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Title:
COMPRESSED-AIR SUPPLY SYSTEM AND METHOD TO OPERATING A COMPRESSED-AIR SUPPLY SYSTEM
Document Type and Number:
WIPO Patent Application WO/2018/109511
Kind Code:
A1
Abstract:
Compressed-air supply system (10) comprising: an air supply, comprising an air compressor unit (21) for supplying compressed air to an compressed air supply (1); a compressed air port (2) to the pneumatic installation (90); an air removal port (3) for releasing air to the environment; a pneumatic main line (60) between the compressed air supply (1) and the compressed air port (2), the pneumatic main line (60) comprising an air dryer (61) and a throttle (62) an air removal line (70) between the compressed air port (2) and the air removal port (3), the air removal line (70) branching of the pneumatic main line (60); an exhaust valve (71) connected in the air removal line (70), wherein the exhaust valve (71) comprises a pressure control port (71S) connected to the compressed air supply (1), and comprises a pressure counter control port (71A) connected to the compressed air port (2), wherein the exhaust valve (71) comprises control chamber which is fluidically partitioned by a diaphragm (75) for switching the exhaust valve (71) between an opened and a closed state (CS), the diaphragm (75) having an effective area (75S) pressurizable via the pressure control port (71S) and an opposing effective area (75A) pressurizable via the pressure counter control port (71A).

Inventors:
ASHARAM, Suresh, Kumar (76/59, Venkatespuram2nd Street P.N. Road, Tirupur - 2, 64160, IN)
JEYASEELAN, Jerald (F5 Ezhil Garden, B30A 1st Main Road,Thiruvengadam Nagar, Ambattur, Chennai - 8, 60005, IN)
Application Number:
IB2016/001769
Publication Date:
June 21, 2018
Filing Date:
December 16, 2016
Export Citation:
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Assignee:
WABCO EUROPE BVBA (Chaussée de la Hulpe 166, Bruxelles, B-1170, BE)
International Classes:
B60G17/052; B01D53/26; B60T17/00; F15B21/00
Domestic Patent References:
WO2013152868A12013-10-17
WO2012079698A12012-06-21
Foreign References:
DE19627403A11998-01-08
JPS58210825A1983-12-08
CN105822531A2016-08-03
CN101632893A2010-01-27
EP0537483A11993-04-21
DE3523403A11987-01-02
DE102014009419A12015-12-31
DE19724747C11998-06-25
US4974911A1990-12-04
DE19724747C11998-06-25
DE102014009419A12015-12-31
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Claims:
Claims

1. Compressed-air supply system (10) for operating a pneumatic installation (90), in particular an air-suspension system of a vehicle, comprising:

- an air supply, comprising an air compressor unit (21 ) for supplying compressed air to an compressed air supply ( );

- a compressed air port (2) to the pneumatic installation (90);

- an air removal port (3) for releasing air to the environment;

- a pneumatic main line (60) between the compressed air supply (1 ) and the compressed air port (2), the pneumatic main line (60) comprising an air dryer (61 ) and a throttle (62)

- an air removal line (70) between the compressed air port (2) and the air removal port (3), the air removal line (70) branching of the pneumatic main line (60);

- an exhaust valve (71 ) connected in the air removal line (70), wherein the exhaust valve (71 ) comprises a pressure control port (71 S) connected to the compressed air supply (1 ), and comprises a pressure counter control port (71 A) connected to the compressed air port (2),

characterized in that the exhaust valve (71 ) comprises control chamber (76) which is fluidically partitioned by a diaphragm (75) for switching the exhaust valve (71 ) between an opened and a closed state (OS; CS), the diaphragm (75) having an effective area (75S) pressurizable via the pressure control port (71 S) and an opposing effective area (75A) pressurizable via the pressure counter control port (71 A).

2. System according to claim 1 , wherein the exhaust valve (71 ) is configured to be normally opened.

3. System according to claim 1 or 2, wherein the pressure control port (71 S) and the pressure counter control port (71 A) are fluidically connected to each other, independently of pressure, via the air dryer (61 ) and the throttle (62).

4. System according to any of the claims 1 to 3, wherein the exhaust valve (71 ) is configured to switch to and/or remain in the closed state (CS) if a force (FS) exerted on the effective area (75S) is higher than a counterforce (FA) exerted on the opposing effective area (75A), and is configured to switch to and/or remain in the open state (OS) if a force (FS) exerted on the effective area (75S) is lower than a counterforce exerted (FA) on the opposing effective area (75A).

5. System according to any of the claims 1 to 4, wherein the exhaust valve (71 ) is configured to relief, in a charging cycle (CC), compressed air into the air removal line (70) if the absolute pressure on both sides (75A, 75S) of the diaphragm (75) exceeds 16 bars.

6. System according to any of the claims 1 to 5, wherein the exhaust valve (71 ) comprises an orifice (77) defining a valve seat (77'), and a plunger (79) having a valve seal (78) for opening and closing the orifice (77), wherein the plunger (79) js coupled to the diaphragm (75).

7. System according to claim 6, wherein the diaphragm (75) and the valve seal (78) are arranged on opposite sides (77L; 77R) of the orifice (77).

8. System according to claim 6 or 7, wherein the exhaust valve (71 ) comprises a valve spring (72) that is serially coupled to the diaphragm (75) and arranged to hold the exhaust valve (71 ) normally opened.

9. System according to claim 8, wherein the exhaust valve (71 ) comprises a counter spring (73) that is serially coupled to the diaphragm (75) and arranged to counteract the valve spring (72).

10. System according to claim 9, wherein the diaphragm (75) is coaxially arranged to the orifice (77).

1 1 . System according to claims 9 or 10, wherein a preload (PL) of the counter spring (73) is adjustable, in particular by a screw (73S).

12. System according to any of the claims 9 to 1 1 , wherein the valve spring (72) and the counter spring (73) have identical spring constants.

13. System according to any of the claims 1 to 12, wherein the effective area (75S) and the opposing effective area (75A) are equal in effective size (AS; AA).

14. System according to any of the claims 1 to 13, wherein the throttle (62) has an orifice diameter (OD) between 0.7 Millimeter and 1 .2 Millimeter.

15. Pneumatic system comprising (100) comprising a compressed-air supply system (10) according to any of the claims 1 to 14 and a pneumatic installation (90) in form of an air-suspension system (90S) of a vehicle (1000).

16. Method for operating a compressed-air supply system (10) according to any of the claims 1 to 14, comprising, in a charge cycle (CC), the steps:

- (CC1 ) operating the air compressor unit (21 ) for supplying compressed air to the compressed air supply (1 ):

- (CC2) guiding a flow of compressed air from the compressed air supply (1 ) to the pressure control port (71 S) and thereby pressurizing the effective area (75S) of the exhaust valve (71 ) in order to switch the exhaust valve (71 ) into the closed state (CS);

- (CC3) guiding a flow of compressed air from the compressed air supply

(1 ) via the air dryer (61 ) and the throttle (62) to the compressed air port

(2) in order to SUDDIV a pneumatic installation (90) connected to the compressed air port (2);

- (CC4) guiding a flow of compressed air from the compressed air supply (1 ) via the air dryer (61 ) and the throttle (62) to the pressure counter control port (71 A) and thereby pressurizing the opposing effective area (75A) of the exhaust valve (71 )

- (CC5) holding the exhaust valve (71 ) in a closed state (CS) if a force (FS) exerted on the effective area (75S) is higher than a counterforce (FA) exerted on the opposing effective area (75A), and/or comprising , in a regeneration cycle (RC), the steps:

- (RC1 ) keeping the air compressor unit (21 ) suspended from operation;

- (RC2) guiding a flow of compressed air from the compressed air port (2) to the counter pressure control port (71 A) and thereby pressurizing the opposing effective area (75A) of the exhaust valve (71 );

- (RC3) guiding a flow of compressed air from the compressed air port (2) to the pressure control port (71 S) via the air dryer (61 ) and the throttle (62) and thereby pressurizing the opposing effective area (75S) of the exhaust valve (71 );

- (RC4) switching the exhaust valve (71 ) into the opened state (OS) if a force (FS) exerted on the effective area (75S) is lower than a counterforce (FA) exerted on the opposing effective area (75A);

- (RC5) guiding a flow of compressed air from the compressed air port (2) via the air removal line (70) to the air removal port (3).

17. Method according to claim 16, comprising the step:

- (CC6) switching the exhaust valve (71 ) into the opened state (OS) if a force (FS) exerted on the effective area (75S) is lower than a counterforce (FA) exerted on the opposing effective area (75A).

18. Method according to claim 16 or 17, wherein the exhaust valve (71 ) is held in and/or switched into the closed state (CS) if a force (FS) exerted on the effective area (75S) due to pressurizing the effective area (75S) of the exhaust valve (71 ) is higher than a counterforce (FA) exerted on the opposing effective area (75A) due to pressurizing the opposing effective area (75A) of the exhaust valve (71 ).

19. Method according to any of the claims 16 to 18, wherein the exhaust valve (71 ) is held in and/or switched into the opened state (OS) if a force (FS) exerted on the effective area (75S) due to pressurizing the effective area (75S) of the exhaust valve (71 ) is lower than a counterforce (FA) exerted on the opposing effective area (75A) due to pressurizing the opposing effective area (75A) of the exhaust valve (71 ).

20. Method according to claim 17, wherein the force (FS) exerted on the effective area (75S) comprises a first force component (FS1 ) originating from compressed air acting on the effective area (75S) and a second force component (FS2) originating from the counter spring (73).

21. Method according to claim 17 or 18, wherein the counterforce (FA) exerted on the opposing effective area (75A) comprises a first counterforce component (FA1 ) originating from compressed air acting on the opposing effective area (75A) and a second counterforce component (FA2) originating from the valve spring (72).

Description:
COMPRESSED-AIR SUPPLY SYSTEM AND METHOD TO OPERATING A COMPRESSED-AIR SUPPLY SYSTEM

The invention relates to a compressed-air supply. The invention also relates to a pneumatic system and a method for operating a compressed-air supply system.

A compressed-air supply system is typically used in vehicles, particularly for operating a pneumatic installation in form of an air-suspension system of a vehicle. Such air-suspension system is typically operated in a pressure range between 5 and 20 bar to be supplied by a compressed-air supply.

Compressed air from the compressed-air supply is supplied to the air- suspension - the air-suspension being an exemplary pneumatic installation - via a compressed air port. For this purpose, a compressed air passes a pneumatic main line between the compressed-air supply and the compressed air port, wherein the pneumatic main line comprises an air dryer and a throttle. The air dryer serves the purpose of adsorbing humidity from the compressed air supplied by the compressed-air supply before entering the compressed air port. In order to depressurize the air-suspension system, dry compressed air is recirculated through the air dryer in order to generate the air dryer. After leaving the air dryer, the compressed air is typically fed to an air removal line between the compressed air port and an air removal port or releasing air to the environment. Ari exhaust valve controls removal of compressed air to the air removal port. The exhaust valve comprises a pressure control port connected to the compressed air supply and a pressure counter control port connected, to the compressed air port. A ride control system for vehicles with air springs is known from DE 19 724 747 C1. DE 10 2014 009 419 A1 discloses a compressed air supply system for operating an air-suspension system of a vehicle.

It is a technical object of the invention to provide a compressed-air supply system that is particularly robust.

This object is achieved by a compressed-air supply system, which, according to the invention, comprises an exhaust valve comprising a control chamber, which is fluidically partitioned by a diaphragm for switching the exhaust valve between an opened and a closed state. The diaphragm has an effective area pressurized via the pressure control port in an opposing effective area pressurized via the pressure counter control port.

So to say, the exhaust valve can be switched via a differential pressure between the pressure control port and the pressure counter control port. Preferably the differential pressure between the pressure control port and the pressure counter control port results from the throttle comprised by the pneumatic main line. Preferably, the exhaust valve is adapted to switch and/or remain in the closed state, when the pressure effective on the opposing effective area is less than pressure acting on the effective area. Furthermore preferred, the exhaust valve is adapted to switch to an open state and/or remain in the open state if the pressure acting on the opposing effective area is larger than the pressure acting on the effective area. Preferably a switching of the exhaust valve can be / is effected solely via by a pressure difference over the throttle.

Preferably,, the exhaust valve is configured to be normally opened. According to another preferred embodiment, the pressure control port and the pressure control counter port are fluidically connected to each other, preferably independently of pressure, via the air dryer and the throttle. The exhaust valve can be configured to switch to and/or remain in the closed state if force exerted on the effective area is higher than a counterforce exerted on the opposing effective area. The exhaust valve can be configure to switch to and/or remain in the open state if a force exerted on the effective area is lower than a counterforce exerted on the opposing effective area.

According to a preferred embodiment, the exhaust valve is configured to relieve, in a charging cycle, compressed air into the air removal line, if the absolute pressure on both sides of the diaphragm exceeds 16 bars. A charging cycle is a cycle when compressed air is supplied from the compressed-air supply to the compressed air port.

In another preferred embodiment, the exhaust valve comprises an orifice defining a valve seat. The exhaust valve can comprise a plunger having a valve seal for opening and closing the orifice. Preferably, the plunger is coupled to the diaphragm.

In order to provide a compact arrangement, the diaphragm and the valve seal can be arranged on opposite sides of the orifice.

It is furthermore preferred, when the exhaust valve comprises a valve spring. The valve spring can be serially coupled to the diaphragm. Preferably, the valve spring is arranged to hold the exhaust valve normally opened.

In a particularly preferred embodiment, the exhaust valve comprises a counter spring. The counter spring can be serially coupled to the diaphragm. The counter spring can be arranged to counteract the valve spring.

Preferably, the diaphragm is coaxially arranged to the orifice. It is particularly preferred when a preload of the counter spring is adjustable, preferably adjustable by a screw. Thereby, the differential pressure and/or the absolute pressure threshold, upon which compressed air is relieved into the air removal line, can be adjusted. According to a preferred embodiment, the valve spring and the counter spring have identical spring constants. The effective area and the opposing effective area can be equal in effective size.

In a preferred embodiment, the throttle has an orifice diameter between 0.7 mm and 1.2 mm.

The technical object is also solved by a pneumatic system comprising a pneumatic installation in form of an air-suspension system for a vehicle, wherein the pneumatic system comprises a compressed-air supply system according to the invention or an embodiment thereof, wherein the pneumatic installation is connected or correctable to the compressed airport of the pneumatic system.

With regard to the method, the technical object is solved by a method for operating a compressed-air supply system, preferably a compressed-air supply system according to the invention or its embodiments, wherein the method - in charging cycle - comprises the steps:

Operating the air compressor unit for supplying compressed air to the compressed-air supply

- guiding a flow of compressed air from the compressed-air supply to the pressure control port and thereby pressurizing the effective area of the exhaust valve in order to switch the exhaust valve into the closed state

- guiding a flow of compressed air from the compressed air supply via the air dryer and the throttle to the compressed air port in order to supply a pneumatic installation connected to the compressed air port

- guiding a flow of compressed air from the compressed air supply via the air dryer and the throttle to pressurize the counter control port and thereby pressurizing the opposing effective area of the exhaust valve

- holding the exhaust valve in a closed state if force exerted on the effective area is higher than the counterforce exerted on the opposing effective area - switching the exhaust valve into the open state if force exerted on the effective area is lower than the counterforce exerted on the opposing effective area.

Alternatively or additionally the method comprises, in a regeneration cycle, the steps:

- keeping the air compressor units suspended from operation

- guiding a flow of compressed air from the compressed air port to the counter pressure control port and thereby pressurizing opposing effective area of the exhaust valve

- guiding a flow of compressed air from the compressed air port to the pressure control port via the air dryer and the throttle and thereby pressurizing the opposing effective area of the exhaust valve

- switching the exhaust valve into the open state if a force exerted on the effective area is lower than a counterforce exerted on the opposing effective area

- guiding a flow of compressed air from the compressed air port via the air removal line to the air removal port.

Preferably, the force exerted on the effective area comprises a first component originating from the compressed air acting on the effective area and a force component originating from the counter spring.

It is also preferred when the force exerted on the opposing effective area comprises a first component originating from compressed air acting on the opposing effective area and a force component originating from the valve spring.

Preferably, within the method, a switching of the exhaust valve can be / is effected solely via by a pressure difference over the throttle. In the following, preferred embodiments of the invention are exemplarily described with respect to the figures, which show in:

Fig. 1 a schematic diagram of a compressed-air supply system;

Fig. 2 two cross-sections of a compressed-air supply system in the charging state;

Fig. 3 cross-sections of a compressed-air supply system from Fig. 2; Fig. 4 cutout enlargements from Fig. 2; Fig. 5 cutout enlargements from Fig. 3;

Fig. 6 a schematic diagram of a pressure build-up in the diaphragm chambers;

Fig. 7 a preferred embodiment of a method for operating a compressed-air supply system.

Fig. 1 depicts a schematic diagram of a compressed-air supply system 10 according to a preferred embodiment of the invention. The compressed-air supply system 10 is suitable for operating a pneumatic installation in particular an air suspension system of a vehicle (not shown). Such pneumatic installation can be connected to the compressed air port to the compressed-air supply system 10.

The compressed-air supply system 10 comprises an air supply having an air compressor unit 21 for supplying compressed air to a compressed air supply 1. The air compressor unit 21 comprises an air compressor 21 .1 having a compressor chamber 21.2. The air compressor unit also comprises an electrical motor 21.3 which is electrically connected via two leads 61 .1 , 61 .2. The compressed-air supply system 10 comprises an air removal port 3 for releasing air to the environment. An air filter 5 is connected between the air removal port 3 and air compressor 21.1.

A pneumatic main line 60 is arranged between the compressed air supply 1 and the compressed air port 2. A pneumatic main line 60 comprises an air dryer 61 and a throttle 62. An air removal line 70 branches off the pneumatic main line 60 between the compressed air port 2 and the air removal port 3. In the embodiment according to Fig. 1 the air removal line 70 branches off the pneumatic main line 60 between the compressed air supply 1 and the air dryer 61.

The compressed air supply system 10 also comprises an exhaust valve 71 which is connected in the air removal line 70. The exhaust valve 71 comprises a pressure control port 71 S connected to the compressed air supply. The exhaust valve 71 also comprises a pressure counter control port 71 A connected to the compressed air port 2.

The exhaust valve 71 is configured to be normally opened as can be seen from Fig. 1. The pressure control port 71 S and the pressure counter control port 71 A are fluidically connected to each other, independently of pressure, via the air dryer 61 and the throttle 62. The exhaust valve 71 comprises a valve spring 72 and a counteracting counter spring 73. A preload PL of the counter spring 73 is adjustable. The exhaust valve 71 comprises a pressure relief component PRC (Pmax function) which is configured to relief compressed air from the air supply 1 to the air removal line 70 if a predefined pressure, for example 16 bar, is exceeded. The pressure relief component PRC relies on the same adjustable counter spring 73. According to the invention the exhaust valve 71 comprises a control chamber 76 which is fluidically partitioned by a diaphragm 75 for switching the exhaust valve 71 between an opened state OS (seen in Fig. 1 ) and a closed state (not depicted in Fig. 1 ). The diaphragm 75 has an effective area 75S pressurizable via the pressure control port 71 S and an opposing effective area 75A pressurizable via the pressure counter control port 71 A. Fig. 1 a) shows a pneumatic system comprising 100 comprising a compressed- air supply system 10 and a pneumatic installation 90 in form of an air- suspension system 90S of a vehicle 1000. The compressed air port 2 of the a compressed-air supply system 10 is connected to the pneumatic installation 90.

The control chamber 76, the diaphragm 75, the effective area 75S and the opposing effective area 75A are not shown in detail in Fig. 1 but their function will become apparent from the following figures.

Fig. 2 shows two cross sections of one and the same compressed air supply system 10 in the charging cycle CC. Fig. 4a shows a cutout enlargement of Fig. 2a, wherein Fig. 4b shows a cutout enlargement of Fig. 2b.

The left-hand side of Fig. 2a and b shows a compressor chamber 21.2 for supplying compressed air to an air supply 1. On the upper right side on Fig. 2a and 2b is located a compressed air port 2 which can lead to a pneumatic installation to be supplied with compressed air. An air removal port 3 for releasing air to the environment is depicted on the lower right side of Fig. 2a. The air supply 1 leads to a supply chamber 1 '. The air removal port 60 leads to an air removal chamber 3'. A pneumatic main line 60 having an air dryer 61 and a throttle 62 in form of a throttle plate is connected between the compressed air supply 1 and the compressed air port 2. An air removal line 70 (as can best be seen from Fig. 4a) branches off the pneumatic main line 60 and is arranged between the compressed air port 2 and the air removal port 3.

The compressed air supply system 10 also comprises an exhaust valve 71 connected in the air removal line 70. The exhaust valve 71 comprises a pressure control port 71 S. As can be seen from Fig. 2b the pressure control port 71 S is embodied by a piloting port of the air removal chamber 3'.

The exhaust valve 71 also comprise a pressure counter control port 71 A connected to the compressed air port. As becomes apparent from Fig. 2a and 2b the pressure counter control port 71 A is embodied as a small opening in the left sub-chamber 76A of the control chamber 76. According to the invention the exhaust valve 71 comprises a control chamber 76 which is fluidically partitioned by a diaphragm 75 for switching the exhaust valve 71 between an opened OS and a closed state CS. In the embodiments according to the figures the diaphragm 75 is embodied by a circular rubber diaphragm which is fixed to a casing part adjacent to the air dryer 61 .

The diaphragm 75 has effective area 75S pressurizable via the pressure control port 71 S and an opposing effective area 75A pressurizable via the pressure counter control port 71 A. As can be seen for example from Fig. 4a the exhaust valve 71 comprises an orifice 77 defining a valve seat 77'. The exhaust valve 71 also comprises a plunger 79 having a valve seal 78 for opening and closing the orifice. The plunger 79 is coupled to the diaphragm 75. As becomes apparent from Fig. 4a, the diaphragm 75 and the valve seal 78 are arranged on opposite sides 77L, 77R of the orifice 77.

The exhaust valve 71 comprises a valve spring 72 that serially coupled to the diaphragm 75. The valve spring 72 is arranged to hold the exhaust valve 71 normally opened (not shown). An exhaust valve 71 in the opened state OS that is when the valve seal 78 does not seal the orifice 77, can be seen in Fig. 5a. The closes state CS of exhaust valve 71 , that is the valve seal 78 sealing the orifice 77 becomes apparent from Fig. 4a.

The exhaust valve 71 also comprises a counter spring 73 that is serially coupled to both the diaphragm 75 and the valve spring 72. The counter spring 73 is arranged to counteract the valve spring 72. The diaphragm 75 is coaxially arranged to the orifice, the plunger 79. Furthermore the counter spring 73 and the valve spring 72 coaxially arranged to each other.

A preload PL of the counter spring 73 is adjustable via a screw 73S.

In the following the function of the compressed air supply system 10, particularly the diaphragm 75 will be described with respect to the figures. Fig. 2a and 2b, 4a and 4b depict a charging cycle CC in which air is to be supplied from the compressed air supply 1 to the compressed air port 2. Fig. 3a and 3b and Fig. 5a and 5b show a compressed air supply system 10 in a regeneration cycle RC in which air is relieved from the compressed air port 2 via the air dryer 61 (in order to regenerate the air dryer) to the air removal port 3.

After beginning to operate the air compressor unit 21 , part of the compressed air originating from the compressed air supply l is guided to the pressure control port 71 S which is embodied as a pilot chamber in the air removal port 3'. The flow of compressed air from the air supply 1 to the pressure control port 71 S is depicted in Fig. 2b and 4b as a dot-dashed line. This air flow from the compressed air supply to the pressure control port 71 S pressurizes the effective area 75S of the exhaust valve 71. The effective area 75S of the exhaust valve 71 is located on the right-hand side of the diaphragm 75.

Also, compressed air flows from the compressed air supply 1 via the air dryer

61 and the throttle 62 (which is embodied as a throttle plate), to the pressure counter control port 71 A. This flow is depicted by the multiple solid arrows in Fig. 2b and 4b. This flow of compressed air via the air dryer 61 and the throttle

62 serves to pressurize the opposing effective area 75A which, in the figures, is the left-hand sjde of control chamber 76. As the compressed air guided from the compressed ajr supply 1via the air dryer 61 also passes the throttle 62, which has a smaller diameter than the pilot port of the air removal chamber 3', the pressure on the opposing effective area 75A (left-hand side of diaphragm 75) is lesser than the pressure on the effective area 75S (right-hand side of the diaphragm 75). Thus the diaphragm 75 with a connected plunger 79 moves to the left so that the valve seal 78 seals the valve orifice 77.

Holding the exhaust valve 71 in the closed state CS, air from the air dryer 61 passes through the pneumatic main line 60 to the compressed air port 2 in order to supply a pneumatic installation connected to compressed air port. This charging flow is depicted in Fig. 2a and 4a via the solid line exiting from the air dryer 61 and leading to the compressed air port 2.

The exhaust valve 71 is held in the closed state CS as a force FS exerted on the effective area 75S due to pressurizing the effective area 75S of the exhaust valve 71 is higher than a counterforce FA exerted on the opposing effective area 75A due to pressurizing the opposing effective area 75A of the exhaust valve 7 .

The force FS exerted on the effective area 75S comprises a first force component FSi originating from compressed air acting on the effective area 75S and a second force component FS2 originating from the counter spring 73. Likewise, the counterforce FA exerted on the opposing effective area 75A comprises a first counterforce component FA1 originating from compressed air acting on the opposing effective area 75A and a second counterforce component FA2 originating from the valve spring 72.

In the following the regeneration cycle RC will be described. The regeneration cycle RC can be best understood from Fig. 5a and 5b. When the air compressor unit 21 is suspended from operation and compressed air is to be released from the compressed air port 2, a flow of compressed air from the compressed air port 2 is guided to the counter pressure control port 71 A thereby pressurizing the opposing effective area 75A (left-hand side of diaphragm 75). Also a flow of compressed air that originates from the compressed air port 2 is guide via the throttle 62 and the air dryer 61 (indicated by the solid arrows pointing to the left) and reaches (indicated by the dot-dashed line) the opposing effective area 75S via the pressure control port 71 S, which is embodied by a pilot port exiting the air removal chamber 3'. As a portion of the compressed air passes through the air dryer 61 and particularly the throttle 62 the pressure on the opposing effective area 75A (left-hand side of diaphragm 75) is higher than on the effective area 75S (right-hand side of the diaphragm 75).

Thus the exhaust valve 71 is switched into the open state thereby the valve seal 78 unseals the valve orifice 77 and compressed air can pass from the compressed air port 2 via the air dryer 61 and the throttle 62, which are arranged in the air removal line 70 to the air removal port 3 shown on the lower right hand side of Fig. 5a.

In the preferred embodiment of Fig. 2 to Fig. 6, the throttle 62 has an orifice diameter OD between 0.7 mm and 1.2 mm.

A pressure build-up in the control chamber 76 during a charging cycle becomes apparent from Fig. 6. The y-axis depicts the pressure in bar of the respective sub-chamber 76A, 76S of the control chamber 76 while the x-axis depicts time in seconds.

Initially (t=0s) the air compressor 21 is set into operation. The solid line represents a build-up of a pressure acting on the effective 75S, while the dashed line represents the build-up of pressure acting on the opposing effective area 75A. The solid line shows faster pressure build-up as the compressed air reaching the effective area 75S does not pass the air dryer and the throttle 62. As the pressure force exerted on the effective area 75S is higher than a counter force exerted on the opposing effective 75A, the exhaust valve 71 is held in closed state CS for about 140 seconds until a pressure of about 17bar on both opposing effective area side 75A and effective area side 75S is reached.

At a pressure of about 17bar the relief function enabled by the serial arrangement of the diaphragm 75, the valve spring 72 and counter spring 73 becomes apparent. That is at about 17bar the pressure on both sub-chambers 76A, 76S of the control chamber 76 are roughly equal, so that compressed air is relieved into the air removal line 70. As can be seen from the diagram starting from about 140 seconds, the pressure acting on the effective area 75S immediately drops to about 1 bar as this air freely, that is without throttling via throttle 62, enters the air removal line 70 to the air removal port 3. The dashed line representing the pressure on the opposing effective area 75S exhibits a typical exponential relief due to the air passing through the throttle 62 and from there via the air dryer 61 into the air removal line 70. Fig. 7 shows a typical method of operating a compressed air supply system 10. The step CC1 to CC6 represent the charging cycle, while the steps RC 1 to RC 5 represent the regeneration cycle. in a first step CC1 the air compressor unit 21 is operated to force plain compressed air to the compressed air supply 1. In a step CC2 compressed air is guided from the compressed air supply 1 to the pressure control port 71 S thereby pressurizing the effective area 75S of the exhaust valve in order to switch the exhaust valve 71 into the closed state CS. In step CC3 a flow of compressed air is guided from the compressed air supply 1 via the air dryer 61 and the throttle 62 to the compressed air port 2 in order to supply a pneumatic installation connected to the compressed air port. In step CC4 a flow of compressed air is guided from the compressed air supply 1 via the air dryer 61 and the throttle 62 to the pressure counter control port 71 A and thereby pressurizing the opposing effective area 75A of the exhaust valve 71. In step CC5 the exhaust valve 71 is held in a closed state CS if a force exerted on effective area 75S is higher than a counter force exerted on the opposing effective area 75A, while. In step CC6 the exhaust valve 71 is switched to open state if a force exerted on effective area 75S is lower than a counter force exerted on the opposing effective area 75A. One or more steps can be performed parallel.

In a first step RC1 of the regeneration cycle the air compressor unit 21 is suspended from operation. In second step RC2 a flow of compressed air is guided from the compressed air port 2 to the counter pressure control port 71 A and thereby the opposing effective area 75A of the exhaust valve 71 is pressurized.

In a third step RC3 a flow of compressed air is guided from the compressed air port 2 to the pressure control port 71 S via air dryer 61 and the throttle 62. Thereby the opposing effective area 65S of the exhaust valve 71 is pressurized. In a fourth step RC4 the exhaust valve 71 is switched into the open state if a force exerted on effective area 75S is lower than a counter force exerted on the opposing effective area 75A.

In step RC5 a flow of compressed air from the compressed air port 2 is guided via the air removal line 70 to the air removal port 3.

In a sixth step RC6 the exhaust valve 71 is switched into the open state if a force exerted on the effective area 75S is lower than a counter force exerted on the opposing effective area 75A.

On or more of the steps RC1 ...to RC5 can be performed parallel.

List of references (part of the description)

1 air supply

1 ' supply chamber

2 compressed air port

2' delivery chamber

3 air removal port

5 air filter

10 Compressed-air supply system

21 Air compressor unit

21.1 air compressor

21.2 compressor chamber

21.3 motor

60 pneumatic main line

61 air dryer

62 throttle

70 air removal line

71 exhaust valve

71 A pressure counter control port

7 S pressure control port

72 valve spring

73 counter spring

75 diaphragm

75A second effective area of diaphragm

75S first effective area of diaphragm

76 control chamber

76A, 76S sub-chambers of the control chamber

77 valve orifice

77L, 77R opposite sides of the valve orifice

77' valve seat

78 valve seal

IS 79 plunger

90 pneumatic installation

100 pneumatic system

1000 vehicle

AA effective size of the effective area

AS effective size of the opposing effective area

CC charge cycle

CC1..CC6 steps of the charge cycle

FS force exerted on the effective area

FS1 first force component originating from compressed air acting on effective area

FS2 second force component originating from the counter spring

FA counterforce exerted on the opposing effective area

FA1 first counterforce component originating from compressed air acting the opposing effective area

FA2 second counterforce component originating from the valve spring OS opened state of the exhaust valve

OD orifice diameter of the throttle

CS closed state of the exhaust valve

PL preload of the counter spring

RC regeneration cycle

RC1..RC 5 steps of the regeneration cycle

PRC pressure relief component