Compressor for an air pressure system of a rail vehicle, air supply unit comprising such a compressor, system comprising an HVAC system for a rail vehicle and an air supply unit, and method for providing air for an air pressure system

Abstract

A compressor (7, 12) for an air pressure system of a rail vehicle (1), an air supply unit comprising such a compressor, a system comprising an HVAC system and an air supply unit for a rail vehicle, and a method of providing air for an air pressure system are provided. The compressor (7, 12) comprises an intake duct (10) configured to be connected to an HVAC system (2) of the rail vehicle (1) to enable process air conditioned by the HVAC system (2) to flow from the HVAC system (2) to the compressor (7, 12).

Description

Technical Field

[0001] The invention relates to a compressor for an air pressure system of a rail vehicle, an air supply unit comprising such a compressor, a system comprising an HVAC system for a rail vehicle and an air supply unit, and a method for providing air for an air pressure system, in particular for a rail vehicle designed for use in a wide range of ambient conditions. Background Art

[0002] Since rail vehicles are usually designed for use in areas with low ambient temperatures as well as for use in areas with high ambient temperatures, the requirements on the materials used are high. In particular, the temperature varies between -40°C and 45°C. Therefore, special sealing materials to avoid leakage below 0°C and special lubricating oil properties below 0°C or around 45°C are necessary. In addition, the properties of the intercooler in the range from -40°C to over 45°C are ineffective, and in addition, there are start-up problems and requirements for electric heaters below 0°C. Finally, under environmental conditions of high ambient temperatures, wear and tear of the pistons and cylinders of the compressors occur.

[0003] In addition to these problems due to the wide temperature range and temperature extremes, water can enter the oil tank when the compressor is used in a humid environment. Relative humidity can vary from 30% to 80%. In addition, there is a further risk of wear and tear on the piston and cylinder due to dust in the air.

[0004] So far, these problems have been solved by removing dust through filters, reducing the temperature of compressed air through coolers, removing water particles through dehydrators, removing liquid content in the air through dryers, and by electric heaters. However, these measures are only temporary solutions, they increase manufacturing and operating costs, and they reduce reliability due to additional components. Summary of the invention

[0005] It is therefore an object of the present invention to provide a system which remedies the above-mentioned problems and provides compressed air to the air pressure system of a rail vehicle substantially independently of the ambient conditions.

[0006] This object is achieved by a compressor according to claim 1, an air supply unit according to claim 2, a system comprising an HVAC system and an air supply unit for a rail vehicle according to claim 5, a rail vehicle according to claim 12, and a method for directly supplying an air pressure system of a rail with air according to claim 13. Further advantageous developments of the invention are included in the dependent claims.

[0007] According to one aspect of the invention, a compressor for an air pressure system of a rail vehicle includes an air intake duct configured to be connected to an HVAC system of the rail vehicle to enable process air conditioned by the HVAC system to flow from the HVAC system to the compressor.

[0008] Accordingly, the compressor is enabled to introduce air with predetermined properties, in particular, the properties are maintained within a predetermined range, from the HVAC system, thereby avoiding the introduction of ambient air with various properties such as temperature, humidity and purity into the compressor and its use by the compressor. Advantageously, the target properties of the process air are a temperature between 15°C and 22°C and / or a relative humidity between 35% and 50%. By providing the compressor with air of appropriate properties, the requirements for the materials used in the compressor are reduced and the operating conditions of the components are facilitated. Since rail vehicles used for passenger service are usually equipped with HVAC systems, no additional costs are incurred.

[0009] According to another aspect of the present invention, an air supply unit includes a compressor and an aftercooler configured to cool process air compressed by the compressor, wherein the aftercooler is connected to an outlet of the compressor.

[0010] This configuration of the air supply unit enables the introduction of air having predetermined properties within a predetermined range, so that in addition to the advantage of a compressor connectable to an HVAC system, the efficiency of the entire air supply unit is improved. The air conditioned by the HVAC system and introduced into the compressor and compressed by the compressor is the so-called process air.

[0011] In an advantageous embodiment of the air supply unit, the compressor is designed as a single-stage compressor.

[0012] Single-stage compressors are an economical solution for systems that do not have extreme demands on compressed air demand.

[0013] In a further advantageous embodiment of the air supply unit, the compressor forms a two-stage compressor having a first stage and a second stage, and the air supply unit further comprises an intercooler which is configured to cool the process air compressed by the first stage of the two-stage compressor, wherein the intercooler is interposed between the first stage and the second stage.

[0014] This embodiment enables an effective solution to be provided in situations where there are high demands on the compressed air demand.

[0015] According to another aspect of the present invention, a system includes an HVAC system and an air supply unit for a rail vehicle, wherein the HVAC system includes an HVAC unit configured to condition air and a duct system configured to enable circulation of air conditioned by the HVAC unit, and a compressor is connected to the duct system to enable process air to flow to the compressor.

[0016] Thanks to this system, process air having predetermined properties can flow to the compressor, whereby advantages can be obtained with regard to the materials used for the compressor and a high efficiency of the air supply unit.

[0017] In an advantageous embodiment of the system, the system comprises a first damper configured to enable or shut off the flow of process air to the compressor and / or to switch between air conditioned by the HVAC unit and air from the environment so that ambient air flows to the compressor.

[0018] Controlling the first damper allows the selection of whether process air from the HVAC system is admitted to the compressor or ambient air is admitted to the compressor under suitable ambient conditions. Thus, air that enables the system to have the highest efficiency is available to the air pressure system.

[0019] According to a further advantageous embodiment of the system, the first damper is interposed between a system duct of the HVAC system and an air intake duct of the compressor.

[0020] This position of the first damper enables the air intake duct of the compressor to be exactly separated from the system duct of the HVAC system, so that, when possible, ambient air is introduced from the environment for the compressor, and the ambient air does not enter the system duct of the HVAC system, thereby avoiding possible contamination of the system duct of the HVAC system or the air in the system duct.

[0021] According to an advantageous embodiment of the system, the system comprises a further air intake duct which is configured to connect an aftercooler and / or an intercooler to the system duct, wherein the further air intake duct is configured to enable cooling air conditioned by the HVAC system to flow to the aftercooler and / or the intercooler.

[0022] The air conditioned by the HVAC system and introduced from the HVAC system to the aftercooler and / or the intercooler and used to cool the process air compressed by the compressor is the so-called cooling air.

[0023] Due to the system, the cooling air also has predetermined properties because it is conditioned by the HVAC system. Therefore, since this cooling air will flow into the aftercooler and / or the intercooler, advantages related to the materials used for the aftercooler and / or the intercooler and the high efficiency of the cooler can also be obtained. Due to another advantageous embodiment of the system, the system includes a second damper, which is configured to enable the cooling air conditioned by the HVAC unit to flow to the aftercooler and / or the intercooler and to cut off the cooling air conditioned by the HVAC unit from flowing to the aftercooler and / or the intercooler, and / or the second damper is configured to switch between air conditioned by the HVAC unit and air from the environment to allow air to pass to the aftercooler and / or the intercooler.

[0024] The second damper enables the selection of whether to allow cooled air from the HVAC system or ambient air under suitable ambient conditions to enter the aftercooler and / or intercooler. Thus, the air that enables the system to have the highest efficiency is available to the air pressure system.

[0025] In a further advantageous embodiment of the system, a second air flap is interposed between a system duct of the HVAC system and the further air intake duct of the aftercooler and / or the intercooler.

[0026] This position of the second damper enables the air intake duct of the compressor to be positively separated from the system duct of the HVAC system so that, if possible, ambient air is introduced from the environment without entering the system duct of the HVAC system and contaminating the system duct.

[0027] In a further advantageous embodiment of the system, the HVAC system and the air supply unit are formed as an integrated assembly.

[0028] With this configuration, synergistic effects such as a common housing and / or a common controller can be used to reduce installation work and manufacturing costs.

[0029] According to another aspect of the invention, a rail vehicle includes a system including an HVAC system and an air supply unit.

[0030] According to another aspect of the invention, a method of providing air to an air pressure system of a rail vehicle comprises the steps of introducing process air conditioned by an HVAC unit of an HVAC system from the HVAC system to a compressor of an air supply unit; and compressing the process air by the compressor.

[0031] By adopting this method, the compressor can receive air with predetermined properties from the HVAC system, and can prevent ambient air with various characteristics such as temperature, humidity and dust from being introduced into the compressor. Therefore, the requirements for the materials used are reduced and the operating conditions of the components are facilitated.

[0032] In an advantageous embodiment of the method, the method comprises the step of aftercooling the process air compressed by the compressor by an aftercooler, in particular by introducing cooling air having predetermined properties from an HVAC unit to the aftercooler for cooling the process air.

[0033] This approach enables an efficient solution, especially in case of high demands on compressed air demand, to provide cooling air from the air coming from the HVAC system and the design of the aftercooler can also be optimized due to more exactly defined operating conditions.

[0034] According to an advantageous embodiment of the method, the compressor forms a two-stage compressor comprising a first stage and a second stage, the air supply unit comprises an intercooler, which is interposed between the first stage and the second stage; the method comprises the following steps: introducing cooling air with predetermined properties from the HVAC unit into the intercooler.

[0035] In the case of higher demands on the compressed air demand, this approach enables an efficient solution to be achieved and the design of the intercooler can also be optimized due to more precisely defined operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Hereinafter, the present invention will be described by way of embodiments with reference to the accompanying drawings.

[0037] in particular:

[0038] Figure 1 A diagram showing a portion of a rail vehicle equipped with a system including an HVAC system and a separate air supply unit;

[0039] Figure 2 Show Figure 1 A schematic cross-sectional view of the HVAC system and air supply unit shown;

[0040] Figure 3 A diagram showing a portion of a rail vehicle equipped with a system in the form of an integrated assembly of an HVAC system and an air supply unit;

[0041] Figure 4 is a block diagram of a system, the system including an HVAC system and an air supply unit, the air supply unit including a single-stage compressor;

[0042] Figure 5 is a block diagram of a system, the system including an HVAC system and an air supply unit, the air supply unit including a two-stage compressor;

[0043] Figure 6 is a flow chart of a method of providing air to an air pressure system of a rail vehicle. DETAILED DESCRIPTION

[0044] Figure 1 A diagram of a portion of a rail vehicle 1 is shown, which is equipped with a system 2 comprising an HVAC system 3 and a separate air supply unit 4 for the rail vehicle 1. The HVAC system 3 is a system for heating, ventilating and air conditioning the air provided to, for example, the passenger compartment of the rail vehicle. The air supply unit 4 provides compressed air that is processed to be suitable for, for example, the air pressure system of the rail vehicle. The air pressure system supplies compressed air to components of the vehicle, such as brakes or doors.

[0045] Figure 2 A schematic cross-sectional view of a system 2 comprising an HVAC system 3 and an air supply unit 4 is shown. The HVAC system 3 comprises an HVAC unit 5 and a system duct 6, which is connected to the HVAC unit 5 and leads to the passenger compartment of the rail vehicle 1 on the one hand and to the air supply unit 4 on the other hand. In particular, the system duct 6 is part of an insulated air duct system of the rail vehicle 1. The HVAC unit 5 conditions the ambient air with various temperatures, humidity and purity introduced into the HVAC unit 5 so as to produce air within a predetermined range with a predetermined temperature, humidity, and purity suitable for introduction into the passenger compartment of the rail vehicle 1. The system duct 6 comprises a branching portion, so that the air conditioned by the HVAC unit 5 can flow both to the passenger compartment of the rail vehicle 1 and to the air supply unit 4.

[0046] Figure 3 The illustration shows a portion of a rail vehicle 1 which is equipped with a system 2 in the form of an integrated assembly of an HVAC system 3 and an air supply unit 4 .

[0047] Figure 4 A block diagram of a system 2 is shown including an HVAC system 3 and an air supply unit 4. The air supply unit 4 includes a single-stage compressor 7, an aftercooler 8, and an air drying unit 9.

[0048] The single-stage compressor 7 is configured for compressing air in order to provide compressed air for the air pressure system of the rail vehicle 1. The single-stage compressor 7 comprises an air inlet pipe 10, which is connected to the HVAC system 3 of the rail vehicle 1, in particular to the system duct 6, so that process air conditioned by the HVAC system 3, in particular by the HVAC unit 5, can flow from the HVAC system 3 to the single-stage compressor 7. As already mentioned above, the air conditioned by the HVAC system 3 and introduced into the compressor is the so-called process air. The air inlet pipe 10 is tubular and has an inner diameter suitable for allowing the process air to circulate. The air inlet pipe 10 is connected to the system duct 6 by a flange. In alternative embodiments, other connection elements, such as press-in connections, can be used.

[0049] The aftercooler 8 includes a heat exchanger that cools the air compressed by the single-stage compressor 7, and in particular, in order to cool the air, the aftercooler 8 is connected to the outlet of the single-stage compressor 7. In addition, an air drying unit 9 that dries the air compressed by the single-stage compressor 7 and cooled by the aftercooler 8 is provided in the air supply unit 4. In an alternative embodiment, the air drying unit 9 is not a component of the air supply unit 4, but may be omitted or allocated to another component.

[0050] The system 2 also includes a first damper 11. The first damper 11 is capable of enabling or shutting off the flow of process air to the single-stage compressor 7. The first damper 11 is interposed between the system duct 6 of the HVAC system 3 and the intake duct 10 of the single-stage compressor 7. In alternative embodiments, the first damper 11 may be located elsewhere, such as in the system duct 6 or in the intake duct 10, or may be omitted.

[0051] In addition, the system 2 optionally includes an additional first suction duct (not shown), which enables ambient air from the environment to flow to the single-stage compressor 7, and the first damper 11 switches between air conditioned by the HVAC system 3 and ambient air from the environment to allow conditioned air, or ambient air, further or a mixture to flow to the single-stage compressor 7.

[0052] Figure 5 1 is a block diagram of another embodiment of a system 2, the system 2 comprising an HVAC system 3 and an air supply unit 4, the air supply unit 4 comprising a two-stage compressor 12. The two-stage compressor 12 is provided with a first stage 13 and a second stage 14.

[0053] The air supply unit 4 including the two-stage compressor 12 also includes the Figure 4 An aftercooler 8 and an air drying unit 9 are shown. All comments concerning the same elements also apply here.

[0054] The two-stage compressor 12 also comprises an intake duct 10, which is connected to the HVAC system 3 of the rail vehicle 1, in particular to the system duct 6, so that process air conditioned by the HVAC unit 5 can flow from the HVAC system 3 to the two-stage compressor 12. Also in the air supply unit 4 with the two-stage compressor 12, a first damper 11 can enable or shut off the process air to the two-stage compressor 12. The first damper 11 is interposed between the system duct 6 of the HVAC system 3 and the intake duct 10 of the two-stage compressor 12. In alternative embodiments, the first damper 11 can be located elsewhere, for example in the system duct 6 or in the intake duct 10.

[0055] The air supply unit 4 including the two-stage compressor 12 also includes an intercooler 15. The intercooler 15 cools the air compressed by the first stage 13 of the two-stage compressor 12, and the intercooler is interposed between the first stage 13 and the second stage 14. In addition, the air supply unit 4 includes a further air intake pipe 17, which connects the intercooler 15 and the system duct 6. Through this further air intake pipe 17, the intercooler 15 is supplied with cooling air from the HVAC system 3. The air conditioned by the HVAC system 3 and introduced into the cooler for cooling the process air compressed by the compressor is the so-called cooling air. The process air compressed by the first stage 13 is cooled by the cooling air from the HVAC system 3 through the heat exchanger in the intercooler 15.

[0056] Furthermore, the system 2 comprises a second damper 16 which enables or shuts off the air conditioned by the HVAC unit 3 to flow as so-called cooling air to the intercooler 15. The second damper 16 is interposed between the system duct 6 of the HVAC system 3 and the further air intake duct 17 of the intercooler 15. In alternative embodiments, the second damper 16 may be located elsewhere, for example in the system duct 6 or in the further air intake duct 17 or may be omitted.

[0057] In addition, the system 2 optionally includes an additional second intake duct (not shown), which enables ambient air from the environment to flow to the aftercooler 8 and / or to the intercooler 15, and a second damper 16 switches between air conditioned by the HVAC unit 3 and ambient air from the environment to allow conditioned air or ambient air or a mixture to flow to the aftercooler 8 and / or the intercooler 15.

[0058] The intercooler 15 and the aftercooler 8 are integrally formed and either the cooling air from the HVAC system 3 or the ambient air from the environment or a mixture flows through the intercooler 15 and the aftercooler 8 in parallel. In an alternative embodiment, the aftercooler 8 and the intercooler 15 are formed as separate components and the cooling air flows through the intercooler 14 and the aftercooler 8 in sequence.

[0059] Figure 6 is a flow chart of a method for providing air to an air pressure system of a rail vehicle 1 .

[0060] In operation, in step S1, process air conditioned by the HVAC unit 5 of the HVAC system 3 is introduced from the HVAC system 3 to the compressor 7, 12 of the air supply unit 4. Subsequently, in step S2, the process air is compressed by the compressor 7, 12, and in step S3, the process air compressed by the compressor 7, 12 is optionally aftercooled by the aftercooler 8. In particular, when the ambient temperature is below 5°C, the compressor 7, 12 is supplied with process air conditioned by the HVAC system 3. The operating mode of the compressor 7 and / or the supply of the compressor 7 with process air from the HVAC system 3 or with ambient air is controlled by a controller (not shown).

[0061] In the case where the compressor is formed by a two-stage compressor 12 comprising a first stage 13 and a second stage 14, an intercooler 15 is provided between the first stage 13 and the second stage 14, so-called cooling air, also conditioned by the HVAC unit 4, is introduced into the intercooler 15 and the compressed process air is cooled by the heat exchanger. The cooling air from the HVAC system 3 flowing through the intercooler 15 can flow through the aftercooler 8 connected in parallel. In particular, when the ambient temperature is above 25° C., the intercooler 15 is supplied with cooling air. The supply of the intercooler 15 and / or the aftercooler 8 with cooling air from the HVAC system 3 or with ambient air is also controlled by a controller (not shown).

[0062] In particular, the air conditioned by the HVAC unit 5 flows through the system duct 6, and when the first damper 11 enables the process air to flow to the compressors 7, 12, the process air flows to the compressors 7, 12 and is compressed by the compressors 7, 12. After being compressed by the compressors 7, 12, the compressed process air is cooled in the aftercooler 8 by the cooling air in the heat exchanger, and then the compressed process air flows to the air pressure system of the rail vehicle 1.

[0063] Thus, the compressors 7, 12 are already supplied with process air whose characteristics, in particular temperature, humidity, and purity, are within predetermined ranges, so that the overall performance of the air supply unit 4 is improved, and auxiliary devices such as filters, dehydrators, dryers and electric heaters are not necessary in the air supply unit 4, wherein the overall life of the compressors 7, 12 is increased.

[0064] In the case of a two-stage compressor 12, the intercooler 15 is also supplied with cooling air, which can flow to the intercooler 15 through a further air intake duct 17 when the second damper 16 enables the cooling air to flow to the intercooler 15. Since the first stage 13 of the two-stage compressor 12 compresses the process air from the HVAC unit 5, the characteristics of the compressed air are within a narrow predetermined range without any further pre-treatment. Likewise, the characteristics of the cooling air from the HVAC unit 5 flowing into the intercooler 15 are also within a narrow predetermined range without any further pre-treatment. Therefore, the intercooler 15, in particular its heat exchanger, can be designed to optimize the heat exchange between the compressed process air and the cooling air.

[0065] The cooling air can flow through the intercooler 15 and the aftercooler 8 connected in parallel, or, in an alternative embodiment, from the intercooler 15 to the aftercooler 8 via the outlet 18 of the intercooler 15 and the inlet 19 of the aftercooler 8, wherein, on the one hand, the characteristics of the process air compressed by the second stage 14 of the two-stage compressor 12 and, on the other hand, the characteristics of the cooling air from the HVAC system 3 or after flowing through the intercooler 15 are within a corresponding narrow predetermined range, so that, likewise, the aftercooler 8, and in particular its heat exchanger, can be designed in an optimized manner.

[0066] In alternative embodiments, the intercooler 15 and / or the aftercooler 8 are fed with cooling air from other sources, such as from the environment.

[0067] The compressed air flowing through the aftercooler 8 is then further processed in an air drying unit 9 (if provided).

[0068] Although the present invention has been described with reference to the specific features and embodiments of the present invention, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of the present invention. Therefore, the specification and drawings are only regarded as an illustration of the present invention as defined by the appended claims, and any and all modifications, variant combinations or equivalents falling within the scope of the present invention shall be covered. List of Reference Numerals

[0069] 1Railway Vehicles

[0070] 2 System

[0071] 3HVAC system

[0072] 4 Air supply unit

[0073] 5HVAC Unit

[0074] 6 System catheter

[0075] 7Single-stage compressor

[0076] 8 Aftercooler

[0077] 9 Air drying unit

[0078] 10 Intake pipe

[0079] 11First Air Gate

[0080] 12 Two-stage compressor

[0081] 13First stage (of the compressor)

[0082] 14 Second stage (of the compressor)

[0083] 15 Intercooler

[0084] 16 Second air door

[0085] 17 Additional intake pipe

[0086] 18 Intercooler outlet

[0087] 19 Aftercooler inlet

Claims

1. A compressor (7, 12) for an air pressure system of a rail vehicle (1), the compressor (7, 12) comprising an air intake duct (10) configured to be connected to an HVAC system (2) of the rail vehicle (1) so as to enable process air conditioned by the HVAC system (2) to flow from the HVAC system (2) to the compressor (7, 12).

2. An air supply unit (4), comprising: The compressor (7, 12) according to claim 1, and an aftercooler (8) configured to cool process air compressed by the compressor (7, 12), The aftercooler (8) is connected to the outlet of the compressor (7, 12).

3. The air supply unit (4) according to claim 2, wherein: The compressor (7, 12) is formed as a single-stage compressor (7).

4. The air supply unit (4) according to claim 2, wherein: The compressor (7, 12) is formed as a two-stage compressor (12) having a first stage (13) and a second stage (14), and The air supply unit (4) further includes an intercooler (15) configured to cool process air compressed by the first stage (13) of the two-stage compressor (12), the intercooler (15) being interposed between the first stage (13) and the second stage (14).

5. A system (2) comprising an HVAC system (3) for a rail vehicle (1) and an air supply unit (4) according to any one of claims 2 to 4, wherein: The HVAC system (3) includes an HVAC unit (5) configured to condition air and a system duct (6) configured to enable circulation of air conditioned by the HVAC unit (5), and The compressor (7, 12) is connected to the system duct (6) to enable process air to flow to the compressor (7, 12).

6. The system (2) according to claim 5, wherein: The system (2) comprises a first damper (11) configured to enable or shut off the process air flow to the compressor (7, 12), and / or The first damper (11) is configured to switch between air conditioned by the HVAC unit (5) and air from the environment to allow air to flow to the compressor (7, 12).

7. The system (2) according to claim 6, wherein: The first damper (11) is interposed between the system duct (6) of the HVAC system (3) and the air intake duct (10) of the compressor (7, 12).

8. The system (2) according to any one of claims 5 to 7, wherein: The system (2) comprises a further air intake duct (17) configured to connect an aftercooler (8) and / or an intercooler (15) to the system duct (6), wherein the further air intake duct (17) is configured to enable cooling air conditioned by the HVAC system (2) to flow to the aftercooler (8) and / or the intercooler (15).

9. The system (2) according to claim 8, wherein: System (2) includes: a second damper (16) configured to enable cooling air conditioned by the HVAC unit (5) to flow to the aftercooler (8) and / or the intercooler (15) and to shut off cooling air conditioned by the HVAC unit from flowing to the aftercooler and / or the intercooler, and / or The second damper (16) is configured to switch between air conditioned by the HVAC unit (5) and air from the environment so that the air flows to the aftercooler (8) and / or the intercooler (15).

10. The system of claim 9, wherein: The second damper (16) is interposed between the system duct (6) of the HVAC system (3) and the further air intake duct (17), which connects the aftercooler (8) and / or the intercooler (15) to the system duct (6).

11. The system (2) according to any one of claims 5 to 10, wherein: The HVAC system (3) and the air supply unit (4) are formed as an integrated assembly.

12. A rail vehicle (1) comprising a system (2) according to any one of claims 5 to 11.

13. A method for providing air to an air pressure system of a rail vehicle (1), the method comprising the following steps: introducing process air conditioned by an HVAC unit (5) of an HVAC system (3) from the HVAC system (3) to a compressor (7, 12) of an air supply unit (4) (S1); and The process air (S2) is compressed by a compressor (7, 12).

14. The method according to claim 13, comprising the steps of: The process air compressed by the compressor (7, 12) is aftercooled (S3) by the aftercooler (8), in particular by introducing cooling air having predetermined properties from the HVAC unit (5) into the aftercooler (8) for cooling the process air.

15. The method according to claim 14, wherein: The compressor (12) is formed as a two-stage compressor (12) comprising a first stage (13) and a second stage (14), The air supply unit (4) comprises an intercooler (15) interposed between the first stage (13) and the second stage (14); and The method comprises the following steps: Cooling air having predetermined properties is introduced from the HVAC unit (5) into the intercooler (15).

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