature monitoring unit of this application comprises an estimation module 10 as shown in Figure 5. The estimation module 10 constitutes a physical model for the process of detecting the temperature of the brake disc.

[0035] The linear model equations for estimated module 10 are as follows:

number

[0036] Estimation module 10 also establishes the observation model equation as follows:

number

[0037] The optimized autoregressive process based on the above model equations includes a state prediction step that predicts the current state and state covariance based on the system's dynamic model and the state estimation from the previous moment.

[0038] The state prediction equation is as follows:

number

number

[0039] This is followed by an update step in which the Kalman gain is calculated based on the observed data and predicted state, and the state estimate and state covariance are updated.

[0040] The following iterative update equation is used during the iterative process of estimating the brake disc temperature value.

number

number

[0041] As mentioned above, in addition to the accuracy range of the temperature sensor itself used to detect the observed values, the covariance of the percentage values ​​is included in the Kalman filtering formula for calculation. Furthermore, when using the Kalman filter to predict temperature and establish a dynamic temperature model, it is necessary to take this into account based on the actual vehicle. Therefore, ambient heat capacity, heat source, thermal resistance, etc., may also be taken into consideration.

[0042] For example, this refers to the effect of the entire thermal circuit, which consists of the heat capacity, heat source, and thermal resistance of a temperature sensor.

[0043] Furthermore, this application uses a temperature sensor to measure the vicinity of the brake disc, but the degree of proximity is limited by many factors such as vehicle vibration and brake disc wear. Therefore, the gap between the brake disc surface and the temperature sensor is not fixed. This gap can also be considered a parameter. For example, the amount of brake disc wear can be determined by identifying the final degree of brake disc wear based on the change in the gap, and then the amount of brake disc wear can be used directly to determine whether the brake disc is still within a safe operating range, or the gap can be associated with the temperature of the brake disc.

[0044] In this application, a temperature sensor is selected that is sufficiently close to the brake disc to obtain greater thermal radiant power. For example, by maintaining the gap 4 between the temperature sensor and the brake disc, as shown in Figure 1, within a predetermined value such as 5 mm or less, for example, 4 to 5 mm or within 1 mm, more accurate and effective data can be obtained. Of course, the above value of gap 4 is merely an example and may be adjusted as needed, and different noise covariances can be used to estimate this gap.

[0045] Figure 5 shows in detail the estimation module 10 of the brake disc temperature monitoring unit. In this figure, the indirect temperature value detected by the brake disc temperature sensor 2 and the estimated value from the estimation unit are optimized and evaluated based on the state estimation equation, observation equation, and Kalman gain coefficient to obtain the optimal estimate that is closest to the actual brake disc temperature.

[0046] In other words, in estimation module 10, the optimal estimate is obtained by combining the observation model and the prediction model with the Kalman filtering parameters.

[0047] Figure 6 shows a schematic block diagram of a brake disc temperature monitoring unit according to an embodiment of the present application. As described above, parameter information S1, such as the brake disc temperature value detected by the brake disc temperature sensor 2, or the temperature change over time, or other temperature control parameters of the brake disc such as brake pressure and brake disc wear, is input to the estimation module 10. The output information of the estimation module 10 is the estimated optimal brake disc temperature information T, which is the value that is most likely to be closest to the actual brake disc temperature. Next, the temperature information T is collected by the control module 20 to output and monitor the brake disc temperature in real time. The braking state of the vehicle brake system is adjusted and controlled by the estimated temperature value and the temperature sensor detection value to identify whether the operating state of the brake disc is abnormal and to quickly warn the vehicle driver.

[0048] The estimation module 10 may also receive other arbitrary information as random input parameters, such as vehicle location information, vehicle driving status and road surface information, and environmental parameter information that can significantly affect the detection error of the temperature sensor.

[0049] In this application, the advantages of combining a temperature sensor consisting of a thermocouple or thermistor with a Kalman filter include preventing sensor wear due to contact with the brake disc and reducing costs. On the other hand, the accuracy of temperature detection is improved by calibrating the actual target temperature using software and hardware. Furthermore, the standard lifespan of the vehicle, such as 15 years / 300,000 kilometers, can be taken into consideration when selecting the temperature sensor, thereby improving the service life of the sensor.

[0050] While the present invention has been described in relation to preferred embodiments, this is not intended to limit the invention. The scope of protection of the present invention is defined by the appended claims and can be modified in various ways by those skilled in the art without departing from that scope.

Claims

1. A vehicle brake disc temperature monitoring unit, A temperature collection module that collects temperature values ​​near the brake disc that change over time during vehicle braking, A temperature estimation module that estimates the temperature of the brake disc by a Kalman filtering process using an observation model and a state estimation model, based on the temperature values ​​collected by the temperature acquisition module and the estimated actual temperature of the brake disc, A control module that adjusts and controls the braking state of the vehicle brake system via estimated temperature values ​​and temperature sensor detection values, A vehicle brake disc temperature monitoring unit equipped with the following features.

2. The state estimation model of the temperature estimation module is given by the following equation: [Math 1] (In the formula, x ｋ represents a calculated value obtained from previous calculated values, A is a state transition coefficient or function that shows how to estimate the state at the current moment from the state at a previous moment, B is a control coefficient that shows how the controlled variable u acts on the current state, the controlled variable u is the change in temperature over time or the temperature input value, w ｋ The vehicle brake disc temperature monitoring unit according to claim 1, wherein the state estimation error has a normal distribution.

3. The observation model of the temperature estimation module is given by the following equation: [Math 2] (In the formula, v ｋ This is observation noise, and z ｋ The vehicle brake disc temperature monitoring unit according to claim 1 or 2, wherein (where is an observed value, and H is an observation coefficient, which is a function or parameter representing a parameter related to the measurement accuracy of the temperature sensor itself).

4. The temperature estimation module uses the following predictive update iterative equation: [Math 3] (In the formula, [Math 4] A vehicle brake disc temperature monitoring unit according to any one of claims 1 to 3, comprising: (where is the residual between the actual observed value and the expected observed value, and K is the Kalman coefficient or gain).

5. The vehicle brake disc temperature monitoring unit according to claim 2, wherein the state transition coefficient or function takes into account the following factors, namely, the vehicle driving position, road conditions, ambient temperature, etc.

6. The vehicle brake disc temperature monitoring unit according to claim 2, wherein the control coefficient takes into account the following elements: namely, the gap between the temperature sensor and the surface of the brake disc, and the heat transfer loss between the brake disc and the temperature sensor.

7. A vehicle brake disc temperature monitoring system, A temperature sensor for detecting the temperature of the brake disc in the vehicle's brake system, A sensor holder for holding the temperature sensor, the sensor holder holding the temperature sensor with a predetermined gap between it and the surface of the brake disc, A vehicle brake disc temperature monitoring unit according to any one of claims 1 to 6, which estimates the optimal value closest to the actual brake disc temperature based on the temperature observation value detected by the temperature sensor and the estimated value of the actual brake disc temperature, A vehicle brake disc temperature monitoring system equipped with the following features.

8. The vehicle brake disc temperature monitoring system according to claim 7, wherein the temperature sensor has a gap of less than a predetermined value between itself and the surface of the brake disc.

9. The vehicle brake disc temperature monitoring system according to claim 7, further comprising an information instruction device that transmits a warning to the vehicle control unit when the brake disc temperature exceeds a predetermined value, indicating that a problem may occur with the brake disc.

10. A method for monitoring the temperature of a vehicle's brake disc, The above method is carried out by the vehicle brake disc temperature monitoring unit according to any one of claims 1 to 6. The above method involves the following steps: A temperature sensor is provided for detecting the temperature of the brake disc, and the temperature sensor is positioned near the surface of the brake disc such that there is a predetermined gap between the temperature sensor and the surface of the brake disc. The temperature sensor is used via the temperature acquisition module to collect temperature values ​​near the brake disc as input values ​​for the observation model, Based on the observed and estimated temperatures of the brake disc, the estimation of the temperature is repeatedly performed instantaneously via a temperature estimation module, and Kalman filtering is performed on the estimated and observed temperatures to obtain the optimal temperature estimate. Methods that include...

Images