Air suspension system and method of controlling the same

Abstract

The application relates to an air suspension system and a control method thereof, the system comprising an air spring, an air tank and a pump for inflating the air spring or the air tank, the pump comprising a brushless motor, a driving module and a voltage boosting module; wherein the driving module comprises an MCU and a driving circuit, the MCU comprising an input end for receiving a normal instruction signal and a voltage boosting instruction signal, a first output end for outputting a normal driving signal when the normal instruction signal is received, and a second output end for outputting a voltage boosting driving signal when the voltage boosting instruction signal is received; the driving circuit is connected between the first output end of the MCU and the brushless motor; and the voltage boosting circuit is connected between the second output end of the MCU and the driving circuit. By adopting the pump with the brushless motor as a power source and adding the voltage boosting module in the driving module, the disadvantages of the traditional brush motor are overcome, and the emergency inflation demand can be met without increasing the pipeline.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and in particular to an air suspension system and its control method. Background Technology

[0002] With the development of electric and intelligent vehicles, more and more vehicles are equipped with adjustable air suspension systems to enhance the driving experience. Adjustable air suspension changes the volume of gas within the air springs, thus adjusting the damping stiffness and vehicle height. It can automatically lower the vehicle height at high speeds to reduce wind resistance and improve handling and stability; and automatically raise the vehicle height on bumpy roads to improve ground clearance and allow the vehicle to handle road conditions more easily. Compared to models with lower-spec traditional suspensions, vehicles with adjustable air suspension are more adaptable to different road conditions, offering greater comfort and stability.

[0003] See Figure 1 As shown, Figure 1 The diagram shows the air circuit architecture of the air suspension system. The air pump 1 is the core component of the entire air suspension system, consisting of a pump head and a motor. The motor drives the piston inside the pump head, compressing the intake atmospheric pressure gas into high-pressure gas, which is then supplied to the air springs 2 (including air springs without dampers and those with dampers) or to the air tank 3 via the distribution valve 4. Specifically, there are currently two air supply logics for the air pump: one is that the air pump 1 first supplies air to the air tank 3, and then the air tank 3 supplies air to the air springs 2 to adjust the vehicle's attitude; the other is that when the air pressure in the air tank 3 is insufficient, the air pump 1 directly supplies air to the air springs 2 to adjust the vehicle's attitude.

[0004] Currently, air pumps in commercially available air suspension systems are typically driven by brushed motors, which can only meet the needs of general operating conditions. For situations requiring rapid replenishment of air springs, especially when the air tank pressure is significantly insufficient and the air pump needs to be used directly to replenish the air springs for vehicle attitude adjustment, the pump's efficiency severely impacts the vehicle attitude adjustment capability. To address this emergency replenishment need, some manufacturers have proposed adding an air path: returning residual gas from the air tank directly to the air pump for secondary compression, using this repressurized gas to inflate the air springs to meet the rapid replenishment requirement. However, this approach requires additional piping, solenoid valves, and other hardware, increasing the complexity of the control logic, and has virtually no market prospect for a cost-oriented market. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an air suspension system and its control method. By employing an air pump powered by a brushless motor and adding a booster module to the drive module, the drawbacks of traditional brushed motors are overcome, and emergency air inflation needs can be met without increasing the number of pipelines.

[0006] This invention is achieved through the following scheme: an air suspension system, comprising an air spring, an air tank, and an air pump for inflating the air spring or the air tank. The air pump includes a brushless motor, a drive module for driving the brushless motor, and a boost module integrated on the drive module for adjusting the drive voltage; wherein,

[0007] The drive module includes an MCU and a drive circuit. The MCU includes an input terminal for receiving a conventional command signal and a boost command signal, a first output terminal for outputting a conventional drive signal when the conventional command signal is received, and a second output terminal for outputting a boost drive signal when the boost command signal is received. The drive circuit is connected between the first output terminal of the MCU and the brushless motor.

[0008] The boost circuit is connected between the second output terminal of the MCU and the drive circuit.

[0009] A further improvement of the air suspension system of the present invention is that the boost module is a Boost boost circuit.

[0010] A further improvement of the air suspension system of the present invention is that the drive circuit is a three-phase full-bridge inverter circuit.

[0011] A further improvement of the air suspension system of the present invention is that the input terminal of the MCU is communicatively connected to the vehicle control system.

[0012] A further improvement of the air suspension system of the present invention is that the drive module further includes a sensor group connected between the MCU and the brushless motor for commutation positioning and speed control of the brushless motor.

[0013] A further improvement of the air suspension system of the present invention is that the drive module further includes a sampling resistor, one end of which is connected to the drive circuit and the other end is grounded, for overload protection and torque control of the brushless motor.

[0014] A further improvement of the air suspension system of the present invention is that the air pump further includes a two-stage compression mechanism that adjusts the air pressure in the working chamber by the reciprocating motion of a piston, and the brushless motor is driven and connected to the compression mechanism.

[0015] A further improvement of the air suspension system of the present invention is that the air pump further includes a drying mechanism for drying the compressed high-pressure gas, the drying mechanism being connected to the compression mechanism.

[0016] The present invention also provides a control method for an air suspension system, comprising the following steps:

[0017] When the air pump receives a conventional command signal, it controls the brushless motor to rotate at a conventional speed using a conventional drive signal, thereby performing conventional air pumping on the air tank or air spring.

[0018] When the air pump receives a pressure boosting command signal, it starts the pressure boosting module with a pressure boosting drive signal, and controls the brushless motor to rotate at high speed under the pressure boosting regulation of the pressure boosting module, so as to realize rapid air inflation of the air spring.

[0019] This invention includes, but is not limited to, the following beneficial effects:

[0020] 1. This invention employs an air pump powered by a brushless motor, combined with a booster module added to the drive module. Upon receiving a booster instruction from the vehicle, the drive module can activate the booster module to increase the motor's operating voltage, meeting the need to increase motor speed in emergency situations and thus rapidly supplying air to the air springs. This eliminates the need to modify the original piping layout of the air suspension system, improving air pump efficiency and saving costs compared to existing methods.

[0021] 2. This invention, by employing a brushless motor controlled by a drive module, enables soft-start functionality with a low starting current. This protects the motor from high-current surges and extends its lifespan. Furthermore, the motor speed is infinitely adjustable, allowing for real-time adjustment of the inflation speed based on vehicle operating conditions, resulting in better NVH (Noise, Vibration, and Harshness) performance and inflation efficiency.

[0022] 3. This invention can realize the thermal protection function of brushless motor through software, which further saves costs compared with the external temperature sensor of traditional brushed motor. Attached Figure Description

[0023] Figure 1 The diagram shows the air circuit system architecture of the air suspension system.

[0024] Figure 2 A diagram showing the internal parts arrangement of the air pump in this invention is provided.

[0025] Figure 3 A hardware block diagram of an existing drive module for brushless motors is shown.

[0026] Figure 4A hardware block diagram of the drive module for a brushless motor in this invention is shown.

[0027] Figure 5 The circuit diagram of the boost module in this invention is shown.

[0028] Figure 6 A flowchart of the control method for the air suspension system of the present invention is shown. Detailed Implementation

[0029] To address the problems of complex control logic, low inflation efficiency, and high cost in existing air suspension systems for emergency air replenishment, this invention provides an air suspension system and its control method. By employing an air pump powered by a brushless motor and incorporating a booster module in the drive module, it overcomes the drawbacks of traditional brushed motors and meets emergency inflation needs without adding piping. The following detailed description, in conjunction with the accompanying drawings, further illustrates this air suspension system and its control method using specific embodiments.

[0030] See Figure 1 and Figure 2 As shown, an air suspension system includes an air spring 2, an air tank 3, and an air pump 1 for inflating the air spring 2 or the air tank 3. The air pump 1 includes a brushless motor 11, a drive module 12 for driving the brushless motor 11, and a boost module integrated on the drive module 12 for adjusting the drive voltage. The system is designed to work in conjunction with... Figure 4 As shown, the drive module 12 includes an MCU and a drive circuit. The MCU includes an input terminal for receiving a conventional command signal and a boost command signal, a first output terminal for outputting a conventional drive signal when the conventional command signal is received, and a second output terminal for outputting a boost drive signal when the boost command signal is received. The drive circuit is connected between the first output terminal of the MCU and the brushless motor. The boost circuit is connected between the second output terminal of the MCU and the drive circuit.

[0031] In this embodiment, as Figure 2 As shown, the air pump 1 also includes a two-stage compression mechanism 13 that adjusts the air pressure in the working chamber through the reciprocating motion of a piston. A brushless motor 11 is connected to the compression mechanism 13, and the rotational speed of the brushless motor 11 directly affects the compression efficiency of the compression mechanism 13, thus affecting the air pump efficiency of the air pump 1. Furthermore, to ensure that the gas output by the air pump 1 is dry, the air pump 1 also includes a drying mechanism 14 for drying the compressed high-pressure gas. The drying mechanism 14 is connected to the compression mechanism 13 through an air passage. In addition, the air pump 1 is equipped with a solenoid valve 15 to control the opening and closing of part of the air passage, thereby guiding the airflow direction.

[0032] This embodiment employs a brushless motor 11 controlled by a drive module 12, enabling soft-start functionality and a low starting current. This protects the motor from high-current surges and extends its lifespan. Furthermore, the motor speed is infinitely adjustable, allowing real-time adjustment of the inflation speed based on vehicle operating conditions, resulting in better NVH (Noise, Vibration, and Harshness) performance and inflation efficiency. NVH performance can reach an average of <57 dBA @1m. Additionally, by eliminating the carbon brushes and commutator structure, and controlling the commutation of the brushless motor 11 via the drive module 12, an even longer lifespan can be achieved, exceeding 1200 hours.

[0033] The principle of stepless speed adjustment of brushless motor 11 via drive module 12 can be found in [reference needed]. Figure 3 As shown, Figure 3 A hardware block diagram of an existing drive module for a brushless motor is shown. The drive module 12 includes a sensor group connected between the MCU and the brushless motor. This sensor group consists of three Hall effect sensors arranged in a 120° electrical angle difference configuration, used for commutation positioning, speed calculation, and speed control of the brushless motor 11. The drive circuit employs a three-phase full-bridge inverter circuit (other existing drive circuits can also be used). This three-phase full-bridge inverter circuit consists of six MOSFETs and is primarily used to drive the brushless motor 11. The MCU is used for PWM driving of the MOSFETs. Additionally, the drive module 12 typically includes a sampling resistor, Shunt, with one end connected to the drive circuit and the other end grounded (GND), used for overload protection and torque control of the brushless motor 11. Thermal protection of the brushless motor 11 is implemented through software, further reducing costs compared to the external temperature sensors used in traditional brushed motors.

[0034] While existing drive modules for brushless motors offer many advantages, they still fall short of requirements for emergency air inflation. Therefore, this embodiment integrates a boost module into the drive module; see details below. Figure 4 and Figure 5 As shown, Figure 4 The hardware block diagram of the driver module in this embodiment is shown. Figure 5 The circuit diagram of the boost module is shown. Compared to Figure 3The drive module design incorporates a boost module, specifically a Boost converter circuit in this embodiment, which can boost the power supply voltage (e.g., 12V) to a higher voltage. Specifically, this Boost converter circuit can adjust different PWM duty cycles to regulate the boost voltage amplitude. For example, with a PWM duty cycle of 50%, Vout = 2Vin, meaning a 12V power input can yield 24V to drive the brushless motor 11. Of course, this boost module is not limited to a Boost converter circuit; other forms of boost circuits can also be used, which will not be elaborated here. In addition to receiving conventional command signals, the MCU's input terminal can also receive boost command signals issued when the vehicle requires emergency power. Specifically, this input terminal can be configured as a LIN communication interface capable of communicating with the vehicle control system, allowing the vehicle control system to directly issue commands to the MCU.

[0035] For information on the software control method of this air suspension system, please refer to [link / reference]. Figures 1-2 , Figures 4-6 As shown: When regular inflation is required, the air pump 1 receives a regular command signal from the vehicle control system via the input terminal of the MCU, and then outputs a regular drive signal to control the drive circuit to drive the brushless motor 11 to rotate at a regular speed, thereby performing regular inflation on the air tank 3 or the air spring 2. When rapid inflation is required, the air pump 1 receives a boost command signal from the vehicle control system via the input terminal of the MCU, and then outputs a boost drive signal to activate the Boost circuit. Under the boost regulation of the Boost circuit, the brushless motor 11 is controlled to rotate at a high speed, thereby performing rapid inflation on the air spring 2.

[0036] It should be noted that when the normal inflation speed is sufficient for the air suspension system, it is not recommended to activate the Boost circuit for rapid inflation. This is because with the Boost circuit activated, the brushless motor 11 operates at a high speed, generating significant heat, which can negatively impact the system's lifespan. Furthermore, the high speed of the brushless motor 11 also results in greater noise from the air pump 1 compared to normal mode, affecting ride comfort. Therefore, when using this rapid inflation function, while meeting the emergency inflation needs of the air suspension, the impact of the air pump 1's noise on comfort must be considered, along with the lifespan of the brushless motor 11.

[0037] The following experiment compares the inflation efficiency of an air pump with and without a Boost circuit, using a vehicle power input of 12V, an air tank load of 3.7L, and an inflation pressure range of 0-17bar as examples. The comparison table is as follows:

[0038]

[0039]

[0040] As can be seen from the comparison table, after using the Boost circuit to boost the pressure, the time it takes for the air pump to reach the maximum pressure of 17 bar is shortened by more than 40%, which meets the requirements for emergency air replenishment of the air spring. If the vehicle requires a higher inflation speed, the duty cycle of the Boost circuit can be adjusted to increase the drive voltage pump to a higher level, thereby obtaining a higher motor speed and achieving the purpose of rapid inflation.

[0041] This invention employs an air pump powered by a brushless motor, combined with a booster module added to the drive module. Upon receiving a booster instruction from the vehicle, the drive module can activate the booster module to increase the motor's operating voltage, meeting the need for increased motor speed in emergency situations and thus rapidly supplying air to the air springs. This eliminates the need to modify the original piping layout of the air suspension system, improving air pump efficiency and saving costs compared to existing methods.

[0042] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. An air suspension system, comprising an air spring, an air tank, and an air pump for inflating the air spring or the air tank, characterized in that, The air pump includes a brushless motor, a drive module for driving the brushless motor, and a boost module integrated on the drive module for adjusting the drive voltage; wherein, The drive module includes an MCU and a drive circuit. The MCU includes an input terminal for receiving a conventional command signal and a boost command signal, a first output terminal for outputting a conventional drive signal when the conventional command signal is received, and a second output terminal for outputting a boost drive signal when the boost command signal is received. The drive circuit is connected between the first output terminal of the MCU and the brushless motor. The boost circuit is connected between the second output terminal of the MCU and the drive circuit.

2. The air suspension system as described in claim 1, characterized in that, The boost module is a Boost converter circuit.

3. The air suspension system as described in claim 1, characterized in that, The drive circuit is a three-phase full-bridge inverter circuit.

4. The air suspension system as described in claim 1, characterized in that, The input terminal of the MCU is communicatively connected to the vehicle control system.

5. The air suspension system as claimed in claim 1, characterized in that, The drive module also includes a sensor group connected between the MCU and the brushless motor for commutation positioning and speed control of the brushless motor.

6. The air suspension system as claimed in claim 1, characterized in that, The drive module also includes a sampling resistor, one end of which is connected to the drive circuit and the other end is grounded, for overload protection and torque control of the brushless motor.

7. The air suspension system as claimed in claim 1, characterized in that, The air pump also includes a two-stage compression mechanism that adjusts the air pressure in the working chamber through the reciprocating motion of a piston, and the brushless motor is driven and connected to the compression mechanism.

8. The air suspension system as claimed in claim 7, characterized in that, The air pump also includes a drying mechanism for drying the compressed high-pressure gas, and the drying mechanism is connected to the compression mechanism.

9. A control method for an air suspension system as described in any one of claims 1 to 8, characterized in that, Including the following steps: When the air pump receives a conventional command signal, it controls the brushless motor to rotate at a conventional speed using a conventional drive signal, thereby performing conventional air pumping on the air tank or air spring. When the air pump receives a pressure boosting command signal, it starts the pressure boosting module with a pressure boosting drive signal, and controls the brushless motor to rotate at high speed under the pressure boosting regulation of the pressure boosting module, so as to realize rapid air inflation of the air spring.

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