Pneumatic system and motor vehicle

Abstract

Pneumatic system (1) comprising a compressor (8), a pneumatic accumulator (20) for a gaseous pressure transmission medium, at least one valve assembly (12) and at least one pneumatically actuated actuator (4), wherein the pneumatic accumulator (20) has a variable volume to which the compressor (8) is connected, characterized in that the pneumatic accumulator (20) is made of a flexible and / or elastic material, wherein the pneumatic accumulator (20) can be connected to the environment via a shut-off valve (26), and wherein the pneumatic accumulator (20) contains a desiccant (22).

Description

[0001] The invention relates to a pneumatic system according to the preamble of claim 1. The invention further relates to a motor vehicle with such a pneumatic system.

[0002] European patent EP 1 319 585 B1 discloses a motor vehicle with an air guidance device that includes a pneumatic actuating element for moving the air guidance device from a rest position to an operating position. German patent DE 10 2004 038 705 B3 discloses a compressed air system for a motor vehicle with an intermediate compressed air storage tank and a main compressed air storage tank that can be filled with air through an air dryer. German patent application DE 102 03 681 A1 discloses a closed pneumatic system with a storage container in which a gaseous medium is present below a threshold temperature, at least partially in a liquid state and / or in a form chemically bound to a liquid or solid medium.and with at least one cavity with a variable volume connected to this storage container. German patent application DE 197 24 015 A1 discloses a suspension system for adapting to changing loads for vehicle axles, particularly in commercial vehicles, with a hydraulic accumulator whose preload pressure can be controlled via a control device and which is connected to at least one hydraulic working cylinder that acts on the respective vehicle axle with a predefinable spring characteristic, wherein the spring characteristic of the working cylinder can be adjusted by controlling the preload pressure of the hydraulic accumulator via the control device, wherein the control device comprises a control unit and a supply unit, wherein the control unit has a pressure sensor for determining the preload pressure of the hydraulic accumulator and at least one switching valve and / or control valve for alternately filling and draining the working medium.in particular nitrogen gas, with increasing or decreasing axle load, wherein the supply unit has a gas compressor which generates the pre-charge pressure and is connected to the control unit via a supply line, wherein at least one storage tank is provided as a buffer unit into which the gas compressor supplies the working medium, wherein the gas compressor is connected to a compressed air network of the vehicle and wherein a gas separation module separates the working gas, in particular nitrogen gas, from the compressed air and supplies it to the gas compressor.

[0003] The object of the invention is to create a pneumatic system according to the preamble of claim 1 which functions flawlessly even at extreme temperatures and is simple in design and cost-effective to manufacture.

[0004] This problem is solved by a pneumatic system with the features of claim 1 and by a motor vehicle equipped with such a pneumatic system. The variable volume offers the advantage that the gaseous pressure transmission medium can be stored in the pneumatic reservoir at zero pressure, low pressure, or a low pressure. Using the compressor, the gaseous pressure transmission medium can be pumped either from the pneumatic reservoir to the actuator or from the actuator to the pneumatic reservoir. This creates a simple, closed system that can be operated with dry air or with a substitute gas, such as nitrogen. This reliably prevents the actuator from freezing, even at extremely low temperatures. The storage volume can be limited, for example, by a flexible plastic film arranged within a cage-like housing.The variable-volume storage tank offers the advantage of being easily adapted to installation spaces of varying sizes or shapes. If the amount of pressure transfer medium stored in the tank is insufficient to supply the actuator via the compressor, the shut-off valve opens, allowing ambient air to enter the tank. Opening the shut-off valve allows for the simple compensation of pressure losses in the closed system, for example, due to leakage. Since, as previously described, the otherwise closed system is only opened by the shut-off valve to compensate for pressure losses, only a comparatively small amount of desiccant is required.

[0005] A preferred embodiment of the pneumatic system is characterized in that the pneumatic accumulator is designed as a low-pressure accumulator. According to a key aspect of the invention, the pneumatic accumulator is designed without pressure, i.e., pressurized at atmospheric pressure or normal pressure, or at a slight overpressure of approximately one bar.

[0006] Another preferred embodiment of the pneumatic system is characterized in that the compressor is designed for a pressure of less than two bar. The compressor is preferably designed for a pressure of approximately 1.2 bar. This allows the costs of the pneumatic system to be kept low.

[0007] Another preferred embodiment of the pneumatic system is characterized in that the compressor is designed and / or connected between the storage tank and the actuator such that, during operation of the compressor, gaseous pressure transmission medium is either pumped out of or into the storage tank, with the volume of the storage tank decreasing or increasing. The compressor can, for example, be designed as a vane compressor that can be operated in opposite directions of rotation. Alternatively, the compressor can be designed as a piston compressor that, with the aid of changeover valves, can be operated such that the pressure transmission medium is pumped by the compressor either into the actuator or into the storage tank.

[0008] Another preferred embodiment of the pneumatic system is characterized in that the valve assembly is connected between the compressor and the actuator. The valve assembly serves to actuate the actuator with the aid of the compressor. The pneumatic system can also comprise several actuators and / or several valve assemblies.

[0009] Another preferred embodiment of the pneumatic system is characterized in that a microfilter is connected between the compressor and the valve assembly. The microfilter prevents contaminants in the form of abrasion or dust from the compressor from entering the valve assembly. This prevents unwanted contamination or clogging of the valve assembly.

[0010] Another preferred embodiment of the pneumatic system is characterized in that a pressure sensor is connected between the storage tank and the compressor. This pressure sensor preferably serves to control the shut-off valve described above.

[0011] Another preferred embodiment of the pneumatic system is characterized in that a pressure sensor is connected between the valve assembly and the actuator. This pressure sensor preferably serves to control the actuation of the actuator.

[0012] The invention further relates to a motor vehicle with a pneumatic system as described above. The actuator is, for example, a drive element for a spoiler or for a convertible top of the motor vehicle. Alternatively or additionally, the pneumatic system according to the invention can also include actuators of a pneumatic suspension, an active seating system, or a headrest actuation system.

[0013] Further advantages, features and details of the invention will become apparent from the following description, in which an exemplary embodiment is described in detail with reference to the drawing.

[0014] The accompanying single figure shows a pneumatic system according to the invention in the form of a pneumatic circuit diagram. In Fig.Figure 1 shows a pneumatic system 1 with an actuator 4 in the form of a pneumatic circuit diagram. The actuator 4 can be a pneumatic cylinder containing a piston that can be moved back and forth by actuating a compressor 8. The compressor 8 is driven by a motor M, for example, an electric motor. Two arrows within the compressor symbol 8 indicate that the compressor 8 can deliver pressure transmission medium into and out of the actuator 4.

[0015] A microfilter 10 is connected adjacent to the compressor 8. The microfilter 10 is connected upstream of a valve assembly 12, which serves to actuate the actuator 4. The valve assembly 12 is designed as an electromagnetically actuated 3 / 3-way valve, which is biased in the center position shown. A pressure sensor 15 is connected between the valve assembly 12 and the actuator 4.

[0016] The compressor 8 is connected to a pneumatic accumulator 20 via a pneumatic line 18, the pressure of which is detected by a further pressure sensor 19. According to a key aspect of the invention, the pneumatic accumulator 20 has a variable volume and is pressurized at low pressure. The pneumatic accumulator 20 contains a relatively small quantity of desiccant 22.

[0017] The pneumatic storage tank 20 can be connected to the environment via a further pneumatic line 24. For this purpose, the pneumatic line 24 is connected to a shut-off valve 26, which is connected to the environment via a further pneumatic line 28 in which a further filter 30 is arranged. The shut-off valve 26, like the valve assembly 12 described above, is designed as an electromagnetically actuated 3 / 3-way valve, which is biased in its illustrated neutral position.

[0018] The interior of a motor vehicle 35 is indicated by a dashed line 34. The actuator 4 is preferably located outside the vehicle interior 34 and is therefore exposed to extreme temperatures depending on the weather. The actuator 4 serves, for example, to extend or raise a spoiler of the motor vehicle 35 as needed and to retract or return it to its original position.

[0019] The pneumatic system 1 can, for example, be filled with a gaseous pressure transfer medium via the pneumatic line 28. The pressure transfer medium is preferably completely dehumidified air or a substitute gas, such as nitrogen. The pressure transfer medium is stored in the pneumatic reservoir 20, but according to a key aspect of the invention, it is only pressurized at low pressure.

[0020] With the aid of the compressor 8, the pressure transmission medium is drawn from the pneumatic reservoir 20 as required and fed to the actuator 4 via the valve assembly 12. The variable volume of the reservoir 20 ensures that no negative pressure or vacuum is created in the pneumatic reservoir 20 when the pressure transmission medium is drawn.

[0021] When the actuator 4 is reset, the compressor 8 operates in reverse, whereby the pressure transmission medium escaping from the actuator 4 is reduced back to low or normal pressure and fed back into the pneumatic reservoir 20. By returning the pressure transmission medium from the actuator 4 via the compressor 8, the volume of the pneumatic reservoir 20 is increased again.

[0022] The shut-off valve 26 serves to compensate for leaks in the otherwise closed system. If the pressure sensor 19 detects that the amount of pressure transfer medium stored in the pneumatic reservoir 20 is insufficient to supply the actuator 4 with pressure transfer medium via the compressor 8, the shut-off valve 26 opens, allowing ambient air to flow into the pneumatic reservoir 20. The incoming ambient air is dried by the desiccant 22 in the pneumatic reservoir 20.

Claims

[1] Pneumatic system (1) comprising a compressor (8), a pneumatic storage unit (20) for a gaseous pressure transmission medium, at least one valve assembly (12) and at least one pneumatically actuated actuator (4), wherein the pneumatic storage unit (20) has a variable volume to which the compressor (8) is connected, characterized by , that the pneumatic storage device (20) is made of a flexible and / or elastic material, wherein the pneumatic storage device (20) can be connected to the environment via a shut-off valve (26), and wherein the pneumatic storage device (20) contains a desiccant (22). [2] Pneumatic system (1) according to claim 1, characterized by , that the pneumatic storage unit (20) is designed as a low-pressure storage unit. [3] Pneumatic system (1) according to one of the preceding claims, characterized by , that the compressor (8) is designed for a pressure of less than two bar. [4] Pneumatic system (1) according to one of the preceding claims, characterized by , that the compressor (8) is designed and / or connected between the pneumatic storage (20) and the actuator (4) such that during operation of the compressor (8) gaseous pressure transmission medium is conveyed either out of the pneumatic storage (20) or into the pneumatic storage (20), whereby the volume of the pneumatic storage (20) decreases or increases. [5] Pneumatic system (1) according to one of the preceding claims, characterized by , that the valve assembly (12) is connected between the compressor (8) and the actuator (4). [6] Pneumatic system (1) according to claim 5, characterized by , that a microfilter (10) is connected between the compressor (8) and the valve assembly (12). [7] Pneumatic system (1) according to one of the preceding claims, characterized by, that a pressure sensor (19) is connected between the pneumatic storage tank (20) and the compressor (8). [8] Pneumatic system (1) according to one of the preceding claims, characterized by , that a pressure sensor (15) is connected between the valve assembly (12) and the actuator (4). [9] Motor vehicle with a pneumatic system (1) according to any of the preceding claims.

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