AIR SUSPENSION SYSTEM FOR VEHICLES AND METHOD FOR CONTROLLING THE SAME

Abstract

Air suspension system with: Air springs (70) each having a first input port connected to a main hydraulic unit (100) configured to regulate a compressed air flow and adjust a vehicle height in accordance with a roll situation of a vehicle, wherein the air springs (70) adjust heights of the left and right front and rear wheels of the vehicle based on the compressed air; a data acquisition unit (20) configured to acquire a vehicle state from a vehicle control unit; and a solenoid valve (50) configured to control the flow of compressed air additionally introduced into a second input port of each of the air springs (70); characterized by a double-acting cylinder (60) whose piston rod is moved bilaterally to direct the compressed air flow to the left and right, so that the compressed air is individually supplied to the left and right air springs through the solenoid valves (50) connected to the respective left and right sides of the double-acting cylinder (60); a drive unit (40) with a drive motor for bilaterally moving the piston rod; and a sub-control unit (30) configured to determine a roll moment situation, set a driving position and a driving acceleration based on the vehicle state detected by the data acquisition unit, and actuate the solenoid valve (50) and the drive unit (40).

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority under 35 USC § 119(a) to Korean Patent Application No. 10-2018-0148392, filed on November 27, 2018, in the Korean Intellectual Property Office, which is incorporated herein by reference in its entirety. BACKGROUND 1. Technical field

[0002] Embodiments of the present disclosure relate to an air spring system for vehicles and a method for controlling the same, and more particularly, to an air spring system capable of improving a roll suppression effect by adding a sub-hydraulic unit to a main hydraulic unit, interfering with a control operation of the main hydraulic unit or electrically controlling a pressure of an air spring in a roll moment situation independently of the main hydraulic unit to enhance its responsiveness, and a method for controlling the same. 2. State of the art

[0003] In general, suspension is limited to providing both ride comfort and steering stability simultaneously. Increased ride comfort leads to reduced steering stability, while increased steering stability leads to reduced ride comfort.

[0004] The reason for this is as follows: Softening the spring of the suspension makes it easier to absorb shocks from uneven roads, resulting in improved ride comfort. However, this makes the vehicle body unstable, resulting in a deterioration in steering stability. On the other hand, hardening the spring improves steering stability but deteriorates ride comfort because shocks transmitted from uneven roads are not adequately absorbed.

[0005] However, the strength of the conventional steel coil spring cannot be optionally adjusted. For this reason, an air spring is manufactured that uses air. The air spring can be made stiff or soft as needed by simply adjusting the air pressure. The suspension system that uses this type of air spring is called an air suspension.

[0006] In a conventional air suspension system, the vehicle height is raised using the air in an air tank compressed by a compressor or the compressor and atmospheric pressure, whereas the vehicle height is lowered by operating an exhaust valve.

[0007] In a process where an air spring is controlled by each independent solenoid valve, it is necessary to perform a release to reduce the air spring pressure on one side and a pressurization to increase the air spring pressure on the other side. However, due to the characteristics of a pneumatic circuit, the time required to reach a desired vehicle height value is consequently limited by the compressor and the air tank, even if the valve is switched on / off quickly.

[0008] However, since high-speed spin or slalom roll occur in a short situation, quick response is required to improve ride comfort.

[0009] In some vehicles, a stabilizer bar is used to suppress roll in the air suspension. However, due to its properties, the stabilizer bar results in harsh ride comfort and causes a deterioration in shock absorption capacity, which is the purpose of the suspension. DE 199 20 109 A1 discloses a spring system operated by a pressure medium, from which the features of the preamble of patent claim 1 emerge. Other spring systems are known from EP 0 201 425 A1 and DE 197 55 375 A1. OVERVIEW

[0010] Various embodiments relate to an air spring system capable of improving a roll suppression effect by adding a sub-hydraulic unit to a main hydraulic unit, interfering with a control operation of the main hydraulic unit or electrically controlling a pressure of an air spring in a roll moment situation independently of the main hydraulic unit to enhance its responsiveness, and a method for controlling the same.

[0011] In one embodiment, an air suspension system is provided, comprising: air springs, each having a first input port connected to a main hydraulic unit configured to regulate a compressed air flow and adjust a vehicle height according to a roll situation of a vehicle, wherein the air springs adjust heights of the left and right front and rear wheels of the vehicle based on the compressed air; a data acquisition unit configured to detect a vehicle condition from a vehicle control unit; a solenoid valve configured to control the flow of compressed air additionally introduced into a second input port of each of the air springs;a double-acting cylinder whose piston rod is moved bilaterally to direct the compressed air flow to the left and right, so that the compressed air is individually supplied to the left and right air springs through the solenoid valves connected to the respective left and right sides of the double-acting cylinder; a drive unit with a drive motor for bilaterally moving the piston rod; and a sub-control unit configured to determine a roll moment situation, adjust a driving position and driving acceleration based on the vehicle state detected by the data acquisition unit, and actuate the solenoid valve and the drive unit.

[0012] Each of the air springs may be a dual chamber air spring having first and second input ports.

[0013] The vehicle state may include at least one of a steering angle, a vehicle speed, a roll angle, a roll moment, and a difference between the left and right vehicle heights.

[0014] The data acquisition unit may further acquire an air spring trigger signal from a main control unit, and the sub-control unit may actuate the solenoid valve and the drive unit according to at least one of the air spring trigger signal and the vehicle condition acquired by the data acquisition unit.

[0015] The drive motor of the drive unit can be connected to the piston rod in a rack and pinion connection.

[0016] The double-acting cylinder may include a first double-acting cylinder configured to supply the compressed air to the first and second solenoid valves that control the compressed air additionally introduced into the first and second air springs installed on the respective left and right front wheels, and may include a second double-acting cylinder configured to supply the compressed air to the third and fourth solenoid valves that control the compressed air additionally introduced into the third and fourth air springs installed on the respective left and right rear wheels.

[0017] The first double-acting cylinder may have a first left line through which the compressed air discharged by a leftward movement of a first piston rod to the left is supplied to the first solenoid valve installed on the left front wheel, and may have a first right line through which the compressed air discharged by a rightward movement of the first piston rod to the right is supplied to the solenoid valve installed on the right front wheel.

[0018] The second double-acting cylinder may have a second left line through which the compressed air discharged by a leftward movement of a second piston rod to the left is supplied to the third solenoid valve installed on the left rear wheel, and may have a second right line through which the compressed air discharged by a rightward movement of the second piston rod to the right is supplied to the solenoid valve installed on the right rear wheel.

[0019] The solenoid valve can be a normally closed valve.

[0020] In one embodiment, a method for controlling an air spring system is provided, comprising: receiving, by a sub-control unit, at least one of an air spring trigger signal detected by a main control unit and a vehicle condition detected by a vehicle control device through a data acquisition unit; actuating, by the sub-control unit, a solenoid valve to control a flow of compressed air additionally supplied to each of the air springs installed on the respective left and right front and rear wheels according to at least one of the air spring trigger signal and the vehicle condition; and actuating, by the sub-control unit, a drive unit after actuating the solenoid valve so that the drive unit moves a piston rod bilaterally to direct the compressed air flow left and right into a double-acting cylinder and supply the compressed air to the solenoid valve.

[0021] When a solenoid valve is actuated by the sub-control unit, the sub-control unit can open the closed solenoid valve in response to the air spring release signal.

[0022] The vehicle state may include at least one of a steering angle, a vehicle speed, a roll angle, a roll moment, and a difference between the left and right vehicle heights.

[0023] When the sub-control unit operates a drive unit, the sub-control unit can adjust the drive unit by setting a driving position and a driving acceleration according to the vehicle condition.

[0024] As apparent from the above description, in the air suspension system and the method for controlling the same according to the embodiments of the present invention, it is possible to improve a roll suppression effect and control a sudden instantaneous change by adding a sub-hydraulic unit to the main hydraulic unit, interfering with the control operation of the main hydraulic unit, or electrically controlling the pressure of the air spring in a roll moment situation independently of the main hydraulic unit to enhance its responsiveness. Thus, it is possible not only to improve the steering stability and ride comfort of the vehicle, but also to distribute the operating load between the main hydraulic unit and the sub-hydraulic unit, thereby expanding the operating range of the air suspension system. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing an air spring system according to an embodiment of the invention. Fig. 2 is a diagram showing in more detail the air spring system according to the embodiment of the invention. Fig. 3 is a diagram showing a state in which a right air spring is lifted in the air spring system according to the embodiment of the present invention. Fig. 4 is a diagram showing a state in which a left air spring is decompressed in the air spring system according to the embodiment of the present invention. Fig. 5 is a block diagram showing an air spring system according to another embodiment of the invention. Fig. 6 is a diagram showing a state in which a right air spring is raised and a left air spring is decompressed in the air spring system according to another embodiment of the present invention. Fig. 7 is a flowchart illustrating a method for controlling an air spring system according to an embodiment of the invention. DETAILED DESCRIPTION

[0025] As is common in the relevant field, some embodiments may be depicted in the drawings as functional blocks, units, and / or modules. Those skilled in the art will understand that these blocks, units, and / or modules are physically implemented by electronic (or optical) circuits such as logic circuits, discrete components, processors, wired circuits, memory elements, wire connections, and the like. When the blocks, units, and / or modules are implemented by processors or similar hardware, they may be programmed and controlled by software (e.g., code) to perform various functions discussed herein. Alternatively, each block, unit, and / or module may be implemented by dedicated hardware or as a combination of dedicated hardware for performing some functions and a processor (e.g.,One or more programmed processors and associated circuitry) may be implemented to perform other functions. Each block, unit, and / or module of some embodiments may be physically separated into two or more interacting discrete blocks, units, and / or modules without departing from the scope of the inventive concept. Furthermore, blocks, units, and / or modules of some embodiments may be physically combined into more complex blocks, units, and / or modules without departing from the scope of the inventive concept.

[0026] An air spring system and a method for controlling the same according to the present invention will now be described with reference to the accompanying drawings. It should be noted that the drawings are not necessarily to scale and may differ from the actual illustration in terms of line thickness or component sizes for the sake of clarity and simplicity of description. Furthermore, the terms used herein are defined with respect to functions of the invention and may be changed depending on the purpose or practice of a user or operator. The terms should therefore be defined in accordance with the present overall disclosure.

[0027] Fig. 1 is a block diagram showing an air spring system according to an embodiment of the invention. Fig. 2 is a diagram showing in more detail the air spring system according to the embodiment of the invention.

[0028] As in the Fig. 1 and Fig. 2, the air suspension system comprises a main hydraulic unit 100, an air spring 70, a data acquisition unit 20, a solenoid valve 50, a double-acting cylinder 60, a drive unit 40 and a sub-control unit 30.

[0029] The main hydraulic unit 100 includes a first flow path 110, a second flow path 120, a third flow path 130, a fourth flow path 140, a fifth flow path 150, and a sixth flow path 160. The main hydraulic unit 100 can adjust a height of a vehicle body using air pressure.

[0030] The first flow path 110 connects outside air to a compressor 170. The compressor 170 is a device for generating air pressure by driving a motor and may include a single-stage cylinder for generating air pressure or a single-stage cylinder and a two-stage cylinder for generating multi-stage air pressure.

[0031] The second flow path 120 connects the compressor 170 to the air spring 70. The air spring 70 consists of first to fourth air springs 71 to 74, which are attached to lower arms connected to the respective left and right front and rear wheels of the vehicle, and supports the vehicle body at its upper end to absorb shocks. Here, the air spring 70 is a dual-chamber air spring with two input ports and can be adjusted in height using air pressure to adjust the vehicle height.

[0032] The third flow path 130 connects the compressor 170 to the second flow path 120, the fourth flow path 140 connects outside air to the second flow path 120, and the fifth flow path 150 connects a storage tank 190 to the second flow path 120. The sixth flow path 160 is connected to the storage tank 190 for supplying air pressure.

[0033] The first flow path 110 includes a first pneumatic line 111 and a first check valve 112. The first flow path 110 can conduct a fluid such that outside air is supplied to the compressor 170 when the compressor 170 is driven.

[0034] The first pneumatic line 111 connects outside air to the compressor 170. The first check valve 112 is formed in the first pneumatic line 111 to allow unidirectional pneumatic flow. For example, the first check valve 112 can allow a first pneumatic flow so that outside air reaches the compressor 170 and can block the release of air pressure from the compressor 170 to the outside.

[0035] The second flow path 120 includes a second pneumatic line 121, a second branch line 122, a second dehumidifier 123, a second valve 124, a second check valve 125, and a second regenerator 126. The second flow path 120 can carry the fluid compressed by the compressor 170 and direct the fluid flow for adjusting the vehicle height.

[0036] The second pneumatic line 121 is connected to the compressor 170 at one end. The second branch line 122 consists of a plurality of second branch lines 122a, 122b, 122c, and 122d branching from the second pneumatic line 121 to connect to the respective first to fourth air springs 71 to 74. The second branch lines 122a, 122b, 122c, and 122d are formed with second spring valves 127a, 127b, 127c, and 127d, which open and close the second branch lines 122a, 122b, 122c, and 122d. The second spring valves 127a, 127b, 127c and 127d may be solenoid valves that open and close the second branch lines 122a, 122b, 122c and 122d depending on whether or not power is supplied to the valves.

[0037] The second dehumidifier 123 is configured in the second pneumatic line 121 to dry the fluid passing through the second pneumatic line 121. For example, the second dehumidifier 123 can filter moisture from the fluid passing through the second pneumatic line 121.

[0038] The second valve 124 is formed in the second pneumatic line 121 to open and close the second pneumatic line 121. The second valve 124 may be a solenoid valve that opens and closes the second pneumatic line 121 depending on whether or not power is supplied to the valve.

[0039] The second check valve 125 is formed in the second pneumatic line 121. More specifically, the second check valve 125 is arranged in the second pneumatic line 121, which is located between the compressor 170 and the second dehumidifier 123, to allow pneumatic flow in one direction. For example, the second check valve 125 can allow pneumatic flow so that the air compressed by the compressor 170 reaches the second dehumidifier 123 and can block the air flow from the second dehumidifier 123 to the compressor 170.

[0040] The second regenerator 126 is formed in the second pneumatic line 121. More specifically, the second regenerator 126 is arranged in the second pneumatic line 121, which is positioned between the second dehumidifier 123 and the second valve 124. For example, the second regenerator 126 can be an orifice, with the result that, according to the Bernoulli principle, a fluid can be compressed and its temperature increased as it passes through the second regenerator 126. The second regenerator 126 can be used to remove moisture from the second dehumidifier 123.

[0041] The third flow path 130 includes a third pneumatic line 131, a third valve 132, and a third check valve 133. The third flow path 130 can conduct a fluid flow when the vehicle height is lowered.

[0042] One end of the third pneumatic line 131 is connected to the compressor 170, and the other end of the third pneumatic line 131 is connected to the second pneumatic line 121. More specifically, the third pneumatic line 131 is connected to the second pneumatic line 121, which is positioned between the second valve 124 and the second branch line 122.

[0043] The third valve 132 is formed in the third pneumatic line 131 to open and close the third pneumatic line 131. The third valve 132 may be a solenoid valve that opens and closes the third pneumatic line 131 depending on whether power is supplied to the valve.

[0044] The third check valve 133 is formed in the third pneumatic line 131. More specifically, the third check valve 133 is arranged between the compressor 170 and the third valve 132 to allow unidirectional pneumatic flow. For example, the third check valve 133 can block the air compressed by the compressor 170 from flowing to the third valve 132 and can allow the air passing through the third valve 132 to flow to the compressor 170.

[0045] The fourth flow path 140 includes a fourth pneumatic line 141, a fourth valve 142, and a fourth regenerator 143. The fourth flow path 140 may be a passage for discharging the fluid in the main hydraulic unit 100 to the outside.

[0046] The fourth pneumatic line 141 is connected to the second pneumatic line 121. More specifically, the fourth pneumatic line 141 is connected at one of its ends to the second pneumatic line 121, which is positioned between the second dehumidifier 123 and the second check valve 125. The fourth pneumatic line 141 can be connected to outside air at its other end to discharge the fluid to the outside.

[0047] The fourth valve 142 is formed in the fourth pneumatic line 141 to open and close the fourth pneumatic line 141. The fourth valve 142 may be a solenoid valve that opens and closes the fourth pneumatic line 141 depending on whether or not power is supplied to the valve.

[0048] The fourth regenerator 143 is formed in the fourth pneumatic line 141. More specifically, the fourth regenerator 143 is arranged in the fourth pneumatic line 141, which is positioned between the fourth valve 142 and the second pneumatic line 121. For example, the fourth regenerator 143 can be an orifice, with the result that, according to the Bernoulli principle, a fluid can be compressed and its temperature increased as it passes through the fourth regenerator 143. The fourth regenerator 143 can be used to remove moisture from the second dehumidifier 123.

[0049] The fifth flow path 150 includes a fifth pneumatic line 151 and a fifth valve 152. The fifth flow path 150 directs a fluid to flow into the storage tank 190.

[0050] One end of the fifth pneumatic line 151 is connected to the second pneumatic line 121, and the other end of the fifth pneumatic line 151 is connected to the storage tank 190. More specifically, the fifth pneumatic line 151 is connected to the second pneumatic line 121, which is positioned between the second regenerator 126 and the second valve 124.

[0051] The fifth valve 152 is formed in the fifth pneumatic line 151 to open and close the fifth pneumatic line 151. The fifth valve 152 may be a solenoid valve that opens and closes the fifth pneumatic line 151 depending on whether or not power is supplied to the valve.

[0052] The sixth flow path 160 has a sixth pneumatic line 161 and a sixth check valve 162. The sixth flow path 160 connects outside air to the storage tank 190 to supply the outside air to the storage tank 190.

[0053] The sixth pneumatic line 161 communicates with the outside and is connected to the storage tank 190. The sixth check valve 162 is formed in the sixth pneumatic line 161 to allow unidirectional pneumatic flow. For example, the sixth check valve 162 can block the fluid stored in the storage tank 190 from flowing outward and can allow outside air to flow into the storage tank 190. An air injector can be detachably attached to the end of the sixth pneumatic line 161.

[0054] The air spring 70 is a dual-chamber air spring with two input ports and may consist of first to fourth air springs 71 to 74 installed on the left and right front and rear wheels of the vehicle, respectively. The fourth to fifth air springs 71 to 74 may be connected at their first input ports 71a and 74a to the second branch lines 122a, 122b, 122c, and 122d of the main hydraulic unit 100 to adjust the compressed air flow according to the roll situation of the vehicle, thereby adjusting the heights of the left and right front and rear wheels of the vehicle based on the compressed air.

[0055] The data acquisition unit 20 may acquire an air spring trigger signal from the main control unit 90 to drive the main hydraulic unit 100 and may acquire a vehicle condition from the vehicle control unit to provide it to the sub-control unit 30.

[0056] Here, the air spring trigger signal detected by the main control unit 90 is generated to perform roll suppression by intervening in a roll situation occurring during steering in conjunction with an electronic steering device based on the vehicle state input from the main control unit 90.

[0057] In addition, the vehicle state may include at least one of a steering angle, a vehicle speed, a roll angle, a roll moment, and a difference between the left and right vehicle heights.

[0058] The solenoid valve 50 is a normally closed valve and may be composed of first to fourth solenoid valves 51 to 54 installed corresponding to the first to fourth air springs 71 to 74 to control the flow of compressed air additionally introduced into each of the second input ports 71b to 74b of the first to fourth air springs 71 to 74.

[0059] The double-acting cylinder 60 can direct the compressed air flow to the left and right by bilateral movement of its piston rod to supply the compressed air to each of the left and right air springs 70 through the solenoid valves 50 connected to the respective left and right sides of the double-acting cylinder 60.

[0060] The drive unit 40 may include a drive motor connected to the piston rod in a rack and pinion manner to move the piston rod bilaterally and adjust the inflow direction of compressed air into the double-acting cylinder 60.

[0061] The double-acting cylinder 60 may here comprise a first double-acting cylinder 61 for adjusting the left and right front wheels and a second double-acting cylinder 62 for adjusting the left and right rear wheels, as in Fig. 2 shown.

[0062] The first double-acting cylinder 61 can supply the first solenoid valve 51 installed on the left front wheel with compressed air through a first left line 81, which is discharged by a leftward movement of a first piston rod 63, and can supply the second solenoid valve 52 installed on the right front wheel with compressed air through a first right line 82, which is discharged by a rightward movement of the first piston rod 63, whereby the compressed air is additionally supplied to each of the first and second air springs 71 and 72 installed on the respective left and right front wheels.

[0063] The second double-acting cylinder 62 can supply the third solenoid valve 53 installed on the left rear wheel with compressed air through a second left line 83, which is discharged by a leftward movement of a second piston rod 64 to the left, and can supply the fourth solenoid valve 54 installed on the right rear wheel with compressed air through a second right line 83, which is discharged by a rightward movement of the second piston rod 64 to the right, whereby the compressed air is additionally supplied to each of the third and fourth air springs 73 and 74 installed on the left and right rear wheels.

[0064] The sub-control unit 30 can actuate the solenoid valve 50 and the drive unit 40 according to at least one of the air spring trigger signal and the vehicle condition detected by the data acquisition unit 20.

[0065] In this case, the sub-control unit 30 can actuate the solenoid valve 50 and the drive unit 40 in response to the air spring trigger signal detected by the main control unit 90, thereby compensating for the slow response of the main hydraulic unit 100 due to its characteristics and controlling a sudden instantaneous change by the drive motors 41 and 42 of the drive unit 40.

[0066] In addition, the sub-control unit 30 can open the closed solenoid valve 50 only above a set roll moment, such as above an air spring trigger signal, thereby preventing air leakage by keeping the solenoid valve 50 closed during normal times.

[0067] Fig. 3 is a diagram showing a state in which the right air spring is raised in the air spring system according to the embodiment of the present invention.

[0068] As in Fig. 3, an example is described in which the air pressure in the storage tank is used to raise the right air spring in the roll moment situation. The second valve 124 opens the second pneumatic line 121, the fifth valve 152 opens the fifth pneumatic line 151, and the second spring valves 127b and 127d open the second branch lines 122b and 122d. In this state, the air stored in the storage tank 190 sequentially flows into the fifth pneumatic line 151, the second pneumatic line 121, and the second branch lines 122b and 122d to reach the second and fourth air springs 72 and 74. In this case, the air pressure in each of the second and fourth air springs 72 and 74 increases.

[0069] In the case where the compressor 170 is used, when the fifth valve 152 is closed and the compressor 170 is driven in the above state, outside air is supplied through the fourth pneumatic line 141 to the compressor 170 to be compressed there, so that the compressed air sequentially flows to the second branch lines 122b and 122d to reach the second and fourth air springs 72 and 74.

[0070] By opening the first to fourth solenoid valves 51, 52, 53 and 54 and moving the first piston rod 63 of the first double-acting cylinder 61 and the second piston rod 64 of the second double-acting cylinder 62 to the right, the compressed air can also be supplied to the second and fourth air springs 72 and 74 through the first right line 82 and the second right line 84, thereby enabling the second and fourth air springs 72 and 74 to be lifted.

[0071] Fig. 4 is a diagram showing a state in which a left air spring is decompressed in the air spring system according to the embodiment of the present invention.

[0072] As in Fig. 4, an example will be described in which air pressure is supplied to the storage tank to decompress the left air spring in the roll moment situation. The second spring valves 127a and 127c open the second branch lines 122a and 122c, the third valve 132 opens the third pneumatic line 131, and the fifth valve 152 opens the fifth pneumatic line 151. When the compressor 170 is driven in this state, the air stored in the first and third air springs 71 and 73 reaches the compressor 170 through the third pneumatic line 131. The compressed air passing through the compressor 170 is dehumidified while passing through the second dehumidifier 123 and is then stored in the storage tank 190. In this case, the first and third air springs 71 and 73 can be decompressed and lowered by removing air from them.

[0073] In the case where air pressure is discharged to the outside, when the fifth valve 152 is closed in the above state and the compressor 170 is driven with the fourth pneumatic line 141 opened by the fourth valve 142, the air stored in the first and third air springs 71 and 73 reaches the compressor 170 through the third pneumatic line 131. The compressed air passed through the compressor 170 is discharged to the outside through the fourth pneumatic line 141.

[0074] By opening the first to fourth solenoid valves 51, 52, 53 and 54 and moving the first piston rod 63 of the first double-acting cylinder 61 and the second piston rod 64 of the second double-acting cylinder 62 to the right, the air is removed from the first and third air springs 71 and 73 through the first and second left lines 81 and 83, thereby enabling decompression of the first and third air springs 71 and 73.

[0075] Fig. 5 is a block diagram showing an air spring system according to another embodiment of the invention.

[0076] As in Fig. 5, the air spring system may include: an air spring 70, a data acquisition unit 20, a solenoid valve 50, a double-acting cylinder 60, a drive unit 40, and a sub-control unit 30.

[0077] The air spring 70 is a dual-chamber air spring with two input ports and may consist of first to fourth air springs 71 to 74 installed on respective left and right front and rear wheels of the vehicle. The first to fourth air springs 71 to 74 may be connected at their first input ports 71a to 74a to second branch lines 122a, 122b, 122c, and 122d of a main hydraulic unit 100 to adjust the compressed air flow for adjusting the vehicle height, thereby adjusting the heights of the left and right front and rear wheels of the vehicle according to the roll situation of the vehicle based on the compressed air.

[0078] The data acquisition unit 20 can acquire a vehicle state from a vehicle control unit to provide it to the sub-control unit 30.

[0079] Here, the vehicle state may include at least one of a steering angle, a vehicle speed, a roll angle, a roll moment, and a difference between the left and right vehicle heights.

[0080] The solenoid valve 50 is a normally closed valve and may be composed of first to fourth solenoid valves 51 to 54 installed corresponding to the first to fourth air springs 71 to 74 to control the flow of compressed air additionally introduced into each of the second input ports 71b to 74b of the first to fourth air springs 71 to 74.

[0081] The double-acting cylinder 60 can direct the compressed air flow to the left and right by bilateral movement of its piston rod to supply the compressed air to each of the left and right air springs 70 through the solenoid valves 50 connected to the respective left and right sides of the double-acting cylinder 60.

[0082] The drive unit 40 may include a drive motor connected to the piston rod in a rack and pinion manner to move the piston rod bilaterally and adjust the inflow direction of compressed air into the double-acting cylinder 60.

[0083] The double-acting cylinder 60 may here comprise a first double-acting cylinder 61 for adjusting the left and right front wheels and a second double-acting cylinder 62 for adjusting the left and right rear wheels, as in Fig. 6 shown.

[0084] The first double-acting cylinder 61 can supply the first solenoid valve 51 installed on the left front wheel with compressed air through a first left line 81, which is discharged by a leftward movement of a first piston rod 63, and can supply the second solenoid valve 52 installed on the right front wheel with compressed air through a first right line 82, which is discharged by a rightward movement of the first piston rod 63, whereby the compressed air is additionally supplied to each of the first and second air springs 71 and 72 installed on the respective left and right front wheels.

[0085] The second double-acting cylinder 62 can supply the third solenoid valve 53 installed on the left rear wheel with compressed air through a second left line 83, which is discharged by a leftward movement of a second piston rod 64 to the left, and can supply the fourth solenoid valve 54 installed on the right rear wheel with compressed air through a second right line 84, which is discharged by a rightward movement of the second piston rod 64 to the right, whereby the compressed air is additionally supplied to each of the third and fourth air springs 73 and 74 installed on the left and right rear wheels.

[0086] The sub-control unit 30 can operate the solenoid valve 50 and the drive motors 41 and 42 of the drive unit 40 to control a sudden instantaneous change by intervening in a roll situation occurring during steering in conjunction with an electronic steering device based on the vehicle state input from the data acquisition unit 20 and by adjusting a driving position and a driving acceleration to perform roll suppression.

[0087] In addition, the sub-control unit 30 can open the closed solenoid valve 50 only above a set roll moment, such as above an air spring trigger signal, thereby preventing air leakage by keeping the solenoid valve 50 closed during normal times.

[0088] Fig. 6 is a diagram showing a state in which a right air spring is raised and a left air spring is decompressed in the air spring system according to another embodiment of the present invention.

[0089] As in Fig. 6, an example is described in which the right air spring is raised and the left air spring is decompressed in the roll moment situation of the air suspension system. When the first to fourth solenoid valves 51, 52, 53, and 54 are opened and the first piston rod 63 of the first double-acting cylinder 61 and the second piston rod 64 of the second double-acting cylinder 62 are moved to the right, the compressed air can be supplied to the second and fourth air springs 72 and 74 through the first and second right lines 82 and 84, thereby enabling the second and fourth air springs 72 and 74 to be raised. The air can also be removed from the first and third air springs 71 and 73 through the first and second left lines 81 and 83, thereby enabling the first and third air springs 71 and 73 to be decompressed.

[0090] As described above, in the air suspension system according to the present invention, it is possible to enhance a roll suppression effect and control a sudden instantaneous change by adding a sub-hydraulic unit to the main hydraulic unit, interfering with the control operation of the main hydraulic unit, or electrically controlling the pressure of the air spring in the roll moment situation independently of the main hydraulic unit to enhance its responsiveness. Thus, it is possible not only to improve the steering stability and ride comfort of the vehicle, but also to distribute the operating load between the main hydraulic unit and the sub-hydraulic unit, thereby expanding the operating range of the air suspension system.

[0091] Fig. 7 is a flowchart illustrating a method for controlling an air spring system according to an embodiment of the invention.

[0092] As in Fig. 7, in the method for controlling an air spring system according to an embodiment of the invention, a sub-control unit 30 first receives at least one of an air spring trigger signal detected by a main control unit 90 and a vehicle state detected by a vehicle control unit through a data acquisition unit 20 (S10).

[0093] Here, the air spring trigger signal detected by the main control unit 90 is generated to perform roll suppression by intervening in a roll situation occurring during steering in conjunction with an electrical control device based on the vehicle state input from the main control unit 90.

[0094] In addition, the vehicle state may include at least one of a steering angle, a vehicle speed, a roll angle, a roll moment, and a difference between the left and right vehicle heights.

[0095] In this case, the sub-control unit 30 may further generate a trigger signal for actuating a drive unit 40 and a solenoid valve 50 by independently intervening in a roll moment occurring during steering in conjunction with an electric steering device based on the vehicle state input from the data acquisition unit 20 and by setting a driving position and a driving acceleration to perform roll suppression.

[0096] In step S10, the sub-control unit 30 actuates the solenoid valve 50 to control the flow of compressed air additionally introduced into each of the air springs 70 installed on the respective left and right front and rear wheels according to at least one of the air spring actuation signal and the vehicle state input thereto (S20).

[0097] Here, the solenoid valve 50 may consist of first to fourth solenoid valves 51 to 54 installed corresponding to first to fourth air springs 71 to 74 to control the compressed air flow additionally introduced into each of the second input ports 71b to 74b of the first to fourth air springs 71 to 74.

[0098] The sub-control unit 30 can also control the closed solenoid valve 50 only above a set roll moment, such as above an air spring trigger signal, thereby preventing air leakage by keeping the solenoid valve 50 closed during normal times.

[0099] In step S20, after the solenoid valve 50 is actuated, the sub-control unit 30 may actuate the drive unit 40, which moves a piston rod bilaterally to direct the compressed air flow left and right into a double-acting cylinder 60 and supply the compressed air to the solenoid valve 50, thereby compensating for the slow response of the main hydraulic unit 100 due to its pneumatic characteristics and controlling a sudden instantaneous change by the drive motors 41 and 42 of the drive unit 40 (S30).

[0100] As described above, in the method for controlling an air suspension system according to the present invention, it is possible to improve a roll suppression effect and control a sudden instantaneous change by adding a sub-hydraulic unit to the main hydraulic unit, interfering with the control operation of the main hydraulic unit, or electrically controlling the pressure of the air spring in the roll moment situation independently of the main hydraulic unit to enhance its responsiveness. Thus, it is possible not only to improve the steering stability and ride comfort of the vehicle, but also to distribute the operating load between the main hydraulic unit and the sub-hydraulic unit, thereby expanding the operating range of the air suspension system.

[0101] Although various embodiments have been described above, it will be appreciated by those skilled in the art that the embodiments described herein are merely exemplary. Furthermore, it will be appreciated by those skilled in the art that various modifications and other equivalent embodiments are possible without departing from the spirit and scope of the disclosure.

[0102] Accordingly, the actual technical scope of the invention is to be defined in the appended claims.

Claims

[1] Air suspension system with: Air springs (70) each having a first input port connected to a main hydraulic unit (100) configured to regulate a compressed air flow and adjust a vehicle height in accordance with a roll situation of a vehicle, wherein the air springs (70) adjust heights of the left and right front and rear wheels of the vehicle based on the compressed air; a data acquisition unit (20) configured to acquire a vehicle state from a vehicle control unit; and a solenoid valve (50) configured to control the flow of compressed air additionally introduced into a second input port of each of the air springs (70); characterized by a double-acting cylinder (60) whose piston rod is moved bilaterally to direct the compressed air flow to the left and right, so that the compressed air is individually supplied to the left and right air springs through the solenoid valves (50) connected to the respective left and right sides of the double-acting cylinder (60); a drive unit (40) with a drive motor for bilaterally moving the piston rod; and a sub-control unit (30) configured to determine a roll moment situation, set a driving position and a driving acceleration based on the vehicle state detected by the data acquisition unit, and actuate the solenoid valve (50) and the drive unit (40). [2] The air spring system of claim 1, wherein each of the air springs (70) is a dual-chamber air spring having first and second input ports (71a-74a, 71b-74b). [3] The air suspension system according to claim 1, wherein the vehicle condition includes at least one of a steering angle, a vehicle speed, a roll angle, a roll moment, and a difference between the left and right vehicle heights. [4] The air spring system according to claim 1, wherein the data acquisition unit (20) further acquires an air spring trigger signal from a main control unit (90), and the sub-control unit (30) actuates the solenoid valve (50) and the drive unit (40) according to at least one of the air spring trigger signal and the vehicle condition acquired by the data acquisition unit (20). [5] Air spring system according to claim 1, wherein the drive motor of the drive unit (40) is in a rack and pinion connection with the piston rod. [6] Air spring system according to claim 1, wherein the double-acting cylinder (60) comprises: a first double-acting cylinder (61) adapted to supply the compressed air to the first and second solenoid valves (51, 52) which regulate the compressed air additionally introduced into the first and second air springs (71, 72) installed on the respective left and right front wheels; and a second double-acting cylinder (62) adapted to supply the compressed air to the third and fourth solenoid valves (53, 54) which regulate the compressed air additionally introduced into the third and fourth air springs (73, 74) installed on the respective left and right rear wheels. [7] Air spring system according to claim 6, wherein the first double-acting cylinder (61) comprises: a first left line (81) through which the compressed air discharged to the left by a leftward movement of the first piston rod (63) is supplied to the first solenoid valve (51) installed on the left front wheel; and a first right line (82) through which the compressed air discharged to the right by a rightward movement of the first piston rod (63) is supplied to the solenoid valve (50) installed on the right front wheel. [8] Air spring system according to claim 6, wherein the second double-acting cylinder (62) comprises: a second left line (83) through which the compressed air discharged to the left by a leftward movement of a second piston rod (64) is supplied to the third solenoid valve (53) installed on the left rear wheel; and a second right line (84) through which the compressed air discharged to the right by a rightward movement of the second piston rod (64) is supplied to the solenoid valve (50) installed on the right rear wheel. [9] Air spring system according to claim 1, wherein the solenoid valve (50) is a normally closed valve. [10] Method for controlling an air spring system comprising the following steps: Receiving, by a sub-control unit (30), at least one of an air spring trigger signal detected by a main control unit (90) and a vehicle state detected by a vehicle control unit through a data acquisition unit (20); Actuating, by the sub-control unit (30), a solenoid valve (50) for controlling a flow of compressed air additionally supplied to each of the air springs (70) installed on the respective left and right front and rear wheels in accordance with at least one of the air spring trigger signal and the vehicle condition; and Actuating, by the sub-control unit (30), a drive unit after actuating the solenoid valve (50), so that the drive unit moves a piston rod bilaterally to direct the compressed air flow to the left and right into a double-acting cylinder (60) and supply the compressed air to the solenoid valve (50). [11] The method of claim 10, wherein upon actuation of a solenoid valve (50) by the sub-control unit (30), the sub-control unit (30) opens the closed solenoid valve (50) in response to the air spring trigger signal. [12] The method of claim 10, wherein the vehicle state comprises at least one of a steering angle, a vehicle speed, a roll angle, a roll moment, and a difference between the left and right vehicle heights. [13] The method according to claim 10, wherein when the sub-control unit (30) operates a drive unit (40), the sub-control unit (30) adjusts the drive unit (40) by setting a driving position and a driving acceleration according to the vehicle state.

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