Valve assembly

Abstract

Valve assembly for an air suspension system of a vehicle, comprising a level control valve (11), wherein the level control valve (11) has an air reservoir connection (26) for connecting an air reservoir (10), with at least one bellows connection (24, 25) for connecting one or more air spring bellows (14, 15) and with at least one solenoid valve (20, 21) for locking or opening a connection between the air reservoir connection of the level control valve (11) and the bellows connection (24, 25), wherein the solenoid valve (20, 21) is arranged between the level control valve (11) and the bellows connection (24, 25), wherein at least one bellows pressure sensor (16) is provided and the solenoid valve (20, 21) is controllable depending on the bellows pressure, wherein a control unit (13) is provided for controlling the solenoid valve (20, 21), wherein the control unit (13) is a brake control unit, preferably for an electronic brake system of the vehicle, and wherein a lifting / lowering valve (12) is provided between the bellows connection (24, 25) and the solenoid valve (20, 21), wherein the lifting / lowering valve (12) is additionally connected to the air supply (10) bypassing the solenoid valve (20, 21) and the level control valve (11).

Description

[0001] The invention relates to a valve device for an air suspension system of a vehicle, comprising a level control valve, wherein the level control valve has an air supply connection for connecting an air supply, at least one bellows connection for connecting one or more air suspension bellows and at least one solenoid valve for blocking or opening a connection between the air supply connection of the level control valve and the bellows connection, wherein the solenoid valve is arranged in series with the level control valve and preferably between the level control valve and the bellows connection, wherein at least one bellows pressure sensor is provided and wherein the solenoid valve is controllable as a function of the bellows pressure. The invention further relates to an air suspension system comprising such a valve device and to a vehicle comprising such an air suspension system.

[0002] Commercial vehicles and other motor vehicles have a braking system with electronic control. In the simplest case, this is an anti-lock brake system. More modern vehicles are equipped with an electronic braking system that allows for more advanced control. In all cases, at least one electronic control unit with suitable software is required.

[0003] The electronic controls influence the vehicle's existing braking system. Commercial vehicles are preferably equipped with a pneumatic braking system. One component of the pneumatic braking system is a compressed air reservoir.

[0004] Modern commercial vehicles feature an air suspension system with air bellows. The air suspension system can be indirectly connected to the compressed air supply of the pneumatic braking system or have its own compressed air supply.

[0005] The level of a vehicle chassis above the axles or above the road surface can be changed by loading the vehicle, the pressure in the air bellows, and by activating a raising / lowering valve. A constant level is ensured by a level control valve (also known as an air spring valve) in the air suspension system. The level control valve is preferably assigned a sensor that detects the distance from an axle to the vehicle chassis. Typically, the sensor is implemented as a deflection mechanism that connects the level control valve to an axle. Depending on the distance to the axle, a specific state of the deflection mechanism is established. Depending on the state of the deflection mechanism, the level control valve regulates the supply of compressed air from the compressed air supply to the air suspension system and the release of air from the air suspension system. Each adjustment by the level control valve involves air consumption.

[0006] During normal vehicle operation, namely when driving, suspension movements and level changes occur, for example, when cornering, over uneven road surfaces, and when braking. Each time, the level control valve is activated, causing additional air consumption.

[0007] From DE 195 44 622 C1, it is known to associate solenoid valves with the level control valve, which can be opened and closed depending on the vehicle speed. When the solenoid valves are open, the level control valve functions as intended. Closed solenoid valves block compressed air lines upstream or downstream of the level control valve, preventing compressed air consumption.

[0008] Compensation via the level control valve may also be necessary while driving, for example, with gritters or in the event of leaks in the air suspension system. It's also possible that the vehicle is loaded while driving slowly. Braking, especially on long downhill stretches, also causes a change in the vehicle's level and bellows pressure.

[0009] DE 199 44 873 C1 discloses a control system for raising and lowering the body of a vehicle with air suspension. It comprises a compressed air source in the form of a compressed air reservoir, a level control valve, two switching valves, and air suspension bellows. The switching valves are implemented as solenoid valves. A pressure sensor detects the pressure in the air suspension bellows and transmits corresponding signals to both the vehicle's ABS / EBS system and an electronic control unit of the control system, which monitors and, if necessary, adjusts the pressure in the air suspension bellows.

[0010] From EP 2 177 381 A1 an electronic control device is known which serves for the automatic, electronically controlled level control of a vehicle body of a vehicle, to which a travel sensor and two pressure sensors are connected and which can be an ABS or EBS control unit.

[0011] The object of the present invention is to create a valve device for an air suspension system with lower air consumption. In particular, slow discharge, leaks, slow loading, and / or braking are to be detected and taken into account.

[0012] To achieve this object, the valve device according to the invention has the features of claim 1. In particular, at least one bellows pressure sensor is provided. Furthermore, the solenoid valve is controllable depending on the bellows pressure. The bellows pressure sensor provides important information from which the need or lack of control by the level control valve can be derived. In principle, the solenoid valve can remain closed while driving. The bellows pressure only fluctuates within the range of normal vibrations. If the bellows pressure slowly drops (while driving), there may be a leak or a slow discharge is taking place. In both cases, this is detected by the characteristic change in the bellows pressure. The solenoid valve is opened so that the vehicle level can be raised again by the level control valve. A slowly increasing bellows pressure can be caused by a load (even while driving).In this case, the solenoid valve is also opened so that the vehicle level can be adjusted by the level control valve.

[0013] Preferably, the temporal progression of the bellows pressure is also taken into account. A reduced or increased bellows pressure is present over a defined longer time interval, for example, 10 seconds or more. In particular, only then is the solenoid valve opened, allowing compensation via the level control valve.

[0014] The valve device has a control unit for controlling the solenoid valve. The control unit is a brake control unit, preferably for an electronic braking system of the vehicle. However, the control unit can also be primarily intended for anti-lock braking control or have another primary function.

[0015] According to a further concept of the invention, the bellows pressure sensor is integrated into the control unit. This ensures that the software, control unit, and bellows pressure sensor are optimally coordinated.

[0016] According to a further concept of the invention, the solenoid valve is controllable depending on a braking operation. A higher bellows pressure over a longer period of time can also occur during a longer braking phase. The control unit regulating the braking is aware that braking is taking place. During braking, the solenoid valve can remain closed, despite temporarily increased bellows pressure.

[0017] According to a further concept of the invention, the solenoid valve is additionally controllable as a function of the speed. In principle, evaluation of the bellows pressure is sufficient, since adjusting the vehicle level is also or particularly useful when the vehicle is stationary. However, the speed can also be evaluated. The signals required for this come from existing wheel speed sensors. Above a limit speed of, for example, 1 to 10 km / h, the solenoid valve generally remains closed, apart from defined exceptions, which in turn can depend on the bellows pressure or other parameters. According to a further concept of the invention, the solenoid valve is integrated into the level control valve and arranged with the latter in a common valve housing. This saves additional effort for lines and connections.

[0018] According to a further aspect of the invention, a height sensor is provided, which can at least detect whether a defined normal level or a deviating level of the vehicle is present. The height sensor can be assigned to the solenoid valve, the control unit, and / or the level control valve, or integrated into the respective component. The signals from the height sensor are processed by the control unit. The height sensor is preferably provided in addition to a deflection mechanism that detects the distance from an axle to the vehicle chassis.

[0019] According to a further concept of the invention, the solenoid valve is controlled depending on signals from the height sensor, such that the solenoid valve is only opened when the actual level of the vehicle has deviated from the defined normal level for more than a defined period of time. Only then should the vehicle level be compensated via the level control valve.

[0020] A raise / lower valve is provided between the bellows connection and the solenoid valve. The raise / lower valve is also connected to the air supply, bypassing the solenoid valve and the level control valve. This allows manual adjustment of the vehicle level even when the solenoid valve is closed.

[0021] According to a further aspect of the invention, two or more solenoid valves are provided, preferably at least one solenoid valve per vehicle side. The level control valve can also have two or more connections for the solenoid valves or for lines leading to the solenoid valves.

[0022] The invention also relates to an air spring system with a valve device as shown above.

[0023] Furthermore, the invention also relates to a vehicle with the aforementioned air suspension system.

[0024] The invention does not relate to a method for controlling a valve device for an air suspension system of a vehicle, wherein a level control valve temporarily connects an air supply to air bellows, wherein at least one solenoid valve blocks or opens a connection between the air supply and the air bellows, and wherein the solenoid valve is arranged in series with the level control valve. According to the invention, the solenoid valve is controlled as a function of a bellows pressure.

[0025] Advantageously, the solenoid valve is additionally controlled depending on the speed and / or a braking operation.

[0026] It is also advantageous to control the solenoid valve depending on signals from a height sensor, such that the solenoid valve is only opened when the actual level of the vehicle has left a defined normal level for more than a defined period of time.

[0027] A control unit for implementing the method is also not part of the invention. The control unit has the necessary software and evaluates the signals from the bellows pressure sensor and, if necessary, signals from other sensors, such as wheel speed sensors or height sensors. The control unit can also simultaneously serve as a control unit for an anti-lock brake system or for an electronic braking system of the vehicle.

[0028] Further features of the invention will become apparent from the description and the claims. Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. They show: Fig. 1 a schematic representation of an air suspension for a three-axle vehicle with six wheels, Fig. 2 the air suspension according to Fig. 1, but in a modified form.

[0029] Components of an air suspension system according to Fig. 1 are an air reservoir 10, a level control valve 11 (air suspension valve), a raising / lowering valve 12 (lift valve), an electronic control unit 13 and air suspension bellows 14, 15. The functions of the valves 11 and 12 are known and need not be explained in more detail.

[0030] A bellows pressure sensor 16 is integrated into the control unit 13 and connected to a pressure line 17. Alternatively, the bellows pressure sensor 16 can be arranged on a pressure line and connected to the control unit 13 via a signal line.

[0031] The air bellows 14, 15 are supplied with air from the air reservoir 10 via pressure lines 18, 19 and the level control valve 11. For additional control of the compressed air supply to the air bellows 14, 15, solenoid valves 20, 21 are provided in the pressure lines 18, 19, i.e., in series with the level control valve 11. The solenoid valves 20, 21 are connected to the control unit 13 via signal lines 22, 23.

[0032] The solenoid valves 20, 21 are connected indirectly to the air bellows 14, 15, namely via the raising / lowering valve 12 to bellows connections 24, 25. The level control valve 11 is connected to an air supply connection 26 on the air supply 10 side. The raising / lowering valve 12 is also connected to the air supply connection 26 on the inlet side and to the bellows connections 24, 25 on the outlet side. When the solenoid valves 20, 21 and / or the level control valve 11 are blocked, the connection from the air supply connection 26 to the bellows connections 24, 25 is blocked and can only be established by bypassing it, namely by actuating the raising / lowering valve 12.

[0033] Control unit 13 is preferably also a control unit of an electronic braking system, which controls the function of a pneumatic braking system (also not shown). For this purpose, control unit 13 also receives and processes signals from wheel speed sensors (not shown) in a known manner, from which a vehicle speed is derived.

[0034] The solenoid valves 20, 21 are controlled in accordance with the signals of the bellows pressure sensor 16 and, if applicable, in conjunction with information about the vehicle speed, in particular as follows: a) When driving, the bellows pressure oscillates only within the range of normal, driving-related vibrations. The driving condition is derived from the recorded speed and compared with a predefined limit speed. The limit speed is, for example, between 1 km / h and 10 km / h. The solenoid valves 20, 21 remain closed, unlike in Fig. 1, so that no air is consumed in any position of the level control valve 11. b) While driving, the bellows pressure drops slowly, for example, due to a leak in the air suspension or a slow unloading of the vehicle. Slow unloading occurs, for example, in a gritting vehicle. The falling bellows pressure is detected by the bellows pressure sensor 16. The control unit 13 opens the solenoid valves 20, 21 so that the vehicle level can be compensated by the level control valve 11. This function can be performed independently of speed detection or in conjunction with a speed signal. c) The bellows pressure slowly increases, which can be caused, for example, by a slow load while driving. This is detected based on the signals from the bellows pressure sensor 16. The control unit 13 opens the solenoid valves 20, 21 so that the vehicle level can be adjusted by the level control valve 11. Here, too, the function can be performed independently of the speed or in conjunction with the speed evaluation. d) During braking, the vehicle level may change due to the braking forces. The bellows pressure may temporarily increase or change. Control unit 13 is aware that braking is taking place (since it is preferably also the brake control unit). Control unit 13 keeps solenoid valves 20, 21 closed during the braking process so that level control valve 11 does not compensate for the temporary change in the vehicle level. The air suspension does not consume any air in this situation.

[0035] Fig. Figure 2 shows two additional functions. First, the level control valve 11 and the solenoid valves 20, 21 are integrated with each other and have a common valve housing 27. Separate piping between the level control valve 11 and the solenoid valves 20, 21 is eliminated.

[0036] On the other hand, a height sensor 28 is provided. This is preferably assigned to the level control valve 11 or integrated into it, as in Fig. 2. In the simplest case, the height sensor 28 merely detects whether the vehicle is at a defined normal level or deviates from it. The signals from the height sensor 28 are transmitted to the control unit 13 via a signal line 29. The control unit 13 opens the solenoid valves 20, 21 only if the detected vehicle level deviates from the normal level for more than a defined period of time. The defined period of time is, for example, a value between 10 and 60 seconds.

[0037] The solenoid valves 20, 21 are arranged downstream of the level control valve 11, starting from the air reservoir 10. Two solenoid valves 20, 21 are shown here, corresponding to the supply of the spring bellows 14 on one side and the spring bellows 15 on the other side of the vehicle. Alternatively, only one solenoid valve can be provided with only one further pressure line (instead of the two pressure lines 18, 19). Not shown but preferably present is a deflection mechanism or other device for detecting the distance between one of the axles and the vehicle chassis in a conventional manner and for controlling the basic function of the level control valve 11.

Claims

[1] Valve device for an air suspension system of a vehicle, with a level control valve (11), wherein the level control valve (11) has an air supply connection (26) for connecting an air supply (10), with at least one bellows connection (24, 25) for connecting one or more air spring bellows (14, 15) and with at least one solenoid valve (20, 21) for blocking or opening a connection between the air supply connection of the level control valve (11) and the bellows connection (24, 25), wherein the solenoid valve (20, 21) is arranged between the level control valve (11) and the bellows connection (24, 25), wherein at least one bellows pressure sensor (16) is provided and the solenoid valve (20, 21) is controllable as a function of the bellows pressure, wherein a control unit (13) is provided for controlling the solenoid valve (20, 21), wherein the control unit (13) is a brake control unit, preferably for an electronic brake system of the vehicle, and wherein a lifting / lowering valve (12) is provided between the bellows connection (24, 25) and the solenoid valve (20, 21), wherein the lifting / lowering valve (12) is additionally connected to the air supply (10), bypassing the solenoid valve (20, 21) and the level control valve (11). [2] Valve device according to claim 1, characterized by that the bellows pressure sensor (16) is integrated into the control unit (13). [3] Valve device according to claim 1 or 2, characterized by that the solenoid valve (20, 21) can be controlled as a function of a braking operation. [4] Valve device according to claim 1 or one of the further claims, characterized by that the solenoid valve (20, 21) is controllable depending on the speed. [5] Valve device according to claim 1 or one of the further claims, characterized by that the solenoid valve (20, 21) is integrated into the level control valve (11) and is arranged with the latter in a common valve housing (27). [6] Valve device according to claim 1 or one of the further claims, characterized by that a height sensor (28) is provided with which it is at least possible to detect whether a defined normal level or a level of the vehicle deviating therefrom is present. [7] Valve device according to claim 6, characterized by a control of the solenoid valve (20, 21) in dependence on signals from the height sensor (28) such that the solenoid valve (20, 21) is only opened when the actual level has left the defined normal level for more than a defined period of time. [8] Valve device according to claim 1 or one of the further claims, characterized by that two or more solenoid valves (20, 21) are provided, preferably at least one solenoid valve per vehicle side. [9] Air spring system with a valve device according to one of the preceding claims. [10] Vehicle with an air suspension system according to claim 9.

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