RU2513439C1 - Method of prevention of automotive tire and brakes emergent overheating and system to this end - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to automotive industry, particularly to active and passive safety means. At control over tire and brake temperature, data processing unit generates in real time the estimates of overheating temperatures and boundary speeds defined at braking to full stop with reaching of boundary overheating temperatures. Proceeding from signals of wheel rotational speed, acceleration generated by accelerometer, on ambient temperature and control parameters programmed microcontroller generates control effects for visual data display to be output to driver. Said data includes reaching or exceeding critical overheating temperatures or reaching critical overheating boundary rates. Here, additionally actuated at least one means to indicate dangerous states to attract attention of the driver.

EFFECT: ruled out overheating of tire and brake.

4 cl, 4 dwg, 1 tbl

Description

The invention relates to the automotive industry, in particular to methods and devices for increasing the active safety of vehicles.

Known pneumatic tire of a vehicle with temperature stabilization. A pneumatic tire consists of a tread, power elements in the form of breakers and / or a carcass, cavities formed by power elements in the form of brokers and / or a carcass with elastic rubber shells, cavities are filled with thermo-accumulating material with a melting temperature of 70-75 ° С, for example, alloy Wood, with a melting point of about 70 ° C. When the vehicle is moving, the heat released in the pneumatic tire during its deformation is transferred to the heat-accumulating material in the cavities. The heat storage material, heating to 70-75 ° C, melts and, remaining at a constant temperature, continues to accumulate thermal energy. Elastic rubber shells compensate for the thermal expansion of the heat storage material. Due to the strictly fixed temperature of the transition of the heat-accumulating material from the solid state to the liquid temperature of the tire, it is maintained at the required level within the cavities. (RF patent No. 2345905, IPC В60С 23/18, publ. 02/10/2009)

The disadvantages of this invention are the final amount of thermal energy that the heat-accumulating material is able to accept until it completely transitions to the liquid state of aggregation with the loss of the temperature stabilization property, the difficulty of predicting the moments of time when the pneumatic tire loses the temperature stabilization property.

A known system for monitoring the condition of tires, which contains a remote measurement unit for the state of the tire installed in the tire, a central controller, a voice message unit and a braking device using brakes. The remote unit for measuring the state of the tire measures the pressure and temperature inside the bus with a frequency of 5-20 Hz and generates signals containing the measured values of the parameters, which are then transmitted over the air to the central controller. The central controller receives over the air the signals containing information about the status of the bus, and processes them. As a result, he develops commands for issuing voice information messages and braking commands using brakes. After that, the commands are transmitted respectively to the block of voice messages and to the braking device using brakes. The block of voice messages is intended for receiving the appropriate commands from the central controller and issuing voice information messages. The braking device using brakes is designed to receive the appropriate commands from the central controller and to perform braking using the brakes. (RF patent No. 2398680, IPC B60C 23/02, G08C1 17/02, published on 09/10/2010)

The disadvantages of this system include the need to use tires without metal cord shielding electromagnetic radiation, the strictly limited life of the remote control unit for measuring the state of the tire, determined by the resource used as a power source for the lithium thionyl chloride element.

A known vehicle control system with advanced tire monitoring, which includes vehicle dynamics sensors, provides a signal about the dynamics of the vehicle. The sensors of the tire monitoring system in each wheel generate signals that include temperature, pressure, and acceleration data. The controller interacts with the sensors of the tire monitoring system and at least one vehicle dynamics sensor and generates an assessment of the road surface condition as a function of acceleration data along several axes contained in the signals from the sensors of the tire monitoring system. The road surface condition assessment is transmitted to the suspension control system to adjust the vehicle suspension characteristics in accordance with the road surface condition assessment. An advanced tire monitoring system, which is part of the invention, tracks air pressure, temperature and accelerations in several axes in the front right tire, front left tire, rear right tire and rear left tire. Each bus has a corresponding sensor of an advanced monitoring system, each of which has a corresponding antenna. Each tire is mounted on a corresponding wheel. Each tire may have a corresponding initiator located in a recess of the wheel adjacent to the tire. The initiator generates a low-frequency RF signal and is used to initiate a response from each wheel so that the position of each wheel can be recognized automatically by an advanced tire monitoring system. The initiators are connected directly to an advanced tire monitoring system. The controller, which is part of an advanced bus monitoring system, can be a microcontroller with a programmable central processor, which can be programmed to perform various functions and processes. (US patent No. 8032281, IPC G06F 17/00, publ. 04.10.2011)

The disadvantages of the known tire monitoring system include the need to use tires without metal cord shielding electromagnetic radiation, loss of tire parameter monitoring in the event of a failure of the corresponding wheel sensor or initiator, and a rather complicated technical implementation of the system.

A device for infrared remote sensing and a system for checking the status of the brakes of a vehicle are known. The infrared remote sensing system includes a video recorder for recording the vehicle and providing video information, an infrared remote sensing device for detecting infrared radiation from the brake drums of the vehicle and providing data, a power source for providing electric power to the infrared remote sensing device, a computer for receiving video information from the device video and data from an infrared device remote sensing, a computer for analyzing data from an infrared remote sensing device and providing analyzed data, a display for displaying video information and analyzed data from a computer, where the observer can see video information and analyzed data on a display device that indicates violations in thermal models of brake drums to determine vehicle brake status. The present invention uses an infrared remote sensing device located at a road level in the middle of a lane to monitor one lane of a road. The infrared remote sensing device is simultaneously directed to both sides of the lane in order to measure infrared radiation, that is, temperatures emitted by the brake drums of the vehicle when the vehicle is decelerated by the braking system. (US patent No. 5942753, IPC G01N 21/00, publ. 08.24.1999)

The disadvantages of this system include point monitoring of brake drum temperatures, carried out only on specially equipped sections of the road, the need for the operator (observer) to participate in the operation of this system, the possibility of using the system only for vehicles with brake drums.

A known system for measuring the state of friction material of a vehicle. This system uses a sensor to monitor both the wear and tear of the vehicle's brake lining. The thermistor is installed in the brake pad, and its resistance is measured using a microprocessor-based electronic control unit. Long-term changes in the thermistor resistance, measured after the vehicle is stopped for a period of time, show wear on the lining, while the relatively short-term changes made when the vehicle is running show temperature gradients. The electronic control unit determines the proper classification of the change in the resistance of the thermistor and provides an output signal to the vehicle operator and / or stores the signals for later reading on external diagnostic equipment. (European patent No. 0768474 B1, IPC F16D 66/00, F16D 66/02, publ. 22.12.2004.)

The disadvantages of this system include the need to make changes to the design of the brake pad of the vehicle, the use of a sensor that is built into the pad and consumes electrical energy, as well as the need to establish an appropriate communication line with the sensor, the inability to assess the temperature of the brake pad in the event of a sensor failure or line break communication.

Known anti-union machine and data acquisition system for the brake system of the vehicle. (US Patent No. 7489996 B2, 02/10/2009, IPC B60T 8/68, B64C 27/22) The system includes a wheel speed sensor including a magnetic device connected to the wheel, and a sensor connected to the wheel axis provides data indicating the wheel speed . A processor mounted on the axis of the wheel receives data about the speed of the wheel and processes them to perform the functions of the anti-union machine. Speed data is stored in a data hub, also mounted on an axis. The tire pressure sensor, brake temperature sensor and brake torque sensor, each of which is connected to the wheel, send data to the processor on the wheel axis and for storage in a data hub. A transmit antenna connected to the axis and connected to a data hub transmits the stored data to a receiving antenna connected to the wheel. A data port located on the wheel and connected to the receiving antenna provides an interface with an external device for receiving data. The system contains one or more additional sensors to provide additional operational information to the processor for storage in a data concentrator.

The disadvantages of the system include a rather complicated technical implementation, the inability to monitor parameters in the event of failure of the respective sensors.

A known method of measuring the temperature of the brake surfaces of an automobile wheel brake. (UK patent No. 2289765, IPC F16D 66/00, B60T 17/22, publ. 11/29/1995.) In the indirect method of calculating the temperature of a brake element (for example, a disk or pad) by cyclically subtracting the cooling temperature decrement dTk from the previous temperature T (at least up to a predetermined minimum temperature) and similarly, by adding a heating increment, depending on the functioning of the brake, this increment dThn corresponding to normal braking is calculated depending on the vehicle deceleration a, caused by the use of the braking system minus the deceleration component associated with road resistance (including engine braking) and aerodynamic drag. The last component is taken from the stored empirical characteristics diagram. The cooling decrement dTk depends on the previous temperature T and the vehicle speed V. If the wheel slip stabilization system (longitudinal and / or transverse) is turned on, another temperature increment dThr is added, depending on the wheel rotation speed Rd and the prevailing brake pressure ps (for example, calculated based on valve opening times). Such braking can be stopped if the calculated temperature exceeds the limit value. This method requires sensors to record the rotational speeds of all four wheels, which are usually present on existing vehicles, data on the state of the brake light and on the operation of the wheel slip stabilization system.

The disadvantage of this method is that when calculating the heating increment based on the vehicle deceleration, the deceleration component caused by the ascent or descent of the road is not taken into account. The noted drawback limits the adequacy of this method of indirect temperature measurement by the condition of movement on flat terrain. The second disadvantage of this method is the inability to obtain estimates of the temperature of the working surfaces of the brake wheel device in case of failure of the speed sensor of the corresponding wheel.

A known method for determining the temperature of the wheel brake device of the brake system. According to this method for determining the temperature of a wheel brake device having a brake disk and a brake caliper, the current value of the temperature of the brake disk determined by the previous determined value of the temperature of the disk, the energy transferred to the brake disk after the previous temperature determination, and by the energy given to the brake after the previous temperature determination, in which the current value of the temperature of the caliper of the wheel brake device is determined as a function from the temperature of the brake disc. In this method, the energy transmitted to the brake disc is determined as a function depending on the brake pressure in the wheel brake device, wheel speed, vehicle speed and a coefficient that, in turn, depends on the brake pressure in the wheel brake device, the previous temperature disc and / or previous brake caliper temperature. The energy given by the brake disc is defined as the sum of the energies: the energy given by the brake disc to the environment and the energy given by the brake disc to the caliper. In this method, only the energies given out by the brake disc through heat exchange and convection are considered. The current brake caliper temperature is defined as a function of the energy transferred to the caliper from the brake disc and the energy given by the caliper to the brake disc and the environment. The energy transmitted from the brake disc to the caliper, or the energy transmitted from the brake caliper to the disk, is determined as a function of the temperature difference between the previous value of the temperature of the brake disk and the previous value of the temperature of the caliper. A warning signal of a certain duration is transmitted to the driver when the current value of the disk temperature exceeds a predetermined maximum value. A warning signal is sent to the driver when the current caliper temperature exceeds a predetermined maximum value. When the ignition is turned off, the temperature of the disc and the temperature of the hydraulic unit (valve block) of the brake system are stored in memory. When the vehicle ignition is turned on, the current value of the temperature of the disk is determined by the corresponding ambient temperature in case the current value of the temperature of the hydraulic unit is lower than the stored value of the temperature of the hydraulic unit, and if the current value of the temperature of the hydraulic unit is lower than the predetermined maximum value of the on temperature. Otherwise, when the ignition is turned on, the current value of the disk temperature is determined as a function of the stored value of the disk temperature. (UK patent No. 2382390 B, IPC B60T 17/22, publ. December 17, 2003)

The disadvantages of this method include the need to use additional brake fluid pressure sensors in the brake lines of the wheel brake devices, the inability to complete estimates of the temperature of the brake device in the event of a failure of the corresponding pressure sensor.

The closest in technical essence are the way to prevent collisions of the car with obstacles and a system for its implementation. The system consists of wheel speed sensors mounted on the vehicle’s wheels, connected by communication lines through an optocoupler couple with a microcontroller, means for inputting tuning information, and means for displaying data and indicating dangerous conditions. This method is implemented by recording pulses from the sensors of the primary information and transmitting it to the information processing unit, in which indirect measurements of physical variables are carried out and boundary values of physical variables are calculated. If the boundary values of physical variables are exceeded, the system generates a signal to the appropriate means of indicating a dangerous condition. The driver generates control actions on the car’s controls to exit the car from a dangerous state. The boundary values of the physical variables of the system include the marginal speed of rollover of the car, the marginal speed of skidding of the rear wheels, the marginal speed of demolition of the front wheels, the marginal speed of rupture of the cord of tires, the marginal speed of slipping of the drive wheels, the marginal speed determined by the asymmetry of the wheelsets due to the pressure difference in the tires , the speed determined by the asymmetry of the wheelsets, due to the use of a wheel of reduced radius (dokatka), etc. (RF Patent No. 2335805, MHK G08G 1/16, publ. 10.10.2008.)

The disadvantage of this system is not a wide enough vector of restrictions, in particular, the system does not take into account the temperature of overheating in the field of the tire shoulder and in the sidewall, which can be critical from a safety point of view, and the temperature of the wheel braking devices.

The technical problem to which the invention is directed is to prevent accidental overheating of tires and brakes of a car by dynamically stabilizing the temperatures of overheating of tires and brakes of a car.

The stated technical problem is solved in that in a method for preventing accidental overheating of tires and brakes of a car, which consists in recording signals generated by pulse sensors of the vehicle’s wheel speeds and a three-axis accelerometer, and transmitting them through the interface unit to the information processing unit, in which the values of physical variables are determined and compare them with boundary values characterizing the critical condition of the car, and form control signals at the output of the information processing unit, transmitted to the output device of graphic information and / or indicators of dangerous conditions, according to the proposed invention in the information processing unit in real time form estimates of the temperature of the superheat of tires, wheel braking devices of the car and boundary speeds determined from the condition of the braking movement at any time stops with the exit at the moment of a complete stop to the limit values of the temperature of the tire and / or brake devices overheating, based on signals about the rotation frequencies wheels, about accelerations from the accelerometer and tuning parameters using a microcontroller with software, and form control actions on the graphic information output device to transmit information to the driver about the temperature conditions of tires and brake devices of the car, as well as about approaching or exceeding critical temperatures of critical overheating or to the critical critical overheating boundary speeds, in this case, at least one means of indicating dangerous conditions d I draw the attention of the driver.

The technical task is also solved by the fact that, according to the proposed invention, the system for preventing accidental overheating of tires and brakes of a vehicle includes wheel speed sensors and a three-axis accelerometer associated with a line interface unit, an information processing unit receiving from the wheel speed sensors of a car and a three-axis accelerometer by means of communication lines and a conjugation unit, the corresponding signals and forms on their basis and on the basis of the tuning parameters of the assessment of physical parameters characterizing the state of the car, forming control actions on the graphic information output device (LCD) and hazardous state indicators, an information input and display unit, including an input device for inputting tuning information and selecting an information display mode, graphic information output device, indicators hazardous condition, a secondary power source that stabilizes and converts the voltage received from the vehicle's on-board network into ins voltage required to power the microcontroller, image display and the three-axis accelerometer. In addition, it further comprises an ambient temperature sensor for receiving by the microcontroller a signal about the ambient temperature necessary for automatically entering the ambient temperature value.

The technical result consists in the dynamic stabilization of temperatures of the overheating of tires and brakes of the car, due to which their emergency overheating is prevented.

The invention is illustrated by drawings, where:

figure 1 presents the layout of passengers and cargo in a passenger car (top view);

figure 2 presents a functional diagram of a system for preventing emergency overheating of tires and brakes of a car;

Fig. 3 shows the experimental dependence of the rolling friction coefficient on tire pressure;

figure 4 presents the kinematic diagram of the movement of a car on a bend.

Figure 2 contains the following positions:

1-4 - wheel speed sensors;

5 - three-axis accelerometer;

6 - information processing unit;

7 - interface unit;

8 - microcontroller;

9 - secondary power source;

10 - communication lines;

11 - input device;

12 - a device for outputting graphic information (LCD);

13 - indicators of dangerous conditions;

14 - block input and display information;

15 - ambient temperature sensor.

A system for preventing accidental overheating of tires and brakes of a car, including wheel speed sensors 1, 2, 3, 4, a three-axis accelerometer 5 and an ambient temperature sensor 15 connected to the interface unit 7 by communication lines 10, the microcontroller 8 receives wheel speed sensors vehicle 1, 2, 3, 4, a three-axis accelerometer 5 and an ambient temperature sensor 15 through communication lines 10 and interface unit 7 and generates the corresponding signals based on them and on the basis of the tuning parameters for assessing physical parameters characterizing the state of the car, including temperatures of tires and wheel braking devices of the car, as well as boundary speeds determined from the condition that the braking movement at any moment of time reaches a complete stop, and when the tire stops at the moment of a full stop, it reaches the limit values of the tire overheating temperatures and / or brake devices. In the information processing unit 6, control actions are generated on the graphic information output device (LCD) 12 and hazardous state indicators 13 in order to transmit information to the driver about the temperature conditions of tires and brake devices of the car, as well as about approaching (or exceeding) to the temperature limits critical overheating or to boundary critical overheating rates. The input and display information unit 14, in addition to the output device of graphic information 12 and hazardous status indicators 13, contains an input device 11, for example, a touch panel or multi-mode keys, for entering configuration information and selecting an information display mode. A secondary power source 9 stabilizes and converts the voltage received from the vehicle’s on-board network into voltage values necessary to power the microcontroller 8, input device 11, graphic information output device 12, hazardous condition indicators 13, also a three-axis accelerometer 5 and an ambient temperature sensor 15. The system for preventing emergency overheating of tires and brakes of a vehicle may include an ambient temperature sensor 15 for receiving a temperature signal by a microprocessor Ur environment required for automatic input of ambient temperatures.

The method is as follows.

The signals generated by the pulse sensors of the vehicle’s wheel speeds and the three-axis accelerometer are recorded and transmitted through the interface unit to the information processing unit.

In the information processing unit, the values of the physical variables are determined and compared with the boundary values characterizing the critical condition of the vehicle. Namely, in the real-time information processing unit, estimates of the temperature of the superheat of the tires, wheel braking devices of the car and boundary speeds are determined, which are determined from the condition for the braking movement to stop completely at any time and exit at the limit temperature of the tire overheat at / or brake devices. Further, on the basis of signals about the frequencies of rotation of the wheels, about accelerations from the accelerometer, about the ambient temperature and tuning parameters, control signals are transmitted to the output of the information processing unit using the microcontroller with software, which are transmitted to the output device of graphic information and / or to dangerous state indicators for transmitting information to the driver about the temperature conditions of tires and braking devices of the car, as well as about approaching or exceeding critical temperature limits overheating or overheating critical velocity boundary, in this case further activated by at least one means indicating dangerous states to attract the driver's attention.

As a mathematical model of the process of heating tires and brakes, a system of equations is used, built on the basis of the first law of thermodynamics in differential form:

и $$C_{0i}^{*}$$

- константы теплоемкости и теплообмена i-го тормоза; $$T_i^{*}$$

и $$T_{ос}^{*}$$

- температура i-го тормозного устройства и окружающей среды; W_Ti - тепловая мощность, выделяемая в i-м тормозном устройстве при торможении.where C _Ti and C _0i are the heat capacity and heat transfer constants of the ith bus; T _i and T _OS - temperature of the i-th tire and the environment; W _1i , W _2i and W _3i - thermal power released on the i-th tire as a result of the action of rolling friction forces, sliding and functioning of the brakes; $$C_{Ti}^{*}$$

and $$C_{0i}^{*}$$

- constants of heat capacity and heat transfer of the i-th brake; $$T_i^{*}$$

and $$T_{\mathrm{about}\mathrm{from}}^{*}$$

- temperature of the i-th braking device and the environment; W _Ti - thermal power released in the i-th braking device during braking.

Thermal power W _1i , W _2i and W _{3i are} determined in the form:

where F _Ni is the normal component of the dynamic load on the ie wheel; k _TRI (P _i ) - coefficient of rolling friction of the i-th tire with internal pressure P _i ; k _Si (S _i ) is the sliding friction coefficient of the i-th tire with the sliding value S _i ; V _i ; and ΔV _Si are the linear speeds of rotation and longitudinal sliding of the i-th wheel.

The normal component of the dynamic load on the i-th wheel (F _Ni ) is defined as a function (f _i ) depending on the mass (m _i ) per wheel; from pitch angle (α _T ) equal to the angle between the velocity vector of the center of mass and the horizon; from the roll angle of the road (β _K ); from the height of the center of mass of the vehicle (h _m ), from the dynamic radius of the wheels (R _d ); from traction and brake acceleration of the car (a _dT ); from lateral acceleration of the car (a _q ); from the speed of the center of mass of the car (V _m ) and from the aerodynamic drag coefficient of the wing along the vertical axis (k _zi ):

F _Ni = f _i (m _i , α _T , β _K , h _m , R _d , a _dT , a _q , V _m , k _zi ).

Under the assumptions about the small roll angles (β _K ) and pitch (α _T ), the distribution of vehicle mass between the front and rear axles close to 50/50, the proximity of the height of the center of mass of the vehicle (h _m ) to the dynamic radius of the wheels (R _d ), normal components of dynamic wheel loads are determined taking into account traction and braking ( a _dT ) longitudinal and transverse ( a _q ) accelerations, additional vertical accelerations (Δ a _z ) and aerodynamic downforce of the wing:

- суммарная масса автомобиля; b - колесная база; а - ширина колеи колес; h_m - высота центра масс автомобиля; $$k_{z3}=k_{z4}=(b-b_w^{*})\cdot b^{-1}\cdot k_z$$

; $$k_{z1}=k_{z2}=(b-b_w^{*})\cdot b^{-1}\cdot k_z$$

; $$b_w^{*}$$

- расстояние между центром антикрыла и задней осью автомобиля; k_z - коэффициент аэродинамического сопротивления по вертикальной оси; α_T - угол тангажа (подъема) дороги, равный углу между вектором скорости автомобиля и горизонтальной плоскостью; α_кр - угол крена дороги.where m ₁ , m ₂ , m ₃ , m ₄ are the masses per wheel; g is the acceleration of gravity; and _z is an additional component of vertical acceleration; $${\mathrm{<figure-callout\; id="0"\; label="m"\; filenames="00000058.png,00000059.png"\; state="\{\{state\}\}">m</figure-callout>}}_0={\displaystyle \sum _{i=\mathrm{one}}^{\mathrm{four}}{m}_i}$$

- total mass of the car; b - wheelbase; a - wheel gauge; h _m is the height of the center of mass of the vehicle; $${\mathrm{<figure-callout\; id="3"\; label="k\; z"\; filenames="00000057.png,00000058.png"\; state="\{\{state\}\}">k\; </figure-callout>}}_z=k_{z\mathrm{four}}=(b-b_w^{*})\cdot b^{-\mathrm{one}}\cdot k_z$$

; $$k_{z\mathrm{one}}={\mathrm{<figure-callout\; id="2"\; label="k\; z"\; filenames="00000057.png,00000058.png"\; state="\{\{state\}\}">k\; </figure-callout>}}_z=(b-b_w^{*})\cdot b^{-\mathrm{one}}\cdot k_z$$

; $$b_w^{*}$$

- the distance between the center of the wing and the rear axle of the car; k _z - drag coefficient along the vertical axis; α _T is the pitch (lift) angle of the road, equal to the angle between the vehicle’s speed vector and the horizontal plane; α _cr - roll angle of the road.

The masses per wheel are determined taking into account the location and masses of passengers and cargo in the car:

where F is a vector of dimension 6, which corresponds to the number of seats in a car in the sequence in which they are numbered in figure 1, plus one place for cargo in the trunk. F = (f ₁ f ₂ f ₃ f ₄ f ₅ f ₆ ) ⁷ is defined as follows: if f _i = 0, where 1≤i≤6, then the corresponding place is vacant, if f _i = 1, where 1≤i≤ 6, the corresponding place is occupied by the driver or passenger (cargo for i = 6);

m ₁₀ , m ₂₀ , m ₃₀ , m ₄₀ - masses per wheel in the curb condition of the car (without driver, passengers and baggage); Δm _i is the mass of the person sitting on the i-th place in the car, or at i = 6 the mass of the cargo that is in the trunk of the car; x _i and q _i are the coordinates of the center of mass of the i-th passenger or cargo (figure 1).

The dependence of the rolling friction coefficient k _ti (Pi) is approximated by a piecewise linear function in a limited speed range:

и $$P_{грi}^H$$

определяются экспериментально.A _i , B _i , $$P_{gRi}^H$$

and $$P_{gRi}^H$$

determined experimentally.

So, for Continental ContiPremium Contact 2 225/55 R16 95 V tires, dependence (5), taking into account experimentally determined coefficients, has the following form:

This experimental dependence in graphical form is shown in figure 3.

The dependence of the sliding friction coefficient k _Si (S _i ) is approximated by a piecewise linear function:

- максимальное значение k_Si(S_i), достигаемое в диапазоне скольжений от 0.15 до 0.3; S_i=ΔV_Si(V_m)^-1 - скольжение i-го колеса; a_0i, b_0i, c_0i и d_0i - экспериментальные коэффициенты; S_ij, 1≤j≤4 - экспериментальные значения скольжений. В частном случае могут быть следующие экспериментальные значения коэффициентов и скольжений S_ij: a _0i=0.25; b_0i=5; c_0i=1.1; d_0i=0.3; S_i1=0.01; S_i2=0.15; S_i3=0.3; S_i4=3.Where $$k_{Si}^{*}$$

- the maximum value of k _Si (S _i ) achieved in the range of slip from 0.15 to 0.3; S _i = ΔV _Si (V _m ) ^-1 - sliding of the i-th wheel; a _0i , b _0i , c _0i and d _0i are experimental coefficients; S _ij , 1≤j≤4 - experimental values of the slip. In a particular case, the following experimental values of the coefficients and slides S _ij can be: a _0i = 0.25; b _0i = 5; c _0i = 1.1; d _0i = 0.3; S _i1 = 0.01; S _i2 = 0.15; S _i3 = 0.3; S _i4 = 3.

The value of the thermal power W _Ti released in the brake device is equal to:

; $$U_3=P_T\cdot P_{T\max }^{-1}$$

; S_Ti - площадь поперечного сечения тормозных цилиндров i-го тормоза; k_Ti - коэффициент трения скольжения рабочих поверхностей; R_Ti - радиус тормозного диска (барабана); R_ci и R_di - свободный и динамический радиусы i-го колеса.Where $$k_{3i}={10}^5\cdot S_{Ti}\cdot k_{Ti}\cdot R_{Ti}\cdot R_{di}^{-\mathrm{one}}\cdot P_{T\max }$$

; $${\mathrm{<figure-callout\; id="3"\; label="U"\; filenames="00000057.png,00000058.png"\; state="\{\{state\}\}">U</figure-callout>}}_3=P_T\cdot P_{T\max }^{-\mathrm{one}}$$

; S _Ti is the cross-sectional area of the brake cylinders of the i-th brake; k _Ti is the coefficient of friction of sliding of the working surfaces; R _Ti is the radius of the brake disc (drum); R _ci and R _di are the free and dynamic radii of the i-th wheel.

Overheating temperatures in the internal cavity of the i-th bus are determined in real time as a result of solving a system of finite-difference equations:

- температуры перегрева шин и тормозов соответственно.Where

- temperatures of overheating of tires and brakes, respectively.

Vectors V = (V ₁ , V ₂ , V ₃ , V ₄ ) ^T , ΔV _S = (ΔV _S1 , ΔV _S2 , ΔV _S3 , ΔV _S4 ) ^T , а = ( a _dT , a _q , a _m ) ^T , P = (P ₁ , P ₂ , P ₃ , P ₄ ) ^{T are} determined as the result of solving the incorrect problem of the unique transformation of the vector ω = (ω ₁ , ω ₂ , ω ₃ , ω ₄ ) ^{T of the} measured angular speeds of rotation of the wheels. The brake control action U _{3 is} calculated in real time using an algorithm for identifying vehicle controls based on data on wheel speeds and data on accelerations along the longitudinal, transverse and vertical axes of the vehicle (certificate of official registration of computer program No. 2007710819. Identification of the status of controls Automobile / Buznikov S.E., Elkin D.S. // Rospatent, 2007).

The input data when using equation (8) to determine the estimates of the overheating temperatures of automobile brakes are the control brake action U ₃ (k), the estimates of which the intelligent active safety system under consideration generates even with one working wheel speed sensor using an identification algorithm, and linear rotation speeds wheels.

The system of equations of linear wheel speeds V _i = R _i · ω _m + ΔV _Si ; (1≤i≤4) of a car in a bend taking into account the longitudinal sliding speeds of the wheels ΔV _{Si is} reduced to the following form:

Δω _m - additional angular velocity of rotation of the center of mass of the car when skidding the rear wheels or demolishing the front wheels.

In figure 4, the following notation: b - wheelbase of the car; ψ ₁ and ψ ₂ - rotation angles of the 1st and 2nd steered wheels, respectively; ψ _R is the yaw angle; ψ _C is the angle of rotation of the steered wheels; a ₁ and a ₂ - the gauge of the front and rear wheels; V _i - linear speed of rotation of the i-th wheel; R _i are the turning radii of the respective wheels; R _m and V _m - respectively, the turning radius and linear velocity of the center of mass of the vehicle; b ^* is the distance from the center of mass to the rear axle of the vehicle; ω _m - the angular velocity of rotation of the center of mass of the car.

при всех исправных датчиках первичной информации формирует на основе измеряемых угловых скоростей вращения колес ω_i.Grades $${\widehat{V}}_i(k)={\widehat{R}}_{ci}(k)\cdot {\widehat{\omega }}_i(k)$$

with all serviceable sensors primary information forms on the basis of the measured angular speeds of rotation of the wheels ω _i .

Under the assumptions about the smallness of | ψ _C |, a ₁ ≈a, a ₂ ≈a and Δω _m = 0, system (9) is reduced to

, $${\widehat{\psi }}_C$$

, $$\Delta {\widehat{V}}_{Si}$$

(1≤i≤4) по известным оценкам $${\widehat{V}}_i$$

, настроечным параметрам а и b на основании (10) приведено в алгоритме идентификации состояния органов управления автомобиля (свидетельство об официальной регистрации программы для ЭВМ №2007610819. Идентификация состояния органов управления автомобиля / Бузников С.Е., Елкин Д.С. // Роспатент, 2007). Информационное резервирование оценок $${\widehat{V}}_i$$

для ненаблюдаемых колес основано на использовании системы уравнений линейных скоростей V_i вращения колес автомобиля на вираже (10). В неполной конфигурации измерительной части системы активной безопасности достраивание оценок $$\Delta {\widehat{V}}_{Si}$$

и $${\widehat{V}}_i$$

(1≤i≤4) выполняется на основании:Solving the incorrect task of determining grades $${\widehat{V}}_m$$

, $${\widehat{\psi }}_C$$

, $$\Delta {\widehat{V}}_{Si}$$

(1≤i≤4) according to well-known estimates $${\widehat{V}}_i$$

, the tuning parameters a and b based on (10) are given in the algorithm for identifying the state of car controls (certificate of official registration of a computer program No. 2007710819. Identification of the state of car controls / Buznikov S.E., Elkin D.S. // Rospatent , 2007). Rating Reservation $${\widehat{V}}_i$$

for unobserved wheels, it is based on the use of a system of equations of linear velocities V _{i of} rotation of the wheels of a car on a bend (10). In an incomplete configuration of the measuring part of the active safety system, completing estimates $$\Delta {\widehat{V}}_{Si}$$

and $${\widehat{V}}_i$$

(1≤i≤4) is performed based on:

формируется в случае поступления сигналов с датчиков разных бортов (i,j=1, 2; 3, 4; 1, 4; 3, 2) . Если работоспособным остается только один датчик частоты вращения колеса или датчики одного борта (i,j=1, 3; 2, 4), то задается $${\widehat{\psi }}_C$$

=0 , что совпадает с ψ_C=0 на подавляющем большинстве временных интервалов движения в реальных условиях. Формирование оценки $${\widehat{V}}_m$$

в неполной конфигурации датчиков первичных измерений осуществляется аналогично формированию оценки в полной конфигурации путем исключения оценок $${\widehat{V}}_i$$

ненаблюдаемых колес.Adequate assessment $${\widehat{\psi }}_C$$

formed in the case of signals from sensors of different sides (i, j = 1, 2; 3, 4; 1, 4; 3, 2). If only one wheel speed sensor or sensors on one side (i, j = 1, 3; 2, 4) remain operational, then $${\widehat{\psi }}_C$$

= 0, which coincides with ψ _C = 0 in the vast majority of time intervals of movement in real conditions. Assessment Formation $${\widehat{V}}_m$$

in an incomplete configuration of primary measurement sensors, it is carried out similarly to the formation of an estimate in the full configuration by eliminating estimates $${\widehat{V}}_i$$

unobserved wheels.

для использования в системе (6) определяются в результате решения обратной задачи идентификации коэффициентов k_Si. Для решения этой задачи вводится допущение, что значения коэффициентов k_Si(S)=k_Si(S) для колес одного борта, а в случае отсутствия сигналов датчиков левого или правого бортов вводится допущение о равенстве k_Si(S)=k_Si(S) для всех четырех колес. Данное допущение выполняется при использовании всех четырех шин одной марки и одного типоразмера при движении по однородной поверхности.Wheel Slide Ratings $${\widehat{S}}_i$$

for use in system (6) are determined by solving the inverse problem of identifying the coefficients k _Si . To solve this problem, an assumption is introduced that the values of the coefficients k _Si (S) = k _Si (S) for wheels of one side, and in the absence of signals from the sensors of the left or right sides, the assumption is made that k _Si (S) = k _Si (S ) for all four wheels. This assumption is fulfilled when using all four tires of the same brand and one size when driving on a homogeneous surface.

для наблюдаемых колес выполняется с использованием программного обеспечения в процессе движения автомобиля, оснащенного системой. Программное обеспечение зарегистрировано в Роспатенте (Свидетельство №2007610818 об официальной регистрации программы для ЭВМ «Идентификация максимальных значений коэффициентов трения скольжения колес автомобиля» / Бузников С.Е., Елкин Д.С. // Роспатент, 2007). Входными данными для решения этой задачи являются измеряемые скольжения S_i колес и текущие значения коэффициентов трения скольжения k_Si, определяемые в соответствии с III законом Ньютона из уравнения равновесия тягово-тормозных сил и сил трения скольжения. Для ненаблюдаемых колес решается обратная задача идентификации S_i при известных $$k_{Si}^{*}$$

и вычисленных k_Si.Identification $$k_{Si}^{*}$$

for the observed wheels is performed using software during the movement of a car equipped with a system. The software is registered with Rospatent (Certificate No. 2007610818 on the official registration of the computer program “Identification of the maximum values of the sliding friction coefficients of car wheels” / S. Buznikov, D. Elkin // Rospatent, 2007). The input data for solving this problem are the measured slip S _{i of the} wheels and the current values of the sliding friction coefficients k _Si , determined in accordance with Newton’s III law from the equilibrium of the traction and braking forces and sliding friction forces. For unobserved wheels, the inverse identification problem S _i is solved for known $$k_{Si}^{*}$$

and calculated k _Si .

Traction and braking force F is balanced by the sliding friction force F _Si = F _Ni · k _Si , where F _Ni is the normal component of the dynamic load on the ith wheel,

F _i = [0.5 · M _Si · m ₀ · a _d -k _3i · U ₃ ], where

M _Si - coefficient taking into account the distribution of torque on the i-th wheel.

определяется из уравнения равновесия сил: $$\left|k_{Si}\right|=\left|F_i\right|\cdot F_{Ni}^{-1}$$

.Module $$|\; |\; |k_{Si}|\; |\; |$$

determined from the equation of equilibrium of forces: $$|\; |\; |k_{Si}|\; |\; |=|\; |\; |F_i|\; |\; |\cdot F_{Ni}^{-\mathrm{one}}$$

.

.The slip identification S _{i of the} unobservable i-th wheel is carried out on the basis of (6) using the pre-determining condition for the existence of a unique solution to the inverse problem on the slip interval $$\text{[}-{\text{S}}_{\text{i}}^{\text{*}}÷{\text{S}}_{\text{i}}^{\text{*}}\text{]}$$

.

определяются с учетом знака тягово-тормозных сил F_i на первом линейном участке кусочно-линейной аппроксимации (6):Slide Ratings $${\widehat{S}}_i$$

are determined taking into account the sign of the traction and braking forces F _i in the first linear section of the piecewise linear approximation (6):

and γ ₁ and γ ₂ are experimental coefficients.

, которые в условиях эксплуатации могут изменяться в широких пределах.The solution of the inverse identification problem S _i implies the presence of reliable estimates $$k_{Si}^{*}$$

which in operating conditions can vary within wide limits.

Information backup of wheel speed sensors in the proposed system is carried out by completing estimates of the linear rotation speed V _r and the longitudinal sliding speed ΔV _{Sr of the} rth unobservable wheel, that is, the wheel for which the speed sensor failed.

The full matrix of states of the wheel speed sensors is shown in Table 1. The symbol “1” in the table indicates the serviceable state of the corresponding sensor, the symbol “0” indicates the faulty state, C _i , 1≤i≤4 is a binary sign of the state of the wheel speed sensor of the corresponding wheel.

Table 1 State number C ₁ C ₂ C ₃ C ₄ one one one one one 2 one one one 0 3 one one 0 one four one one 0 0 5 one 0 one one 6 one 0 one 0 7 one 0 0 one 8 one 0 0 0 9 0 one one one 10 0 one one 0 eleven 0 one 0 one 12 0 one 0 0 13 0 0 one one fourteen 0 0 one 0 fifteen 0 0 0 one 16 0 0 0 0

State No. 1 from table 1 corresponds to a set of serviceable wheel speed sensors.

Estimates of the longitudinal sliding speeds of the wheels, the longitudinal velocity of the center of mass, the angle of rotation of the steered wheels, the longitudinal and transverse accelerations of the center of mass are obtained by processing data on the frequency of rotation of the wheels.

State Group No. 2; 3; 5; 9 from table 1 with one faulty wheel speed sensor.

и угла поворота управляемых колес $${\widehat{\psi }}_C$$

на основании алгоритма выбора достоверных источников данных. Для ненаблюдаемого колеса оценки скорости вращения и продольного скольжения достраиваются по уравнениям (11) и уравнению равновесия сил трения скольжения и тягово-тормозных сил (12).In this case, based on data on the rotational speeds of three wheels for which the rotational speed sensors are operational, estimates of the velocity of the center of mass are completed $${\widehat{V}}_m$$

and steering angle $${\widehat{\psi }}_C$$

based on the algorithm for selecting reliable data sources. For an unobservable wheel, estimates of rotational speed and longitudinal sliding are completed according to equations (11) and the equation of equilibrium of sliding friction forces and traction-brake forces (12).

A group of conditions with two serviceable sensors on different (left and right) sides No. 4; 7; 10; 13 from table 1.

, угла поворота управляемых колес $${\widehat{\psi }}_C$$

, скоростей продольного скольжения $$\Delta {\widehat{V}}_{Si}$$

и вращения $${\widehat{V}}_i$$

колес с исправными датчиками частот вращения определяются аналогично предыдущему; оценки скоростей скольжения и вращения для ненаблюдаемых колес достраиваются аналогично предыдущему.Estimates of the center of mass velocity $${\widehat{V}}_m$$

steering angle $${\widehat{\psi }}_C$$

, longitudinal sliding speeds $$\Delta {\widehat{V}}_{Si}$$

and rotation $${\widehat{V}}_i$$

wheels with serviceable speed sensors are determined similarly to the previous one; estimates of sliding and rotation speeds for unobserved wheels are completed similarly to the previous one.

A group of states with two sensors on one board No. 6; 11 and with one operational sensor No. 8; 12; fourteen; 15 from table 1.

принимается равной нулю, скорость центра масс $${\widehat{V}}_m(k)$$

и оценки $$\Delta {\widehat{V}}_{Si}$$

продольных скольжений для наблюдаемых колес определяется на основании алгоритма выбора достоверных источников данных. Оценки скоростей продольных скольжений и вращения для ненаблюдаемых колес определяются из (11).To determine the angle ψ _{With there are} no necessary data on the linear speeds of rotation of the wheels of different sides. Rating $${\widehat{\psi }}_C$$

taken equal to zero, the speed of the center of mass $${\widehat{V}}_m(k)$$

and assessments $$\Delta {\widehat{V}}_{Si}$$

longitudinal slides for the observed wheels is determined based on the algorithm for selecting reliable data sources. Estimates of the longitudinal slip and rotation velocities for unobserved wheels are determined from (11).

The group of conditions with four faulty wheel speed sensors is one of the inoperative ones.

Determination of pitch, roll and additional vertical component of acceleration.

The axes of the accelerometer X, Y and Z are set so that the X axis coincides with the longitudinal axis of the vehicle, Y with the transverse, and Z with the vertical.

Estimates of pitch angles α _T and roll β _{K are} determined from solving the system of equations of accelerations along the X, Y, and Z axes:

a _m and a _q are the longitudinal and transverse accelerations of the center of mass; ψ _R = (m ₁ + m ₂ ) m ₀ ^-1 ψ _C is the yaw angle; ψ _C is the angle of rotation of the steered wheels; ξ _x , ξ _y, and ξ _z are the measurement noise of the accelerometer along the X, Y, and Z axes, including their own noise, vibration acceleration along the axes, as well as errors caused by additional roll angles and attack of the car relative to the road.

For the measured a _m and a _{q, the} estimates of the angles α _T , β _K and the additional acceleration component Δа _z for small a.,., B are equal to:

The assumption that α _T , β _K and Δ a _z slowly changes over time, as well as high-frequency noise measurements of ξ _x , ξ _y and ξ _z with zero mean values, allows filtering the estimates of α _T , β _K and Δ a _z using a discrete low-pass filter first order:

, $${\beta }_K^{*}(k)\approx {\beta }_K(k)$$

и $$\Delta {\widehat{a}}_z^{*}(k)\approx \Delta a_z(k)$$

.where T is the time constant of the low-pass filter; ΔT is the integration step. In this case $${\widehat{\alpha }}_T^{*}(k)\approx {\alpha }_T(k)$$

, $${\beta }_K^{*}(k)\approx {\beta }_K(k)$$

and $$\Delta {\widehat{a}}_z^{*}(k)\approx \Delta a_z(k)$$

.

The building of temperature estimates at critical points of the tire is based on the property established on the basis of experimental data (Guslitser RL Tire and car. - M.: Scientific and Technical Center "NIISHP", 2007. - 283 pp.), Which consists in steady-state thermal conditions, the ratio of temperatures at various points of the multilayer tire structure is maintained at different speeds. Knowing the experimental coefficients of this proportion for a particular tire model, it is possible to complete estimates of superheat temperatures at critical points of the tire, which, in particular, include the shoulder of the tire, where three layers converge (tread, breaker, and carcass), and in case of critical overheating, destruction begins tires (delamination).

System benefits

Among the advantages of the proposed method and system for preventing accidental overheating of tires and car brakes, it is possible to single out the possibility of building adequate temperature estimates for all four tires and all four wheel braking devices both in the full configuration of the wheel speed sensors and in the event of failure of one or more primary information sensors (wheel speed sensors and a three-axis accelerometer) up to the state with one working wheel speed sensor, system implementation in min mally possible configuration of primary data sensors, low power consumption, the lack of restrictions on the types of used tires, in a data processing system using software that allows to increase the number of functions performed by the system without making any changes in the hardware configuration of the system.

Claims (4)

1. A method of preventing accidental overheating of tires and brakes of a car, which consists in recording signals generated by pulse sensors of the vehicle’s wheel speeds, a three-axis accelerometer and an ambient temperature sensor, and transmitting them through the interface unit to the information processing unit, in which the values of physical variables and compare them with the boundary values characterizing the critical condition of the car, and form control signals transmitted at the output of the information processing unit e to the output device of graphical information and / or to indicators of dangerous conditions, characterized in that in the information processing unit in real time, estimates of the temperature of the superheat of the tires, wheel braking devices of the vehicle and boundary speeds are determined, which are determined from the condition that the braking movement at any time a full stop with the exit at the moment of a full stop to the limit values of the temperature of the tire and / or brake devices overheating, based on signals about the frequencies of rotation of the wheels, about accelerations from Elerometer, about the ambient temperature and tuning parameters using a microcontroller with software, and form control actions on the output device of graphic information to transmit information to the driver about the temperature conditions of tires and brake devices of the car, as well as about approaching or exceeding critical temperatures of critical overheating or to the critical critical overheating speeds, in this case, at least one more means of indicating dangerous conditions s to attract the driver's attention. 2. A system for preventing accidental overheating of tires and brakes of a vehicle, including wheel speed sensors and a three-axis accelerometer associated with a linking unit, a data processing unit that receives signals from the wheel speed sensors of a car and a three-axis accelerometer by means of communication lines and a linking unit and forms, on their basis and on the basis of tuning parameters, estimates of physical parameters characterizing the state of the car, forming control actions on the graphic information output device (LCD) and hazardous state indicators, an information input and display unit including an input device for inputting configuration information and selecting an information display mode, a graphic information output device, hazardous status indicators, a secondary power source that provides stabilization and conversion of voltage received from the vehicle’s on-board network into voltage values necessary for powering the microcontroller, visual display means information, a three-axis accelerometer and an ambient temperature sensor. 3. The system according to claim 2, characterized in that the completion of adequate temperature estimates for all four tires and all four wheel braking devices can be performed both in the full configuration of the wheel speed sensors and in the event of failure of one or more primary information sensors (sensors wheel speeds and a three-axis accelerometer) up to a state with one working wheel speed sensor. 4. The system according to claim 2, characterized in that it further comprises an ambient temperature sensor for receiving by the microprocessor a signal about the ambient temperature necessary for automatically entering the ambient temperature value.

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