EP4293224A1

EP4293224A1 - Compressor for an air pressure system of a rail vehicle, air supply unit comprising such a compressor, system comprising a hvac system for a rail vehicle and the air supply unit, and method for providing air for the air pressure system

Info

Publication number: EP4293224A1
Application number: EP22179151.0A
Authority: EP
Inventors: Ajay Utpat; Michael Winkler; Thomas Kipp
Original assignee: Knorr Bremse Systeme fuer Schienenfahrzeuge GmbH
Current assignee: Knorr Bremse Systeme fuer Schienenfahrzeuge GmbH
Priority date: 2022-06-15
Filing date: 2022-06-15
Publication date: 2023-12-20
Also published as: WO2023241975A1

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

Description

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 a HVAC system for a rail vehicle and the air supply unit, and a method for providing air for the air pressure system, in particular, for rail vehicles designed to be used in a wide range of environmental conditions.
Since rail vehicles are usually designed for being used in regions having a low ambient temperature as well as in regions having a high ambient temperature, the requirements for the used materials are very high. In particular, a temperature variation range is between -40°C to +45°C. Therefore, special materials for seals to avoid leakages below 0°C and specific oil properties below 0°C or at about 45°C are necessary. Furthermore, a performance of an intercooler in a range from -40°C to plus 45°C is not effective and, moreover, there are starting issues and requirements for electric heaters below 0°C. Finally, wear and tear of piston and cylinder of the compressor occur in high ambient temperature environmental conditions.
Except from these problems due to the wide temperature range and extreme temperatures, when the compressor is used in a high humidity environment, water is entering an oil reservoir. The variation range of the relative humidity is from 30% to 80%. Moreover, due to dust in the air, there is a further risk of wear and tear of the piston and the cylinder.
Up to now, these problems have been solved by filters to remove dust, by coolers to reduce the temperature of compressed air, by water separators to remove water particles, by dryers to remove liquid content of air, and by electrical heaters. However, these measures are treating symptoms and not the root cause, they increase the manufacturing and operational costs, and they deteriorate reliability due to additional components.
Therefore, the object underlying the invention is to provide a system which remedies the above problems and which provides compressed air for an air pressure system of a rail vehicle while it is not essentially influenced by the environmental conditions.
The object is achieved by a compressor according to claim 1, an air supply unit according to claim 2, a system comprising a HVAC system for a rail vehicle and an air supply unit according to claim 5, a rail vehicle according to claim 12, and a method for providing air for an air pressure system of a rail directly according to claim 13. Advantageous further developments of the invention are included in the dependent claims.
According to an aspect of the invention, a compressor for an air pressure system of a rail vehicle comprises an intake duct configured to be connected to a HVAC system of the rail vehicle for enabling flow of process air conditioned by the HVAC system from the HVAC system to the compressor.
Accordingly, the compressor is enabled to introduce air from the HVAC system having predefined properties which, in particular, lie within a predefined range so that it can be avoided that ambient air having a great variety of properties such as temperature, humidity and purity is introduced into and used by the compressor. The aimed properties for the process air are advantageously a temperature between 15°C and 22°C and/or a relative humidity between 35% and 50%. By providing appropriate properties of air for the compressor, the requirements for the used materials in the compressor are decreased and the operational conditions of the components are facilitated. Since the rail vehicles for passenger service are usually provided with the HVAC system, no additional costs are incurred therefore.
According to a further aspect of the invention, an air supply unit comprises the compressor, and an aftercooler configured to cool process air compressed by the compressor, wherein the aftercooler is connected to an outlet of the compressor.
Such a configuration of the air supply unit enables intake of air having the predefined properties within the predefined range such that, except from the advantages of the compressor connectable to the HVAC system, the efficiency of the entire air supply unit is increased. The air conditioned by the HVAC system and introduced into the compressor and compressed by the compressor is the so-called process air.
In an advantageous implementation of the air supply unit, the compressor is formed to be a single-stage compressor.
The single-stage compressor is an economic solution for a system not having enormous requirements to the compressed air demand.
In another advantageous implementation of the air supply unit, the compressor is formed to be a two-stage compressor having a first stage and a second stage, and the air supply unit further comprises an intercooler 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.
This implementation enables an efficient solution in case of a higher requirements to the compressed air demand.
According to a further aspect of the invention, a system comprises a HVAC system for a rail vehicle and an air supply unit, wherein the HVAC system comprises a HVAC unit configured to condition air and a system duct configured to enable flow of air conditioned by the HVAC unit, and the compressor is connected to the system duct for enabling flow of the process air to the compressor.
Due to this system, the process air having the predefined properties can flow to the compressor so that the advantages concerning the used materials for the compressor and the high efficiency of the air supply unit can be achieved.
In an advantageous implementation of the system, it comprises a first damper configured to enable or to cut off flow of the process air to the compressor and/or the first damper is configured to switch between the air conditioned by the HVAC unit and ambient air from an environment for passing the ambient air to the compressor.
The first damper is controlled such that it enables to choose whether process air from the HVAC system or, in case of suitable ambient conditions, ambient air enters into the compressor. Therefore, the air enabling the highest efficiency of the system can be used for the air pressure system.
According to a further advantageous implementation of the system, the first damper is interposed between the system duct of the HVAC system and the intake duct of the compressor.
This location of the first damper enables an exact separation of the intake duct of the compressor from the system duct of the HVAC system, such that, in a possible case that ambient air is introduced from the environment for use in the compressor, this ambient air does not enter the system duct of the HVAC system so that it can be avoided that it possibly soil the system duct of the HVAC system or the air in the system duct.
According to an advantageous implementation of the system, it comprises a further intake duct configured to connect the after cooler and/or an intercooler to the system duct, wherein the further intake duct is configured to enable flow of cooling air conditioned by the HVAC system to the after cooler and/or the intercooler.
The air conditioned by the HVAC system and introduced from the HVAC system into the aftercooler and/or into the intercooler and which servers for cooling the process air compressed by the compressor is the so-called cooling air.
Due to this system, the cooling air does also have the predefined properties due to the fact that it is conditioned by the HVAC system. Hence, as this cooling air is to be flown into the aftercooler and/or into the intercooler, the advantages concerning the used materials for the aftercooler and/or the intercooler and the high efficiency of the coolers can be achieved, too. Due to a further advantageous implementation of the system, the system comprises a second damper configured to enable and to cut off flow of the cooling air conditioned by the HVAC unit to the aftercooler and/or the intercooler and/or the second damper is configured to switch between the air conditioned by the HVAC unit and the air from an environment for passing the air to the aftercooler and/or to the intercooler.
The second damper enables to choose whether cooling air from the HVAC system or, in case of suitable ambient conditions, ambient air can enter into the aftercooler and/or into the intercooler. Therefore, the air enabling the highest efficiency of the system can be used for the air pressure system.
In a further advantageous implementation of the system, the second damper is interposed between the system duct of the HVAC system and the further intake duct of the aftercooler and/or of the intercooler.
This location of the second damper enables an exact separation of the intake duct of the compressor from the system duct of the HVAC system, such, in the case that ambient air is introduced from the environment, this ambient air does not enter the system duct of the HVAC system and it does not soil the system duct.
In a further advantageous implementation of the system, the HVAC system and the air supply unit are formed as an integrated assembly.
By this configuration, synergy effects, such as a common housing and/or a common controller can be used to reduce installation efforts and manufacturing costs.
According to a further aspect of the invention, a rail vehicle comprises a system comprising a HVAC system and an air supply unit.
According to another aspect of the invention, a method for providing air for an air pressure system of a rail vehicle comprises the steps: introducing process air conditioned by a HVAC unit of a HVAC system from the HVAC system to a compressor of an air supply unit; and compressing the process air by the compressor.
By this method, the compressor is enabled to receive air having predefined properties from the HVAC system and ambient air having a great variety of characteristics such as temperature, humidity and dust can be prevented from being introduced into the compressor. Therefore, the requirements for the used materials are decreased and the operational conditions of the components are facilitated.
In an advantageous implementation of the method, it comprises the step: after-cooling the process air compressed by the compressor by an aftercooler, in particular by introducing cooling air having predefined properties from the HVAC unit into the after cooler for cooling the process air.
This method enables an efficient solution, in particular, by providing cooling air out of the air from the HVAC system in case of a higher requirement to the compressed air demand, and also the design of the aftercooler can be optimized due to more exact defined operational conditions.
According to an advantageous implementation of the method, the compressor is formed to be a two-stage compressor comprising a first stage and a second stage, the air supply unit comprises an intercooler interposed between first stage and the second stage; and the method comprises the step: introducing cooling air having predefined properties from the HVAC unit into the intercooler.
This method enables an efficient solution in case of a higher requirement to the compressed air demand and also the design of the intercooler can be optimized due to more exact defined operational conditions
Subsequently, the invention is elucidated by means of embodiments referring to the attached drawings.
In particular,

Fig. 1: shows an illustration of a portion of a rail vehicle provided with a system comprising an HVAC system and a separate air supply unit;
Fig. 2: shows a principle sectional view of the HVAC system and the air supply unit of Fig. 1;
Fig. 3: shows an illustration of a portion of a rail vehicle provided with the system in the form of an integrated assembly of the HVAC system and the air supply unit;
Fig. 4: shows a block diagram of the system comprising the HVAC system and the air supply unit comprising a single-stage compressor;
Fig. 5: shows a block diagram of the system comprising the HVAC system and the air supply unit comprising a two-stage compressor; and
Fig. 6: shows a flowchart of a method for providing air for an air pressure system of a rail vehicle.

Fig. 1 shows an illustration of a portion of a rail vehicle 1 provided with a system 2 comprising an HVAC system 3 for the rail vehicle 1 and a separate air supply unit 4. The HVAC system 3 is a system for Heating, Ventilating and Air Conditioning air supplied to a passenger compartment, e.g., of a rail vehicle. The air supply unit 4 provides compressed air treated for being suitable for an air pressure system of, e.g., a rail vehicle. The air pressure system supplies components of the vehicle, e.g., brakes or doors, with compressed air.
Fig. 2 shows a principle sectional view of the system 2 comprising the HVAC system 3 and the air supply unit 4. The HVAC system 3 comprises an HVAC unit 5 and a system duct 6 connected to the HVAC unit 5 and leading, on the one hand, to a passenger compartment of the rail vehicle 1 and, on the other hand, to the air supply unit 4. In particular, the system duct 6 is part of an insulated air ducting system of the rail vehicle 1. The HVAC unit 5 conditions ambient air with a great variety in temperature, humidity and purity introduced into the HVAC unit 5 in order to generate air in a predefined range with a predefined temperature, humidity, and purity suitable for being introduced into the passenger compartment of the rail vehicle 1. The system duct 6 comprises a branch so that it enables flow of the air conditioned by the HVAC unit 5 to both the passenger compartment of the rail vehicle 1 and to the air supply unit 4.
Fig. 3 shows an illustration of a portion of the rail vehicle 1 provided with the system 2 in the form of an integrated assembly of the HVAC system 3 and the air supply unit 4.
Fig. 4 shows a block diagram of the system 2 comprising the HVAC system 3 and the air supply unit 4. The air supply unit 4 comprises a single-stage compressor 7, an aftercooler 8, and an air dryer unit 9.
The single-stage compressor 7 is configured to compress air in order to provide compressed air for the air pressure system of the rail vehicle 1. The single-stage compressor 7 comprises an intake duct 10 connected to the HVAC system 3 of the rail vehicle 1, in particular, to the system duct 6, for enabling flow of process air conditioned by the HVAC system 3, in particular, by the HVAC unit 5, 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 a compressor is the so-called process air. The intake duct 10 is tube-shaped and has an inner diameter suitable for enabling the flow of the process air. The intake duct 10 is connected to the system duct 6 by means of a flange. In alternative embodiments, other connecting elements, such as press-in connections are possible.
The aftercooler 8 comprises a heat exchanger which cools the air compressed by the single-stage compressor 7, in particular, in order to cool the air, and, thereto, it is connected to an outlet of the single-stage compressor 7. Further, the air dryer unit 9 which 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 alternative embodiments, the air dryer unit 9 is not a component of the air supply unit 4 but it can be omitted or assigned to another assembly.
The system 2 further comprises a first damper 11. The first damper 11 enables or cuts off flow of the 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 can be located at another place, for example in the system duct 6 or in the intake duct 10 or it can be omitted.
Furthermore, the system 2 optionally comprises a first further air intake duct (not shown) which enables flow of ambient air of the environment to the single-stage compressor 7 and the first damper 11 switches between the air conditioned by the HVAC system 3 and the ambient air from an environment for passing either the conditioned air or the ambient air further or a mixture to the single-stage compressor 7.
Fig. 5 shows a block diagram of a system 2 of another embodiment comprising the HVAC system 3 and 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.
The air supply unit 4 comprising the two-stage compressor 12 also comprises the aftercooler 8 and the air dryer unit 9 as already described related to Fig. 4. All explanations regarding the same elements are referred hereto as well.
The two-stage compressor 12 also comprises the intake duct 10 connected to the HVAC system 3 of the rail vehicle 1, in particular, to the system duct 6, for enabling the flow of the process air conditioned by the HVAC unit 5 from the HVAC system 3 to the two-stage compressor 12. Also in the air supply unit 4 having the two-stage compressor 12, the first damper 11 enables or cuts off flow of 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 at another place, for example in the system duct 6 or in the intake duct 10.
The air supply unit 4 comprising the two-stage compressor 12 further comprises an intercooler 15. The intercooler 15 cools air compressed by the first stage 13 of the two-stage compressor 12 and it is interposed between the first stage 13 and the second stage 14. Furthermore, the air supply unit 4 comprises a further intake duct 17 connecting the intercooler 15 and the system duct 6. By this further intake duct 17, the intercooler 15 is provided with cooling air from the HVAC system 3. The air conditioned by the HVAC system 3 and introduced into a 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 by means of a heat exchanger in the intercooler 15.
Moreover, the system 2 comprises a second damper 16 which enables or cuts off flow of the air conditioned by the HVAC unit 3 to the intercooler 15 as the so called cooling air. The second damper 16 is interposed between the system duct 6 of the HVAC system 3 and the further intake duct 17 of the intercooler 15. In alternative embodiments, the second damper 16 can be located at another place, for example in the system duct 6 or in the further intake duct 17 or it can be omitted.
Furthermore, the system 2 optionally comprises a second further air intake duct (not shown) which enables flow of ambient air of the environment to the aftercooler 8 and/or to the intercooler 15 and the second damper 16 switches between the air conditioned by the HVAC unit 3 and the ambient air from an environment for passing either the conditioned air or the ambient air or a mixture to the aftercooler 8 and/or to the intercooler 15.
The intercooler 15 and the aftercooler 8 are formed integrally 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 alternative embodiments, the aftercooler 8 and the intercooler 15 are formed as being separate components and the cooling air flows subsequently through the intercooler 14 and the aftercooler 8.
Fig. 6 shows a flowchart of a method for providing air for an air pressure system of a rail vehicle 1.
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 after-cooled by the aftercooler 8. In particular, the compressor 7, 12 is provided with the process air conditioned by the HVAC system 3 when an ambient temperature is below 5°C. An operation mode of the compressor 7 and/or a provisioning of the compressor 7 with the process air from the HVAC system 3 or with ambient air is controlled by a controller (not shown).
In the case that the compressor is formed by the two-stage compressor 12 comprising the first stage 13 and the second stage 14 and the intercooler 15 between the first stage 13 and the second stage 14 is provided, the so called cooling air, also conditioned by the HVAC unit 4, is introduced into the intercooler 15 and cools the compressed process air by means of the heat exchanger. The cooling air from the HVAC system 3 passing through the intercooler 15 is enabled to pass through the aftercooler 8 in parallel. In particular, the intercooler 15 is provided with the cooling air when the ambient temperature is above 25°C. The provisioning of the intercooler 15 and/or of the aftercooler 8 with cooling air from the HVAC system 3 or with ambient air is also controlled by a controller (not shown).
In particular, the air conditioned by the HVAC unit 5 is passed through the system duct 6 and, when the first damper 11 enables the flow of the process air to the compressor 7, 12, the process air flows to the compressor 7, 12 and is compressed by the compressor 7, 12. After being compressed by the compressor 7, 12, the compressed process air is cooled in the aftercooler 8 by means of the cooling air in the heat exchanger and, then, the compressed process air flows into the air pressure system of the rail vehicle 1.
Thus, the compressor 7, 12 is already supplied with the process air, the characteristics of which, in particular, temperature, humidity, and purity, are in predefined ranges so that the overall performance of the air supply unit 4 is increased and auxiliary devices like filters, water separators, dryers and electrical heaters in the air supply unit 4 are not necessary, wherein the overall life of the compressor 7, 12 is increased.
In the case of the two-stage compressor 12, the intercooler 15 is also provided with the cooling air which can flow to the intercooler 15 by the further intake duct 17 when the second damper 16 enables the flow of the cooling air 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 in a narrow predefined range without any further preprocessing. Also, the characteristics of the cooling air from the HVAC unit 5 flowing into the intercooler 15 are in a narrow predefined range without any further preprocessing. Therefore, the intercooler 15, in particular, its heat exchanger, can be designed in order to optimize the heat exchange between the compressed process air and the cooling air.
The cooling air is enabled to pass through the intercooler 15 and the aftercooler 8 in parallel or, in an alternative embodiment, from the intercooler 15 to the aftercooler 8 via the outlet of the intercooler 18 and the inlet 19 of the aftercooler 8, wherein, the characteristics, on the one hand, of the process air compressed by the second stage 14 of the two-stage compressor 12 and, on the other hand, of the cooling air from the HVAC system 3 or after being passed through the intercooler 15, are in a respective narrow predefined range and, therefore, also the aftercooler 8, in particular, its heat exchanger, can be designed in an optimized manner.
In alternative embodiments, the intercooler 15 and/or the aftercooler 8 are provided with cooling air from another source, e.g., from the environment.
Then, the compressed air passed through the aftercooler 8 is further processed in the air dryer unit 9, if provided.
Although the present invention has been described with reference to specific features and embodiments thereof, it is evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded simply as an illustration of the invention as defined by the appended claims, and are contemplated to cover any and all modifications, variations combinations or equivalents that fall within the scope of the present invention.

LIST OF REFERENCE SIGNS

1: rail vehicle
2: system
3: HVAC system
4: air supply unit
5: HVAC unit
6: system duct
7: single-stage compressor
8: aftercooler
9: air dryer unit
10: intake duct
11: first damper
12: two-stage compressor
13: first stage (of compressor)
14: second stage (of compressor)
15: intercooler
16: second damper
17: further intake duct
18: outlet of intercooler
19: inlet of aftercooler

Claims

A compressor (7, 12) for an air pressure system of a rail vehicle (1), the compressor (7, 12) comprising an intake duct (10) configured to be connected to a HVAC system (2) of the rail vehicle (1) for enabling flow of process air conditioned by the HVAC system (2) from the HVAC system (2) to the compressor (7, 12).
An air supply unit (4) comprising
the compressor (7, 12) of claim 1, and

an aftercooler (8) configured to cool the process air compressed by the compressor (7, 12),

wherein the aftercooler (8) is connected to an outlet of the compressor (7, 12).
The air supply unit (4) of claim 2, wherein
the compressor (7, 12) is formed to be a single-stage compressor (7).
The air supply unit (4) of claim 2, wherein
the compressor (7, 12) is formed to be a two-stage compressor (12) having a first stage (13) and a second stage (14), and

the air supply unit (4) further comprises an intercooler (15) configured to cool the 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).
A system (2) comprising a HVAC system (3) for a rail vehicle (1) and an air supply unit (4) of anyone of claims 2 to 4, wherein
the HVAC system (3) comprises a HVAC unit (5) configured to condition air and a system duct (6) configured to enable flow of air conditioned by the HVAC unit (5), and

the compressor (7, 12) is connected to the system duct (6) for enabling flow of the process air to the compressor (7, 12).
The system (2) of claim 5, wherein
the system (2) comprises a first damper (11) configured to enable or to cut off flow of the process air to the compressor (7, 12), and/or

the first damper (11) is configured to switch between the air conditioned by the HVAC unit (5) and air from an environment for passing the air to the compressor (7, 12).
The system (2) of claim 6, wherein
the first damper (11) is interposed between the system duct (6) of the HVAC system (3) and the intake duct (10) of the compressor (7, 12).
The system (2) of anyone of claims 5 to 7, wherein
the system (2) comprises a further intake duct (17) configured to connect the after cooler (8) and/or an intercooler (15) to the system duct (6), wherein the further intake duct (17) is configured to enable flow of cooling air conditioned by the HVAC system (2) to the after cooler (8) and/or the intercooler (15).
The system (2) of claim 8, wherein
the system (2) comprises

a second damper (16) configured to enable and to cut off flow of the cooling air conditioned by the HVAC unit (5) to the after cooler (8) and/or to the intercooler (15) and/or

the second damper (16) is configured to switch between the air conditioned by the HVAC unit (5) and the air from an environment for passing the air to the aftercooler (8) and/or to the intercooler (15).
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 intake duct (17) connecting the aftercooler (8) and/or the intercooler (15) with the system duct (6).
The system (2) of anyone of claims 5 to 10, wherein
the HVAC system (3) and the air supply unit (4) are formed to be an integrated assembly.
A rail vehicle (1) comprising a system (2) according to anyone of claims 5 to 11.
A method for providing air for an air pressure system of a rail vehicle (1) comprising the steps:
introducing process air conditioned by a HVAC unit (5) of a HVAC system (3) from the HVAC system (3) to a compressor (7, 12) of an air supply unit (4) (S1); and

compressing the process air by the compressor (7, 12) (S2).
The method of claim 13, comprising the step
after-cooling the process air compressed by the compressor (7, 12) by an aftercooler (8) (S3), in particular by introducing cooling air having predefined properties from the HVAC unit (5) into the aftercooler (8) for cooling the process air.
The method of claim 14, wherein
the compressor (12) is formed to be 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 first stage (13) and the second stage (14) ; and

the method comprises the step:
introducing cooling air having the predefined properties from the HVAC unit (5) into the intercooler (15).