Method for adjusting air suspension system of stationary motor vehicle

Abstract

The invention relates to a method for adjusting an air suspension system of a stationary motor vehicle, characterized by the following steps: comparing a predetermined target horizontal position with an actual horizontal position of the motor vehicle, determining an actual air quantity in at least a number of air springs in the air suspension system, -if the actual horizontal position is lower than the target horizontal position and the measured air quantity is lower than the reference air quantity,-inflating an air spring of the air suspension system, during which the actual horizontal position is monitored, and-if the measured air quantity is lower than the target horizontal position and the measured air quantity is lower than the reference air quantity,-inflating the air spring of the air suspension system. If the actual horizontal position is still lower than the target horizontal position or the actual horizontal position does not change, the inflation operation of the air spring only continues until the actual air amount in the air spring reaches the reference air amount corresponding to the target horizontal position.

Description

Technical Field

[0001] The present invention relates to a method for adjusting an air suspension system of a stationary motor vehicle as described in the preamble of claim 1, and an air suspension system for implementing the method. Background Technology

[0002] Electronically adjustable air suspension systems are increasingly used in passenger vehicle leveling. The main components of an air suspension system include air springs filled with pressurized air to cushion the vehicle body, and an air supply system to provide the pressurized air. These two components are interconnected via pneumatic lines. In addition, various sensors, such as height and pressure sensors, as well as electronic control and adjustment devices are included. Various solenoid valves controlled by the control and adjustment devices are arranged within the pneumatic lines. Clearly, the sensors and valves are connected to the control and adjustment devices via wires.

[0003] For vehicles equipped with air suspension systems, there are various methods for leveling. Essentially, it involves adjusting the vehicle to the desired level and maintaining that level. This is achieved by using sensors to detect the vehicle's height relative to the lane and adjusting its level position accordingly. For example, leveling can be performed after the vehicle is loaded, or the vehicle can be lowered during driving to save fuel.

[0004] An air suspension system can actively change the vehicle's height / level relative to the lane by opening and closing specific on / off valves. Vehicle level is adjusted by filling or purging pressurized air into the air springs as needed. Height refers to the distance of the vehicle body relative to the lane. Because the distance between the vehicle body and the lane can vary at different axles, it is also called level position.

[0005] To determine the current level position of a vehicle, chassis sensors are typically used. These sensors detect the spring travel of the wheels (as unsprung mass) relative to the vehicle body (as sprung mass). Such chassis sensors are installed within the area of ​​the vehicle's wheel suspension or spring damper unit to determine the wheel's spring travel relative to the body. These chassis sensors are also known as height sensors, vertical sensors, level sensors, or spring travel sensors. The spring travel sensor transmits the signal to the vehicle's electronic control and regulation system, where the signal is further processed.

[0006] Air-suspended vehicles are transported at a specific level, known as transport level. This is typically done to increase ground clearance, facilitating the passage over obstacles during loading and unloading. Electronic controls and adjustments periodically activate and check the air suspension system's condition. If a deviation is detected, the level is corrected to the required target level. For example, such a deviation might be caused by a system leak during transport.

[0007] Normally, motor vehicles are secured at the wheels, which does not affect leveling. However, for example, during shipping, motor vehicles are not secured at the wheels, but rather at the trailer rings, i.e., at the vehicle body. By tying the vehicle body to the ground, the chassis is tightened and lowered, thus altering the desired transport position. Due to the securing force, the vehicle body may, for example, drop from an actual height of +50 mm to +40 mm.

[0008] However, this also means that the aforementioned leveling correction cannot be performed normally in this situation. This is because the leveling function attempts to correct the height deviation by supplying pressurized air to the air springs to achieve the target level of +50mm. However, since the vehicle body is fixed, this level position cannot be reached. Instead, the air suspension system is at risk of damage because the air pressure in the system or air springs may exceed the permissible system limits, leading to system failure.

[0009] Furthermore, shipping that lasts several weeks also requires calibration, as natural leaks can occur during this period, causing pressurized air in the system to escape. It is essential to ensure that a certain amount of air is maintained in the air springs to hold the vehicle securely; otherwise, the vehicle may slip and be damaged. Summary of the Invention

[0010] Therefore, the object of the present invention is to provide a method for adjusting an air suspension system that avoids the above-mentioned disadvantages and ensures that the air suspension system is adequately inflated during motor vehicle transportation.

[0011] According to the present invention, when adjusting the air suspension system of a stationary motor vehicle, the following steps are performed:

[0012] - Compare the vehicle's predetermined target horizontal position with its actual horizontal position, and

[0013] - Measure the actual air volume in at least a certain number of air springs in the air suspension system, and compare the measured actual air volume with a reference air volume that depends on the target horizontal position.

[0014] - If the actual horizontal position is lower than the target horizontal position, and the measured air volume is lower than the reference air volume,

[0015] - Inflate the air springs of the air suspension system, monitoring the actual level position during this process, and

[0016] - If the actual horizontal position is still lower than the target horizontal position or the actual horizontal position has not changed, the inflation operation of the air spring will continue only until the actual air volume in the air spring reaches the reference air volume corresponding to the target horizontal position.

[0017] In this way, the air suspension system is protected during vehicle transport and can be put into use immediately after unloading, because the vehicle body directly sets the transport level to the target level position.

[0018] Preferably, multiple height sensors are used to determine the actual horizontal position. These height sensors measure the relative distance between the vehicle body, which is the sprung mass, and the wheel, which is the unsprung mass, at each wheel of the vehicle.

[0019] Preferably, the actual amount of air in the air spring is determined by measuring values ​​from the pressure sensor and the relevant height sensor of the air suspension system.

[0020] The air volume is determined based on the known cross-section of the air spring or the known geometry of the pressure chamber acting as the spring, as well as the spring-related height value of the air spring and the measured air pressure within the air spring. The air spring height value is needed because the pressure chamber of the air spring has volumetric elasticity. The volume enclosed by the rolling piston of the air spring varies depending on the spring stroke and rolling piston profile. Pressure sensors provided in the air suspension system are used to measure the air pressure in the air springs. For example, the pressure sensors are positioned centrally in the air suspension system so that the air pressure in multiple air springs can be measured sequentially. If a pressurized reservoir is present, the pressure in a known reservoir with a constant volume can also be measured using pressure sensors. Therefore, the air volume can be calculated by multiplying the measured pressure in the air spring by its height or volume. After determining the air volume in all air springs, the total air volume in the air suspension system is calculated by addition. If a pressurized reservoir is present, the air volume in that reservoir is also taken into account.

[0021] Preferably, the air springs are inflated using the compressor of the air suspension system. The compressor either draws in ambient air or is supplied with pressurized air by a pressurized reservoir and delivers the compressed pressurized air to the air springs. Attached Figure Description

[0022] Other preferred embodiments of the present invention can be obtained from the following description of embodiments based on the accompanying drawings.

[0023] in:

[0024] Figure 1 The aerodynamic circuit diagram of a closed air suspension system is shown.

[0025] Figure 2 The image shows a stationary motor vehicle strapped to the ground.

[0026] Figure 3 A flowchart illustrating an exemplary method is shown. Detailed Implementation

[0027] Figure 1 The diagram shows the pneumatic circuit of an electronically adjustable air suspension system 1 for a motor vehicle, which operates in a closed air supply mode. The air suspension system 1 includes a compressor 3 driven by an electric motor 2, wherein the compressor 3 is designed as a dual-piston compressor. Multiple air springs 5, acting as pneumatic adjustment units, correspond to one wheel of the motor vehicle to adjust the vehicle height. Each air spring 5 has an air spring valve 17 upstream of it.

[0028] The air suspension system 1 also includes a dryer 4 and a throttling check valve 9 located downstream of the dryer 4. The dryer is used to dry the air drawn in from the environment by the compressor 3. A pressurized reservoir 8 is provided to store the drawn-in air as system air in the air suspension system 1.

[0029] In addition, a switching valve assembly is provided to connect the compressor 3, the pressurized reservoir 8, and the air springs 5 ​​together. This switching valve assembly includes four switching valves 13 to 16, implemented as electronically controllable two-position two-way directional valves (2 / 2-Wegeventil). Furthermore, a pressure sensor 11 is provided for measuring the pressure in the various components of the air suspension system. The pressure sensor 11 is used to measure the pressure in each air spring 5 and the pressurized reservoir 8.

[0030] To supply compressed system air, compressor 3 draws air from the atmosphere through inlet 6. System air is discharged from air suspension system 1 through outlet 7, which has a pre-positioned discharge valve 12. A power limiting valve 10 is provided to bridge the compressor inlet and compressor outlet.

[0031] On the output side of compressor 3, the first pressurized air line 18 leads to the first switching valve 13 and the second switching valve 14. On the input side of compressor 3, the second pressurized air line 19 leads to the third switching valve 15 and the fourth switching valve 16. The third pressurized air line 20 leads from pressurized reservoir 8 to the first switching valve 13 and the fourth switching valve 16.

[0032] Not shown in the figure but an essential component of the air suspension system 1 is an electronic control and regulation device for controlling the compressor 3 or motor 2 and for opening and closing multiple switching valves. Pressure is also measured in the air spring 5 and pressurized reservoir 8 via a controller and pressure sensor 11. Furthermore, multiple height sensors are electrically connected to the control and regulation device to measure the spring travel of each air spring 5.

[0033] Figure 2A stationary motor vehicle 30 is shown, secured and fixed to the ground 38 by fastening straps 39 for easy transport. The motor vehicle 30 includes a body 31, which, as sprung mass, is cushioned relative to each wheel 33 (as unsprung mass) by a plurality of spring damper units 32 (preferably air springs or air spring shock absorbers). The spring damper units 32 of the front and rear axles are each equipped with a height sensor 34. Needless to say, each axle of the motor vehicle 30 has two spring damper units 32 and a corresponding height sensor 34.

[0034] The actual horizontal position 37 of the vehicle body 31 relative to the wheels 33 is measured by the height sensor 34. The actual horizontal position 37 may differ from the target horizontal position 36. The horizontal position itself refers to the relative distance between the upper fixed point of the spring / damper unit 32 on the vehicle body 31 and the lower fixed point of the spring / damper unit 32 on the wheel bracket or wheel 33. Therefore, the height sensor 34 measures the relative distance between the vehicle body 31 (as sprung mass) and the wheels 33 (as unsprung mass). The measurement signal from the height sensor 34 is continuously transmitted to the electronic control and adjustment device 35 of the vehicle 30, where it is processed. In the electronic control and adjustment device, the measurement signal is typically filtered so that it can be further processed as a smoothed height value and used for target-to-actual value adjustment of the horizontal position of the vehicle 30. That is, the measurement signal from the height sensor 34 provides information about the current horizontal position of the vehicle 30.

[0035] Figure 3 The flowchart is used to explain an exemplary adjustment method for a motor vehicle air suspension system.

[0036] In the first step S1, the actual level position of the vehicle body is compared with a predetermined target level position. That is, for example, during vehicle transportation, the difference between the current level and the original level is checked at periodic intervals. For this purpose, the electronic control and adjustment device is automatically activated, for example, every 48 hours.

[0037] In addition, the air volume is measured to determine the actual amount of air currently present in the air springs. If the air suspension system has, for example, a pressurized air reservoir, all the air in the system can also be used as the total system air volume for determination and use. Regardless of the actual height of the vehicle, the air volume is also used as an indicator of whether the vehicle is in a strapped-down or unstuck position. This is because the air volume depends on the target level position of the vehicle body. Under normal conditions of the air suspension system, the amount of air required for each vehicle height is known, therefore the target level position has a reference air volume that can be used to determine the state of the system. Therefore, it can be assumed that, with the correct air volume in the air springs, the vehicle body will return to the set target level after the straps are released. Furthermore, different strap strengths of the vehicle body are irrelevant when considering the reference air volume.

[0038] Therefore, after determining the actual horizontal position and the actual air volume, a comparison is made in the second step S2. If the actual horizontal position is lower than the target horizontal position and the actual air volume is also lower than the reference target air volume, the air springs need to be inflated. Then, in the third step S3, a certain number of air springs are filled with pressurized air. This can be achieved by operating the compressor of the air suspension system, which draws in air from the environment, compresses it, and delivers it to the air springs. Alternatively, pressurized air from a pressurized air reservoir can be used to directly fill the air springs, or the compressor can further compress the air from the reservoir and then deliver it to the air springs.

[0039] During the inflation process in step S3, a height sensor monitors the actual level. If the actual level does not change or fails to rise to the target level as expected, it indicates that the vehicle body is secured. Therefore, if the actual level is lower than the target level, in step S4, the air springs are inflated only until the actual air volume is equivalent to the reference target air volume. This compensates for the air volume loss during transportation, and the air volume in the air springs is sufficient to lift the vehicle body to the target level after untying. In this way, the vehicle can be put into use immediately, and no compensation operation is required after the vehicle is untied.

[0040] When the actual horizontal position reaches the target horizontal position during inflation, the inflation operation is stopped, and the vehicle body can be considered no longer secured. At this point, the vehicle is at the desired transport height.

[0041] List of reference numerals in the attached diagram:

[0042] 1. Air suspension system

[0043] 2 motors

[0044] 3. Compressor

[0045] 4. Dryer

[0046] 5. Air springs

[0047] 6 entrances

[0048] 7 Exports

[0049] 8. Pressurized storage tank

[0050] 9. Throttling check valve

[0051] 10 Power limiting valve

[0052] 11 Pressure Sensor

[0053] 12. Drain valve

[0054] 13 First switching valve

[0055] 14 Second switching valve

[0056] 15 Third switching valve

[0057] 16 Fourth switching valve

[0058] 17. Air spring valve

[0059] 18 First pressurized air line

[0060] 19 Second pressurized air line

[0061] 20 Third pressurized air line

[0062] 21 Fourth pressurized air line

[0063] 30 Motor vehicles

[0064] 31 Body

[0065] 32 Spring Shock Absorber Units

[0066] 33 wheels

[0067] 34 Height Sensors

[0068] 35 Electronic control and regulation device

[0069] 36 Target horizontal position

[0070] 37. Actual horizontal position

[0071] 38 Ground

[0072] 39. Fastening straps.

Claims

1. A method for adjusting the air suspension system (1) of a stationary motor vehicle (30), characterized by the following steps: - Compare the predetermined target horizontal position (36) with the actual horizontal position of the vehicle (37). - Measure the actual air volume in at least a certain number of air springs in the air suspension system (1), and compare the measured actual air volume with a reference air volume that depends on the target horizontal position. - If the actual horizontal position is lower than the target horizontal position, and the measured air volume is lower than the reference air volume, - The air springs (5, 32) of the air suspension system (1) are inflated, and the actual horizontal position (37) is monitored during this period. - If the actual horizontal position (37) is still lower than the target horizontal position (36) or the actual horizontal position (37) has not changed, the inflation operation of the air spring (5, 32) continues only until the actual air volume in the air spring (5, 32) reaches the reference air volume corresponding to the target horizontal position (36).

2. The method according to claim 1, characterized in that, The actual horizontal position (36) is determined using multiple height sensors (34), which measure the relative distance between the body (31) as sprung mass and the wheel (33) as unsprung mass at each wheel (33) of the motor vehicle (30).

3. The method according to claim 2, characterized in that, The actual amount of air in the air springs (5, 32) is determined by measuring the pressure sensor (11) and the relevant height sensor (34) of the air suspension system (1).

4. The method according to any one of claims 1 to 3, characterized in that, The compressor (3) of the air suspension system (1) inflates the air springs (5, 32).

5. An air suspension system (1) for a motor vehicle (30), the air suspension system having an electronic control and adjustment device (35) for implementing the method according to any one of the preceding claims.

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