Vehicle, active drag reduction system, and active drag reduction method thereof

Abstract

The present invention relates to a vehicle, an active drag reduction system, and an active drag reduction method. The method includes real-time monitoring of vehicle information and road information ahead of the vehicle. The road information is used to determine whether the road ahead has a slope and whether the vehicle is operating at a high speed. If the road ahead has a slope and the vehicle is operating at a high speed, the air suspension of the front wheels is controlled to lower to a first height value and the air suspension of the rear wheels to a second height value, where the first height value is less than the second height value. The present invention can address the problem of poor drag reduction in existing vehicles.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle component design and manufacturing, and particularly relates to a vehicle and an active drag reduction system and an active drag reduction method thereof. Background Art

[0002] With the advancement of technology and improvements in living standards, people's expectations for vehicles, particularly multi-purpose vehicles, are becoming increasingly demanding. For example, a high-quality suburban utility vehicle (SUV) must offer the comfort of a sedan, the fuel economy, and the maneuverability of an off-road vehicle. Air suspension systems are often installed in existing vehicles to achieve this balance.

[0003] Currently, air suspension systems are controlled manually or automatically. Manual control involves the driver controlling the airbags in the air suspension system to adjust vehicle height and configuration, such as high, medium, low, and side-kneeling modes, to meet different driving scenarios and enhance vehicle stability at high speeds or maneuverability in complex road conditions. Automatic control involves the vehicle automatically monitoring road and vehicle conditions to control the air compressor and exhaust valve, compressing or extending the springs to lower or raise the chassis ground clearance.

[0004] However, manual control relies on the driver to observe the road conditions, which increases the driver's burden. Automatic control usually adjusts the height of the entire vehicle, which makes it impossible to effectively reduce the air resistance of the vehicle during driving, thereby making the vehicle's fuel economy low. Moreover, whether it is manual control or automatic control, the drag is reduced by adjusting the height of the entire vehicle. Although the drag reduction effect can be achieved to a certain extent, in the face of some special working conditions, such as downhill, this method is still used, and the drag reduction effect is not good. Summary of the Invention

[0005] The present invention provides a vehicle and an active drag reduction system and an active drag reduction method thereof, so as to solve the problem of poor vehicle drag reduction effect in the prior art.

[0006] To solve the above technical problems, the present invention provides a method for active drag reduction of a vehicle, comprising:

[0007] Real-time monitoring of vehicle information and road information ahead of the vehicle, the road information being used to determine whether the road ahead has a slope, and the vehicle information being used to determine whether the vehicle is in a high-speed operating condition; if the road ahead has a slope and the vehicle is in a high-speed operating condition, the air suspension of the front wheels is controlled to be lowered to a first height value, and the air suspension of the rear wheels is controlled to be lowered to a second height value, the first height value being less than the second height value.

[0008] The beneficial effects of the above technical solution are: by real-time detection of vehicle information and road information in front of the vehicle, by judging whether there is a slope on the road in front of the vehicle and whether the vehicle is in a high-speed operating condition, it is determined whether to adjust the air suspension of the front wheels and the air suspension of the rear wheels, so that the vehicle presents a fastback posture with the front higher and the rear lower, thereby using the fastback posture to improve the vortex area and recirculation area at the rear of the vehicle, reduce air resistance, and improve the fuel economy of the vehicle.

[0009] Furthermore, in order to better adapt to different working conditions, the present invention provides a method for active drag reduction of a vehicle, which also includes controlling the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle to drop to the same height value if there is no slope on the road ahead and the vehicle is in a high-speed working condition.

[0010] Furthermore, in order to accurately obtain vehicle information and road information, the present invention provides a method for active drag reduction of a vehicle, which also includes that the vehicle information includes vehicle speed, duration of the vehicle speed and acceleration, and the road information includes road slope and road length. If the road slope is not less than the slope threshold and the road length is not less than the length threshold, and the vehicle speed is not less than the first speed threshold, the duration is not less than the first time threshold and the proportion of non-negative acceleration is not less than a set percentage, then there is a slope on the road ahead and the vehicle is in a high-speed condition; if at least one of the road slope or the road length is less than the corresponding threshold, and the vehicle speed is not less than the second speed threshold, the duration is not less than the second time threshold and the proportion of non-negative acceleration is not less than a set percentage, then there is no slope on the road ahead and the vehicle is in a high-speed condition, wherein the non-negative acceleration proportion is the ratio of the time of non-negative acceleration in the preset time period before the detection moment to the entire preset time period.

[0011] Furthermore, to better reduce air resistance based on different vehicle speeds, the present invention provides a method for active drag reduction of a vehicle, further comprising: providing the first speed threshold with multiple speed thresholds of varying sizes, each speed threshold matching a different first height value and a second height value, wherein a larger speed threshold corresponds to a larger first height value and a larger second height value; comparing the vehicle speed with the speed thresholds to determine a speed threshold interval within which the vehicle speed falls; and if both the duration is not less than the first time threshold and the proportion of non-negative acceleration is not less than a set percentage are satisfied, lowering the front and rear air suspensions of the vehicle by corresponding height values ​​based on the first and second height values ​​corresponding to the speed threshold interval; and providing the second speed threshold with multiple speed thresholds of varying sizes, each speed threshold matching a different descent height value, wherein a larger speed threshold corresponds to a larger descent height value; comparing the vehicle speed with the speed thresholds to determine a speed threshold interval within which the vehicle speed falls; and if both the duration is not less than the second time threshold and the proportion of non-negative acceleration is not less than a set percentage are satisfied, lowering the front and rear air suspensions of the vehicle by corresponding height values ​​based on the descent height values ​​corresponding to the speed threshold interval.

[0012] Furthermore, in order to better reduce drag for different working conditions, the present invention provides an active drag reduction method for a vehicle, which also includes: if there is a slope on the road ahead and the vehicle is in a high-speed working condition, multiple speed thresholds of the first speed threshold form a first speed threshold interval and a second speed threshold interval, the vehicle speed in the second speed threshold interval is greater than the first speed threshold interval, the first height value corresponding to the first speed threshold interval is 20 mm, and the corresponding second height value is 25 mm, the first height value corresponding to the second speed threshold interval is 25 mm, and the corresponding second height value is 30 mm; if there is no slope on the road ahead and the vehicle is in a high-speed working condition, multiple speed thresholds of the second speed threshold form a third speed threshold interval and a fourth speed threshold interval, the vehicle speed in the fourth speed threshold interval is greater than the third speed threshold interval, the height value corresponding to the third speed threshold interval is 20 mm, and the height value corresponding to the fourth speed threshold interval is 30 mm.

[0013] Furthermore, in order to better combine different vehicle operating conditions to improve the air resistance encountered by the vehicle, the present invention provides an active drag reduction method for a vehicle, which also includes monitoring the vehicle body state, wherein the vehicle body state includes a low body state, and the low body state is the lowest posture that the vehicle body can be in; if the vehicle is in a low body state and there is a slope on the road ahead, it is determined whether the vehicle speed is not greater than a third speed threshold and whether the duration is not less than a third time threshold. If the vehicle speed is not greater than the third speed threshold and the duration is not less than the third time threshold, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are controlled to rise respectively; if the vehicle is in a low body state and there is no slope on the road ahead, it is determined whether the vehicle speed is not greater than a fourth speed threshold and whether the duration is not less than a fourth time threshold. If the vehicle speed is not greater than the fourth speed threshold and the duration is not less than the fourth time threshold, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are controlled to rise.

[0014] Furthermore, in order to better combine different vehicle operating conditions to improve the air resistance encountered by the vehicle, the present invention provides a method for active drag reduction of a vehicle, which also includes the third speed threshold having multiple speed thresholds of different sizes, each speed threshold matching a different rising height value, comparing the vehicle speed with each speed threshold, determining the speed threshold interval in which the vehicle speed is located, and if the duration is not less than the third time threshold at the same time, then based on the rising height value corresponding to the speed threshold interval, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are respectively raised to the corresponding height values; the fourth speed threshold having multiple speed thresholds of different sizes, each speed threshold matching a different rising height value, comparing the vehicle speed with each speed threshold, determining the speed threshold interval in which the vehicle speed is located, and if the duration is not less than the fourth time threshold at the same time, then based on the rising height value corresponding to the speed threshold interval, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are respectively raised to the corresponding height values.

[0015] Furthermore, in order to better reduce drag for different working conditions, the present invention provides an active drag reduction method for a vehicle, further comprising: if there is a slope on the road ahead, the vehicle is in a high speed working condition and the vehicle is in a low body state, at this time the vehicle is in a low body state, the air suspension of the front wheels of the vehicle is lowered by 25mm relative to the default body height of the vehicle, and the air suspension of the rear wheels is lowered by 30mm relative to the default body height of the vehicle, the multiple speed thresholds of the third speed threshold form a fifth speed threshold interval and a sixth speed threshold interval, the vehicle speed in the sixth speed threshold interval is greater than the fifth speed threshold interval, and the rising height value corresponding to the sixth speed threshold interval is greater than the fifth speed threshold interval. The 5th speed threshold interval corresponds to a front wheel lift height value of 25mm, and a rear wheel lift height value of 30mm; if there is no slope on the road ahead, the vehicle is in a high-speed condition and the vehicle is in a low-body state, the vehicle is in a low-body state at this time, and the height of the vehicle is reduced by 30mm relative to the default body height of the vehicle. The multiple speed thresholds of the fourth speed threshold form a 7th speed threshold interval and an 8th speed threshold interval. The vehicle speed in the 8th speed threshold interval is greater than that in the 7th speed threshold interval. The lift height value corresponding to the 8th speed threshold interval is 10mm, and the lift height value corresponding to the 7th speed threshold interval is 30mm.

[0016] The present invention also provides an active drag reduction system for a vehicle, which includes a memory and a processor, wherein the processor is used to execute instructions stored in the memory to implement the above-mentioned active drag reduction method for the vehicle.

[0017] The present invention also provides a vehicle, comprising a vehicle body, and the vehicle further comprises the active drag reduction system of the vehicle described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1( a ) is a diagram showing the flow field at the rear of the vehicle of the present invention when the vehicle is at its original height;

[0019] FIG1( b ) is a schematic diagram of the flow field at the rear of the vehicle of the present invention when the vehicle height is lowered;

[0020] FIG1(c) is a diagram illustrating the flow field at the rear of the vehicle of the present invention when the vehicle is in a fastback posture and the height is lowered;

[0021] Figure 2 4 is a flow chart of the active drag reduction method for a vehicle according to the present invention. DETAILED DESCRIPTION

[0022] When a car travels on a level road, the airflow ahead of it flows through the top, bottom, and sides of the car, generating aerodynamic drag. The uneven underside of the car complicates the airflow, making the airflow under the car more restricted than the airflow on the sides and top, creating areas of strong turbulence and various complex eddies. Furthermore, the greater the speed, the greater the proportion of aerodynamic drag to driving resistance. Research has found that reducing ground clearance can reduce the gap between the bottom of the car and the ground where airflow enters, thereby reducing aerodynamic drag.

[0023] Figure 1(a) is a schematic diagram of the flow field at the rear of the vehicle of the present invention when it is at its original height; Figure 1(b) is a schematic diagram of the flow field at the rear of the vehicle of the present invention when its overall height is lowered; Figure 1(c) is a schematic diagram of the flow field at the rear of the vehicle of the present invention when its height is lowered in a sloping back posture. In this embodiment, the drag reduction effect brought about by ground clearances of different height values ​​is studied by aerodynamic means, and then the vehicle is calibrated, which can avoid the unreasonable high-speed setting of the existing vehicle. The adjusted height value in this embodiment reduces the ground clearance to a certain extent. On the one hand, it reduces the impact of the airflow on the bottom components of the vehicle. On the other hand, it reduces the vortex size formed at the rear by the bottom airflow and the airflow flowing through the top and side of the vehicle body, reduces the dissipation of the airflow energy in the tail separation zone, and thus reduces the aerodynamic resistance of the car. For example, for a 12m model and a 7m model, when the ground clearance is reduced by 30mm, the air resistance can be reduced by 2% and 4% respectively. Figure 1(a) to Figure 1(c) As shown in Figure 1(a) at the original vehicle body height, when the overall vehicle body height is reduced by 30 mm, the overall scale of the separation vortex at the tail of Figure 1(b) is smaller and moves forward, and the vortex characteristic area ① moves forward significantly; at the same time, the reflow area ② generated when the airflow flows from the bottom to the rear of the vehicle in Figure 1(a) is more obvious, and after the vehicle body height is reduced by 30 mm, the reflow situation in this area in Figure 1(b) is significantly improved; when the vehicle body height is lowered by adopting a fastback posture in Figure 1(c), the tail flow areas ① and ② are also significantly improved.

[0024] Based on the above research results, the present invention comprehensively considers vehicle information and road information in front of the vehicle, and determines whether to adjust the air suspension of the front wheels and the air suspension of the rear wheels by judging whether there is a slope on the road in front of the vehicle and whether the vehicle is in a high-speed condition, so that the vehicle presents a fastback posture with high front and low rear. The fastback posture can be used to improve the vortex zone and recirculation zone at the rear of the vehicle, reduce air resistance, and improve the fuel economy of the vehicle.

[0025] In order to make the purpose, technical solutions and technical effects of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Active drag reduction method embodiment of a vehicle:

[0027] Figure 2 4 is a flow chart of the active drag reduction method for a vehicle according to the present invention.

[0028] Step 1: Collect road information and vehicle information.

[0029] Specifically, in step 1, Figure 2 As shown, real-time monitoring of vehicle information and road information ahead of the vehicle (i.e., road condition information) is performed. Road information is used to determine whether the road ahead has a slope. Road information includes road slope and road length. Vehicle information is used to determine whether the vehicle is in a high-speed operating condition. Vehicle information includes signals such as vehicle speed (i.e., current speed), duration of that speed (i.e., driving time), and acceleration. Road information is obtained through GPS signals and road spectrum information. Vehicle speed and acceleration are detected by speed sensors and acceleration sensors.

[0030] Step 2: Determine whether the driver manually adjusts the vehicle height value.

[0031] Specifically, in step 2, if Figure 2 As shown, the system determines whether the driver has manually adjusted the vehicle height. If so, the vehicle height adjustment is performed directly. If not, the system proceeds to step 3, determining the slope condition. This allows manual control, allowing the driver to adjust the vehicle height based on different scenarios (i.e., operating conditions). Manual intervention takes precedence over automatic vehicle control.

[0032] Step 3: Determine whether there is a slope on the road ahead of the vehicle based on the collected road information.

[0033] Specifically, in step three, if Figure 2 As shown, it is determined whether the road slope is not less than the slope threshold A, and whether the road length is not less than the length threshold B. If both are not less than the corresponding thresholds, there is a ramp on the road ahead of the vehicle, and step four is executed. If at least one is less than the corresponding threshold, there is no ramp on the road ahead of the vehicle, and step five is executed.

[0034] Step 4: If there is a slope on the road ahead of the vehicle, determine whether to adjust the vehicle body based on the vehicle information.

[0035] Specifically, in step 4, the situation with a slope includes uphill working conditions and downhill working conditions. Figure 2As shown, if there is a slope on the road ahead of the vehicle (i.e., there is an uphill or downhill road ahead of the vehicle), it is determined whether the vehicle speed is not less than the first speed threshold C, whether the duration is not less than the first time threshold D, and whether the non-negative acceleration ratio is not less than a set percentage. If all of them are not less than (i.e., the vehicle is in a high-speed operating condition), a vehicle height adjustment signal is output to adjust the vehicle height value. During the adjustment, the air suspension of the front wheels is lowered to a first height value, and the air suspension of the rear wheels is lowered to a second height value, where the first height value is less than the second height value. If at least one of the conditions is not met, the vehicle height value is not changed. Among them, the non-negative acceleration ratio is the ratio of the time of non-negative acceleration in the preset time period before the detection moment to the entire preset time period. For example, if the preset time period is 2 seconds and the set percentage is 50%, it is determined whether the proportion of non-negative acceleration in the last 2 seconds before the detection moment is not less than 50%. In this way, misjudgment caused by temporary vehicle speed changes can be avoided.

[0036] In step 4, the first speed threshold has multiple speed thresholds of varying sizes. The multiple speed thresholds are two speed thresholds. Each speed threshold matches a different first and second height values, with the larger the speed threshold, the larger the first and second height values ​​matched. The vehicle speed is compared with each speed threshold to determine the speed threshold interval within which the vehicle speed falls. If the duration is not less than the first time threshold and the proportion of non-negative acceleration is not less than a set percentage, the front and rear air suspensions of the vehicle are lowered by the corresponding height values ​​based on the first and second height values ​​corresponding to the speed threshold interval. This achieves multi-level control, effectively reducing air resistance based on different vehicle speeds.

[0037] In step 4, if the road ahead has a slope and the vehicle is in a high-speed operating condition, the multiple speed thresholds of the first speed threshold form a first speed threshold interval and a second speed threshold interval. The vehicle speed in the second speed threshold interval is greater than the first speed threshold interval. The first height value corresponding to the first speed threshold interval is 20 mm, and the corresponding second height value is 25 mm. The first height value corresponding to the second speed threshold interval is 25 mm, and the corresponding second height value is 30 mm. Taking the two speed thresholds of 75 km / h and 85 km / h as an example, the first speed threshold interval is [75 km / h, 85 km / h), and the second speed threshold interval is [85 km / h, +∞). For example, if the road ahead is downhill and the vehicle is in a high-speed operating condition, with a first time threshold of 5 seconds, a preset time period of 2 seconds, and a set percentage of 50%, when the vehicle speed is at least 75 km / h, the duration exceeds 5 seconds, and the acceleration / deceleration signals in the last 2 seconds are non-negative for more than 50%, the front suspension (i.e., the front air suspension) height is controlled to be lowered by 20 mm, and the rear suspension (i.e., the rear air suspension) height is controlled to be lowered by 25 mm, giving the vehicle a high-front-low-rear-back sloping back posture. When the vehicle speed is at least 85 km / h, the duration exceeds 5 seconds, and the acceleration / deceleration signals in the last 2 seconds are non-negative for more than 50%, the front suspension height is controlled to be lowered by 25 mm, and the rear suspension height is controlled to be lowered by 30 mm. In this case, vehicle speed is prioritized, with the duration of speed and acceleration / deceleration signals used as auxiliary factors in determining the operating condition. This avoids frequent adjustments to the vehicle height value and reduces misjudgments caused by sudden braking, traffic jams, and other road conditions.

[0038] In step four, it also includes monitoring the vehicle's body state. The body state includes a high body state, a medium body state, and a low body state. The low body posture refers to the lowest posture that the body can be in under the corresponding control. Under different working conditions, the adjustment height value corresponding to the low body posture is different. Specifically, if there is a slope on the road ahead, the vehicle is in a high speed condition and the vehicle is in a low body state, the vehicle is in a low body state at this time, and the air suspension of the front wheels of the vehicle is lowered by 25mm relative to the default body height of the vehicle, and the air suspension of the rear wheels is lowered by 30mm relative to the default body height of the vehicle. If there is no slope on the road ahead, the vehicle is in a high speed condition and the vehicle is in a low body state, the vehicle is in a low body state at this time, and the height of the vehicle is lowered by 30mm relative to the default body height of the vehicle.

[0039] In step 4, if the vehicle is in the low-body state, the system determines whether the vehicle speed is no greater than a third speed threshold and whether the duration of this state is no less than a third time threshold. If so, the front and rear air suspensions are controlled to rise, respectively. This effectively reduces air resistance in response to varying vehicle operating conditions. Furthermore, when the vehicle is in the low-body state, the number and value of the third speed thresholds for vehicle height increase and the first speed threshold for vehicle height decrease may not necessarily match.

[0040] In step 4, the third speed threshold has multiple speed thresholds of different sizes, and the multiple speed thresholds are two speed thresholds. Each speed threshold matches a different rising height value. The vehicle speed is compared with each speed threshold to determine the speed threshold interval in which the vehicle speed is located. If the duration is not less than the third time threshold at the same time, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are respectively raised to the corresponding height values ​​based on the rising height value corresponding to the speed threshold interval.

[0041] In step 4, if the road ahead has a slope, the vehicle is at a high speed, and the vehicle is in a low-rider position, the multiple speed thresholds of the third speed threshold form a fifth speed threshold interval and a sixth speed threshold interval. The vehicle speed in the sixth speed threshold interval is greater than that in the fifth speed threshold interval, and the corresponding lift height value for the sixth speed threshold interval is 5 mm. The corresponding front wheel lift height value for the fifth speed threshold interval is 25 mm, and the corresponding rear wheel lift height value is 30 mm. Taking two speed thresholds of 70km / h and 60km / h as an example, the fifth speed threshold interval is [0, 60km / h], and the sixth speed threshold interval is (60km / h, 70km / h). For example, if the road ahead is downhill and the vehicle is in a high-speed condition, and the first time threshold is 10s, when the vehicle is already in a low-body state, if the speed is no more than 70km / h and lasts for more than 10s, the front and rear air suspensions are controlled to rise by 5mm. After the raising process is completed, the front suspension height value (i.e., the front wheel air suspension) is reduced by 20mm relative to the original vehicle height value (the default vehicle height before height adjustment), and the rear suspension height value is reduced by 25mm relative to the original vehicle height value. If the speed is no more than 60km / h and lasts for more than 10s, the front wheel air suspension is controlled to rise by 25mm and the rear wheel air suspension is controlled to rise by 30mm to restore the vehicle height value to the original vehicle height value. In this case, vehicle speed is prioritized to avoid frequent adjustments to the vehicle height value.

[0042] Furthermore, in step 4, if the subsequent real-time road information detected does not meet the triggering conditions, meaning that at least one of the road information values ​​is below the corresponding threshold, the vehicle body is initially held in position. After a certain period of time, the road information is re-evaluated and the corresponding control logic is re-evaluated. The certain period of time can be 10 seconds. Furthermore, the corresponding handling method for a slope ahead can also be applied to other suitable operating conditions.

[0043] Step 5: If there is no slope on the road ahead of the vehicle, determine whether to adjust the vehicle body based on the vehicle information.

[0044] Specifically, in step five, if Figure 2 As shown, if there is no slope ahead of the vehicle, the system determines whether the vehicle speed is no less than a second speed threshold E, the duration is no less than a second time threshold F, and the non-negative acceleration ratio is no less than a set percentage. If all of these are true (i.e., the vehicle is in a high-speed operating condition), a vehicle height adjustment signal is output to adjust the vehicle height. If at least one of these conditions is not met, the vehicle height remains unchanged. The vehicle height adjustment involves lowering the front and rear air suspensions by the same amount.

[0045] In step 5, the second speed threshold includes multiple speed thresholds of varying sizes, each comprising two speed thresholds. Each speed threshold matches a different descent height value, with the larger the speed threshold, the larger the descent height value. The vehicle speed is compared with each speed threshold to determine the speed threshold interval within which the vehicle speed falls. If both the duration is no less than the second time threshold and the proportion of non-negative acceleration is no less than a set percentage, the front and rear air suspensions are lowered by the corresponding height values ​​based on the descent height value corresponding to the speed threshold interval. This achieves multi-level control, effectively reducing air resistance based on different vehicle speeds.

[0046] In step 5, if the road ahead does not have a slope and the vehicle is in a high-speed operating condition, the multiple speed thresholds of the second speed threshold form a third speed threshold interval and a fourth speed threshold interval. The vehicle speed in the fourth speed threshold interval is greater than that in the third speed threshold interval. The height value corresponding to the third speed threshold interval is 20 mm, and the height value corresponding to the fourth speed threshold interval is 30 mm. Taking the two speed thresholds of 75 km / h and 85 km / h as an example, the third speed threshold interval is [75 km / h, 85 km / h), and the fourth speed threshold interval is [85 km / h, +∞). Taking the first time threshold of 5 seconds, the preset time period of 2 seconds, and the set percentage of 50% as an example, when the vehicle speed is no less than 75 km / h, the duration exceeds 5 seconds, and the acceleration / deceleration signals in the last 2 seconds are non-negative for more than 50%, the vehicle height is controlled to be lowered by 20 mm, that is, the front suspension height is lowered by 20 mm, and the rear suspension height is lowered by 20 mm. When the vehicle speed is no less than 85 km / h, the duration exceeds 5 seconds, and the acceleration / deceleration signals in the last 2 seconds are non-negative for more than 50%, the vehicle height is controlled to be lowered by 30 mm, that is, the front suspension height is lowered by 30 mm, and the rear suspension height is lowered by 30 mm. In this case, vehicle speed is prioritized, and the duration of speed and acceleration / deceleration signals are used as auxiliary factors in determining the operating condition. This avoids frequent adjustments to the vehicle height value and reduces misjudgments caused by sudden braking, traffic jams, and other road conditions.

[0047] In step five, the vehicle's body state is monitored. If the vehicle is in a low-body state, the system determines whether the vehicle speed is no greater than a fourth speed threshold and whether the duration of this state is no less than a fourth time threshold. If the vehicle speed is no greater than the fourth speed threshold and the duration of this state is no less than the fourth time threshold, the front and rear air suspensions are controlled to rise. This effectively reduces air resistance in response to varying vehicle operating conditions. Furthermore, when the vehicle is in a low-body state, the number and value of the fourth speed thresholds for raising vehicle height and the second speed thresholds for lowering vehicle height may not necessarily be the same.

[0048] In step 5, the fourth speed threshold includes multiple speed thresholds of varying sizes, each consisting of two speed thresholds, each corresponding to a different elevation value. The vehicle speed is compared with each speed threshold to determine the speed threshold interval within which the vehicle speed falls. If the duration of the interval is not less than the fourth time threshold, the front and rear air suspensions are raised by the corresponding elevation values ​​corresponding to the speed threshold interval. This allows for better adaptation to different vehicle operating conditions to improve air resistance.

[0049] In step 5, if the road ahead has no slope, the vehicle is in a high speed condition, and the vehicle is in a low position, the multiple speed thresholds of the fourth speed threshold form a seventh speed threshold interval and an eighth speed threshold interval. The vehicle speed in the eighth speed threshold interval is greater than that in the seventh speed threshold interval, and the corresponding rise height value of the eighth speed threshold interval is 10 mm. The corresponding rise height value of the seventh speed threshold interval is 30 mm. Taking the two speed thresholds of 70km / h and 80km / h as examples, the seventh speed threshold interval is [0, 70km / h], and the eighth speed threshold interval is (70km / h, 80km / h). Taking the first time threshold of 10s as an example, when the vehicle is in the low-body state, if the vehicle speed is no more than 80km / h and the duration exceeds 10s, the vehicle body is controlled to rise by 10mm to reduce the vehicle body height by 20mm relative to the original value. That is, the front and rear air suspensions are controlled to rise to reduce the front and rear suspension heights by 20mm relative to the original value. If the vehicle speed is no more than 70km / h and the duration exceeds 10s, the vehicle body is controlled to rise by 30mm to restore the vehicle body height to normal (i.e., return to the original value). In this case, the vehicle speed is prioritized to avoid frequent adjustments to the vehicle body height and reduce misjudgments caused by sudden braking, traffic jams, and other road conditions.

[0050] The active drag reduction method for a vehicle according to this embodiment detects road and vehicle information in real time to promptly obtain the vehicle's road conditions and makes corresponding adjustments based on different road conditions. The method determines whether the road slope is no less than a slope threshold and the road length is no less than a length threshold. If both are not less than, there is a slope ahead of the vehicle. The method then determines whether the vehicle speed is no less than a first speed threshold, the duration is no less than a first time threshold, and the proportion of non-negative acceleration is no less than a set percentage. If all are not less than, the front wheel air suspension is lowered by a first height value, and the rear wheel air suspension is lowered by a second height value, where the first height value is less than the second height value. The vehicle then exhibits a sloping back posture, with the front higher and the rear lower. This sloping back posture can improve the vortex and recirculation zones at the rear of the vehicle, reducing air resistance and thereby improving vehicle fuel economy. In particular, the sloping back posture can alleviate the problem of the center of gravity tilting forward when the vehicle is descending a slope, improving vehicle comfort and enhancing the passenger experience. Therefore, the method of the present invention balances vehicle comfort and fuel economy, i.e., improving fuel economy while maintaining vehicle comfort. In addition, giving priority to judging vehicle speed, auxiliary time and acceleration can avoid frequent adjustments to the vehicle height value, reduce misjudgments caused by road conditions such as speed maintenance, overtaking, deceleration, sudden braking, and traffic jams, and better meet the needs of the actual driving process.

[0051] In this embodiment, the road information in front of the vehicle is determined first, and then the vehicle information is determined. In other embodiments, the vehicle information can be determined first, and then the road information in front of the vehicle is determined.

[0052] In this embodiment, the first speed threshold, the second speed threshold, the fourth speed threshold, the first time threshold, the second time threshold, the fourth time threshold, and the fourth time threshold are all set according to actual operating conditions to achieve the purpose of adapting to various operating conditions. The various operating conditions can be, for example, special operating conditions based on high vehicle speeds.

[0053] In this embodiment, the first speed threshold, the second speed threshold, the fourth speed threshold, and the fourth speed threshold are each two, i.e., two-level control is implemented. In other embodiments, the first speed threshold, the second speed threshold, the fourth speed threshold, and the fourth speed threshold can be three or more. This allows for more precise control of the vehicle height value.

[0054] In this embodiment, manual adjustment is involved, and manual intervention has a higher priority than automatic control of the vehicle. In other embodiments, manual adjustment can also be omitted and automatic control of the vehicle can be directly performed (i.e., step 3 and subsequent steps are directly executed for processing).

[0055] Active drag reduction system embodiment of a vehicle:

[0056] This embodiment discloses an active drag reduction system for a vehicle. The active drag reduction system for a vehicle based on this embodiment can solve the problem of poor drag reduction effect of existing vehicles.

[0057] In this embodiment, the vehicle's active drag reduction system includes a processor and a memory. The processor is configured to execute instructions stored in the memory to implement the vehicle's active drag reduction method in the method embodiment of the present invention. The vehicle's active drag reduction method has been described in detail in the aforementioned method embodiment. Those skilled in the art can generate corresponding computer instructions based on the vehicle's active drag reduction method to implement the vehicle's active drag reduction system, and will not be further described here. The memory is configured to store the computer instructions generated based on the vehicle's active drag reduction method.

[0058] In this embodiment, the active drag reduction system of the vehicle may be provided in an on-board computer (Electronic Control Unit, ECU).

[0059] Vehicle Example:

[0060] This embodiment also provides a vehicle, which may include a vehicle body and the active drag reduction system of the vehicle in the system embodiment of the present invention. This system can address the issue of poor drag reduction in existing vehicles. The vehicles in this embodiment include, but are not limited to, transportation vehicles, such as sedans, buses, and trucks.

Claims

1. A method for active drag reduction of a vehicle, characterized in that: include: Real-time monitoring of vehicle information and road information ahead of the vehicle, wherein the road information is used to determine whether the road ahead has a ramp, and if the road slope is not less than a slope threshold and the road length is not less than a length threshold, it is considered that there is a ramp; otherwise, it is considered that there is no ramp. The vehicle information is used to determine whether the vehicle is in a high-speed operating condition; If the road ahead has a slope and the vehicle is at a high speed, the air suspension of the front wheels is controlled to lower to a first height value, and the air suspension of the rear wheels is controlled to lower to a second height value, where the first height value is less than the second height value; If there is no slope on the road ahead and the vehicle is at a high speed, the air suspension of the front and rear wheels of the vehicle is controlled to drop to the same height; The vehicle information includes vehicle speed, duration of the speed, and acceleration. The method for determining a high-speed operating condition when there is a slope on the road ahead is as follows: the vehicle speed is not less than a first speed threshold, the duration is not less than a first time threshold, and the proportion of non-negative acceleration is not less than a set percentage. The method for determining a high-speed operating condition when there is no slope on the road ahead is as follows: the vehicle speed is not less than a second speed threshold, the duration is not less than a second time threshold, and the proportion of non-negative acceleration is not less than a set percentage. Among them, the proportion of non-negative acceleration is the ratio of the time of non-negative acceleration in a preset time period before the detection moment to the entire preset time period.

2. The active drag reduction method for a vehicle according to claim 1, characterized in that: The first speed threshold has multiple speed thresholds of different sizes, each speed threshold matches a different first height value and a second height value, and the larger the speed threshold, the larger the matched first height value and second height value; the vehicle speed is compared with each speed threshold to determine the speed threshold interval in which the vehicle speed is located, and if both the duration is not less than the first time threshold and the proportion of non-negative acceleration is not less than a set percentage are satisfied, then based on the first height value and the second height value corresponding to the speed threshold interval, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are lowered by corresponding height values ​​respectively; the second speed threshold has multiple speed thresholds of different sizes, each speed threshold matches a different descent height value, and the larger the speed threshold, the larger the matched descent height value; the vehicle speed is compared with each speed threshold to determine the speed threshold interval in which the vehicle speed is located, and if both the duration is not less than the second time threshold and the proportion of non-negative acceleration is not less than a set percentage are satisfied, then based on the descent height value corresponding to the speed threshold interval, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are lowered by corresponding height values.

3. The active drag reduction method for a vehicle according to claim 2, characterized in that: If there is a slope on the road ahead and the vehicle is in a high-speed condition, the multiple speed thresholds of the first speed threshold form a first speed threshold interval and a second speed threshold interval, the vehicle speed in the second speed threshold interval is greater than the first speed threshold interval, the first height value corresponding to the first speed threshold interval is 20 mm, and the corresponding second height value is 25 mm, the first height value corresponding to the second speed threshold interval is 25 mm, and the corresponding second height value is 30 mm; if there is no slope on the road ahead and the vehicle is in a high-speed condition, the multiple speed thresholds of the second speed threshold form a third speed threshold interval and a fourth speed threshold interval, the vehicle speed in the fourth speed threshold interval is greater than the third speed threshold interval, the height value corresponding to the third speed threshold interval is 20 mm, and the height value corresponding to the fourth speed threshold interval is 30 mm.

4. The active drag reduction method for a vehicle according to claim 1, characterized in that: It also includes monitoring the vehicle's body state, which includes a low body state, which is the lowest posture the body can be in; if the vehicle is in a low body state and there is a slope on the road ahead, it is determined whether the vehicle speed is not greater than a third speed threshold and whether the duration is not less than a third time threshold; if the vehicle speed is not greater than the third speed threshold and the duration is not less than the third time threshold, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are controlled to rise respectively; if the vehicle is in a low body state and there is no slope on the road ahead, it is determined whether the vehicle speed is not greater than a fourth speed threshold and whether the duration is not less than a fourth time threshold; if the vehicle speed is not greater than the fourth speed threshold and the duration is not less than the fourth time threshold, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are controlled to rise.

5. The active drag reduction method for a vehicle according to claim 4, characterized in that: The third speed threshold has multiple speed thresholds of different sizes, each speed threshold matches a different rising height value, and the vehicle speed is compared with each speed threshold to determine the speed threshold interval in which the vehicle speed is located. If the duration is not less than the third time threshold at the same time, then based on the rising height value corresponding to the speed threshold interval, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are respectively raised to the corresponding height values; the fourth speed threshold has multiple speed thresholds of different sizes, each speed threshold matches a different rising height value, and the vehicle speed is compared with each speed threshold to determine the speed threshold interval in which the vehicle speed is located. If the duration is not less than the fourth time threshold at the same time, then based on the rising height value corresponding to the speed threshold interval, the air suspension of the front wheels and the air suspension of the rear wheels of the vehicle are respectively raised to the corresponding height values.

6. The active drag reduction method for a vehicle according to claim 5, characterized in that: If there is a slope on the road ahead, the vehicle is in a high-speed operating condition and the vehicle is in a low-body state, the vehicle is in a low-body state at this time, the air suspension of the front wheels of the vehicle is lowered by 25 mm relative to the default vehicle height, and the air suspension of the rear wheels is lowered by 30 mm relative to the default vehicle height. The multiple speed thresholds of the third speed threshold form a fifth speed threshold interval and a sixth speed threshold interval. The vehicle speed in the sixth speed threshold interval is greater than the fifth speed threshold interval. The corresponding lift height value of the sixth speed threshold interval is 5 mm. The corresponding front wheel lift height value of the fifth speed threshold interval is 25 mm, and the corresponding rear wheel lift height value is 30 mm. If there is no slope on the road ahead, the vehicle is in a high-speed operating condition and the vehicle is in a low-body state, the vehicle is in a low-body state at this time, the height of the vehicle is lowered by 30 mm relative to the default vehicle height. The multiple speed thresholds of the fourth speed threshold form a seventh speed threshold interval and an eighth speed threshold interval. The vehicle speed in the eighth speed threshold interval is greater than the seventh speed threshold interval. The corresponding lift height value of the eighth speed threshold interval is 10 mm, and the corresponding lift height value of the seventh speed threshold interval is 30 mm.

7. An active drag reduction system for a vehicle, characterized in that: include: A memory and a processor, wherein the processor is configured to execute instructions stored in the memory to implement the active drag reduction method for a vehicle according to any one of claims 1 to 6.

8. A vehicle comprising a vehicle body, characterized in that: The vehicle further comprises the active drag reduction system of claim 7 .

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