Integrated air supply unit with air dryer and air spring system, as well as control of an air supply unit

Abstract

An integrated air supply unit (1) for an air suspension system for a motor vehicle, comprising an air compressor (2) with an electric motor (3), an air dryer (4), and a pneumatic block (5), wherein the air compressor (2) and, in part, a switching valve device (32) for air flow control are arranged within the pneumatic block (5), characterized in that an electronic control unit (6) is arranged on the pneumatic block (5), wherein valves (7) of the switching valve device (32) are arranged, in part, within the pneumatic block (5) and, in a matching manner, in part within the electronic control unit (6), wherein a first pneumatic line section (11) is provided in the block (5) between the air compressor (2) and the air dryer (4), and a second pneumatic line section (12) is provided in the block (5) between the air dryer (4) and the switching valve device (32).wherein the first and second line sections (11, 12) run next to one another in the block (5), in particular so close that the air in the first and second line sections (11, 12) acts as an air-to-air heat exchanger (10), wherein the material of the block (5) between the first and second lines (11, 12) acts together with the air in the second line section (12) as a heat sink, and the air in the first line section (11) can be cooled by means of the heat sink for adsorption by the air dryer (4), or the material of the block (5) between the first and second line sections and the air compressor (2) acts together with the air in the first line section (11) as a heat source, and the air in the second line section (12) can be heated by means of the heat source for regeneration of the air dryer (4).

Description

[0001] The invention relates to an integrated air supply unit according to the preamble of claim 1 and to an air spring system. Furthermore, the invention relates to a method for controlling an integrated air supply unit.

[0002] In conventional air suspension systems, air compressors are required for level control. These compressors, preferably dry-running, provide the pressures required for operation in the individual components, such as air springs or compressed air reservoirs. To do this, the compressors draw in air from the ambient air, compress it to a specific pressure level, and supply it to the system components.

[0003] However, the ambient air drawn in contains water or moisture, which can cause individual components, such as valves, to freeze during operation. To prevent this, the dew point of the drawn-in air is lowered using a dryer. This means that the air is dried or dehumidified in a dryer using a desiccant / adsorbent, such as silica gel. The drawn-in air thus releases its moisture to the dryer and is then passed on, for example, to the air springs.

[0004] However, the moisture absorption of the adsorbent depends on the air temperature. Silica gel allows for good water absorption at around 60°C. At higher temperatures, starting at around 80°C, the adsorbent must first cool the drawn-in air, which reduces the usable adsorption area by one-third of the dryer bed length and creates so-called dead zones.

[0005] At a certain point, the dryer becomes saturated and the adsorbent can only partially fulfill its drying function. Therefore, the dryer must be regenerated.

[0006] Desorption regenerates the dryer. This means that the moisture contained in the adsorbent is absorbed by the air flowing through it and released into the environment. The air flows, for example, from a compressed air reservoir via a throttle to further expand the air in countercurrent through the dryer and is released into the environment via a discharge valve.

[0007] Heated air is advantageous for adsorbent regeneration, as higher temperatures allow the air to absorb moisture from the adsorbent more effectively. The air temperature usually corresponds to the ambient temperature of the air suspension system components and is further cooled by expansion. This results in poor regeneration efficiency, which is based solely on the principle of pressure swing regeneration in countercurrent or cocurrent flow.

[0008] In order to achieve sufficient working capacity, the dryer would have to be larger or more regeneration air would have to be passed through the dryer. However, a larger dryer has the disadvantage of increasing its weight and taking up more space. Furthermore, large quantities of regeneration air are usually only possible in open air suspension systems when the air suspension system is discharged from full to empty load. These are exceptions, however, as load changes between two people with luggage and an empty load frequently occur during operation, which leads to small quantities of regeneration air with correspondingly poor desportion. In a closed air suspension system, the options for releasing air described are not available due to the nature of the system. Here, only a portion of the system air can be used for regeneration when the system is filled, otherwise the system would not be filled.This percentage should be as small as possible to minimize compressor runtimes for filling. In these cases, air control is usually achieved by the minimum actuators available, such as an air spring valve, pressure accumulator valve, changeover valve in closed systems, or a drain valve.

[0009] As a result, there is always a risk of water or moisture penetrating the system. This is especially true if leaks in the air suspension system mean that the system air is only partially available for regeneration of the dryer, as the compressor must constantly fill the system with air.

[0010] As an alternative to adsorption and regeneration, there are improved drying principles that require additional lines and actuators. However, additional wiring and electrical connectors are particularly undesirable, as they result in additional components on the compressor, resulting in correspondingly high construction costs and complexity.

[0011] Such a compressor for air suspension systems is known from DE 199 11 933 A1. A dryer filled with a desiccant is connected to a compressor via a first line. The dryer inlet is thus directly connected to the cylinder head. However, the air compressed in the cylinder head is highly heated (usually around 180-200°C) and is fed into the dryer via the shortest possible route. This highly heated air impairs adsorption in the dryer. To regenerate the desiccant, the air also returns through the dryer via the same route.

[0012] DE 10 2004 005 117 A1 discloses another similar compressor for air suspension systems, in which the dryer is connected to the compressor via a line longer than the stroke length of the piston crank mechanism. However, in this compressor, highly heated air is also routed directly from the cylinder head to the dryer, which also reduces the adsorption capacity.

[0013] It would be conceivable to design a larger cylinder head with suitable airflow for cooling, but this would require more space. Cylinder heads are typically made of die-cast aluminum, making it difficult to create internal air ducts.

[0014] DE 10 2010 036 742 A1 addresses dryer regeneration. It is proposed to design the dryer as part of the compressor's drive motor or as part of the compressor itself. For example, the dryer surrounds the electric motor as a housing component or is designed as a double-walled cylinder of the compressor. These designs are intended to utilize the waste heat generated by the electric motor or the compressor to heat the dryer and thus improve the moisture absorption of the outgoing air. However, this has a negative impact on adsorption during operation if ambient air must be drawn into the system and passed through the dryer. The adsorption capacity of the dryer in a heated state is lower than in a cool state.

[0015] Furthermore, DE 102 40 359 A1 and DE 10 2009 003 396 A1 disclose air suspension systems for vehicles in which air is drawn from the atmosphere by a compressor and fed to the individual components, such as air springs and compressed air reservoirs, via a dryer. These describe how the regeneration of a dryer can be achieved by switching valves.

[0016] Therefore, it is an object of the invention to create a compact air supply unit, e.g. for air spring systems, with efficient drying properties.

[0017] Another object of the invention is to provide a method for controlling an air dryer which provides improved dryer availability.

[0018] The problem underlying the invention is solved with the features of the independent patent claim.

[0019] According to the invention, an integrated air supply unit is provided, wherein the air supply unit comprises an air compressor with an electric motor, an air dryer, and a pneumatic block, wherein the air compressor and, in part, a switching valve device for air flow control are arranged within the pneumatic block, wherein an electronic control unit is arranged on the pneumatic block, wherein valves of the switching valve device are arranged partly within the pneumatic block and, in a matching manner, partly in the electronic control unit, wherein a first pneumatic line section is provided in the block between the air compressor and the air dryer, and a second pneumatic line section is provided in the block between the air dryer and the switching valve device, wherein the first and second line sections run next to one another in the block,so that the air in the first and second line sections acts as an air-to-air heat exchanger. The integrated air supply unit is suitable for an air suspension system for a motor vehicle. Preferably, the first and second line sections run close to one another in the block.

[0020] The material of the block, preferably aluminum, acts as a heat sink between the first and second lines together with the air in the second line section.

[0021] Advantageously, the block material ensures rapid heat dissipation of the compression heat through thermal conduction. The heat dissipation surfaces of the air compressor's cylinder heads, formed by the block, can quickly dissipate the heat to the environment. Likewise, the dissipated heat is absorbed and dissipated via the air in the second line section. This leads to effective cooling of the air coming from the air compressor in the first line section. This reduces the air inlet temperature into the air dryer, allowing the adsorbent to absorb moisture.

[0022] For adsorption by the air dryer, the air in the first line section can be cooled by means of the heat sink.

[0023] The improved adsorption rate of the air dryer allows for less adsorbent to be used, saving space. This is advantageous in open air supply systems, as the risk of moisture penetrating the air suspension system is minimized or even completely eliminated.

[0024] The material, preferably aluminum, of the block acts as a heat source between the first and second line sections and the air compressor together with the air in the first line section.

[0025] Advantageously, the block material ensures rapid heat transfer from the air compressor's compression heat through heat conduction. The heat transfer from the air compressor via the block material warms the air in the second line section. The thus heated air leads to improved regeneration of the air dryer and increases its operating capacity. In the process, the air extracts more moisture from the air dryer and releases it into the environment.

[0026] To regenerate the air dryer, the air in the second line section can be heated by means of the heat source.

[0027] The improved regeneration rate allows the amount of air required for regeneration to be reduced. This is advantageous for closed-loop air supply systems, as system filling time is significantly reduced and the proportion of regeneration air to the total air supplied is reduced.

[0028] According to a preferred embodiment, the first and second line sections run next to each other over a length of at least 15 mm and a distance of less than 10 mm.

[0029] The compact air supply unit, essentially consisting of an air compressor, valves, air dryer, and pneumatic line sections, thus has a beneficial effect on the air drying properties. The particularly close arrangement of the two line sections creates an air-to-air heat exchanger.

[0030] According to a further preferred embodiment, the block partially comprises at least one air spring valve and one discharge valve.

[0031] Preferably, the changeover valve device is designed as a combination of four 2 / 2-way valves or two 3 / 2-way valves or one 4 / 2-way valve.

[0032] According to a further preferred embodiment, a heating element is arranged within the block. The heating element is preferably arranged in the second line section.

[0033] Advantageously, the heating element heats the regeneration air so that the heated air flows through the adsorbent and can absorb a particularly high amount of moisture. This significantly improves the operating capacity. This also has the advantage that regeneration of the air dryer can occur at any time with high efficiency. This minimizes the acoustic impact of discharged air during driving.

[0034] Preferably, the heating element is electronically connected directly to the electronic control unit of the air supply unit.

[0035] According to the invention, when controlling an integrated air supply unit for adsorption by the air dryer, air is directed from the air compressor to the air dryer via the first line section, with the air in the first line section being cooled by means of the heat sink comprising the block and the air in the second line section. To regenerate the air dryer, air is directed from the switching valve device to the air dryer via the second line section, with the air in the second line section being heated by means of the heat source comprising the block and the air compressor, together with the air in the first line section.

[0036] Preferably, the air in the second line section is heated by means of the heating element.

[0037] Preferably, the regeneration of the air dryer is carried out after filling at least one air spring and / or one compressed air reservoir.

[0038] The regeneration capacity of the air dryer is even higher if regeneration occurs immediately after air is drawn from the ambient air into the air springs or the pressure accumulator. In this case, the block's heating due to the heat of compression is maximized.

[0039] The integrated air supply unit is used in an air suspension system for a motor vehicle, in particular with the closed air supply concept.

[0040] The method for controlling an air supply unit is also used in an air suspension system for a motor vehicle, in particular with the concept of a closed air supply.

[0041] Further preferred embodiments of the invention emerge from the subclaims and the following description of an embodiment with reference to the figures.

[0042] It shows Fig. 1 an exemplary integrated air supply unit with air dryer, Fig. 2 a pneumatic circuit diagram of an air spring system with an exemplary integrated air supply unit with air dryer, Fig. 3 a pneumatic circuit diagram of an air spring system with an exemplary integrated air supply unit with air dryer and a heating element, and Fig. 4 another pneumatic circuit diagram of an air spring system with an exemplary integrated air supply unit with air dryer and a heating element.

[0043] Fig. Figure 1 schematically shows an integrated air supply unit 1 for a motor vehicle air suspension system. Within a pneumatic block 5 is an air compressor 2, which is driven by a front-mounted electric motor 3. The air compressor 2 essentially consists of a crankcase and at least two reciprocating pistons with corresponding cylinder heads.

[0044] The pneumatic block 5 has receptacles for individual components (not shown in detail). Several valves 7 are schematically indicated, some of which are arranged within the pneumatic block 5 and some of which are arranged in an electronic control unit 6, matching each other.

[0045] The valves 7 are divided into drive units 7a and solenoid valve coils 7b, with drive units 7a being arranged in block 5. Drive units 7a comprise a core, a sleeve, an armature, a spring, and a sealing seat (not shown in detail) and are permanently integrated into block 5. The corresponding solenoid valve coils 7b are preferably arranged separately in the electronic control unit 6 and are electromechanically actuated. Solenoid valve coils 7b are fitted onto the drive units 7a and held in position to compensate for tolerances, preferably by means of spring elements.

[0046] The valves 7 comprise, for example, at least one air suspension valve, a switching valve device for regulating the air flow of the air suspension system and a drain valve for discharging system air into the environment.

[0047] Block 5 also contains pneumatic lines not shown in detail. The pneumatic lines can be implemented as holes in block 5. The lines connect the air compressor 2, air dryer 4, valves 7, and several pneumatic connections 8.

[0048] Furthermore, the air dryer 4 and pneumatic connections 8 are arranged on the front of block 5 in corresponding receptacles of block 5. Connections 8 are used to connect to other components of an air suspension system, such as multiple air springs or a compressed air reservoir.

[0049] In addition to some of the valves 7, the electronic control unit 6 contains an electronic connection 9. The integrated air supply unit 1 is fully connected to the vehicle's electrical system via connection 9, allowing it to be configured and read out. The electric motor 3 and valves 7 are controlled via the electronic control unit 6. Furthermore, a heating element and a pressure sensor can be integrated into the block 5 and connected to the electronic control unit 6.

[0050] Fig. 2 shows a pneumatic circuit diagram of an air suspension system with an exemplary integrated air supply unit with air dryer 4. The integrated air supply unit comprises an air compressor 2 with motor 3, an electronic control unit 6, several air suspension valves 26, a changeover valve device 32 for air flow control and a drain valve 24. A pressure sensor 25 is arranged on the air suspension valves 26 and system air can be drained by means of an ECU vent 30 and a manual vent 31.

[0051] The individual components of the integrated air supply unit are connected via pneumatic lines. The intersection points of the lines with the pneumatic block 5 in the pneumatic circuit diagram represent the pneumatic connections, which are used, for example, to connect the air springs 27, the pressure accumulator 28, or the air filter 29. The individual components of the integrated air supply unit 1 are controlled via the electronic control unit 6.

[0052] In open air supply mode, air is drawn in from the environment via air filter 29 with check valve 34 by air compressor 2 with capacity limiting valve 20. Air compressor 2 delivers air to air dryer 4 and then via a check valve 35 and via check valve 21 to switching valve device 32 or into the air suspension system. The moisture contained in the air must be adsorbed by air dryer 4. This is achieved by an adsorbent in air dryer 4. To regenerate air dryer 4, air is passed from the first switching valve device 32 via check valve 22 and regeneration throttle 23 to air dryer 4 and released to the environment or atmosphere via drain valve 24.

[0053] In closed air supply mode, compressed air from the consumer components such as air springs 27 or compressed air reservoirs 28 is supplied to the air dryer 4 by means of a switching valve device 32, for example in the form of four 2 / 2-way valves. Air can be directed to the air dryer 4 either with or without the air compressor 2. The switching valve device 32 regulates the air flow via the pneumatic lines accordingly for adsorption by the air dryer 4 or for regeneration of the air dryer 4.

[0054] For example, a first pneumatic line section 11 runs between the air compressor 2 and the air dryer 4, and a second pneumatic line section 12 runs between the air dryer 4 and the changeover valve device 32. The first and second line sections 11, 12 run so close to one another that the air contained in the line sections acts as an air-to-air heat exchanger 11.

[0055] The material of block 5, for example, made of aluminum, between the first 11 and second 12 line sections, together with the air in the second line section 12, can act as a heat sink. Thus, the air conveyed to the air dryer 4 via the first line section 11 is cooled for adsorption by the air dryer 4. The cooled air has a beneficial effect on the adsorption rate of the air dryer 4.

[0056] The material of block 5 between the first 11 and second 12 line sections and the air compressor 2, together with the air in the first line section 11, can act as a heat source. Thus, to regenerate the air dryer 4, the air conveyed to the air dryer via the second line section 12 is heated. The heated air has a beneficial effect on the regenerative capacity of the air dryer 4. Regeneration can occur after filling at least one air spring 27 or the pressure accumulator 28.

[0057] Fig. 3 shows a pneumatic circuit diagram of an air spring system with an exemplary integrated air supply unit with air dryer based on the Fig. 2. In addition, the exemplary air supply unit has a heating element 33, which is arranged in the pneumatic line section 12. To regenerate the air dryer 4, the air in the line section 12 is heated by means of the heating element 33. The air is heated to such an extent that even after slight cooling due to the throttling effect of the regeneration throttle 23, heated air flows through the adsorbent of the air dryer 4 and absorbs considerably more moisture from the adsorbent. For example, air at 20°C can absorb water in the amount of 17.3 g / m 3 and at 40°C already 50.7 g / m 3 . For control, heating element 33 is directly electronically connected to electronic control unit 6, whereby the regeneration of the air dryer 4 can take place during driving.

[0058] Fig. 4 shows a pneumatic circuit diagram of an air spring system according to Fig.3, wherein the regeneration throttle 23 is arranged between the switching valve device 32 and the heating element 33 and the check valve 35 is omitted. List of reference symbols 1 integrated air supply unit 2 air compressors 3 electric motor 4 air dryers 5 pneumatic block 6 electronic control unit 7 valves 7a Drive units 7b Solenoid valve coils 8 pneumatic connections 9 electronic connection 10 air-to-air heat exchangers 11 first pneumatic line section 12 second pneumatic line section 20 Power limiting valve 21 Check valve 22 Check valve 23 Regeneration throttle 24 Drain valve 25 Pressure sensor 26 air suspension valves 27 air springs 28 pressure accumulators 29 Air filters 30 ECU venting 31 manual venting 32 Changeover valve device for air flow control 33 Heating element 34 Check valve 35 Check valve

Claims

[1] Integrated air supply unit (1) for an air suspension system for a motor vehicle comprising an air compressor (2) with electric motor (3), an air dryer (4) and a pneumatic block (5), wherein the air compressor (2) and partially a changeover valve device (32) for air flow control are arranged within the pneumatic block (5), characterized bythat an electronic control unit (6) is arranged on the pneumatic block (5), wherein valves (7) of the switching valve device (32) are arranged partly within the pneumatic block (5) and, in a matching manner, partly in the electronic control unit (6), wherein a first pneumatic line section (11) is provided in the block (5) between the air compressor (2) and the air dryer (4), and a second pneumatic line section (12) is provided in the block (5) between the air dryer (4) and the switching valve device (32), wherein the first and the second line sections (11, 12) run next to one another in the block (5), in particular so close that the air in the first and in the second line sections (11, 12) acts as an air-air heat exchanger (10), wherein the material of the block (5) between the first and the second line (11,12) together with the air in the second line section (12) acts as a heat sink and the air in the first line section (11) can be cooled by means of the heat sink for adsorption by the air dryer (4), or the material of the block (5) between the first and second line sections and the air compressor (2) together with the air in the first line section (11) can act as a heat source and the air in the second line section (12) can be heated by means of the heat source for regeneration of the air dryer (4). [2] Air supply unit (1) according to claim 1, characterized by that the first and second line sections (11, 12) run next to each other over a length of at least 15 mm and a distance of less than 10 mm. [3] Air supply unit (1) according to claim 1 or 2, characterized by that the block (5) partially comprises at least one air spring valve (26) and one discharge valve (24). [4] Air supply unit (1) according to one of claims 1 to 3, characterized by that a heating element (33) is arranged within the block (5), in particular in the second line section (12). [5] Air supply unit (1) according to claim 4, characterized by that the heating element (33) is electronically connected directly to the electronic control unit (6) of the air supply unit (1). [6] Air spring system for vehicles, wherein the air spring system comprises an integrated air supply unit (1) according to at least one of claims 1 to 5. [7] Method for controlling an integrated air supply unit (1) according to one of claims 1 to 5, characterized byin that, for adsorption by the air dryer (4), air is conducted from the air compressor (2) via the first line section (11) to the air dryer (4), wherein the air in the first line section (11) is cooled by means of the heat sink from block (5) and the air in the second line section (12), wherein for regeneration of the air dryer (4), air is conducted from the changeover valve device (32) via the second line section (12) to the air dryer (4), wherein the air in the second line section (12) is heated by means of the heat source from block (5) and air compressor (2) together with the air in the first line section (11). [8] Method according to claim 7, when related to an air supply unit (1) according to one of claims 4 or 5, characterized by that the air in the second line section (12) is heated by means of the heating element (33). [9] Method according to claim 7 or 8, characterized bythat a regeneration of the air dryer (4) is carried out after filling at least one air spring (27) and / or one compressed air reservoir (28).

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