Patent Publication Number: US-2023151900-A1

Title: Pneumatic device with an exhaust of a housing for receiving electronic components

Description:
FIELD 
     The present disclosure relates to a pneumatic device for a brake system, the pneumatic device having a housing for receiving electronic components and that is in fluid communication with the environment during operation of the pneumatic device, and an exhaust path having an exhaust port and that is in fluid communication with the housing for exhaust of the pneumatic device to the environment via the exhaust port. The present disclosure further relates to a vehicle having such a pneumatic device and to a method for assembling such a pneumatic device. 
     In particular, such pneumatic devices may be pneumatic brake systems for vehicles, in particular for commercial vehicles, or brake valves and/or relay valves therefor. 
     BACKGROUND 
     Frequently, pneumatic devices of the type described above are used in environments where various foreign media may be present. In particular, pneumatic brake devices and their components, such as relay valves, may be exposed to water from their environment, for example, during cleaning, operation in or after rain, flooding, or deliberate fording of bodies of water. 
     Pneumatic devices of the type described above typically have pneumatic connections to the environment of the pneumatic device, for example, to exhaust excess pressure from a pressurized section of the pneumatic device, or to equalize pressure with the environment of the pneumatic device. However, such a pneumatic connection to the environment of the pneumatic device may allow foreign media located in the environment to enter the pneumatic device. In particular, the ingress of liquids, such as water, can impair the functionality of the pneumatic device. In the case of pneumatic brake systems, for example, ingress of foreign media, especially water, can lead to corrosion or, for example, to complete failure of the brake system as a result of water freezing. Measures must therefore be taken to make the unintentional ingress of foreign media more difficult or, at best, to prevent it. 
     In the prior art, pneumatic devices with sealing devices are known that are designed to prevent the unintentional ingress of small amounts of spray water or water below a certain level. Among others, GB 2 401 330 A, DE 10 2016 011 032 A1, and DE 28 29 290 A1 disclose such pneumatic devices. 
     SUMMARY 
     The object of the present invention is to enable a safe operation of a pneumatic device of the type described at the outset even in environments in which large quantities of a foreign medium, in particular water, are present. 
     In a first aspect, the object is achieved by a pneumatic device having a housing for receiving electronic components and that is in fluid communication with the environment during operation of the pneumatic device, and an exhaust path having an exhaust port and that is in fluid communication with the housing for exhaust of the pneumatic device to the environment via the exhaust port. The pneumatic device has an exhaust element associated with an exhaust path which is configured to provide a liquid impermeable but gas permeable barrier between the housing for receiving electronic components and the environment. In other words, the exhaust element avoids the ingress of liquids but still remains permeable for gases. In this context, a liquid refers to a nearly incompressible fluid that conforms to the shape of its container but retains a nearly constant volume independent of pressure, wherein the volume is definite if the temperature and pressure are constant. A gas refers to a compressible fluid. It will be understood that the described liquid state and gas state refer to the states of matter of the mediums, which occur during operation of the pneumatic device under the environmental conditions. 
     The core benefits during operation of the exhaust element are, on the one hand, that the housing for receiving the electronic components, which is in fluid communication with the exhaust path, is securely protected against an undesired ingress of liquids. On the other hand, gases are allowed to pass through the exhaust element to allow the exhaust of the pneumatic device and provide a reference pressure corresponding to the pressure of the environment for e.g. a pressure sensor arranged in the housing for receiving the electronic components. 
     In the context of the present invention, the environmental conditions include pressure in the range between approximately 0 to 1 bar and a temperature range above −40° C. up to 100° C. The internal or operating pressure within the pneumatic device defines a pressure difference compared to the environmental pressure. The internal pressure may be up to 13 bar occurring in parts of the pneumatic device which are not pressure sensitive. 
     Preferably, the pneumatic device has a pressure sensor being in fluid connection with the exhaust path, which is configured to detect a pressure in the pneumatic device. The sensor is preferably a pressure sensor arranged in the housing for receiving the electronic components. 
     In a preferred embodiment, the pneumatic device further includes a damping chamber, which is in fluid communication with the exhaust port and the environment. Preferably, a flow path from the housing for receiving the electronic components to the environment extends at least partly through the damping chamber to exhaust the pneumatic device. Such a damping chamber may be a silencer configured to reduce overall noise of an operation of the pneumatic device, e.g. during braking. 
     Preferably, said damping chamber is in fluid communication with the environment by a pressure passage. Thus, the damping chamber damps the sound and vibrations occurring during exhaust, at least partly. 
     In a further preferred embodiment, the pneumatic device further includes an equalizing chamber being in fluid communication with the exhaust path and configured to provide an equalizing volume to reduce pressure peaks during operation of the pneumatic device. The present disclosure takes into account that exhaust elements may be sensitive to pressure peaks. By providing an equalizing volume, said pressure peaks are significantly reduced. 
     Preferably, the pneumatic device further includes a throttle provided in the exhaust path which is configured to narrow the flow cross-section in the exhaust path. Such a throttle may preferably cooperate with the equalizing volume such that the throttle connects the equalizing chamber to the exhaust port. Because the throttle narrows the flow cross-section of the exhaust path, pressure peaks and, in particular, backpressure peaks are reduced. Thus, even a sensitive exhaust element is securely protected when arranged upstream the throttle. 
     It is further preferred, according to one aspect, that the volume of the equalizing chamber is adapted to the peak pressure during operation of the pneumatic device. Thus, in total an enlarged volume defined by the exhaust path and the equalizing chamber is provided, thereby significantly reducing the inside pressure of the pneumatic device. It will be understood that the additional volume provided by the equalizing chamber is chosen in accordance with the peak pressure during operation that may be up to 13 bar, such that the pressurized air distributed in the exhaust path and the housing for receiving the electronic components will not exceed a predefined internal pressure, preferably an internal pressure up to 2 bar. 
     Preferably, the flow cross-section of the throttle is adapted to the volume provided by the equalizing chamber to avoid peak pressure during operation of the pneumatic device. It will be understood that when the equalizing chamber has an enlarged volume, the flow cross-section of the throttle is enlarged when compared to a pneumatic device with an equalizing chamber having a lower volume. 
     In a preferred embodiment, the exhaust element is arranged in the exhaust path upstream of the exhaust port. By arranging the exhaust element upstream of the exhaust port, the exhaust element is securely protected from the environment, e.g. from chemicals or paintings used during cleaning or painting of a vehicle. 
     In another preferred embodiment, the exhaust element is arranged in the exhaust port adjacent to the damping chamber. Thus, the exhaust path extending from the exhaust port towards the housing for receiving the electronic components is securely protected against water ingress by the exhaust element. Further, the exhaust element is arranged at a position in the exhaust port where it is securely protected against dirt or chemicals from the environment. 
     Preferably, the pneumatic device further comprises a relay piston arranged in the exhaust path, wherein the exhaust element is coupled to the relay piston. Thus, the exhaust element and the relay piston can be pre-assembled, in order to simplify the mounting of the pneumatic device. The pre-assembling further ensures a repeatable and accurate placement of the exhaust element inside the pneumatic device. 
     Further preferred, the exhaust element is coupled to the relay piston by a snap-fit connection. A snap-fit connection provides a secure attachment of the exhaust element to the relay piston and is cost efficient at the same time. 
     Preferably, the exhaust element is a liquid impermeable but gas permeable membrane. A membrane is a space-saving exhaust element that can be easily integrated in the pneumatic device. 
     In a preferred embodiment, the pneumatic device is a pneumatic brake system, a brake valve arrangement, or a relay valve. Brake systems are often installed at least partly in the vehicle frame, which is exposed during service life to wet weather conditions, splash water, and high-pressure water streams during cleaning e.g., before service actions. At the same time, housings for receiving electrical or electronic components do often contain a pressure sensor, which needs to have the environmental pressure as a reference for measuring the brake pressure of such a brake system. This requires the breathing of the sensor to the environment. By having the exhaust element according to the invention, water ingress is securely avoided. 
     Further preferred, the relay piston is at least partly formed of a polymer. Thus, the relay piston is lightweight. In addition, a high degree of function integration is enabled by the plurality of known technologies for manufacturing polymer parts. For example by injection molding, a relay piston having integral snap-fit elements for coupling with the exhaust element can be manufactured by a so called one-shot process which refers to a molding process including only one process step. 
     In a second aspect, the invention relates to a brake system comprising a pneumatic device according to the first aspect of the invention. By having such a pneumatic device, the preferred embodiments and benefits of the pneumatic device according to the first aspect are at the same time preferred embodiments and benefits of the brake system according to the second aspect. Thus, reference is made to the above description of the pneumatic device according to the first aspect of the invention, in particular to the dependent claims. 
     Preferably, the pneumatic device of the brake system is a brake valve arrangement of the brake system. 
     In a third aspect, the invention relates to a commercial vehicle comprising a brake system according to the second aspect. It should be understood, that by having a brake system according to the second aspect, the aspects and benefits of the brake system are at the same time preferred embodiments and benefits of the commercial vehicle according to the third aspect of the invention, in particular as they are described in the dependent claims. Thus, reference is made to the above description of the pneumatic device according to the first aspect and the brake system having such a pneumatic device according to the second aspect of the invention. 
     According to a fourth aspect of the invention, the above stated problem is solved by a method for assembling a pneumatic device, preferably a pneumatic device according to the first aspect, the method comprising the steps: providing an exhaust element configured to provide a liquid impermeable but gas permeable barrier, arranging the exhaust element in the pneumatic device at a position associated with an exhaust path of the pneumatic device, such that a liquid impermeable but gas permeable barrier between a housing for receiving the electronic components of the pneumatic device and the environment is provided. 
     It should be understood that the method incorporating the arrangement of the exhaust element in the pneumatic device according to the first aspect has similar or equal aspects as the first aspect of the invention, in particular as they are described in the description herein. Thus, reference is made to the above description of the pneumatic device according to the first aspect of the invention and the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure, the disclosure will now be described in detail with reference to the accompanying drawings. In the accompanying drawings: 
         FIG.  1    shows a schematic layout of a vehicle having a brake system comprising a pneumatic device according to the present disclosure; 
         FIG.  2    shows a sectional view of a pneumatic device according to the prior art; 
         FIG.  3    shows a schematic layout of a pneumatic device according to the present disclosure; 
         FIG.  4    shows a sectional view of the pneumatic device according to a first preferred embodiment; and 
         FIG.  5    shows a sectional view of the pneumatic device according to a second preferred embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description below will illustrate and describe what is considered as a preferred embodiment of the invention. It should of course be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention may not be limited to the exact form and detail shown and described herein, nor to anything less than the whole of the invention disclosed herein and as claimed herein after. Further, the features described in the description, the drawings, and the claims disclosing the invention may be essential for the invention considered alone or in combination. In particular, any reference signs in the claims shall not be construed as limiting the scope of the invention. The wording “comprising” does not exclude other elements or steps. The word “a” or “an” does not exclude the plurality. The wording “a number of” items comprising also the number  1 , i.e. a single item, and further numbers like 2, 3, 4 and so forth. 
     A vehicle  200 , as shown in  FIG.  1   , in particular a commercial vehicle, includes a front axle  204  and a rear axle  206 . For braking front wheels  208 . 1 ,  208 . 2  of the front axle  204  and rear wheels  210 . 1 ,  210 . 2  of the rear axle  206  the vehicle  200  may include a brake system  100  having a front axle brake circuit  102  for braking the front wheels  208 . 1 ,  208 . 2  and a rear axle brake circuit  104  for braking the rear wheels  210 . 1 ,  210 . 2 . For braking the wheels  208 . 1 ,  208 . 2 ,  210 . 1 ,  210 . 2 , the brake system  100  comprises front axle brake actuators  106 . 1 ,  106 . 2  and rear axle brake actuators  108 . 1 ,  108 . 2 . The front axle brake actuators  106 . 1 ,  106 . 2  are connected to a front axle brake modulator  110  while the rear axle brake actuators  108 . 1 ,  108 . 2  are connected to a rear axle brake modulator  112 . For providing compressed air at a supply pressure, the brake system  100  comprises a compressed air supply  114 . Of course, it may comprise more than one air supply. 
     In order to brake the vehicle  200  a brake pressure needs to be supplied to the front axle brake modulator  110  and the rear axle brake modulator  112 . For providing the brake pressure, the brake system  100  comprises the pneumatic device  1  (see  FIGS.  3  and  4   ). In the embodiment shown in  FIG.  1   , the pneumatic device  1  is a brake valve arrangement. 
     As shown in  FIG.  1   , the brake valve arrangement  1  includes a lower housing  2  having a supply connection  7 , a working connection  9 , and an exhaust portion  12 . The exhaust portion  12  includes an exhaust path  15  (see  FIGS.  3  to  5   ). The supply connection  7  is connected to the compressed air supply  114  via supply line  120 . 1  for receiving pressurized air at the supply pressure. 
     Upon actuation by a user or an electronic control unit such as a unit for autonomous driving, the brake valve arrangement  1  provides a brake pressure corresponding to the degree of actuation provided by the user or a respective signal. To allow an actuation, the brake valve arrangement  1  includes an actuation element  14 , which is formed as a brake pedal in this embodiment. The brake valve arrangement  1  is configured to modulate the brake pressure supplied to the working connection  9  dependent on a degree of actuation of the actuation element  14 . If the brake pedal  14  is only slightly actuated, a low brake pressure is supplied to the working connection  9  while a high brake pressure is supplied to the working connection  9  when the brake pedal  14  is fully actuated. 
     The brake valve arrangement  1  is connected to the front axle brake modulator  110  and the rear axle brake modulator  114  via connecting lines  116 ,  118 . In this embodiment the brake valve arrangement  1  is formed as a single circuit brake valve arrangement  1  having only one working connection  9  for providing brake pressure. Both, the front axle connecting line  116  connecting the brake valve arrangement  1  to the front axle brake modulator  110  as well as the rear axle connecting line  118  connecting the brake valve arrangement  1  to the rear axle brake modulator  112  are connected to the same working connection  9  of the brake valve arrangement  1 . In other embodiments, the brake valve arrangement  1  also could be formed as a multi circuit brake valve arrangement  1  having multiple working connections  9  for providing the same and/or different brake pressures to the brake circuits  102 ,  104 . 
     The brake modulators  110 ,  112  receive the brake pressure provided by the brake valve arrangement  1  and provide pressurized air at the same brake pressure but at a higher volume to the respective brake actuators  106 . 1 ,  106 . 2 ,  108 . 1 ,  108 . 2 . Therefore, the brake modulators  110 ,  112  are also connected to the compressed air supply via supply lines  120 . 2 ,  120 . 3 . It shall be noted that the front axle brake modulator  110  and/or the rear axle brake modulator  112  may also be configured to further modify the brake pressure. For example, the front axle brake modulator  110  could comprise ABS-modules (not shown) for providing an ABS-function. Moreover, the brake actuators  106 . 1 ,  106 . 2 ,  108 . 1 ,  108 . 2  may also be directly connected to the brake valve arrangement  1 . 
     For releasing the brake of the vehicle  200  the break pressure needs to be released from the brake actuators  106 . 1 ,  106 . 2 ,  108 . 1   108 . 2 . The brake valve arrangement  1  is therefore configured to exhaust the brake actuators  106 . 1 ,  106 . 2 ,  108 . 1   108 . 2  by connecting the working connection  9  to the exhaust portion  12 . In order to exhaust pressurized air, the air needs to be released to the environment through an opening. Such an opening, however, allows water to enter the brake system  100 . Brake valve arrangements, in particular brake valve arrangements having a brake pedal, are usually located in a low position of the vehicle  200 . A maximum fording depth of the vehicle  200  is thereby limited, since water could ingress in the brake system  100  via the exhaust portion  12  when the vehicle  200  drives through water and the water level reaches to the exhaust portion. In regular vehicles, the available maximum fording depth is sufficient and standard brake valve arrangements assemblies can be used. If however, increased fording depths are needed, special measures need to be taken. Therefore, fording versions of brake valve arrangements and/or brake valve arrangement assemblies are provided. 
     In  FIG.  1   , the brake valve arrangement  1  has a housing  3  for receiving the electronic components, which is connected to a damping chamber  11 . The damping chamber  11  may be provided by an exhaust silencer. For releasing the brakes of the vehicle  200 , the brake pressure is released from the brake actuators  106 . 1 ,  106 . 2 ,  108 . 1   108 . 2  via the connecting lines  116 ,  118 , the brake valve arrangement  1 , the housing  3  for receiving the electronic components, the exhaust line  122 , and the remote exhaust silencer (damping chamber)  11 . 
     The pneumatic device  1  shown in  FIG.  2    is a brake valve arrangement according to the prior art. The brake valve arrangement  1  comprises lower housing  2  in which a housing  3  for receiving the electronic components is received. The housing  3  for receiving the electronic components may have several electronic components, as for example sensors detecting the brake pressure, solenoids, Electronic Control Unit (ECU) and the like. 
     The housing  3  for receiving the electronic components has to be in fluid connection with the environment  5  to provide a referenced pressure for, e.g. the sensor detecting the brake pressure. 
     The brake valve arrangement of  FIG.  2    further has a damping chamber  11 . In the shown embodiment, the damping chamber  11  is a silencer that comprises a fixing bracket  21  that engages the lower housing  2  and holds a sound damping material  20  in place. The brake valve arrangement  1  further has an exhaust path  15  that is in fluid connection with housing  3  for receiving the electronic components, an internal chamber of the brake valve arrangement  1 , e.g. a force equalization chamber, and the environment  5  via a flow path  19  that at least partly extends through the silencer  11 . Thus, pressurized air flowing through the exhaust path  15  will be guided by the flow path  19  directly into the sound damping material  20 . Thus, excessive noise is thereby prevented. 
     The housing  3  for receiving the electronic components is connected to the environment by a breathing channel  18 , which may have a labyrinth-like channel structure, to reduce water ingress into the housing  3  for receiving the electronic components. Such a labyrinth-type channel  18  may reduce the water ingress, but cannot provide a secure barrier between the environment and the housing  3  for receiving the electronic components  3  to avoid water ingress. The housing  3  for receiving the electronic components  3  is configured for breathing to the environment via the channel  18  in order to avoid excess pressure difference occurring due to increase in temperature. For instance, the increase in temperature can cause damage to the sealing elements in the pneumatic components and the small leakage occurring because of said pneumatic components can be released via exhaust element  10 . 
     As shown in a schematic view according to  FIG.  3   , a pneumatic device  1  according to the present disclosure provides a housing  3  for receiving the electronic components that is preferably received in lower housing  2 . The housing  3  for receiving the electronic components is in fluid connection with the environment  5 . 
     The pneumatic device  1  further has an exhaust portion  12 , which comprises at least partly an exhaust path  15 , which is configured to connect the housing  3  for receiving the electronic components to the environment  5  via an exhaust port  17 . Thus, pressurized air can exhaust from the housing  3  for receiving the electronic components via the exhaust path  15  and the exhaust port  17  in a flow direction F. 
     The pneumatic device  1  further has an exhaust element  10  that is associated with the exhaust path  15 , preferably arranged within the exhaust path  15  or adjacent to the exhaust port  17 . 
     The exhaust element  10  is configured to provide a gas permeable but liquid impermeable barrier between the environment  5  and the housing  3  for receiving the electronic components. 
     By arranging the exhaust element  10  at a position associated with the exhaust path  15 , the exhaust element  10  is protected against dirt, chemicals and other interfering substances from the environment  5 . 
     On the one hand, the gas permeable exhaust element  10  allows the exhaust of the housing for receiving the electronic components  3  via the exhaust path  15  and the exhaust port  17  in the flow direction F and at the same time allows a gas permeable connection to the environment  5  for any sensors arranged within the housing  3  for receiving the electronic components. On the other hand, the liquid impermeable barrier provided by the exhaust element  10  securely avoids a water ingress into the exhaust path  15  and into the housing  3  for receiving the electronic components, which water ingress may result in damaging the electronic component within the housing  3  for receiving the electronic components. 
       FIG.  4    shows the pneumatic device  1  according to a first preferred embodiment. 
     The pneumatic device  1  is in the form of a brake valve arrangement in the embodiment shown in  FIG.  4   . 
     The brake valve arrangement  1  includes lower housing  2  and a housing  3  for receiving the electronic components coupled to lower housing  2 , which is in fluid connection with the environment  5 . 
     The brake valve arrangement  1  has an exhaust portion  12 , which comprises an exhaust path  15  configured to provide a fluid connection between the housing  3  for receiving the electronic components and the environment  5  via an exhaust port  17 . 
     The brake valve arrangement  1  further has a damping chamber  11 , wherein a flow path  19  is provided and configured to connect the exhaust path  15  to the environment  5  via the damping chamber  11 . 
     In the shown embodiment, the damping chamber  11  is a silencer that comprises a fixing bracket  21  that engages lower housing  2  and holds a sound damping material  20  in place. The brake valve arrangement  1  further has an exhaust path  15  in fluid communication with the housing  3  for receiving the electronic components and the environment via an exhaust port  17  and a flow path  19 , which at least partly extends through the silencer (damping chamber)  11 . Thus, pressurized air flowing through the exhaust path  15  will be guided by the flow path  19  directly into the sound damping material  20 . Thus, excessive noise is prevented. 
     The brake valve arrangement  1  further has an exhaust element  10 , which is associated with the exhaust path  15 . In the embodiment shown in  FIG.  4   , the exhaust element is arranged adjacent to the exhaust port  17 , thereby providing a gas permeable, but fluid impermeable membrane between the housing  3  for receiving the electronic components and the environment  5 . Thus, the exhaust element  10  is easily accessible for purposes of maintenance. 
     The brake valve arrangement  1  further comprises a relay piston  26  having a housing cover  25 , which is arranged in the exhaust path  15  adjacent to the exhaust element  10 . The relay housing cover  25  is received in the relay piston  26 , which is coupled to lower housing  2 . 
     The brake valve arrangement  1  further has a sensor  27  in fluid connection with the housing  3  for receiving the electronic components, preferably arranged inside the housing  3  for receiving the electronic components. 
     An exhaust channel  30  is provided between at least one solenoid valve  29  and the damping chamber  11 . The channel  30  is configured to exhaust a pre-control volume provided by the solenoid valve  29  to move the relay piston  26 , wherein the brake valve arrangement  1  has at least one solenoid valve  29  configured to selectively close the exhaust channel  30 . 
     The embodiment of the brake valve arrangement shown in  FIG.  4    is preferably used for brake systems  100  (see  FIG.  1   ) with a low back-pressure occurring during operation. 
     The pneumatic device  1  shown in  FIG.  5    is a brake valve arrangement and differs from the brake valve arrangement according to  FIG.  4    by the positioning of the exhaust element  10 . 
     In the embodiment shown in  FIG.  5   , the exhaust element  10  is arranged in the exhaust path  15  upstream the exhaust port  17 . Thus, the exhaust element  10  is protected from dust, dirt and other undesired substances entering the damping chamber  11  from the environment  5 . 
     The brake valve arrangement  1  further has an equalizing chamber  22 , which is in fluid connection with the exhaust path  15  and configured to provide an equalizing volume to avoid pressure peaks acting on the exhaust element  10 . 
     The exhaust path  15  further has a throttle  23 , which is in fluid communication with the equalizing chamber  22  and the flow path  19  via the exhaust port  17 . 
     The throttle  23  is configured to narrow the flow path defined by the exhaust path  15 . Thus, pressure peaks acting on the exhaust element  10  are reduced due to the narrowed flow cross-sectional area as indicated by “ 23   a ” in  FIG.  5   . 
     In the following, a method for assembling the pneumatic device  1  according to  FIGS.  4  and  5    is described. Such a method comprises the steps of providing an exhaust element  10  which is configured to provide a liquid impermeable but gas permeable barrier and arranging the exhaust element  10  in the pneumatic device  1  at a position associated with the exhaust path  15  and/or the exhaust port  17 , such that a liquid impermeable bus gas permeable barrier between the housing  3  for receiving the electronic components and the environment  5  is provided, or a barrier between the housing  3  for receiving the electronic components and the damping chamber  11  respectively. It is preferred that the method further comprises the steps of providing a relay piston  26 , pre-assembling the exhaust element  10  and the relay piston  26  and arranging the pre-assembled relay piston  26  with the exhaust element  10  in the exhaust path  15 , wherein the exhaust element  10  and the relay piston  26  are preferably coupled by a snap-fit connection. 
     LIST OF REFERENCE SIGNS (PART OF THE SPECIFICATION) 
     
         
           1  pneumatic device 
           2  lower housing 
           3  housing for electronic components 
           5  environment 
           7  supply connection 
           9  working connection 
           10  exhaust element 
           11  damping chamber, silencer 
           12  exhaust portion 
           14  actuation element 
           15  exhaust path 
           17  exhaust port 
           18  breathing channel 
           19  flow path 
           20  sound damping material 
           21  bracket 
           22  equalizing chamber 
           23  throttle 
           23   a  flow cross-section of the throttle 
           25  housing cover 
           26  relay piston 
           27  sensor 
           29  solenoid valve 
           30  exhaust channel 
           100  brake system 
           102  front axle brake circuit 
           104  rear axle brake circuit 
           106 . 1 ,  106 . 2  front axle brake actuators 
           108 . 1 ,  108 . 2  rear axle brake actuators 
           110  front axle brake modulator 
           112  rear axle brake modulator 
           114  compressed air supply 
           116  front axle connecting line 
           118  rear axle connecting line 
           120 . 1 ,  120 . 2 ,  102 . 3  supply lines 
           122  exhaust line 
           11  remote exhaust silencer 
           200  vehicle 
           204  front axle 
           206  rear axle 
           208 . 1 ,  208 . 2  front wheels 
           210 . 1 ,  210 . 2  rear wheels 
         F flow direction