Commercial vehicle frame height automatic adjusting system and adjusting control method

Abstract

The invention belongs to the technical field of frame height adjustment, and particularly provides a commercial vehicle frame height automatic adjustment system and an adjustment control method, and the method comprises the following steps: obtaining a current vehicle speed and a brake frequency in a set time period; the current driving road condition of the vehicle is judged according to the vehicle speed and the braking frequency, and the received target height is corrected according to the driving road condition; the height difference between the current height and the corrected target height is calculated, and a vehicle frame height control adjusting strategy is output; and outputting a corresponding duty ratio according to the vehicle frame height control adjustment strategy, adjusting the inflation volume of an air spring by controlling the on-off state of an electromagnetic valve, and adjusting the vehicle frame to the corrected target height. By monitoring the vehicle speed and the braking frequency in the set time period in real time, the current driving road condition of the vehicle can be intelligently judged, and the target height of the vehicle frame can be dynamically adjusted according to the road condition. And it is ensured that the vehicle can keep the needed vehicle body posture under different road conditions, and therefore the driving safety and stability are improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle frame height adjustment technology, specifically to an automatic vehicle frame height adjustment system and adjustment control method for commercial vehicles. Background Technology

[0002] Traditional suspensions mainly consist of leaf springs or coil springs, shock absorbers, and guide mechanisms. Their stiffness and damping are not adjustable, making them passive suspensions. With the development of new materials and electronic control technology, as well as new requirements of relevant regulations and new demands from high-end users and the market, the design and application of air suspension systems have gradually improved.

[0003] Air suspension uses air springs as its elastic element and has gained market recognition for its superior stiffness characteristics. It plays a vital role in improving vehicle comfort and can also effectively reduce vehicle damage to the road surface. Its market share is also constantly increasing.

[0004] Existing air suspension systems mostly rely on manual adjustment to cause changes in level, such as during loading or unloading at loading docks, or when commercial vehicles are on ships, to place the vehicle body on rubber buffer pads. They do not take into account actual road conditions and cannot automatically adjust the chassis height according to different vehicle speeds and road conditions. Therefore, there is an urgent need for a control method for automatic adjustment of the chassis height of commercial vehicles to achieve rapid and precise control of the chassis height of commercial vehicle air suspension systems. Summary of the Invention

[0005] To address the problem that air suspension systems cannot automatically adjust the vehicle height according to different vehicle speeds and road conditions, this invention provides an automatic vehicle height adjustment system and control method for commercial vehicles.

[0006] In a first aspect, the present invention provides an automatic adjustment system for the chassis height of a commercial vehicle, including a vehicle height control unit and an air spring mounted on the chassis. The vehicle height control unit is connected to a target height determination unit, a chassis height monitoring unit, and a solenoid valve. The air spring is connected to the solenoid valve, and the solenoid valve is connected to an air source; The target height determination unit determines the target height of the vehicle frame according to the vehicle model and transmits it to the vehicle height control unit; The chassis height monitoring unit acquires the current height of the chassis and transmits it to the vehicle height control unit; The vehicle height control unit acquires the current vehicle speed and the braking frequency over a set time period, determines the current road conditions based on the vehicle speed and the braking frequency, corrects the received target height based on the road conditions, calculates the height difference between the current height and the corrected target height, formulates a frame height control adjustment strategy, outputs the corresponding duty cycle based on the frame height control adjustment strategy, and adjusts the air spring inflation amount by controlling the on / off state of the solenoid valve to adjust the frame to the corrected target height.

[0007] As a preferred embodiment of the present invention, the chassis height monitoring unit includes a first height sensor disposed on the left side of the chassis and a second height sensor disposed on the right side of the chassis. The first height sensor transmits the height of the left side of the chassis to the vehicle height control unit, and the second height sensor transmits the height of the right side of the chassis to the vehicle height control unit.

[0008] As a preferred embodiment of the technical solution of the present invention, the vehicle height control unit obtains the current vehicle speed and the cumulative number of braking times within the current set time period via the CAN bus, i.e., the braking frequency; If the acquired vehicle speed is greater than the set vehicle speed and the braking frequency is lower than the first set threshold, it is determined that the vehicle is traveling in the first road condition. The target height correction value corresponding to the first road condition is acquired, and the target height input by the received target height determination unit is corrected. The corrected target height is equal to the difference between the received target height and the target height correction value. If the acquired vehicle speed is less than or equal to the set vehicle speed and the braking frequency is higher than the first set threshold, it is determined that the vehicle is traveling in the second road condition. The target height correction value corresponding to the second road condition is acquired, and the target height input by the received target height determination unit is corrected. The corrected target height is equal to the sum of the received target height and the target height correction value.

[0009] As a preferred embodiment of the technical solution of the present invention, the vehicle height control unit calculates the first height difference L1 and the second height difference L2 of the left vehicle frame based on the frame height hl1 collected by the first height sensor and the target height h0 after road condition correction; and calculates the first height difference R1 and the second height difference R2 of the right vehicle frame based on the frame height hr1 collected by the second height sensor and the corrected target height h0. The frame height control adjustment strategy is determined by comparing the first and second height differences of the left frame and the first and second height differences of the right frame.

[0010] As a preferred embodiment of the technical solution of the present invention, the chassis height control and adjustment strategy is as follows: If (L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)!= 0 and L1 + R1 > L2 + R2, the vehicle height control unit sends a signal to the solenoid valve; at this time, if L1 > L2, the vehicle height control unit controls the solenoid valve to open, and the air spring on the left frame deflates, reducing the height of the left frame of the vehicle; if R1 > R2, the vehicle height control unit sends a signal to the solenoid valve, the solenoid valve opens, and the air spring on the right frame deflates, reducing the height of the right frame of the vehicle. If (L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)!= 0 and L1 + R1 < L2 + R2, the vehicle height control unit sends a signal to the solenoid valve; at this time, if L1 < L2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, increasing the height of the left frame of the vehicle. If R1 < R2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, increasing the height of the right frame of the vehicle. If ((L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)) == 0, there is no need to adjust the height of the vehicle frame. The vehicle height control unit sends a signal to the solenoid valve, and the solenoid valve closes, keeping the height of the vehicle frame unchanged.

[0011] As a preference of the technical solution of the present invention, the first height difference L1 of the left frame = hl1 - h0 - e, and the second height difference L2 of the left frame = h0 - hl1 - e; The first height difference R1 of the right frame = hr1 - h0 - e, and the second height difference R2 of the right frame = h0 - hr1 - e; In the formula, e is the allowable error value.

[0012] As a preference of the technical solution of the present invention, the vehicle height control unit continuously controls the average flow rate through the solenoid valve by adjusting the duty cycle D, realizes the control of the gas flow rate of the air spring, and further realizes the adjustment of the frame height; The flow rate through the solenoid valve within the set time ; In the formula, Q is the average flow rate through the solenoid valve within the time, is the flow coefficient, is the maximum area of the maximum opening of the solenoid valve, is the pressure difference of the air pressure, is the density of the gas.

[0013] In the second aspect, the technical solution of the present invention also provides a method for automatically adjusting and controlling the height of a commercial vehicle frame, including the following steps: Obtain the current height of the vehicle frame and the preset target height; Obtain the current vehicle speed and the braking frequency within the set time period; The vehicle's current road conditions are determined based on its speed and braking frequency, and the received target height is corrected accordingly. Calculate the height difference between the current height and the corrected target height, and output the chassis height control adjustment strategy; Based on the frame height control adjustment strategy, the corresponding duty cycle is output, and the air spring inflation is adjusted by controlling the on / off state of the solenoid valve to adjust the frame to the corrected target height.

[0014] As a preferred embodiment of the technical solution of the present invention, the step of determining the current road conditions of the vehicle based on the vehicle speed and the braking frequency, and correcting the received target height based on the road conditions includes: If the acquired vehicle speed is greater than the set vehicle speed and the braking frequency is lower than the first set threshold, it is determined that the vehicle is traveling in the first road condition. The target height correction value corresponding to the first road condition is acquired, and the target height input by the received target height determination unit is corrected. The corrected target height is equal to the difference between the received target height and the target height correction value. If the acquired vehicle speed is less than or equal to the set vehicle speed and the braking frequency is higher than the first set threshold, it is determined that the vehicle is traveling in the second road condition. The target height correction value corresponding to the second road condition is acquired, and the target height input by the received target height determination unit is corrected. The corrected target height is equal to the sum of the received target height and the target height correction value.

[0015] As a preferred embodiment of the technical solution of the present invention, the vehicle height control unit calculates the first height difference L1 and the second height difference L2 of the left vehicle frame based on the frame height hl1 collected by the first height sensor and the target height h0 after road condition correction; and calculates the first height difference R1 and the second height difference R2 of the right vehicle frame based on the frame height hr1 collected by the second height sensor and the corrected target height h0. The frame height control adjustment strategy is determined by comparing the first and second height differences of the left frame and the first and second height differences of the right frame.

[0016] As a preferred embodiment of the technical solution of the present invention, the steps of calculating the height difference between the current height and the corrected target height, and outputting the chassis height control and adjustment strategy include: The first height difference L1 and the second height difference L2 of the left frame are calculated based on the frame height hl1 collected by the first height sensor and the target height h0 after road condition correction; the first height difference R1 and the second height difference R2 of the right frame are calculated based on the frame height hr1 collected by the second height sensor and the corrected target height h0. If (L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)!= 0 and L1 + R1 > L2 + R2, the vehicle height control unit sends a signal to the solenoid valve; at this time, if L1 > L2, the vehicle height control unit controls the solenoid valve to open, and the air spring on the left frame deflates, reducing the height of the left frame of the vehicle; if R1 > R2, the vehicle height control unit sends a signal to the solenoid valve, the solenoid valve opens, and the air spring on the right frame deflates, reducing the height of the right frame of the vehicle. If (L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)!= 0 and L1 + R1 < L2 + R2, the vehicle height control unit sends a signal to the solenoid valve; at this time, if L1 < L2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, increasing the height of the left frame of the vehicle. If R1 < R2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, increasing the height of the right frame of the vehicle. If ((L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)) == 0, there is no need to adjust the height of the vehicle frame. The vehicle height control unit sends a signal to the solenoid valve, and the solenoid valve closes, keeping the height of the vehicle frame unchanged.

[0017] As a preference of the technical solution of the present invention, the first height difference L1 of the left frame = hl1 - h0 - e, and the second height difference L2 of the left frame = h0 - hl1 - e; The first height difference R1 of the right frame = hr1 - h0 - e, and the second height difference R2 of the right frame = h0 - hr1 - e; In the formula, e is the allowable error value.

[0018] As a preference of the technical solution of the present invention, the vehicle height control unit continuously controls the average flow rate through the solenoid valve by adjusting the duty cycle D, realizes the control of the gas flow rate of the air spring, and further realizes the adjustment of the frame height; The flow rate through the solenoid valve within a set time ; In the formula, Q is the average flow rate through the solenoid valve within the time, is the flow coefficient, is the maximum area of the maximum opening of the solenoid valve, is the pressure difference of the air pressure, is the density of the gas.

[0019] As can be seen from the above technical solutions, the present invention has the following advantages: For commercial vehicles equipped with air suspension, an error range is set, which can not only effectively adjust the overall vehicle frame height, but also automatically adjust the overall vehicle frame height according to different road conditions compared with traditional control methods, effectively avoiding the impact of unsuitable air suspension height, thereby increasing the vehicle's handling stability and improving its fuel economy.

[0020] By monitoring vehicle speed and braking frequency over a set time period in real time, this invention can intelligently determine the current road conditions and dynamically adjust the target height of the chassis accordingly. This dynamic adjustment ensures that the vehicle maintains the required body posture under different road conditions, thereby improving driving safety and stability. The air spring inflation is precisely adjusted according to the corrected target height, which can more effectively absorb and dampen road vibrations, providing passengers with a smoother and more comfortable ride whether the vehicle is traveling on a smooth highway or a bumpy road.

[0021] This invention uses a target height determination unit to preset a target height based on the vehicle model, enabling the system to be applied to different commercial vehicle models without requiring individual settings for each vehicle type, greatly enhancing the system's versatility and adaptability. By intelligently adjusting the chassis height, this invention can minimize unnecessary energy consumption during vehicle operation while ensuring driving safety. For example, appropriately lowering the chassis height on flat roads can lower the vehicle's center of gravity, reduce wind resistance, and thus achieve energy conservation and emission reduction. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a system block diagram of an embodiment of the present invention.

[0024] Figure 2 This is a schematic flowchart of a method according to an embodiment of the present invention.

[0025] In the diagram, 1-first height sensor, 2-second height sensor, 3-air spring, 4-vehicle height control unit, 5-target height determination unit, 6-solenoid valve, 7-left side frame, 8-right side frame, 9-inflation source. Detailed Implementation

[0026] For different road conditions, the target height of the vehicle is determined based on vehicle parameters. The absolute value of the difference between the target height and the actual height is calculated. The chassis height is adjusted according to the magnitude of the absolute value of the difference to improve vehicle ride comfort, fuel economy, and overall vehicle passability. This invention provides an automatic chassis height adjustment system and control method for commercial vehicles. To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0027] like Figure 1 As shown, this embodiment of the invention provides an automatic vehicle frame height adjustment system, including a vehicle height control unit 4 and an air spring 3 mounted on the frame. The vehicle height control unit 4 is connected to a target height determination unit 5, a frame height monitoring unit, and a solenoid valve 6. The air spring 3 is connected to the solenoid valve 6, and the solenoid valve 6 is connected to the air source 9; The target height determination unit 5 determines the target height of the vehicle frame according to the vehicle model and transmits it to the vehicle height control unit 4; The chassis height monitoring unit acquires the current height of the chassis and transmits it to the vehicle height control unit; The vehicle height control unit acquires the current vehicle speed and the braking frequency over a set time period, determines the current road conditions based on the vehicle speed and the braking frequency, corrects the received target height based on the road conditions, calculates the height difference between the current height and the corrected target height, formulates a frame height control adjustment strategy, outputs the corresponding duty cycle based on the frame height control adjustment strategy, and adjusts the air spring inflation amount by controlling the on / off state of the solenoid valve to adjust the frame to the corrected target height.

[0028] The specific logic behind the adjustments is as follows: The vehicle speed sensor acquires real-time vehicle speed information. The vehicle height control unit records and analyzes the activation frequency of the braking system within a set time period (e.g., the past 1 minute, 5 minutes, etc.). Based on the collected vehicle speed and braking frequency, and combined with a preset algorithm or rule base, it determines whether the vehicle is currently in suburban, highway, or other special road conditions (e.g., mountain roads, slopes, etc.). A preset target chassis height value is received from the target height determination unit. Based on the determined road conditions, the received target height is adjusted appropriately. For example, on bumpy mountain roads, the chassis height may need to be lowered to improve stability, while on highways, it may need to be raised to improve ride comfort. The actual current chassis height is acquired via a height sensor and compared with the corrected target height, calculating the difference between the two. Based on the magnitude and direction of the height difference, and potential vehicle dynamic response requirements, a specific strategy for chassis height adjustment is formulated, including the direction of adjustment (up or down). Based on the formulated chassis height control adjustment strategy, the corresponding solenoid valve control signal duty cycle is calculated and output. The duty cycle determines the ratio of the solenoid valve's opening and closing time, thereby controlling the inflation or deflation rate of the air spring. The calculated duty cycle signal is converted into the actual control signal for the solenoid valve, and the air spring inflation is adjusted by controlling the on / off state of the solenoid valve. Changes in frame height are continuously monitored, and the solenoid valve control signal is adjusted as needed until the frame height reaches the corrected target height. The final frame height adjustment result is fed back to the vehicle control system or other relevant modules for further monitoring and analysis. During vehicle operation, the vehicle height control unit should continuously monitor changes in frame height and make necessary fine-tuning adjustments based on actual conditions to ensure the frame height remains at its optimal state.

[0029] In some embodiments, the frame height monitoring unit includes a first height sensor 1 disposed on the left frame 7 and a second height sensor 2 disposed on the right frame 8. The first height sensor 1 transmits the height of the left frame 7 to the vehicle height control unit 4, and the second height sensor 2 transmits the height of the right frame 8 to the vehicle height control unit 4.

[0030] It should be noted that the first height sensor and the second height sensor are used to obtain the current height signals of the vehicle frame on the left and right sides respectively, and the current height signals are filtered and then transmitted to the vehicle height control unit.

[0031] In some embodiments, the vehicle height control unit obtains the current vehicle speed and the cumulative number of braking actions within a set time period via the CAN bus, i.e., the braking frequency. If the acquired vehicle speed is greater than the set vehicle speed and the braking frequency is lower than the first set threshold, it is determined that the vehicle is traveling in the first road condition. The target height correction value corresponding to the first road condition is acquired, and the target height input by the target height determination unit is corrected. The corrected target height is equal to the difference between the received target height and the target height correction value. Here, the first road condition is a smooth road condition such as a highway or national road. Under this road condition, the target height of the vehicle frame should be appropriately reduced to reduce wind resistance and improve fuel economy.

[0032] If the acquired vehicle speed is less than or equal to the set vehicle speed and the braking frequency is higher than the first set threshold, it is determined that the vehicle is traveling in the second road condition. The target height correction value corresponding to the second road condition is acquired, and the target height input by the target height determination unit is corrected. The corrected target height is equal to the sum of the received target height and the target height correction value. The second road condition is a congested road condition such as rural roads or mountain roads. Under this road condition, the target height of the vehicle frame should be appropriately increased to improve the smoothness of vehicle driving.

[0033] In some embodiments, the vehicle height control unit calculates the first height difference L1 and the second height difference L2 of the left side frame based on the frame height hl1 collected by the first height sensor and the target height h0 after road condition correction; and calculates the first height difference R1 and the second height difference R2 of the right side frame based on the frame height hr1 collected by the second height sensor and the corrected target height h0. The chassis height control and adjustment strategy is determined by comparing the first and second height differences of the left and right chassis. By controlling the on / off states of solenoid valves related to the overall chassis height adjustment, the left chassis 7 and right chassis 8 are adjusted from their current heights to the target heights.

[0034] Here, the chassis height control and adjustment strategy is as follows: If (L1>0)||(L2>0)||(R1>0)||(R2>0)!=0 and L1+R1>L2+R2, the vehicle height control unit sends a signal to the solenoid valve. At this time, if L1>L2, the vehicle height control unit controls the solenoid valve to open, and the air spring on the left side of the frame deflates, thus lowering the height of the left side of the vehicle frame. If R1>R2, the vehicle height control unit sends a signal to the solenoid valve, and the solenoid valve opens, and the air spring on the right side of the frame deflates, thus lowering the height of the right side of the vehicle frame. If (L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0) != 0 and L1 + R1 < L2 + R2, the vehicle height control unit sends a signal to the solenoid valve; at this time, if L1 < L2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring to increase the height of the left frame of the vehicle. If R1 < R2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring to increase the height of the right frame of the vehicle. If ((L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)) == 0, there is no need to adjust the vehicle frame height. The vehicle height control unit sends a signal to the solenoid valve, and the solenoid valve closes, and the vehicle frame height remains unchanged.

[0035] It should be noted that ((L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)) == 0 holds when L1 <= 0, L2 <= 0, R1 <= 0, and R2 <= 0 are all established simultaneously.

[0036] The first height difference L1 of the left frame = hl1 - h0 - e, and the second height difference L2 of the left frame = h0 - hl1 - e; The first height difference R1 of the right frame = hr1 - h0 - e, and the second height difference R2 of the right frame = h0 - hr1 - e; In the formula, e is the allowable error value. In the embodiment of the present invention, the range of the allowable error value e is [-5, +5] mm.

[0037] In some embodiments, during the deflation process, the vehicle height control unit determines the adjustment mode according to the height difference and applies this series of control instructions to the electromagnetic coil of the solenoid valve. Then, within a cycle time there is time when the valve passage is open and there is a flow Q passing through, and there is time when the valve is closed and there is no flow passing through. The ratio of time to is the pulse width modulation rate (also called the duty cycle), denoted as D = / , is the pulse width, is the pulse period. Let Q be the average flow rate passing through the solenoid valve, is the flow coefficient, is the maximum area of the maximum opening of the high-speed switching valve, is the pressure difference, D is the pulse width signal modulation rate, is the density of the gas, and the output flow rate of the solenoid valve within this time can be expressed by the average flow rate Q:

[0038] By adjusting the duty cycle D of the regulating station, the average flow rate through the solenoid valve can be continuously controlled, achieving quasi-continuous flow control. This controls the solenoid valve to open, allowing gas in the air spring to be discharged through its exhaust port. When the venting process ends, the vehicle height control unit sends a control signal to the solenoid valve to close it, stopping the gas discharge from the air spring.

[0039] During inflation, the vehicle height control unit sends a control signal to the solenoid valve to open it, and then the air source inflates the air spring. When the inflation process ends, the vehicle height control unit sends a control signal to the solenoid valve to close it, and the air source stops inflating the air spring.

[0040] In this embodiment of the invention, the adjustment of the frame height needs to include, but is not limited to, ensuring that the left and right frames are at the same height.

[0041] The vehicle height control unit continuously controls the average flow rate through the solenoid valve by adjusting the duty cycle D, thereby controlling the air flow rate of the air spring and adjusting the vehicle frame height. Flow rate through the solenoid valve within a set time period ; In the formula, Q is the average flow rate through the solenoid valve within a time interval. For flow coefficient, This represents the maximum area of ​​the solenoid valve's largest opening. The pressure difference is the air pressure. To measure the density of the gas, the gas pressure inside the air spring needs to be measured by a pressure sensor. Given the current vehicle weight, when the pressure changes, the corresponding height sensor provides real-time feedback on the frame height, thereby obtaining the corresponding height change. This reveals a correlation between pressure change and duty cycle, enabling the adjustment of the frame height.

[0042] Ensure the height sensor accurately reflects the actual height of the chassis. This typically needs to be done when the vehicle is stationary and the load is stable. Based on vehicle design and manufacturer recommendations, establish a baseline pressure value and corresponding duty cycle as a reference point for subsequent adjustments. Collect chassis height information in real time via the height sensor and transmit it to the vehicle height control unit. Based on vehicle design and experimental data, establish a mapping relationship between pressure changes, chassis height changes, and the solenoid valve duty cycle. This mapping relationship may be linear or non-linear, depending on the specific characteristics and requirements of the vehicle. Based on the sensed height changes (and possible pressure changes), and in conjunction with the mapping relationship, determine the solenoid valve duty cycle that needs adjustment; send the calculated target duty cycle signal to the solenoid valve controller to adjust the on / off state of the solenoid valve, thereby changing the inflation or deflation rate of the air spring. Continue to receive data from the height sensor in real time to monitor the actual changes in chassis height. If the chassis height does not reach the expected target, recalculate the duty cycle based on the new height data and readjust the solenoid valve until the chassis height stabilizes within the target range. In practical applications, machine learning or adaptive algorithms are introduced to continuously optimize the pressure-height-duty cycle mapping relationship based on historical data and real-time feedback, thereby improving the accuracy and efficiency of regulation.

[0043] like Figure 2 As shown in the figure, this embodiment of the invention also provides a method for automatically adjusting and controlling the height of a commercial vehicle frame, comprising the following steps: Step 1: Obtain the current height of the vehicle frame and the preset target height; Step 2: Obtain the current vehicle speed and braking frequency over a set time period; Step 3: Determine the current road conditions based on the vehicle speed and braking frequency, and correct the received target height according to the road conditions; Step 4: Calculate the height difference between the current height and the corrected target height, and output the chassis height control adjustment strategy; Step 5: Output the corresponding duty cycle according to the frame height control adjustment strategy, and adjust the air spring inflation by controlling the on / off state of the solenoid valve to adjust the frame to the corrected target height.

[0044] In some embodiments, the step of determining the current road conditions based on vehicle speed and braking frequency, and correcting the received target height based on the road conditions, includes: If the acquired vehicle speed is greater than the set vehicle speed and the braking frequency is lower than the first set threshold, it is determined that the vehicle is traveling in the first road condition. The target height correction value corresponding to the first road condition is acquired, and the target height input by the received target height determination unit is corrected. The corrected target height is equal to the difference between the received target height and the target height correction value. If the obtained vehicle speed is less than or equal to the set vehicle speed and the braking frequency is higher than the first set threshold, it is determined that the vehicle is traveling on the second road condition, the target height correction value corresponding to the second road condition is obtained, and the target height input by the received target height determination unit is corrected; wherein, the corrected target height is equal to the sum of the received target height and the target height correction value.

[0045] In some embodiments, the vehicle height control unit calculates the first height difference L1 and the second height difference L2 of the left frame according to the frame height hl1 collected by the first height sensor and the corrected target height h0 corresponding to the road condition; calculates the first height difference R1 and the second height difference R2 of the right frame according to the frame height hr1 collected by the second height sensor and the corrected target height h0; The vehicle frame height control adjustment strategy is determined by comparing the first height difference and the second height difference of the left frame and the first height difference and the second height difference of the right frame.

[0046] In some embodiments, the steps of calculating the height difference between the current height and the corrected target height and outputting the vehicle frame height control adjustment strategy include: Calculate the first height difference L1 and the second height difference L2 of the left frame according to the frame height hl1 collected by the first height sensor and the corrected target height h0 corresponding to the road condition; calculate the first height difference R1 and the second height difference R2 of the right frame according to the frame height hr1 collected by the second height sensor and the corrected target height h0; If (L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)!= 0 and L1 + R1 > L2 + R2, the vehicle height control unit sends a signal to the solenoid valve; at this time, if L1 > L2, the vehicle height control unit controls the solenoid valve to open, and the air spring of the left frame deflates, reducing the height of the left frame of the vehicle; if R1 > R2, the vehicle height control unit sends a signal to the solenoid valve, the solenoid valve opens, and the air spring of the right frame deflates, reducing the height of the right frame of the vehicle; If (L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)!= 0 and L1 + R1 < L2 + R2, the vehicle height control unit sends a signal to the solenoid valve; at this time, if L1 < L2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, increasing the height of the left frame of the vehicle, if R1 < R2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, increasing the height of the right frame of the vehicle; If ((L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)) == 0, there is no need to adjust the vehicle frame height, the vehicle height control unit sends a signal to the solenoid valve, the solenoid valve closes, and the vehicle frame height remains unchanged.

[0047] It should be noted that ((L1>0) || (L2>0) || (R1>0) || (R2>0)) == 0 is true when L1<= 0, L2<= 0, R1<= 0 and R2<= 0 are all true at the same time.

[0048] Here, the first height difference of the left frame is L1 = hl1 - h0 - e, and the second height difference of the left frame is L2 = h0 - hl1 - e; The first height difference of the right frame is R1 = hr1 - h0 - e, and the second height difference of the right frame is R2 = h0 - hr1 - e; In the formula, e is the allowable error value.

[0049] In some embodiments, the method provided in this application is based on the system method described in the above embodiments, as follows: The vehicle height control unit receives the target height of the vehicle frame from the target height determination unit based on the vehicle model; and receives the current height of the frame from the frame height monitoring unit. The vehicle height control unit acquires the current vehicle speed and the braking frequency over a set time period, and determines the current road conditions based on the vehicle speed and the braking frequency. It corrects the received target height based on the road conditions, calculates the height difference between the current height and the corrected target height, and formulates a frame height control adjustment strategy. Based on the frame height control adjustment strategy, it outputs the corresponding duty cycle and adjusts the air spring inflation by controlling the on / off state of the solenoid valve to adjust the frame to the corrected target height.

[0050] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0051] The embodiments of the present invention provide an automatic adjustment control method for the chassis height of commercial vehicles. This method belongs to the same inventive concept as the automatic adjustment system for the chassis height of commercial vehicles described in the above embodiments. For details not described in detail in the embodiments of the automatic adjustment control method for the chassis height of commercial vehicles, please refer to the embodiments of the automatic adjustment system for the chassis height of commercial vehicles described above.

[0052] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A commercial vehicle frame height automatic adjustment system, characterized in that: It includes a vehicle height control unit and an air spring arranged on a vehicle frame, wherein the vehicle height control unit is connected to a target height determination unit, a vehicle frame height monitoring unit and a solenoid valve; The air spring is connected to a solenoid valve, and the solenoid valve is connected to an air filling source; The target height determination unit determines the target height of the vehicle frame according to the vehicle model and transmits it to the vehicle height control unit; The frame height monitoring unit obtains the current height of the frame and transmits it to the vehicle height control unit; The vehicle height control unit obtains the current vehicle speed and the braking frequency in a set time period, and determines the current driving condition of the vehicle according to the vehicle speed and the braking frequency, corrects the received target height according to the driving condition, calculates the height difference between the current height and the corrected target height, and formulates a frame height control adjustment strategy, outputs a corresponding duty cycle according to the frame height control adjustment strategy, adjusts the inflation amount of the air spring by controlling the on-off state of the solenoid valve, and adjusts the frame to the corrected target height.

2. The automatic height adjustment system for commercial vehicle frame according to claim 1, characterized in that: The frame height monitoring unit includes a first height sensor arranged on the left frame and a second height sensor arranged on the right frame. The first height sensor transmits the collected height of the left frame to the vehicle height control unit, and the second height sensor transmits the collected height of the right frame to the vehicle height control unit.

3. The automatic height adjustment system for commercial vehicle frame according to claim 2, characterized in that: The vehicle height control unit obtains the current vehicle speed and the cumulative number of brakes within the current set time period, i.e. the braking frequency, through the CAN bus; If the acquired vehicle speed is greater than the set vehicle speed and the braking frequency is lower than a first set threshold, it is determined that the vehicle is traveling on a first road condition, a target height correction value corresponding to the first road condition is acquired, and the target height received from the target height determination unit is corrected; wherein the corrected target height is equal to the difference between the received target height and the target height correction value; If the acquired vehicle speed is less than or equal to the set vehicle speed, and the braking frequency is higher than the first set threshold, it is determined that the vehicle is traveling on a second road condition, and a target height correction value corresponding to the second road condition is obtained, and the target height input by the target height determination unit is corrected; wherein the corrected target height is equal to the sum of the received target height and the target height correction value.

4. The automatic height adjustment system for commercial vehicle frame according to claim 3, characterized in that: The vehicle height control unit calculates the first height difference L1 and the second height difference L2 of the left frame according to the frame height hl1 collected by the first height sensor and the target height h0 corrected according to the road conditions; calculates the first height difference R1 and the second height difference R2 of the right frame according to the frame height hr1 collected by the second height sensor and the corrected target height h0; The frame height control adjustment strategy is determined by comparing the first height difference and the second height difference of the left frame with the first height difference and the second height difference of the right frame.

5. The automatic height adjustment system for commercial vehicle frame according to claim 4, characterized in that: The frame height control adjustment strategy includes: When ((L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0))!= 0 and L1 + R1 > L2 + R2, the vehicle height control unit sends a signal to the solenoid valve. At this time, if L1 > L2, the vehicle height control unit controls the solenoid valve to open, and the air spring on the left frame deflates, reducing the height of the left frame of the vehicle. If R1 > R2, the vehicle height control unit sends a signal to the solenoid valve, the solenoid valve opens, and the air spring on the right frame deflates, reducing the height of the right frame of the vehicle. When ((L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0))!= 0 and L1 + R1 < L2 + R2, the vehicle height control unit sends a signal to the solenoid valve. At this time, if L1 < L2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, increasing the height of the left frame of the vehicle. If R1 < R2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, increasing the height of the right frame of the vehicle. When ((L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)) == 0, there is no need to adjust the height of the vehicle frame. The vehicle height control unit sends a signal to the solenoid valve, and the solenoid valve closes, keeping the height of the vehicle frame unchanged.

6. The automatic height adjustment system for commercial vehicle frame according to claim 5, characterized in that: The first height difference L1 of the left frame = hl1 - h0 - e, and the second height difference L2 of the left frame = h0 - hl1 - e; The first height difference R1 of the right frame = hr1 - h0 - e, and the second height difference R2 of the right frame = h0 - hr1 - e; In the formula, e is the allowable error value.

7. The automatic height adjustment system for commercial vehicle frame according to claim 1, characterized in that: The vehicle height control unit continuously controls the average flow rate through the solenoid valve by adjusting the duty cycle D, realizes the control of the gas flow rate of the air spring, and further realizes the adjustment of the frame height; The flow rate through the solenoid valve within the set time ; Where Q is the average flow rate through the solenoid valve during the time period. is the flow coefficient, is the maximum area of ​​the largest opening of the solenoid valve, is the pressure difference of the air, is the density of the gas.

8. A commercial vehicle frame height automatic adjustment control method, characterized in that: It includes the following steps: Obtain the current height of the vehicle frame and the preset target height; Obtain the current vehicle speed and the braking frequency in the set time period; Determine the current driving road condition of the vehicle according to the vehicle speed and the braking frequency, and correct the received target height according to the driving road condition; Calculate the height difference between the current height and the corrected target height, and output the frame height control adjustment strategy; Output the corresponding duty cycle according to the frame height control adjustment strategy, adjust the inflation amount of the air spring by controlling the on-off state of the solenoid valve, and adjust the frame to the corrected target height.

9. The commercial vehicle frame height automatic adjustment control method according to claim 8, characterized in that: The step of determining the current driving road condition of the vehicle according to the vehicle speed and the braking frequency, and correcting the received target height according to the driving road condition includes: If the obtained vehicle speed is greater than the set vehicle speed and the braking frequency is lower than the first set threshold, it is determined that the vehicle is driving on the first road condition, obtain the target height correction value corresponding to the first road condition, and correct the target height input by the target height determination unit received; among them, the corrected target height is equal to the difference between the received target height and the target height correction value; If the obtained vehicle speed is less than or equal to the set vehicle speed and the braking frequency is higher than the first set threshold, it is determined that the vehicle is traveling on the second road condition, the target height correction value corresponding to the second road condition is obtained, and the target height input by the received target height determination unit is corrected; wherein, the corrected target height is equal to the sum of the received target height and the target height correction value.

10. The commercial vehicle frame height automatic adjustment control method according to claim 9, characterized in that: The steps of calculating the height difference between the current height and the corrected target height and outputting the vehicle frame height control adjustment strategy include: Calculating the first height difference L1 and the second height difference L2 of the left vehicle frame according to the vehicle frame height hl1 collected by the first height sensor and the corrected target height h0 corresponding to the road condition; calculating the first height difference R1 and the second height difference R2 of the right vehicle frame according to the vehicle frame height hr1 collected by the second height sensor and the corrected target height h0; If (L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)!= 0 and L1 + R1 > L2 + R2, the vehicle height control unit sends a signal to the solenoid valve; at this time, if L1 > L2, the vehicle height control unit controls the solenoid valve to open, and the air spring of the left vehicle frame deflates, so that the height of the left vehicle frame of the whole vehicle decreases; if R1 > R2, the vehicle height control unit sends a signal to the solenoid valve, the solenoid valve opens, and the air spring of the right vehicle frame deflates, so that the height of the right vehicle frame of the whole vehicle decreases; If (L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)!= 0 and L1 + R1 < L2 + R2, the vehicle height control unit sends a signal to the solenoid valve; at this time, if L1 < L2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, so that the height of the left vehicle frame of the whole vehicle increases, if R1 < R2, the vehicle height control unit controls the solenoid valve to open, and the inflation source inflates the air spring, so that the height of the right vehicle frame of the whole vehicle increases; If ((L1 > 0) || (L2 > 0) || (R1 > 0) || (R2 > 0)) == 0, there is no need to adjust the vehicle frame height of the whole vehicle, the vehicle height control unit sends a signal to the solenoid valve, the solenoid valve closes, and the vehicle frame height of the whole vehicle remains unchanged.

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