Heavy Vehicle Emergency Braking System Based on Central Inflation and Deflation Tires

Abstract

The invention discloses an emergency braking system for heavy vehicles based on central inflation and deflation tires, which includes an ECU controller, an air storage tank, a tank pressure sensor, and tires. A tire pressure sensor and a tire temperature sensor are arranged inside the tires, and an air deflation solenoid valve and an air inflation solenoid valve are arranged on the tires. The air storage tank, the tank pressure sensor, the tire pressure sensor and the tire temperature sensor arranged inside the tires are respectively connected to the ECU controller, and the air deflation solenoid valve and the air inflation solenoid valve are also respectively connected to the ECU controller. The system has four braking modes: overloading monitoring, rollover monitoring, air leakage / flat tire monitoring, and mountainous working condition identification. The invention realizes the emergency braking of heavy vehicles in case of overloading, rollover, air leakage / flat tire, and mountainous working conditions through the four braking modes, thus improving the driving safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of automotive tire braking, and particularly relates to an emergency braking system for heavy vehicles based on a central inflation and deflation tire. Background Art

[0002] The braking system of large trucks generally includes two parts: a service brake (brake) and an auxiliary braking system (gear braking, engine exhaust braking, retarder braking, etc.). Among them, the service brake is generally used for temporary and rapid braking in case of emergency and is not suitable for continuous braking; while the auxiliary braking system is designed for continuous braking during continuous downhill driving. Prolonged use of engine braking is likely to cause damage to the engine and transmission. However, exhaust braking is only an auxiliary brake and cannot replace the vehicle braking system. It can only be used to reduce and control the vehicle speed, cannot provide rapid deceleration and emergency braking, and is prone to dangerous situations such as skidding and tire slippage on ice or slippery roads. Due to disadvantages such as large volume, high cost, and easy damage at high temperatures, it is difficult for retarders to be widely used.

[0003] For heavy-duty trucks during driving, the existing driving resistances always include air resistance and rolling resistance. However, for heavy-duty trucks in plateau mountainous areas, they generally drive at medium and low speeds, and the influence of air resistance is not as large as that of rolling resistance. During a long downhill drive, in order to control the vehicle speed, the brakes are frequently used, resulting in a certain degree of heat fade phenomenon, causing a significant decline in braking force. Watering for cooling in winter is likely to cause road icing and easily lead to accidents. In mountainous areas, there are characteristics of large summer rainfall, slippery road surfaces, and easy icing of snow on roads in winter, resulting in a low road adhesion coefficient and an extended braking distance.

[0004] The basic principle of continuous downhill braking of a vehicle is actually a process of mutual conversion of potential energy, kinetic energy, and heat energy. During the process of driving from the top of the slope to the bottom, the gravitational potential energy of the vehicle will naturally be converted into the kinetic energy of the vehicle's driving and the heat energy of the vehicle's braking system. The service brake of a heavy vehicle is prone to heat fade phenomenon. To improve the braking force of the vehicle, on the one hand, the tire pressure is adjusted through a central tire inflation system to increase the tire rolling resistance coefficient and increase the rolling resistance to increase the braking force and reduce the braking distance; on the other hand, through the dynamic adjustment of the tire pressure, the vehicle adhesion coefficient in complex situations is increased, and at the same time, the balance of the whole vehicle is adjusted. Summary of the Invention

[0005] The purpose of the present invention is to provide an emergency braking system for heavy vehicles based on a central inflation and deflation tire. By monitoring the tire pressure, it can roughly estimate whether the vehicle is overloaded before driving; during driving, it can automatically adjust the air pressure to keep the tire pressure near the standard value; when encountering emergency braking, it can reduce the tire pressure to increase the rolling resistance and reduce the braking distance.

[0006] To achieve the above object, the present invention provides the following technical solutions: A heavy vehicle emergency braking system based on a central inflation and deflation tire, including an ECU controller, an air storage tank, a tank pressure sensor, and a tire. A tire pressure sensor and a tire temperature sensor are provided inside the tire, and an air deflation solenoid valve and an air inflation solenoid valve are provided on the tire; the air storage tank, the tank pressure sensor, the tire pressure sensor and the tire temperature sensor provided inside the tire are respectively connected to the ECU controller, and the air deflation solenoid valve and the air inflation solenoid valve are also respectively connected to the ECU controller; the system has four braking modes: overloading monitoring, rollover monitoring, air leakage / flat tire monitoring, and mountain condition recognition; among them,

[0007] (1) Overloading monitoring braking mode:

[0008] During the static inspection of the vehicle, the current air pressure is analyzed through an atmospheric pressure sensor to analyze the influence on the tire pressure. According to: plain tire pressure + (plain atmospheric pressure - high altitude pressure) = actual tire relative pressure, calculate how much air pressure needs to be released; adjust the vehicle air pressure to T0 to increase the friction when the vehicle is driving on the plateau and avoid the risk of flat tires. T0 is the standard tire pressure for the vehicle when it is unloaded.

[0009] [[ID=!0]]When the vehicle is static, the vehicle tire pressure continuously remains at the standard tire pressure value; when loading the vehicle, the tire pressure sensor reads the tire pressure of the loaded vehicle and sends the read data to the ECU controller; after receiving the data, the ECU controller compares the relationship between the load and the tire pressure to initially estimate the load at this time.

[0010] (2) Rollover monitoring braking mode:

[0011] A. The tire pressure sensors monitor the tire pressures on both sides of the vehicle and transmit the data to the ECU controller; when the tire pressure on one side decreases and there is no air leakage factor for this tire, while the tire pressure on the opposite side increases, calculate the tire pressure difference between the two sides; when it exceeds 20% of the full load tire pressure value, enter the next judgment logic.

[0012] B. Monitor whether the roll angle of the vehicle is greater than 15 degrees. If it is greater than 15 degrees, it is considered that there is a risk of rollover. Start to voice-remind the driver and deflate the tires on the opposite side to lower the center of mass and reduce the speed.

[0013] a. If the driver adjusts the vehicle and the roll angle is less than 15 degrees, this module ends.

[0014] b. If the roll angle of the vehicle further increases, the roll angle is greater than the requirement of 35 degrees in the national standard test, and the tire pressure difference between the two sides is greater than 50%, it is considered that the rollover is inevitable. The engine shuts down and enters the instrument power state. The vehicle sounds the horn and turns on the hazard lights. The power steering of the steering wheel decreases. The glass on both sides of the cab drops, and the airbag pops out.

[0015] C. If the roll angle of the monitored vehicle is between 15 - 36 degrees, continuously reduce the air pressure and limit the vehicle speed until it stops; if the vehicle does not roll over, the tire inflation system only inflates when the vehicle is stationary.

[0016] (3)Leakage / Burst Tire Monitoring Braking Method:

[0017] Burst Tire Monitoring: The tire temperature sensor monitors the tire temperature and transmits the data to the ECU controller; when the tire temperature reaches 90 degrees, remind the driver to rest; when the tire temperature exceeds 120°, turn on the hazard lights and limit the vehicle speed to 70 km / h.

[0018] Leakage Monitoring:

[0019] Through the analysis of the tire pressure sensor, if the tire pressure continuously drops in the past 5 seconds, or the tire pressure drop value exceeds 10%, it is considered that there is a possibility of leakage; analyze the tire pressure drop rate per second or the tire pressure has dropped to 60% of the tire pressure before the drop, voice prompt the leakage rate, remind the driver to stop, open the inflation valve, deflate the opposite tire, keep the tire pressure difference between the two sides within 10%, and turn on the hazard lights; the vehicle starts to slow down automatically until it stops; if there is only a slow leakage, remind the driver to pay attention to the tire, if the tire pressure remains low for 5 minutes, remind the driver to stop and check.

[0020] (4)Mountainous Working Condition Identification Braking Method:

[0021] Analyze the characteristics of the mountainous working conditions in the plateau area, and it is concluded that the mountainous roads in the plateau area have sharp bends, steep slopes, and continuous downhill road conditions, and extract the driving characteristics. The specific characteristics are as follows: the difference between the maximum height and the minimum altitude within 90 seconds is 20 meters, the number of brakings within 90 seconds is greater than 2 times, the average opening of the brake pedal within 90 seconds is greater than 30%, the braking time ratio within 90 seconds is greater than 20%, and the cumulative steering wheel rotation angle within 90 seconds is greater than 120 degrees.

[0022] As long as three of the above five characteristics are met, it is considered a mountainous working condition, and then combined with whether the single braking duration is greater than 15 seconds, judge whether it is a long downhill working condition.

[0023] Preferably, in the overload monitoring braking, the relationship between the load and the tire pressure is as follows:

[0024] A. If the load tire pressure is less than or equal to T1, initially adjust it to the standard tire pressure.

[0025] B. If the load tire pressure is greater than T1 and less than T1.3, it means that the vehicle is overloaded but less than 30%. At this time, remind the driver of overloading and limit the vehicle speed to 80 km / h.

[0026] C. If the loaded tire pressure is greater than T1.3 and less than T1.5, it means the vehicle is overloaded by more than 30% and less than 50%. The driver will be reminded of the overload and the vehicle speed will be limited to 65 km / h.

[0027] D. If the loaded tire pressure is greater than T1.5 and less than T2, it means the vehicle is overloaded by more than 50% but less than 100%. The driver will be reminded of the overload and the vehicle speed will be limited to 50km / h. The vehicle cannot enter the highway and the OBD system will upload the information remotely. If the vehicle obtains special overload transportation items, the background monitoring system will lift the speed limit for the vehicle.

[0028] E. If the tire pressure is greater than T2 or T9, it means the vehicle is overloaded by more than 100% or has reached the tire pressure limit. Driving at this time is dangerous and the driver will be reminded of the overload, the double flash lights will remain on, and the vehicle speed will be limited to 30km / h. The vehicle cannot enter the highway and remote upload is made via OBD. If the vehicle obtains documents such as special documents for transporting overloaded items, the background monitoring system will lift the speed limit for the vehicle.

[0029] Among them, T1 is the static load of the car when fully loaded, T1.3 is the static load of the car when fully loaded plus 0.3 times, T1.5 is the static load of the car when fully loaded plus 0.5 times, T2 is the static load of the car when fully loaded plus 1 times, and T9 is the maximum pressure value of the car tire.

[0030] Preferably, in mountainous conditions, through combined camera recognition and joint judgment, in both mountainous conditions and long downhill conditions, if the driver performs full emergency braking, the brake pedal is fully open and the time exceeds 2 seconds, the vehicle will reduce the tire pressure from the last wheel to 50%; all auxiliary brakes start to work to increase braking force; for mountainous conditions, frequent light braking and turning can easily cause the brake and tire temperatures to rise, resulting in a decrease in braking performance. When the tire temperature sensor is greater than 90 degrees or the brake temperature is greater than 260 degrees, the driver is reminded to take a break, the tire pressure is reduced to 80% of the full-load standard tire pressure, and the vehicle speed is limited to 60km / h until the vehicle stops; in long downhill conditions, the tire pressure is reduced to 80% of the full-load standard tire pressure, and the vehicle speed is limited to 60km / h, increasing the vehicle's rolling resistance, improving braking performance, and slowing down the decline in braking performance caused by the rise in brake temperature. When the brake fails, the tire pressure is reduced to 30% to complete vehicle control.

[0031] Preferably, the structure of the tire in the tire blowout monitoring is as follows: multiple separate small inner tubes are added to the tire inner tube, and adjacent small inner tubes are connected by a one-way valve, and the last small inner tube is connected to the large inner tube; when inflating, the small inner tubes are inflated first, and when the small inner tubes are full, the large inner tubes are inflated; when deflating, the air in the large inner tubes is first added; when the tire blows out, the large inner tube is punctured, and the small inner tubes still have air, which will not cause the vehicle to lose control. The inflation valve is opened to add air, allowing the driver to move the vehicle to a safe area.

[0032] The present invention collects information on atmospheric pressure, tire pressure, tire temperature, braking temperature, and deceleration, and adjusts the tire pressure to adapt to the current driving conditions. When the vehicle is turned off, the tire pressure is adjusted to the standard tire pressure, and after analyzing the tire pressure after the vehicle is loaded, the weight of the vehicle is roughly estimated. The air pressure is adjusted according to the driving situation faced, increasing the rolling resistance, increasing the braking force, and reducing the braking distance; in case of emergency braking, the air can be quickly released from the rear tires to the front tires in sequence to improve safety.

[0033] The theoretical basis of the present invention: According to the empirical formula in automotive theory regarding the relationship between the rolling resistance coefficient and vehicle speed and inflation pressure, when the tire pressure drops by 32%, the rolling resistance coefficient increases by 23%. This is because the higher the air pressure, the smaller the tire deformation and the resulting hysteresis loss, and the smaller the rolling resistance. Conversely, the rolling resistance increases. The tire rolling resistance and the rolling resistance coefficient value are related to its speed, and the faster the speed, the lower the rolling resistance and the rolling resistance coefficient value, while most trucks travel at medium and low speeds. The rolling resistance is equal to the product of the automotive rolling resistance coefficient and the wheel load. For a fully loaded truck, an increase in the rolling resistance coefficient of 23% is a relatively large braking force; as Figure 7 shown in the relationship between the rolling resistance coefficient and vehicle speed and inflation pressure.

[0034] The beneficial effects of the present invention:

[0035] By setting the relationship between the static vehicle load and tire pressure, the vehicle is roughly estimated whether it is overloaded, and different countermeasures are set according to different overloading rates in accordance with the traffic law, and the overloaded vehicles can be monitored remotely through OBD, greatly improving safety; trucks have air storage tanks, and it is more convenient to implement the tire inflation system;

[0036] 2. When the vehicle is loaded or cornering, the tire pressure of each tire of the vehicle can be adjusted to maintain the tire pressure balance as a whole to adjust the balance of the whole vehicle;

[0037] 3. By monitoring the tire pressure to determine whether the vehicle rolls over, the driving safety is improved;

[0038] 4. Designing a new type of tire can better handle emergency tire blowouts, air leakage identification, and inflation strategies;

[0039] 5. Identification of high-altitude mountainous working conditions and long downhill working conditions;

[0040] 6. By reducing the tire pressure to increase the rolling resistance and reduce the braking distance; to ensure the safe operation of the vehicle, during driving, except for air leakage, other inflations need to be carried out when the vehicle is stationary; there is no restriction on deflation;

[0041] 7. An automatic deflation system combined with AEB, combined with AEB triggering conditions, automatically deflates the tires during automatic emergency braking, improves the adhesion coefficient, increases the braking force, and fully considers the situation of braking force attenuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the system of the present invention;

[0043] Figure 2 It is a flowchart of overloading monitoring braking;

[0044] Figure 3 It is a flowchart of rollover monitoring braking;

[0045] Figure 4 It is a flowchart of air leakage / flat tire monitoring braking;

[0046] Figure 5 It is a flowchart of mountainous working condition identification braking;

[0047] Figure 6 It is a schematic diagram of the new tire designed by the present invention;

[0048] Figure 7 It is a graph of the relationship between the rolling resistance coefficient, vehicle speed, and inflation pressure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the embodiments regarding specific technologies, connection relationships, or conditions, they shall be carried out according to the technologies, connection relationships, and conditions described in the literature in this field or according to the product specifications. For those materials, instruments, or equipment not specified as the manufacturer, they are all conventional products that can be obtained by purchase.

[0051] As Figure 1 shown, the heavy vehicle emergency braking system based on central inflation and deflation tires provided by the present invention includes an ECU controller, an air storage tank, a tank pressure sensor, and tires. A tire pressure sensor and a tire temperature sensor are arranged inside the tires, and an air deflation solenoid valve and an air inflation solenoid valve are arranged on the tires; the air storage tank, the tank pressure sensor, the tire pressure sensor, and the tire temperature sensor arranged inside the tires are respectively connected to the ECU controller, and the air deflation solenoid valve and the air inflation solenoid valve are also respectively connected to the ECU controller; the system has four braking methods: overloading monitoring, rollover monitoring, air leakage / flat tire monitoring, and mountainous working condition identification; among them,

[0052] (1)Overload monitoring and braking

[0053] The longitudinal adhesion coefficient between a heavy-duty truck and the road surface during braking is only related to the vehicle load rate. As the load rate increases, the vehicle braking deceleration gradually decreases, and the longitudinal adhesion coefficient decreases.

[0054] On April 1, 2022, China implemented new traffic regulations. If a freight truck is overloaded by more than the approved load but less than 30%, 1 point will be deducted at a time; if the freight truck is overloaded by more than 30% and less than 50%, 3 points will be deducted; if the freight truck is overloaded by more than 50%, the circumstances are relatively serious and 6 points will be deducted. Through static load testing of the vehicle, the tire air pressures under full load, full load plus 0.3 times, 0.5 times, and 1 times the load mass are obtained respectively, denoted as T1, T1.3, T1.5, and T2, and markings are established. The standard tire pressure T0 of the vehicle when unloaded is also entered into the system; when there are many tires, multiple tire air pressures are obtained, and the average air pressure of the total number of tires is analyzed.

[0055] As Figure 2 shown, during the static inspection of the vehicle, the current air pressure is analyzed through an atmospheric pressure sensor to analyze the impact on the tire pressure (the atmospheric pressure decreases at high altitudes and the tire pressure increases). According to: Plain tire pressure + (Plain atmospheric pressure - High altitude pressure) = Actual relative tire pressure, calculate how much air pressure needs to be released; adjust the vehicle air pressure to T0 to increase the friction when the vehicle is driving on the plateau and avoid the risk of tire blowout. T0 is the standard tire pressure of the vehicle when unloaded.

[0056] When the vehicle is static, the vehicle tire pressure is continuously maintained at the standard tire pressure value; when loading the vehicle, the tire pressure sensor reads the tire pressure of the loaded vehicle and sends the read data to the ECU controller; after receiving the data, the ECU controller compares the load-tire pressure relationship to initially estimate the load at this time:

[0057] A. If the load tire pressure is less than or equal to T1, it is initially adjusted to the standard tire pressure;

[0058] B. If the load tire pressure is greater than T1 and less than T1.3, it means the vehicle is overloaded but less than 30%. At this time, the driver will be reminded of the overload and the vehicle speed will be limited to 80 km / h;

[0059] C. If the load tire pressure is greater than T1.3 and less than T1.5, it means the vehicle is overloaded by more than 30% and less than 50%. At this time, the driver will be reminded of the overload and the vehicle speed will be limited to 65 km / h;

[0060] D. If the loaded tire pressure is greater than T1.5 and less than T2, it means the vehicle is overloaded by more than 50% but less than 100%. The driver will be reminded of the overload and the vehicle speed will be limited to 50km / h. The vehicle cannot enter the highway and the OBD system will upload the information remotely. If the vehicle obtains special overload transportation items, the background monitoring system will lift the speed limit for the vehicle.

[0061] E. If the tire pressure is greater than T2 or T9, it means the vehicle is overloaded by more than 100% or has reached the tire pressure limit. Driving at this time is dangerous and the driver will be reminded of the overload, the double flash lights will remain on, and the vehicle speed will be limited to 30km / h. The vehicle cannot enter the highway and remote upload is made via OBD. If the vehicle obtains documents such as special documents for transporting overloaded items, the background monitoring system will lift the speed limit for the vehicle.

[0062] (2) Rollover monitoring brake

[0063] When a loaded vehicle is loaded, uneven loading is likely to occur, resulting in inconsistent tire pressure, which can easily cause rollover during driving. At this time, find the tire with higher tire pressure on the side with heavier load and add air to that side; for the tire with lower tire pressure on the side with lighter load, deflate it appropriately, but the pressure should not exceed plus or minus 20% of the full load standard pressure for fine-tuning.

[0064] The increased rolling resistance during cornering is close to 50%-100% of that during straight-line driving. When driving on a sharp bend, due to the large size of the truck, it is easy to roll over due to inertia when turning at a high speed, especially when the cargo is high, the center of gravity of the vehicle will move up; when driving to a sharp bend, the inertia of the cargo on the vehicle is too large and exceeds the supporting force of the wheels and the vehicle board, and the vehicle will roll over. During the driving process of the vehicle, the pressure of each tire of the vehicle is monitored. When the vehicle is about to roll over, one wheel will leave the ground, the tire pressure will change, and the tire pressure on the rolling side will increase due to the increased pressure. This theory is used to determine whether the vehicle will roll over. Figure 3 As shown:

[0065] A. The tire pressure sensors monitor the tire pressure on both tires and transmit the data to the ECU. When the pressure on one tire decreases and there is no leakage, while the pressure on the opposite tire increases, the pressure difference between the two tires is calculated. If the pressure exceeds 20% of the fully loaded tire pressure, the next step is determined.

[0066] B. Monitors the vehicle's roll angle to see if it's greater than 15 degrees. If so, it's considered a rollover risk and the driver will be alerted by voice and the tire on the opposite side will be deflated, lowering the center of mass and reducing speed.

[0067] a. If the driver adjusts the vehicle's roll angle to less than 15 degrees, the module ends;

[0068] b. If the vehicle roll angle further increases and is greater than the requirement of 35 degrees in the national standard test, and the tire pressure difference between the two sides is greater than 50% (the rollover limit condition is that one side tire leaves the ground, all the weight is loaded on the opposite side tire, the tire pressure of the opposite side rises sharply, and the tire pressure of the side leaving the ground gradually decreases), it is considered that rollover is inevitable. The engine shuts off and enters the instrument power state, the vehicle sounds the horn and turns on the hazard lights, the steering assist decreases, the glass on both sides of the cab drops, and the airbag deploys;

[0069] C. When the monitored vehicle roll angle is between 15 - 36 degrees, continuously reduce the air pressure and limit the vehicle speed until it stops; if the vehicle does not roll over, the tire inflation system inflates only when the vehicle is stationary;

[0070] (3)Leakage / flat tire monitoring and braking, and its process is as Figure 4 shown:

[0071] Flat tire monitoring: In summer, the ground temperature is high, and long - term driving is likely to cause the tires to be overheated, which is likely to lead to flat tires; monitor the tire temperature through the tire temperature sensor and transmit the data to the ECU controller; when the tire temperature reaches 90 degrees, remind the driver to rest; when the tire temperature exceeds 120°, turn on the hazard lights and limit the vehicle speed to 70 km / h; in order to prevent flat tires, the present invention controls the tire pressure difference between the two sides within 10% to adjust the vehicle balance; specifically, for the situation where the vehicle is initially loaded unevenly, resulting in inconsistent tire pressures of the vehicle, it will automatically reduce the air pressure of the tire with the lower pressure, and keep the tire pressure difference between the two tires within 10%.

[0072] Leakage monitoring:

[0073] Through the analysis of the tire pressure sensor, if the tire pressure continuously drops for nearly 5 seconds, or the tire pressure drop value exceeds 10%, it is considered that there is a possibility of leakage; analyze the tire pressure drop rate every second or when the tire pressure has dropped to 60% of the tire pressure before the drop, and give a voice prompt of the leakage rate, remind the driver to stop the vehicle, open the inflation valve, deflate the opposite side tire, keep the tire pressure difference between the two sides within 10%, and turn on the hazard lights; the vehicle starts to automatically slow down until it stops; if there is only slow leakage, remind the driver to pay attention to the tire, and if the tire pressure remains low for 5 minutes, remind the driver to stop and check;

[0074] (4)Mountainous working condition identification and braking

[0075] Relevant research shows that the adhesion coefficient between an 11-ton unladen truck and the road surface is 0.6. However, when fully loaded with 25 tons, the adhesion coefficient between the tires and the road surface is 0.41, which is only 66.6% of that in the unladen state. The rolling resistance of the tires and the value of the rolling resistance coefficient are related to their speed, and the slower the speed, the higher the rolling resistance and the value of the rolling resistance coefficient. For heavy medium- and low-speed trucks, the proportion of rolling resistance is relatively high. According to the research data, the load has a significant impact on the adhesion coefficient between the tires and the road surface, and the maximum braking deceleration under different loads is further calculated. Overloaded trucks are more likely to cause accidents when driving on mountain roads; when overloaded by 50%, the maximum deceleration drops by 22%. When driving in mountainous areas, there are road conditions such as sharp bends, steep slopes, and continuous downhill sections, which often lead to vehicle braking, resulting in excessively high tire temperatures, poor rubber strength, and prone to accidents such as tire blowouts. At the same time, it will also cause the brake drum temperature to be too high, resulting in thermal decay and a serious decline in braking performance. The following table shows the relationship between the overload rate, adhesion coefficient, and maximum deceleration.

[0076]

[0077] As Figure 5 shown, by analyzing the characteristics of the plateau mountainous working conditions, it is concluded that the plateau mountain roads have road conditions such as sharp bends, steep slopes, and continuous downhill sections. The driving characteristics are extracted, and combined with relevant literature research, the driving characteristics in mountainous areas are obtained, including three aspects: road characteristics, braking characteristics, and steering wheel rotation characteristics. The specific characteristics are as follows: the difference between the maximum height and the minimum altitude within 90 seconds is 20 meters, the number of brakings within 90 seconds is more than 2 times, the average opening of the brake pedal within 90 seconds is greater than 30%, the proportion of braking time within 90 seconds is greater than 20%, and the cumulative rotation angle of the steering wheel within 90 seconds is greater than 120 degrees;

[0078] As long as three of the above five features are met, it is considered a mountainous working condition. Then, combined with whether the single braking duration is greater than 15 seconds (when conducting actual tests in relevant papers, it was statistically found that the average single braking time in mountainous areas is 14 seconds), it is determined whether it is a long downhill working condition; combined with camera recognition for joint judgment. In both working conditions, if the driver performs a full-power emergency braking, the brake pedal is fully opened and the time exceeds 2 seconds, the tire pressure of the vehicle will be reduced to 50% starting from the last wheel in sequence; all auxiliary brakes start to work to increase the braking force; for mountainous working conditions, frequent slight braking and turning are likely to cause the temperature of the brakes and tires to rise, resulting in a decline in braking performance. When the tire temperature sensor is greater than 90 degrees or the brake temperature is greater than 260 degrees, the driver is reminded to rest, the tire pressure is reduced to 80% of the full-load standard tire pressure, and the vehicle speed is limited to 60 km / h until the vehicle stops; in the long downhill working condition, the tire pressure is reduced to 80% of the full-load standard tire pressure, the vehicle speed is limited to 60 km / h, the rolling resistance of the vehicle is increased, the braking performance is improved, the decline in braking performance caused by the rise in the brake temperature is slowed down, and when the brake fails, the tire pressure is reduced to 30% to complete vehicle control. There is also a manual method for braking in the long downhill working condition. When the braking force fails, step on the brake hard for more than 2 seconds, and the tire pressure is reduced to 30% to achieve braking.

[0079] In the case of a flat tire, the tire pressure becomes 0 within 0.1 second, and the reaction time is extremely short. As Figure 6 shown, the present invention designs a new type of tire to prevent the danger after a flat tire. Six separate small inner tubes 1 are added to the inner tube of the tire, and adjacent small inner tubes 1 are connected through one-way valves 2. The last small inner tube 1 is connected to the large inner tube 3; when inflating, first inflate from the small inner tubes 1. When all the small inner tubes 1 are full, then inflate the large inner tube 3; when deflating, first deflate the large inner tube 3; when a flat tire occurs, the large inner tube 3 is punctured, and the small inner tubes 1 still have air, which will not cause the vehicle to lose control. Open the inflation valve to replenish air and let the driver move the vehicle to a safe area; in the figure, 4 - built-in tire pressure monitor, 5 - valve core solenoid valve.

[0080] The ground braking force first depends on the brake braking force, but at the same time is limited by the adhesion. The ground braking force cannot exceed the adhesion. During emergency braking, reducing the air pressure increases the contact area between the tire and the ground, resulting in an increase in the adhesion coefficient. At the same time, the maximum braking force is increased, the braking distance is reduced, and the safety of the vehicle is improved.

[0081] The time to collision (TTC) refers to the time required for a moving vehicle to calculate a possible collision with an object ahead, which is defined as the distance between the vehicle and the obstacle divided by the relative speed. When the TTC is less than the AEB threshold, the system applies emergency braking at a certain deceleration. However, for heavy vehicles, phenomena such as overloading and thermal fade may occur, resulting in a decrease in the maximum deceleration. Calculating according to the designed deceleration may cause traffic accidents, and the maximum deceleration at this time cannot be predicted, which will have a greater impact on the AEB calculation.

[0082] The tire deflation method in the present invention can also be used in AEB. When the AEB of a fully loaded truck starts to decelerate at a certain deceleration, the actual maximum deceleration is less than the designed value. When the AEB is triggered, the tire deflates quickly to increase the deceleration to ensure vehicle safety. When the tire pressure is deflated to 40% of the standard tire pressure, the deflation stops, or the deflation also stops when the vehicle stops.

[0083] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any minor modifications, equivalent replacements, and improvements made to the above embodiments based on the technical essence of the present invention shall be included within the protection scope of the technical solution of the present invention.

Claims

1. Heavy vehicle emergency braking system based on a central inflation and deflation tire, characterized in that, It includes an ECU controller, an air storage tank, a tank pressure sensor, and tires. A tire pressure sensor and a tire temperature sensor are provided inside the tire, and an air release solenoid valve and an air inflation solenoid valve are provided on the tire. The air storage tank, the tank pressure sensor, the tire pressure sensor and the tire temperature sensor inside the tire are respectively connected to the ECU controller, and the air release solenoid valve and the air inflation solenoid valve are also respectively connected to the ECU controller. This system has four braking modes: overloading monitoring, rollover monitoring, air leakage / tire blowout monitoring, and mountainous working condition identification. Among them, (1) Overloading monitoring braking mode: During the static inspection of the vehicle, the current air pressure is analyzed through an atmospheric pressure sensor to analyze the impact on the tire pressure. According to: Plain tire pressure + (Plain atmospheric pressure - High altitude pressure) = Actual relative tire pressure, calculate how much air pressure needs to be released. Adjust the vehicle air pressure to T0 to increase the friction when the vehicle is driving on the plateau and avoid the risk of tire blowout. T0 is the standard tire pressure for the vehicle when it is unloaded. When the vehicle is static, the vehicle tire pressure continuously remains at the standard tire pressure value. When loading the vehicle, the tire pressure sensor reads the tire pressure of the loaded vehicle and sends the read data to the ECU controller. After receiving the data, the ECU controller compares the relationship between the load and the tire pressure to preliminarily estimate the load at this time. (2) Rollover monitoring braking mode: A. The tire pressure sensor monitors the tire pressure of both sides of the tire and transmits the data to the ECU controller. When the tire pressure on one side decreases and there is no air leakage factor for this tire, while the tire pressure on the opposite side increases, calculate the tire pressure difference between the two sides. When it exceeds 20% of the full-load tire pressure value, enter the next judgment logic. B. Monitor whether the roll angle of the vehicle is greater than 15 degrees. If it is greater than 15 degrees, it is considered that there is a rollover risk, start to voice-remind the driver and deflate the tires on the opposite side to lower the center of mass and reduce the speed. a. If the driver adjusts the vehicle and the roll angle is less than 15 degrees after that, the rollover monitoring braking module ends. b. If the roll angle of the vehicle further increases, the roll angle is greater than the requirement of 35 degrees, and the tire pressure difference between the two sides is greater than 50%, it is considered that the rollover is inevitable. The engine shuts down and enters the instrument power state. The vehicle sounds the horn and turns on the hazard lights. The power steering of the steering wheel decreases. The glass on both sides of the cab descends, and the airbag pops out. C. When the roll angle of the vehicle is between 15 - 36 degrees, continuously reduce the air pressure and limit the vehicle speed until it stops. If the vehicle does not roll over, the tire inflation system only inflates when the vehicle is stationary. (3) Air leakage / tire blowout monitoring braking mode: Tire blowout monitoring: The tire temperature sensor monitors the tire temperature and transmits the data to the ECU controller. When the tire temperature reaches 90 degrees, remind the driver to rest. When the tire temperature exceeds 120°, turn on the hazard lights and limit the vehicle speed to 70 km / h. Air leakage monitoring: Through the analysis of the tire pressure sensor, if the tire pressure has been continuously decreasing for the past 5 seconds, or the decrease in tire pressure exceeds 10%, it is considered that there may be a leak; analyze the tire pressure decrease rate every second or if the tire pressure has decreased to 60% of the tire pressure before the decrease, the voice will prompt the leak rate, reminding the driver to stop the vehicle, open the inflation valve, deflate the tire on the opposite side, keep the tire pressure difference between the two sides within 10%, and turn on the hazard lights; the vehicle will start to slow down automatically until it stops; if there is only a slow leak, the driver will be reminded to pay attention to the tire, and if the tire pressure remains low for 5 minutes, the driver will be reminded to stop and check; (4)Brake mode identification for mountain conditions: Analyze the characteristics of high-altitude mountain conditions, and it is concluded that the roads in high-altitude mountain areas have sharp turns, steep slopes, and continuous downhill conditions. Extract the driving characteristics, and the specific characteristics are as follows: the difference between the maximum height and the minimum altitude within 90 seconds is 20 meters, the number of braking times within 90 seconds is greater than 2, the average opening of the brake pedal within 90 seconds is greater than 30%, the proportion of braking time within 90 seconds is greater than 20%, and the cumulative steering wheel rotation angle within 90 seconds is greater than 120 degrees; As long as three of the above five characteristics are met, it is considered a mountain condition, and combined with whether the single braking duration is greater than 15 seconds, it is judged whether it is a long downhill condition.

2. The heavy vehicle emergency braking system based on a central inflation and deflation tire according to claim 1, wherein, In the overloading monitoring and braking, the comparison of the relationship between the load and the tire pressure is as follows: A. If the load tire pressure is less than or equal to T1, it will be initially adjusted to the standard tire pressure; B. If the load tire pressure is greater than T1 and less than T1.3, it means that the vehicle is overloaded, but less than 30%. At this time, the driver will be reminded of overloading, and the vehicle speed will be limited to 80 km / h; C. If the load tire pressure is greater than T1.3 and less than T1.5, it means that the vehicle is overloaded by more than 30% and less than 50%. At this time, the driver will be reminded of overloading, and the vehicle speed will be limited to 65 km / h; D. If the load tire pressure is greater than T1.5 and less than T2, it means that the vehicle is overloaded by more than 50% and less than 100%. At this time, the driver will be reminded of overloading, and the vehicle speed will be limited to 50 km / h. The vehicle cannot enter the highway, and it will be remotely uploaded through OBD. If the vehicle obtains a special permit for transporting overloaded goods, the background monitoring system will lift the speed limit for this vehicle; E. If the tire pressure is greater than T2 or T9, it means that the vehicle is overloaded by more than 100% or reaches the limit of the tire pressure tolerance. At this time, driving is relatively dangerous. The driver will be reminded of overloading, and the hazard lights will flash continuously. The vehicle speed will be limited to 30 km / h. The vehicle cannot enter the highway, and it will be remotely uploaded through OBD. If the vehicle obtains certificates such as a special permit for transporting overloaded goods, the background monitoring system will lift the speed limit for this vehicle; Among them, T1 is the static load of the vehicle when fully loaded, T1.3 is the static load of the vehicle when fully loaded plus 0.3 times, T1.5 is the static load of the vehicle when fully loaded plus 0.5 times, T2 is the static load of the vehicle when fully loaded plus 1 time, and T9 is the maximum pressure value of the vehicle tire.

3. The heavy vehicle emergency braking system based on a central inflation and deflation tire according to claim 1, wherein, During mountainous working condition recognition braking, through combined judgment with camera recognition, in the two working conditions of mountainous working condition and long downhill working condition, if the driver applies full emergency braking, the brake pedal is fully opened and the time exceeds 2 seconds, the tire pressure of the vehicle will be reduced to 50% starting from the last wheel in sequence; the auxiliary braking will all start working to increase the braking force; for the mountainous working condition, frequent slight braking and turning are likely to cause the temperature of the brake and the tire to rise, resulting in a decline in braking performance. When the tire temperature sensor is greater than 90 degrees or the brake temperature is greater than 260 degrees, the driver will be reminded to rest. The tire pressure is reduced to 80% of the full-load standard tire pressure, and the vehicle speed is limited to 60 km / h until the vehicle stops; in the long downhill working condition, the tire pressure is reduced to 80% of the full-load standard tire pressure, the vehicle speed is limited to 60 km / h, the rolling resistance of the vehicle is increased, the braking performance is improved, the decline in braking performance caused by the rising temperature of the brake is slowed down, and when the brake fails, the tire pressure is reduced to 30% to complete vehicle control.

4. The heavy vehicle emergency braking system based on a central inflation and deflation tire according to claim 1, characterized in that, The structure of the tire in tire blowout monitoring is as follows: multiple separate small inner tubes are added in the inner tube of the tire, and the adjacent small inner tubes are connected through one-way valves. The last small inner tube is connected to the large inner tube; when inflating, first inflate from the small inner tubes. When all the small inner tubes are full, then inflate the large inner tube; when deflating, first deflate the large inner tube; when a tire blowout occurs, the large inner tube is punctured, and the small inner tubes still have air, which will not cause the vehicle to lose control. Open the inflation valve to replenish air and let the driver move the vehicle to a safe area.

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