Patent Description:
Brake valves of the aforementioned type are widely used in the vehicle industry to provide braking force for brake mechanisms. Under commercial vehicle, in particular busses, cargo vehicles such as trucks and other heavy duty vehicles are to be understood. The aforementioned brake valves operate as a function of pressurized fluid being provided from a pressure source to the brake actuator such as a brake caliper of a disk brake or a drum brake, for instance. By sliding the valve member to the open position, pressurized air provided to the supply connection at the supply pressure is transmitted to the working port at a brake pressure that corresponds to the position of the valve member between the exhaust position and the open position. When the valve member is in the exhaust position, the working connection is vented and no brake pressure is supplied. When the valve member is in the fully open position a brake pressure substantially equal to the supply pressure will be supplied to the brake actuator. The valve member is movable between the exhaust position and the fully open position by an operator of the vehicle or based on electronic brake signals. For example, the valve member may be biased in the exhaust position and is movable from the exhaust position via a foot pedal attached to the valve member. When a user pushes the pedal, the valve member is moved. As soon as the user releases the pedal, the valve member returns to the exhaust position.

Conventional brake valves comprise an exhaust silencer that reduces noise when the brake actuator is vented via the brake valve. Due to various reasons, for example to allow for foot actuation of the brake valve, conventional brake valves are usually installed close to a base of the vehicle. However, a maximum fording depth of the vehicle is thereby limited. If a water level rises to the exhaust silencer while the vehicle drives through a stream or puddle, water ingresses into the brake valve and adversely affects the brake valve, e.g., by choking a venting path of the brake valve with water. Therefore, fording versions of brake valves have been developed. Instead of an exhaust silencer, the exhaust portion of such brake valves is connected to a spout, which is then connected to an exhaust located at the top of the vehicle via a hose or pipe. However, these fording versions of brake valves are either completely different to standard versions of brake valves or do only have few common parts with standard versions. This results in high development and production costs for fording versions.

<CIT> discloses a valve element which is formed in a cylindrical body to open/close an exhaust port of a brake valve as pneumatic equipment. One end face in an axial direction of the cylindrical body is brought into contact with/separated from a valve seat to close/open an exhaust valve. A mesh member as a silencer element is disposed in the valve element. When the exhaust valve is opened, air passes through the mesh member which is disposed to an inner exhaust passage of the valve element, and is exhausted from the exhaust port.

It is therefore an object of the invention to provide an improved brake valve that is usable for both, as a standard version having an exhaust silencer directly attached to the brake valve as well as a fording version sealingly connectable to an exhaust spaced apart from the brake valve.

This problem is solved by the invention according to claim <NUM>, in particular with a brake valve of the aforementioned type, wherein the exhaust portion comprises one or more valve connection elements arranged downstream of the internal channel, and wherein the brake valve comprises a valve sealing surface, preferably for sealingly connecting the brake valve to a functional exhaust device for further discharging the pressurized air received from the brake valve to the environment, wherein the valve sealing surface is arranged downstream of the channel inlet and upstream of the valve connection elements.

The brake valve according to the invention is thus a modular brake valve connectable to both, an exhaust silencer or alternatively to a venting guide. The inventors have found that the brake valve is particularly suited to be either directly connected to an exhaust silencer or to be connected to a functional exhaust device for further discharging the pressurized air. On the one hand, an exhaust silencer may be connected to the valve connection elements without interfering with the valve sealing surface. On the other hand, the valve connection elements do not prevent a sealing connection between the functional exhaust device and the sealing surface. The valve connection elements may further be used to connect the functional exhaust element to the brake valve. The valve connection elements may therefore have a double function.

The sealing surface is a surface prepared for sealingly connecting to the functional exhaust device. Preferably, the sealing surface comprises one or more grooves and/or slots for receiving a sealing element such as an O-ring. Typically, sealing surfaces are precisely machined or precisely molded to provide a smooth surface whereas other surfaces of the brake valve may be rough machined or not machined at all (i.e. a rough cast surface).

The functional exhaust device is configured to further discharge the pressurized air received from the brake valve to the environment. During operation and when the working port of the brake valve is vented, air passes from the working port along the exhaust flow path through the internal channel to the exhaust portion of the brake valve. At the exhaust portion the air is then either exhausted via an exhaust silencer connected to the valve connection elements of the exhaust portion or, in the fording version, is transferred to the functional exhaust device which discharges the pressurized air further. Discharging further means that the pressurized air is not exhausted to the environment in close proximity to the brake valve but at a location spaced apart from the brake valve. For example, the functional exhaust device may be a venting guide that is connected to a hose that transfers the pressurized air to an exhaust silencer spaced apart from the brake valve when the brake valve is installed in a vehicle. The flow direction is defined from the working connection to the exhaust portion. Hence, the flow direction describes the direction, which air at the working connection provided at a pressure above an environmental pressure follows when it is exhausted to the environment through the brake valve. The pressurized air then flows from the working connection via the exhaust flow path and the exhaust portion to the environment. The brake valve is preferably suited for providing a brake pressure to a pneumatic vehicle brake system of a commercial vehicle.

The valve connection elements may comprise slots for receiving hooks, one or more threaded portions, one or more hooks and/or one or more protrusions. Preferably, the valve connection elements may form a bayonet connector half. It shall be understood that the valve connection elements may also be formed by one element, only. For example, a single threaded portion may form the valve connection elements.

In a first preferred embodiment, the exhaust portion comprises an exhaust cavity formed in the housing, wherein the exhaust cavity comprises an outer opening and wherein the internal channel opens into the exhaust cavity. The outer opening opens towards the environment when no other element such as the functional exhaust device or an exhaust silencer is connected to the brake valve. An end of the internal channel opposite the channel inlet is arranged upstream of the outer opening. The internal channel is thereby protected from damages. Moreover, ingress of water or other substances into the internal channel is effectively prevented when an external element such as the functional exhaust device closes the outer opening.

Preferably, the valve connection elements are arranged between the internal channel and the outer opening of the exhaust cavity. The valve connection elements are formed in the exhaust cavity. A spatial relation between the internal channel and the valve connection elements and/or the outer opening and the valve connection elements can be easily ensured during manufacturing of the brake valve. Moreover, for engaging complementary connection elements of an external element, such as the functional exhaust device with the valve connection elements, the external element needs to be at least partially inserted into the exhaust cavity, whereby sealing of the outer opening is facilitated.

In an alternative embodiment, the connection elements are formed on an exterior surface of the housing. Connection elements formed on an exterior surface of the housing are easily accessible. Machining of the connection elements as well as assembly is facilitated. However, connection elements arranged on an exterior surface of the housing are less protected from damage than connection elements arranged inside the exhaust cavity and sealing of the outer opening can be more difficult.

The valve sealing surface is preferably formed on the guide element. By providing the valve sealing surface on the guide element, sealing of the internal channel can be easily ensured and ingress of water or other substances is effectively prevented. Moreover, the guide element comprises a sliding surface on which the valve member is slidably arranged. This sliding surface needs to be precise. The guide element is preferably machined and/or (injection-)molded. Preferably the guide element is made from plastic material. During manufacturing and/or molding of the precise sliding surface, the valve sealing surface may be formed at a high precision with little additional effort. Manufacturing time and cost of the brake valve as a whole can be reduced. Moreover, a spatial relation of the internal channel and the valve sealing surface is ensured which prevents assembly errors. In other embodiments, the guide element is preferably formed by additive manufacturing (3D-printing). In an alternative embodiment, the valve sealing surface may also be formed on the housing. Preferably, the valve sealing surface is formed on an inner surface of the internal channel. Preferably, the valve sealing surface comprises a cylindrical sealing portion, that according to a particularly preferred embodiment is an inner surface at least partially defining the internal channel. Additionally or alternatively, the valve sealing surface may comprise an axial sealing surface of the internal channel substantially perpendicular to a flow direction defined by the exhaust flow path.

The internal channel preferably comprises a channel outlet opposite the channel inlet, wherein a bottleneck portion of the exhaust flow path is arranged upstream of the channel outlet of the internal channel. The internal channel extends between the channel inlet and the channel outlet and forms part of the exhaust flow path. This exhaust flow path has a bottleneck portion that forms the narrowest cross section of the flow path along its entire path from the working connection to the exhaust connection. By arranging the bottleneck portion upstream of the channel outlet, a defined flow behavior of air travelling along the flow path can be ensured, since the bottleneck portion significantly influences the flow behavior.

In a further preferred embodiment, the internal channel has an upstream section having a first internal channel cross sectional area and a downstream section having a second internal channel cross sectional area larger than the first internal channel cross sectional area, wherein the valve sealing surface is formed on the downstream section. Preferably, the upstream section forms the bottleneck portion of the exhaust flow path. By forming the valve sealing surface on the internal channel, sealing the exhaust flow path is facilitated when the functional exhaust element is connected to the valve sealing surface. Since the second internal cross sectional area is enlarged relative to the first internal cross sectional area, a cross sectional area of a flow path downstream of the upstream section may be kept constant even if the functional exhaust element is received in the downstream section of the internal channel.

According to a second aspect of the invention, the above stated object is solved by a brake valve assembly comprising the brake valve according to any of the preferred embodiments of the fist aspect of the invention described above and a venting guide, wherein the venting guide forms the functional exhaust device. The venting guide is configured for sealingly connecting to the valve sealing surface and for receiving the pressurized air from the brake valve. The venting guide is adapted to further exhaust the air received from the brake valve and is therefore connectable to a pipe, hose or other suitable conduit for guiding the pressurized air to an exhaust spaced apart from the brake valve.

According to a preferred embodiment, the venting guide comprises a spout and a venting guide fixing bracket. The spout is preferably formed as an elongated element for guiding the pressurized air received from the brake valve. Preferably, the spout is adapted to serve as a hose connector. A hose for further discharging pressurized air may be put over the spout and fixed to the spout by a hose clamp or other suitable device. The fixing bracket is preferably adapted for engaging the valve connection elements.

Preferably, the spout and the venting guide fixing bracket are separate elements, wherein a venting guide sealing portion for sealingly connecting to the valve sealing surface is formed on the spout and wherein complementary connection elements for engaging the valve connection elements are preferably formed on the venting guide fixing bracket. During assembly, the venting guide sealing portion of the spout may then be brought into sealing contact with the valve sealing surface and the spout may then be fixed to the brake valve via the fixing bracket.

In a further preferred embodiment, the venting guide fixing bracket is configured to abut the spout on a side opposite the venting guide sealing portion and is preferably configured to press the venting guide sealing portion into contact with the sealing surface. Preferably, the fixing bracket therefore comprises flexible elements adapted to be deformed and to provide a restoring force once deformed. Preferably, the flexible elements are deformed, when the venting guide sealing portion contacts the valve sealing surface and when the bracket abuts the spout and engages the valve connection elements. By pressing the spout into contact with the sealing surface, a tight sealing connection between the spout and the brake valve can be ensured. Ingress of water is prevented. Preferably, the flexible elements are formed by longitudinal slots allowing deformation, preferably of a dome section, of the fixing bracket.

Preferably, a step is formed between the upstream section and the downstream section of the internal channel and the spout abuts the step, preferably such that a smooth transition is formed between the upstream section and an internal spout channel. In a particularly preferred embodiment, the step is perpendicular to first inner surface of the internal channel defining the upstream section proximate to the step and/or perpendicular to a second inner surface of the internal channel defining the downstream section proximate to the step. The step then helps in correctly positioning the spout relative to the guide element. Preferably, the step forms or carries the valve sealing surface. A smooth transition is formed and no sharp transitions of the flow path such as steps are formed between the upstream section and the internal spout channel. Preferably, an internal cross section of the upstream section is substantially identical to an internal spout channel cross section of the internal spout channel. It shall be understood that a smooth transition between the upstream section and the internal spout channel still allows for small inconsistencies in the flow path resulting from manufacturing tolerances. Moreover, a transition element providing a smooth transition between the upstream and the internal spout channel section may be provided.

In a third aspect, the invention solves the above described object with a brake valve assembly comprising the brake valve according to the first aspect of the invention and a silencer, wherein the silencer forms the function exhaust device, the silencer preferably comprising a silencer fixing bracket and sound insulating material. The silencer fixing bracket is adapted to engage the valve connection elements and for holding the sound insulating material in place. The sound insulating material allows flow of the pressurized air received from the brake valve to the environment and is configured to dampen noise resulting therefrom. The brake valve assembly according to the third aspect of the invention is configured for standard use when no large fording depth of a vehicle comprising the brake valve assembly is needed. The brake valve assembly according to the second aspect of the invention provides a fording version of a brake valve assembly. The brake valve according to the first aspect of the invention is usable in both brake valve assemblies (according to the second aspect as well as the third aspect). Hence, the brake valve is flexible to use. No separate brake valve usable as a fording version needs to be designed and the brake valve can be produced at higher total numbers which results in reduced manufacturing cost.

According to a fourth aspect of the invention, the above stated object is solved by a brake system for a vehicle, in particular for a commercial vehicle, comprising a brake valve according to any of the preferred embodiments of the first aspect of the invention, preferably comprising a brake valve assembly according to the second or third aspect of the invention. In a fifth aspect, the invention solves the above stated object by a vehicle, in particular a commercial vehicle, comprising a brake system according to the fourth aspect of the invention.

According to a sixth aspect of the invention, the above stated object is solved by an assembly method for assembling a brake valve assembly, comprising the steps: providing a venting guide as the functional exhaust device; engaging a venting guide sealing portion of the venting guide with a valve sealing surface of the brake valve; engaging a complementary connection element of the venting guide with a valve connection element of the brake valve. Alternatively, the assembly method may comprise the steps of: providing a silencer as the functional exhaust device; and engaging a complementary connection element of the silencer with a valve connection element of the brake valve.

It should be understood that brake valve according to the first aspect of the invention, the brake valve assembly according to the second aspect of the invention, the brake valve assembly according to the third aspect of the invention, the brake system according to the fourth aspect of the invention, the vehicle according to the fifth aspect of the invention and the method according to the sixth aspect of the invention preferably have similar or equal aspects, in particular as they are described in the dependent claims. Thus, reference is made to the above description of the brake valve according to the first aspect of the invention.

For a more complete understanding of the invention, the invention will now be described in detail with reference to the accompanying drawings. The detailed description will illustrate and describe what is considered as preferred embodiments 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" or "including" 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 <NUM>, i.e. a single item, and further numbers like <NUM>, <NUM>, <NUM> and so forth.

A vehicle <NUM>, in particular a commercial vehicle <NUM>, comprises a front axle <NUM> and a rear axle <NUM>. For braking front wheels <NUM>, <NUM> of the front axle <NUM> and rear wheels <NUM>, <NUM> of the rear axle <NUM> the vehicle <NUM> comprises a brake system <NUM> having a front axle brake circuit <NUM> for braking the front wheels <NUM>, <NUM> and a rear axle brake circuit <NUM> for braking the rear wheels <NUM>, <NUM>. For braking the wheels <NUM>, <NUM>, <NUM>, <NUM>, the brake system <NUM> comprises front axle brake actuators <NUM>, <NUM> and rear axle brake actuators <NUM>, <NUM>. The front axle brake actuators <NUM>, <NUM> are connected to a front axle brake modulator <NUM> while the rear axle brake actuators <NUM>, <NUM> are connected to a rear axle brake modulator <NUM>. For providing compressed air at a supply pressure pS, the brake system <NUM> comprises a compressed air supply <NUM>. Of course, it may comprise more than one air supply.

In order to brake the vehicle <NUM> a brake pressure pB needs to be supplied to the front axle brake modulator <NUM> and the rear axle brake modulator <NUM>. For providing the brake pressure pB, the brake system <NUM> comprises a brake valve assembly <NUM> comprising a brake valve <NUM> and a functional exhaust element <NUM>. The brake valve <NUM> comprises a housing <NUM>, having a supply connection <NUM>, a working connection <NUM>, and an exhaust portion <NUM>. The supply connection <NUM> is connected to the compressed air supply <NUM> via supply line <NUM> for receiving pressurized air at the supply pressure pS.

Upon actuation by a user, the brake valve <NUM> of the brake valve assembly <NUM> provides a brake pressure pB corresponding to the degree of actuation provided by the user. To allow an actuation, the brake valve <NUM> comprises an actuation element <NUM>, which is formed as a brake pedal <NUM> in this embodiment. The brake valve <NUM> is configured to modulate the brake pressure pB supplied to the working connection <NUM> dependent on a degree of actuation of the actuation element <NUM>. If the brake pedal <NUM> is only slightly actuated, a low brake pressure pB is supplied to the working connection <NUM> while a high brake pressure pB is supplied to the working connection <NUM> when the brake pedal <NUM> is fully actuated.

The brake valve <NUM> is connected to the front axle brake modulator <NUM> and the rear axle brake modulator <NUM> via connecting lines <NUM>, <NUM>. In this embodiment the brake valve <NUM> is formed as a single circuit brake valve <NUM> having only one working connection <NUM> for providing brake pressure pB. Both, the front axle connecting line <NUM> connecting the brake valve <NUM> to the front axle brake modulator <NUM> as well as the rear axle connecting line <NUM> connecting the brake valve <NUM> to the rear axle brake modulator <NUM> are connected to the same working connection <NUM> of the brake valve <NUM>. In other embodiments, the brake valve <NUM> could also be formed as a multi circuit brake valve <NUM> having multiple working connections <NUM> for providing the same and/or different brake pressures pB to the brake circuits <NUM>, <NUM>.

The brake modulators <NUM>, <NUM> receive the brake pressure pB provided by the brake valve <NUM> and provide pressurized air at the same brake pressure pB but at a higher volume to the respective brake actuators <NUM>, <NUM>, <NUM>, <NUM>. Therefore, the brake modulators <NUM>, <NUM> are also connected to the compressed air supply via supply lines <NUM>, <NUM>. It shall be noted that the front axle brake modulator <NUM> and/or the rear axle brake modulator <NUM> may also be configured to further modify the brake pressure pB. For example, the front axle brake modulator <NUM> could comprise ABS-modules (not shown) for providing an ABS-function. Moreover, the brake actuators <NUM>, <NUM>, <NUM>, <NUM> may also be directly connected to the brake valve <NUM>.

For releasing the brake of the vehicle <NUM> the break pressure pB needs to be released from the brake actuators <NUM>, <NUM>, <NUM><NUM>. The brake valve <NUM> is therefore configured to exhaust the brake actuators <NUM>, <NUM>, <NUM><NUM> by connecting the working connection <NUM> to the exhaust portion <NUM>. 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 <NUM>. Brake valves, in particular brake valves having a brake pedal, are is usually located in a low position of the vehicle <NUM>. A maximum fording depth of the vehicle <NUM> is thereby limited, since water could ingress in the brake system <NUM> via the exhaust portion <NUM> when the vehicle <NUM> 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 valves assemblies <NUM> can be used. If however, increased fording depths are needed, special measures need to be taken. Therefore, fording versions of brake valves and/or brake valve assemblies are provided.

In <FIG>, the brake valve assembly <NUM> is a fording version, wherein the functional exhaust element <NUM> is a venting guide <NUM>. The venting guide <NUM> is connected to an exhaust line <NUM>, which is connected to a remote exhaust silencer <NUM>. For releasing the brakes of the vehicle <NUM>, the brake pressure pB is released from the brake actuators <NUM>, <NUM>, <NUM><NUM> via the connecting lines <NUM>, <NUM>, the brake valve <NUM>, the venting guide <NUM>, the exhaust line <NUM>, and the remote exhaust silencer <NUM>.

The venting guide <NUM> is sealingly connected to the brake valve <NUM> and thereby enables a sealing connection between the brake valve <NUM> and the exhaust line <NUM>. The remote exhaust silencer <NUM> is spaced apart from the brake valve <NUM> and placed at a high position on the vehicle <NUM>. By placing the exhaust silencer <NUM> at a high position of the vehicle <NUM>, ingress of water into the brake system <NUM> is prevented when the vehicle <NUM> drives through water.

<FIG> shows the brake valve assembly <NUM> depicted in <FIG> in more detail. The housing <NUM> defines a first valve cavity <NUM> and a second valve cavity <NUM>. A piston <NUM> of the actuation element <NUM> is slidably arranged in the first valve cavity <NUM>. A valve member <NUM> and a guide element <NUM> are arranged in the second valve cavity <NUM>. The valve member <NUM> is slidably arranged on the guide element <NUM> such that it is movable between an exhaust position <NUM> shown in <FIG> and a fully open position (indicated with the help of reference point or sign "<NUM>" in e.g., <FIG>) including an at least partially open position. In particular, reference sign <NUM> of <FIG> could indicate a contact point between the valve member <NUM> and the guide element <NUM> when e.g., the valve member <NUM> moves/slides towards In the exhaust position <NUM> a fist valve member side <NUM> of a valve member head <NUM> of the valve member <NUM> abuts a first valve seat <NUM> arranged on a transition <NUM> between the first valve cavity <NUM> and the second valve cavity <NUM>. As will be explained in more detail below, movement of valve member <NUM> is possible due to contact between piston head <NUM> and valve member head <NUM>. In the fully open position <NUM> the piston <NUM> abuts a hard stop <NUM> formed by the housing on the transition <NUM> between the first valve cavity <NUM> and the second valve cavity <NUM>. The hard stop <NUM> limits the pistons <NUM> range of movement such that the valve member <NUM> reaches the fully open position <NUM> when the piston <NUM> contacts the hard stop <NUM>. In the fully open position <NUM>, a second valve member side <NUM> of the valve member head <NUM> and the guide element <NUM> are preferably spaced apart to prevent damages on the valve member <NUM>. A gap between valve member <NUM> and valve seat <NUM> reaches its maximum, when the piston <NUM> reaches the fully open position <NUM> (abuts the hard stop <NUM>). Since the stop function is already provided by the hard stop <NUM>, no physical contact is required between the second valve member side <NUM> and the guide element <NUM>. Thus the valve member <NUM> is prevented from damages. The valve member <NUM> is biased into the exhaust position <NUM> by a return spring <NUM> arranged between the second valve member side <NUM> and a bottom section <NUM> of the guide element <NUM>.

The guide element <NUM> is inserted into the second valve cavity <NUM> from a first housing side <NUM> and held in place by a lock ring <NUM>. For sealing a gap between an outer circumferential face <NUM> of the guide element <NUM> and an inner wall <NUM> of the housing <NUM> defining the second valve cavity <NUM>, an O-ring <NUM> is provided between the guide element <NUM> and the inner wall <NUM>.

The piston <NUM> is inserted into the first valve cavity <NUM> from a second housing side <NUM>. Another O-ring <NUM> is provided between the piston <NUM> and a second inner wall <NUM> of the housing <NUM> defining the first valve cavity <NUM>. The piston <NUM> sealingly closes off the first valve cavity <NUM> and is movable between a released position <NUM> shown in <FIG> and a fully actuated position. In the fully actuated position a piston head <NUM> of the piston <NUM> abuts the valve member head <NUM> on the first valve member side <NUM> and the piston <NUM> abuts the hard stop <NUM> formed by the housing on the transition <NUM> between the first valve cavity <NUM> and the second valve cavity <NUM>.

The piston <NUM> is biased towards the released position <NUM> (in <FIG> upwards) by a piston spring <NUM> such that the piston <NUM> remains in the released position <NUM> as long as no force larger than a corresponding force provided by the piston spring <NUM> is provided to the brake pedal <NUM>. A pressure piece <NUM>, a set spring <NUM> and a spring seat <NUM> functionally connect the brake pedal <NUM> to the piston <NUM>. A push rod <NUM> of the brake pedal <NUM> is received in the pressure piece <NUM> which is in turn slidably received in a cover <NUM> closing the housing <NUM> on the second housing side <NUM>. The spring seat <NUM> is received in a transfer cavity <NUM> of the piston <NUM>. A connector <NUM> is screwed on a threaded portion <NUM> of the pressure piece <NUM> and extends through the spring seat <NUM>. The cover <NUM> is fixed to the housing <NUM> and limits movement of the pressure piece <NUM> away from the piston <NUM> (in <FIG> upwards). The set spring <NUM> is arranged between the pressure piece <NUM> and the spring seat <NUM> and around the connector <NUM> for biasing the spring seat <NUM> away from the pressure piece <NUM>. The connector <NUM> is slidably received in the spring seat <NUM>. However, a screw head of a screw <NUM> limits movement of the pressure piece <NUM> together with connector <NUM> away from the spring seat <NUM> such that a maximum distance between the pressure piece <NUM> and the spring seat <NUM> is reached when the screw head of the screw <NUM> abuts the spring seat <NUM>. The set spring <NUM> between pressure piece <NUM> and spring seat <NUM> creates the pneumatic characteristic. A maximum stroke of set spring <NUM> is reached when pressure piece <NUM> is touching piston <NUM>. During assembly spring seat <NUM>, pressure piece <NUM>, set spring <NUM> and connector <NUM> are assembled together, wherein screw <NUM> connects spring seat <NUM> to connector <NUM>. This preassembly is then assembled in piston <NUM>, Moreover, the piston spring <NUM> pushes the piston <NUM> and the spring seat <NUM> towards the second housing side <NUM> (upwards in <FIG>). The screw <NUM> sets dependent on its position a "<NUM> position" between spring seat <NUM> and connector <NUM> attached to pressure piece <NUM>. When the screw <NUM> is loosened, a space between the pressure piece <NUM> and the spring seat <NUM> is increased such that the pre-tension of the set spring <NUM> is decreased.

Upon actuation of the brake pedal <NUM>, the pressure piece <NUM> moves towards the first housing side <NUM> (in <FIG> downwards). This movement compresses the set spring <NUM> and the pressure piece <NUM> moves towards the spring seat <NUM>. The set spring <NUM> provides a compression counter force to the spring seat <NUM> and the piston <NUM>, which in turn moves the piston <NUM> downwards against the piston spring <NUM> arranged between the piston <NUM> and the housing <NUM>. Hence, actuation of the brake pedal <NUM> leads to compression of the piston spring <NUM> as well as the set spring <NUM>. An extent by which the pressure piece <NUM> and the piston <NUM> move, depends on the compression counter forces (or biasing forces) provided by the set spring <NUM> and the piston spring <NUM>, since the forces provided by the set spring <NUM> and the piston spring <NUM> need to be in equilibrium as long as the pressure piece <NUM> is spaced apart from the piston <NUM>. Once the set spring <NUM> has been compressed such that the pressure piece <NUM> abuts the piston <NUM>, the pressure piece <NUM> and the piston <NUM> move in unison. Further actuation of the brake pedal <NUM> moves the piston <NUM> towards the fully open position <NUM> (in <FIG> downwards), since a direction connection is established between the brake pedal <NUM> and the piston <NUM> via the push rod <NUM> and the pressure piece <NUM>.

The set spring <NUM>, the spring seat <NUM> and the screw <NUM> provide means for setting a pedal feedback of the brake pedal <NUM>. When the set spring <NUM> is pretensioned to a high degree, the piston <NUM> is moved at a light actuation of the brake pedal <NUM>, since large forces are required for further compressing the set spring <NUM>. When, on the other hand, pre-tensioning of the set spring <NUM> is low, the pressure piece <NUM> performs a free stroke (or empty stroke) towards the piston <NUM> upon initial actuation of the brake pedal <NUM>, since almost no force is required for compressing the set spring <NUM>. In this case, when the brake pedal <NUM> is initially moved, only the pressure piece <NUM> moves towards the piston <NUM> while the piston <NUM> itself substantially maintains its position. The valve member <NUM> substantially maintains its position as well and consequently no brake pressure pB is provided to the working connection <NUM>.

After a potential free stroke of the pressure piece <NUM>, the piston <NUM> is moved from the released position <NUM> towards the fully open position (in <FIG> downwards) against the biasing force provided by the piston spring <NUM>. In between the released position <NUM> and the fully open position, the piston head <NUM> abuts the valve member <NUM> whereby a sealing contact is formed between the piston head <NUM> and the valve member head <NUM>. When the piston <NUM> is further actuated by the brake pedal <NUM>, it pushes the valve member <NUM> from the exhaust position <NUM> towards the fully open position <NUM>. The piston <NUM> is biased towards the released position <NUM> by the piston spring <NUM> arranged between the piston <NUM> and the housing <NUM> such that the piston <NUM> returns to the released position <NUM> when no actuation force is applied to the brake pedal <NUM>.

The guide element <NUM> comprises an internal channel <NUM> and a through hole <NUM> is provided in the valve member head <NUM> such that the first inner cavity <NUM> is in fluid communication with the exhaust portion <NUM> of the brake valve <NUM>, when the piston head <NUM> is separated from the valve member head <NUM> (when the piston <NUM> is in the released position <NUM>). When the actuation element <NUM> is at least partly actuated, the piston head <NUM> sealingly contacts the valve member head <NUM> and thereby separates the exhaust portion <NUM> from the fist valve cavity <NUM>. However, the valve member <NUM> is then in an at least partially open position wherein the valve member head <NUM> is separated from the valve seat <NUM> such that the second valve cavity <NUM> is in fluid communication with the first valve cavity <NUM>.

The supply connection <NUM> is in direct fluid communication with the second valve cavity <NUM> such that pressurized air at the supply pressure pS is provided thereto. When the valve member <NUM> is in the exhaust position <NUM> the second valve cavity <NUM> is closed off from the first valve cavity <NUM> and the exhaust so that the supply connection <NUM> is not directly connected to the exhaust. If starting from the exhaust position <NUM>, and a brake pressure shall be applied to the working connection <NUM>, the brake pedal <NUM> needs to be actuated (pushed downwards with respect to <FIG>). The piston <NUM> moves against the biasing force of the piston spring <NUM> and abuts the valve member head <NUM> with its piston head <NUM>. The valve member head <NUM> is moved out of the exhaust position and a gap is formed between the valve seat <NUM> and the first valve member side <NUM> of the valve member head <NUM>. Pressurized air provided to the second valve cavity <NUM> via supply connection <NUM> may then flow from the second valve cavity <NUM> to the first valve cavity <NUM>. The working connection <NUM> is in direct fluid communication with the first valve cavity <NUM> such that pressurized air at the brake pressure pB is supplied to the working connection <NUM> when the valve member <NUM> is an at least partially open position. The pressure level of the brake pressure pB depends on the size of the gap formed between the valve seat <NUM> and the valve member head <NUM>. If the gap is small, a high pressure drop occurs and the brake pressure pB supplied to the working connection <NUM> is much smaller than the supply pressure pS. When the valve member <NUM> is in the fully open position <NUM>, the gap formed between the valve seat <NUM> and the valve member head <NUM> is large enough that the brake pressure pB is substantially equal to the supply pressure pS. In this case, the brake actuators <NUM>, <NUM>, <NUM>, <NUM> connected to the working connection <NUM> are fully actuated and a maximum braking force is applied. It shall be noted, that movement of the piston <NUM> depends on actuation of brake pedal <NUM> and deflection of set spring <NUM> as well as additional factors like friction and a force supplied by return spring <NUM>. The set spring <NUM> deflects, since the brake pressure pB established in the first valve cavity <NUM> acts on the exposed area of piston <NUM> facing towards the first valve cavity <NUM>. As the gap between the valve member head <NUM> and the valve seat <NUM> increases, the brake pressure pB also increases. Set spring <NUM> is deflected (compressed) such that part of a movement of the pressure piece <NUM> towards the first housing side <NUM> is compensated by set spring <NUM>. Movement of the piston <NUM> is therefore not necessarily uniform to a movement of push rod <NUM> and pressure piece <NUM>. A partial braking characteristic of the brake valve <NUM> is configurable via set spring <NUM>. When the set spring <NUM> is fully compressed, pressure piece <NUM> contacts piston <NUM> and a uniform movement of piston <NUM> and push rod <NUM> is established. Preferably, contact of piston <NUM> and pressure piece <NUM> results in a sudden increase of the gap between valve seat <NUM> and valve member head <NUM> resulting in a jump of the pressure level of the brake pressure pB supplied to the first valve cavity <NUM> and working connection <NUM>. Further preferred, a pressure level of brake pressure pB substantially equal to the supply pressure pS is established when pressure piece <NUM> abuts piston <NUM>.

When the brake pedal <NUM> is released, the piston <NUM> and the valve member <NUM> are returned to the released position <NUM> and the exhaust position <NUM> respectively by the springs <NUM>, <NUM>. The valve member head <NUM> abuts the valve seat <NUM> and thereby separates the first valve cavity <NUM> from the second valve cavity <NUM>. Once valve member <NUM> has reached the exhaust position <NUM> further movement of valve member <NUM> is stopped by the valve seat <NUM>. The piston <NUM>, however, moves on such that the piston head <NUM> separates from the valve member head <NUM>. The first valve cavity <NUM> is then once again in fluid communication with the exhaust portion <NUM> via a through hole <NUM> and an internal channel <NUM>. Pressurized air at the brake pressure pB may then flow along an exhaust flow path <NUM> from the working connection <NUM> to the exhaust portion <NUM> via the first valve cavity <NUM>, the gap formed between the piston head <NUM> and the valve member head <NUM>, the through hole <NUM> and the internal channel <NUM> formed in the guide element <NUM>.

While the brake valve <NUM> depicted in <FIG> is a single circuit brake valve for providing the brake pressure pB to a single brake circuit <NUM>, <NUM>, the brake valve <NUM> may also be formed of a dual circuit type. <FIG> shows a preferred embodiment of such a brake valve <NUM> of the dual circuit type. The brake valve <NUM> shown in <FIG> is configured for providing the brake pressure pB to one of the brake circuit <NUM>, <NUM> and a secondary brake pressure pB2 to the other brake circuit <NUM>, <NUM>. In the brake valve <NUM> of the dual circuit type, the piston <NUM> does not directly actuate the valve member <NUM>. Instead, a secondary piston <NUM> is arranged between the piston <NUM> and the valve member <NUM>. Movement of the piston <NUM> is initiated as described above with reference to <FIG> by pushing the brake pedal <NUM>. Upon actuation the piston <NUM> moves towards the first housing side <NUM> (in <FIG> downwards).

A secondary piston <NUM> extends through a secondary guide element <NUM> guiding a secondary valve member <NUM>. Upon actuation, the piston <NUM> moves the secondary valve member <NUM>. The secondary valve member <NUM> functions substantially identical to the valve member <NUM>. When contacting a secondary valve seat <NUM>, the secondary valve member <NUM> blocks pressurized air provided at the supply pressure pS to a secondary supply cavity <NUM> via the supply connection <NUM> from flowing to a secondary working cavity <NUM> connected to a secondary working connection <NUM>. When removed from the secondary valve seat <NUM> a gap is formed between the housing <NUM> and the secondary valve member <NUM> at the valve seat <NUM> allowing air to flow from the secondary supply cavity <NUM> to the secondary working cavity <NUM>. A pressure level of the pressurized air provided to the secondary working connection <NUM> via this gap and the secondary working cavity <NUM> depends on the size of the gap. A large gap results in a high secondary brake pressure pB2 being provided to the secondary working connection <NUM> and a small gap results in a low secondary brake pressure pB2 being provided to the secondary working connection <NUM>. When both circuits function correctly, pressure from the secondary working cavity <NUM> acts on the secondary piston <NUM> via secondary guide element <NUM>. The secondary piston <NUM> is moved by this pressure (a force resulting from the pressure) and acts on the valve member <NUM> for supplying the brake pressure pB. In case of a malfunction (no brake pressure supplied to secondary working cavity <NUM>), the piston <NUM> may mechanically actuate the secondary piston <NUM> such that at least the brake pressure pB is supplied. The brake pressure pB and the secondary brake pressure pB2 may have the same or different pressure levels. The pressure level of the brake pressure pB and the secondary brake pressure pB2 depend on the dimensions of the respective valve members <NUM>, <NUM> and characteristics of the springs biasing the valve member <NUM> and the secondary valve member <NUM> towards their respective valve seats <NUM>, <NUM>. Moreover, the pressure level of the brake pressure pB and the secondary brake pressure pB2 depends on the type of seal chosen for secondary piston <NUM>, position of the seals as well as the dimensions of secondary piston <NUM>. For example, the working connection <NUM> could provide the brake pressure pB to the front axle brake circuit <NUM> while the secondary working connection <NUM> provides the secondary brake pressure pB2 having a lower pressure level to the rear axle brake circuit <NUM>.

The exhaust portion <NUM> is configured for exhausting air from the brake valve <NUM>. While in the brake valve assembly <NUM> shown in <FIG>, the air directly exhausts to the environment via an exhaust silencer <NUM>, the exhaust portion <NUM> of the brake valve assembly <NUM> shown in <FIG> does not directly exhaust the pressurized air to the environment. Instead, the pressurized air is provided to the venting guide <NUM>. The exhaust portion <NUM> and the venting guide <NUM> will be further described with relation to <FIG> showing a detail of the brake valve <NUM> depicted in <FIG>.

The exhaust portion <NUM> comprises an exhaust cavity <NUM> formed by the housing <NUM>. The exhaust cavity <NUM> is arranged between the second valve cavity <NUM> and an outer opening <NUM>. The internal channel <NUM> opens into the exhaust cavity <NUM>. If the venting guide <NUM> were not connected to the brake valve <NUM>, the outer opening <NUM> would form an opening of the brake valve <NUM> to the environment. However, in the brake valve assembly <NUM> shown in <FIG>, the venting guide <NUM> is connected to the brake valve <NUM>. Valve connection elements <NUM> are provided on the housing <NUM> downstream of the internal channel <NUM> and upstream of the outer opening <NUM>. In this embodiment, the connection elements <NUM> are formed as slots <NUM>, in which complementary connection elements <NUM> formed as snap hooks <NUM> of the venting guide <NUM> are received.

The venting guide <NUM> comprises a spout <NUM> and a venting guide fixing bracket <NUM>. In this embodiment the spout <NUM> and the venting guide fixing bracket <NUM> are formed as separate elements. The spout <NUM> extends through the venting guide fixing bracket <NUM> which abuts the spout <NUM> on a spout shoulder <NUM>. Flexing slots <NUM> are provided in a dome portion <NUM> of the venting guide fixing bracket <NUM> such that the venting guide fixing bracket <NUM> is partially flexible and configured to press the spout <NUM> towards the brake valve <NUM>.

The brake valve <NUM> comprises a valve sealing surface <NUM>, which is here formed on the guide element <NUM>. In particular, the valve sealing surface <NUM> is an inner sealing face <NUM> formed on the internal channel <NUM>. The inner sealing face <NUM> comprises a first sealing face <NUM> oriented substantially perpendicular to the exhaust flow path <NUM> and a second sealing face <NUM> substantially parallel to the exhaust flow path <NUM>. To ensure the sealing connection between the functional exhaust element <NUM> and the brake valve <NUM>, a sealing element in the form of an O-ring <NUM> is arranged between the spout <NUM> and the second sealing face <NUM>. Additionally or alternatively, a seal may be formed between the first sealing face <NUM> and the spout <NUM>. In this embodiment, the first sealing face <NUM> is formed by a step <NUM> between an upstream section <NUM> and a downstream section <NUM> of the internal channel <NUM>. The venting guide fixing bracket <NUM> presses a venting guide sealing portion <NUM> of the spout <NUM> towards the step <NUM>, preferably into contact with the step <NUM>, and thereby ensures a sealing connection of the spout <NUM> to the valve sealing surface <NUM>.

The valve sealing surface <NUM> is provided downstream of a channel inlet <NUM> of the internal channel <NUM> that is oriented towards the working connection <NUM>. Moreover, the valve sealing surface <NUM> is provided upstream of the valve connection elements <NUM>. This ensures that water is prevented from entering into the internal channel <NUM> and the valve cavities <NUM>, <NUM> even if water enters through the valve connection elements <NUM>.

The upstream section <NUM> of the internal channel <NUM> has a first internal channel cross sectional area A1 and the downstream section <NUM> has a second internal cross sectional area A2 that is larger than the first internal channel cross sectional area A1. A bottleneck portion <NUM> of the exhaust flow path <NUM> is arranged upstream of a channel outlet <NUM> of the internal channel <NUM>. When the valve member <NUM> is in the fully open position <NUM> the bottleneck portion <NUM> of the exhaust flow path <NUM> is arranged upstream of a channel outlet <NUM> and in the upstream section <NUM> of the internal channel <NUM>.

The spout <NUM> has an elongate shape extending out of the exhaust cavity <NUM> and away from the brake valve <NUM>. In this embodiment, the spout <NUM> is straight. At a spout end <NUM> oriented away from the brake valve <NUM>, the spout <NUM> is adapted to be inserted in a hose (not shown) which can be clamped onto the spout <NUM> with a hose clamp (not shown). For guiding the pressurized air received from the exhaust portion <NUM> of the brake valve <NUM>, the spout <NUM> further comprises a spout channel <NUM>. The spout channel <NUM> tapers towards the spout end <NUM>. Near the valve sealing surface <NUM> (opposite the spout end <NUM>) a spout cross sectional area A3 of the spout channel <NUM> is substantially equal to the first internal channel cross sectional area A1 such that a smooth transition is provided between the internal channel <NUM> of the guide element <NUM> and the spout channel <NUM> of the spout <NUM>.

<FIG> depicts a standard version of the brake valve assembly <NUM>. In this embodiment, the brake valve <NUM> is identical to the brake valve <NUM> shown in <FIG> and <FIG>. The embodiment shown in <FIG> differs from the embodiments shown in <FIG> and <FIG> in that the functional exhaust element <NUM> is formed as a silencer <NUM>. The silencer <NUM> comprises a silencer fixing bracket <NUM> that engages the valve connection elements <NUM> and holds a sound insulating material <NUM> in place. The guide element <NUM> extends into the sound insulating material <NUM> such that pressurized air is directly discharged from the exhaust portion <NUM> into the sound insulating material <NUM>. Excessive noise is thereby prevented. The brake valve <NUM> is usable in the fording version of the brake valve assembly <NUM> shown in <FIG> and <FIG> as well as in the standard version shown in <FIG>. Hence, no brake valve <NUM> needs to be developed that is only usable in a fording version. Excessive development, tooling and manufacturing cost are thereby prevented.

The spout <NUM> may also be provided in an elbow version having a bend <NUM> (<FIG>). The bend <NUM> is preferably bent in a single plane having a bending angle α of larger <NUM>° to <NUM>°, preferably <NUM>° to <NUM>°, preferably <NUM>° to <NUM>°, preferably <NUM>° to <NUM>°, particularly preferred <NUM>°. Preferably, the spout <NUM> can also be bent in multiple planes.

<FIG> shows a detailed view of the silencer fixing bracket <NUM> while <FIG> shows a detailed view of the venting guide fixing bracket <NUM>. Both brackets <NUM>, <NUM> are substantially similar shaped having complementary connection elements <NUM>, the dome portion <NUM> and the flexing slots <NUM>. The venting guide fixing bracket <NUM> differs from the silencer fixing bracket <NUM> in that a spout hole <NUM> is provided in the dome portion <NUM> for receiving the spout <NUM>. In the silencer fixing bracket <NUM> the hole <NUM> is closed by a cap <NUM> connected to the dome portion <NUM> via narrow bridges <NUM>. Both, the venting guide fixing bracket <NUM> and the silencer fixing bracket <NUM> can be manufactured with only small changes in the manufacturing process. If for example both pieces are manufactured by injection moulding, the venting guide fixing bracket <NUM> can be manufactured using the same tool used for manufacturing the silencer fixing bracket <NUM> with an additional core element provided in the location of the spout hole <NUM>. If no changes shall be made to the tool, the silencer fixing bracket <NUM> can be converted to the venting guide fixing bracket <NUM> by manually braking the narrow bridges <NUM> and removing the cap <NUM>.

<FIG> illustrates an assembly method <NUM> for assembling a brake valve assembly <NUM>. In a first step S1, a brake valve <NUM> is provided. Following the first step S1 the method splits into a first flow <NUM> for assembling a brake valve assembly <NUM> in a fording version and a second flow <NUM> for assembling a brake valve assembly <NUM> in a standard version.

Claim 1:
A brake valve (<NUM>), comprising
a housing (<NUM>);
a supply connection (<NUM>) for receiving supply pressure (pS);
a working connection (<NUM>) for providing (control) brake pressure (pB);
an exhaust portion (<NUM>) for discharging pressurized air from the brake valve (<NUM>);
a valve member (<NUM>) continuously slidable from an exhaust position (<NUM>) to a fully open position (<NUM>) including an at least partially open position, wherein the working connection (<NUM>) is in fluid communication with the exhaust portion (<NUM>) when the valve member (<NUM>) is in the exhaust position (<NUM>), and wherein the working connection (<NUM>) is in fluid communication with the supply connection (<NUM>) and sealed from the exhaust portion (<NUM>) when the valve member (<NUM>) is in the at least partially open position, and
a guide element (<NUM>), characterized in that :
the valve member (<NUM>) is slidably arranged on the guide element (<NUM>), the guide element (<NUM>) comprising an internal channel (<NUM>), wherein the internal channel (<NUM>) forms part of an exhaust flow path (<NUM>) formed between the working connection (<NUM>) and the exhaust portion (<NUM>) when the valve member (<NUM>) is in the exhaust position (<NUM>), wherein a channel inlet (<NUM>) of the internal channel (<NUM>) is oriented towards the working connection (<NUM>),
wherein the exhaust portion (<NUM>) comprises one or more valve connection elements (<NUM>) arranged downstream of the internal channel (<NUM>),
and wherein the brake valve (<NUM>) comprises a valve sealing surface (<NUM>) for sealingly connecting the brake valve (<NUM>) to the exhaust portion (<NUM>), or preferably to a functional exhaust device (<NUM>), for further discharging the pressurized air received from the brake valve (<NUM>) to the environment, wherein the valve sealing surface (<NUM>) is arranged downstream of the channel inlet (<NUM>) and upstream of the valve connection elements (<NUM>).