GB2446948A

GB2446948A - Vehicle brake line coupling having a filter

Info

Publication number: GB2446948A
Application number: GB0803154A
Authority: GB
Inventors: Stephen Charles Jones; Clive Martin Dunn
Original assignee: Forster & Hales Ltd
Current assignee: Forster & Hales Ltd
Priority date: 2007-02-20
Filing date: 2008-02-20
Publication date: 2008-08-27
Also published as: GB0803154D0; GB0703283D0

Abstract

A vehicle pneumatic brake line coupling 100 has a housing 126, an inlet port 101 and an outlet port 102, formed along a longitudinal axis A-A. A filter 104 is provided in the housing 126, between the inlet port 101 and the outlet port 102, the filter 104 having inlet and outlet surfaces. The coupling has a filtering configuration in which the majority airflow passes through the filtration medium 104, and also has a bypass configuration in which a bypass airflow bypasses the inlet surface of the filtration medium above a threshold inlet pressure set by spring element 112 at the filter, allowing bypass of unfiltered air without entraining dirt from the filter downstream of the filter into the pneumatic braking system. The filter may be cleanable and the coupling may have quick release locking means.

Description

VEHICLE BRAKE LINE COUPLING

The present invention relates to vehicle brake line couplings and particularly pneumatic brake line couplings for trucks and trailers, or articulated vehicles including lorries and heavy goods vehicles.

Large vehicles, such as heavy goods vehicles, typically have a braking system actuated by a pneumatic system. In a pneumatic braking system compressed air is fed into the pneumatic braking system from the truck which drives the brakes in both the truck and any the trailer the truck may be towing. The pneumatic braking system of the trailer is connected to the compressed air supply in the truck by pneumatic lines.

Sometimes it is desirable to uncouple the trailer from the truck, for example for increasing the manoeuvrability of the truck or during maintenance of the truck. When the truck and trailer are uncoupled, the pneumatic braking system of the trailer must also be uncoupled.

Thus the pneumatic braking system of the trailer is typically coupled to the compressed air supply in the truck via releasable pneumatic brake line couplings.

During uncoupling, the pneumatic brake line couplings are exposed to the environment. It is possible for dirt to contaminate the inside of the exposed pneumatic brake line couplings when the pneumatic brake line couplings rest on the ground or other dirty surfaces. Such dirt can enter the brake line and cause problems.

Dirt in the pneumatic braking system may damage the sensitive pneumatic devices in the pneumatic braking system, which means the pneumatic braking system requires increased maintenance. Indeed, continued contamination in the pneumatic braking system may affect the performance of the pneumatic brake system and ultimately the safety of the vehicle.

One pneumatic braking system has an in-line air filter (manufactured by Knorr-Bremse of Munich, Germany, part number LA2103) for filtering the dirt before it reaches the pneumatic brakes. The in-line air filter is placed at a point in the pneumatic braking system on the trailer between the pneumatic brake line coupling and the brakes.

The in-line air filter has a housing with an inlet port and an outlet port and a filter is mounted in the housing between the ports. The air inlet and outlet ports are connected to the pneumatic brake lines.

In normal use, the filter of the in-line air filter collects dirt and requires regular maintenance.

Typically, the pneumatic line and hence the in-line air filter is placed on the underside of the trailer making the in-line air filter difficult for maintenance or replacement of the filter.

The in-line air filter has a bypass mechanism which allows unfiltered air to flow to the sensitive pneumatic devices in the pneumatic braking system in the event that the filter is blocked with dirt. In this way, the bypass mechanism of the in-line air filter allows the pneumatic braking system to operate even if the filter is blocked.

The bypass mechanism of the in-line air filter will now be explained. The bypass mechanism incorporates the filter, which has a top-hat shape. The filter fits inside a first spring element such that the rim of the filter rests on a first end of the first spring element.

A second end of the first spring element engages an internal wall of the in-line air filter housing. The rim of the filter abuts against a first plate and the first plate has projections for engaging a first end of a smaller, second spring element. A second end of the second spring element abuts against a second plate, the second plate having a recess for receiving and aligning the second end of the second spring element. An 0-ring sits between a rim on the in-line air filter housing.

The second plate abuts against the 0-ring providing a seal between the second plate and the in-line air filter housing. A slide member slides into a slot in the housing compressing the second plate and the spring elements against the housing and ensuring the bypass mechanism remains assembled. The second plate has a nipple for locating a hole in the slide member. When the in-line air filter is assembled the nipple projects through the hole. Thus, the first and second spring elements are in opposition, each urging the filter in opposite directions.

In normal operation, air flows from the inlet port to the outlet port, through the filter. The rim of the filter and the first plate form a seal because the first spring element and the second spring element urge the filter and the first plate respectively towards each other. The dirt in the airflow flowing from the inlet port to the outlet port is collected on the outside surface of the top hat shaped filter.

If the filter is blocked, the pressure of the airflow moves or distorts the filter, providing a gap between the filter and the first plate and unfiltered air may bypass the filter. When the filter is blocked and moves, the unfiltered air must pass over the outside surface of the top hat shaped filter.

DE-B-19931162 discloses a pneumatic coupling head which incorporates a filter device for compressed air. The filter device is located between an inlet port and an outlet port of the coupling head. The pneumatic coupling head has a similar bypass mechanism to the previously mentioned in-line air filter.

The filter device of the pneumatic coupling head is mounted between a first pressure spring element and a second pressure spring element, mounted in opposition to each other. When the compressed airflow reaches a threshold pressure, the filter moves against the first pressure spring element into a position to open a bypass connection between the inlet and outlet ports. The filter device of DE-B-19931162 is also arranged to collect dirt and foreign bodies on the outside of the filter device. When unfiltered air bypasses the filter, the unfiltered air flows over the outside surface of the top-hat shaped filter.

The present inventors have realised that such known devices for filtering air in pneumatic braking systems suffer from the problem of downstream contamination of the pneumatic braking system when the filter is bypassed.

Such contamination can be caused by the unfiltered air flowing over and entraining previously collected dirt on the filter. Dislodged dirt from the filter may be carried downstream of the filter. This is undesirable because the dirt and foreign bodies can affect the performance and safety of the pneumatic braking system.

Accordingly in a general aspect, the present invention provides a vehicle pneumatic brake line coupling having a filter and a safety bypass airflow path located so as to bypass an inlet side of the filter.

In a first preferred aspect, the invention provides a vehicle pneumatic brake line coupling having a housing; an inlet port; an outlet port; a filter having a filtration medium with inlet and outlet surfaces, the filter being mounted in the housing between the inlet port and the outlet port; wherein the coupling further has: a filtering configuration in which the majority airflow passes through the filtration medium; and a bypass configuration in which a bypass airflow bypasses the inlet surface of the filtration medium above a threshold inlet pressure at the filter.

In this case, when the filter becomes blocked by a certain amount of dirt on the inlet surface of the filtration medium (or within the filtration medium on an inlet side of the filtration medium), and the pressure incident on the inlet surface is above a threshold pressure, the airflow bypasses the inlet surface. This means the airflow does not flow over previously collected dirt on the inlet side of the filtration medium.

(Throughout the specification, the term "dirt" is used to refer to particulate matter which is collected on the filtering surface. The particulate matter may be mud, dust or any other foreign body which could contaminate the brakes.) This means that the previously filtered dirt collected on the filter remains on the inlet side of the filtration medium. Therefore, the unfiltered air entering the inlet port is not further contaminated by previously filtered dirt and this reduces the contamination of the brakes when the coupling is in the bypass configuration.

Preferably, the filter is moveable between a filtering position, in which the coupling is in the filtering configuration, and a bypass position, in which the coupling is in the bypass configuration, and when the inlet pressure at the filter is above the threshold inlet pressure, the filter is arranged to move from the filtering position to the bypass position.

In this way, when the filter becomes clogged by dirt on the inlet surface of the filtration medium, the rate of air flowing from the inlet surface to the outlet surface is reduced. This means that the pressure incident on the inlet side of the filter increases as the filtration medium becomes clogged with dirt. When the pressure of the airflow incident on the inlet side of the filter is above a threshold inlet pressure, the filter moves from the filtering position to the bypass position.

Occasionally, the pressure of the airflow may dislodge previously collected matter on the inlet surface of the filtration medium. Preferably, the filter has a recess projecting towards the outlet port. Alternatively and / or additionally, the filter may be top-hat shaped. In these cases, the inlet surface of the filtration medium is on the inside surface of the recess and this confines the dirt and foreign bodies within the filter.

Furthermore, the airflow also forces dislodged dirt against a base of the filter.

The inlet surface of the filtration medium may be walls and / or a base of the recess. Advantageously, this increases the surface area of the filtering surface.

Additionally, the inlet surface may have ridges, bumps, folds, troughs or wrinkles to increase the surface area of the filtering surface.

Preferably, the inlet port and the outlet port are aligned along a longitudinal axis of the coupling. This arrangement provides a more compact coupling or coupling system.

Preferably, the coupling is substantially tubular or cylindrical. In this case, a cylindrical coupling is easier to manufacture. The coupling may comprise of multiple cylinders or tubes having different diameters.

More preferably, the filter is axially aligned with the inlet port and the outlet port. In this case, the air flowing along a longitudinal axis of the vehicle pneumatic brake line coupling limits asymmetric forces on the filter. Asymmetric forces incident on the filter may mean that the filter twists / rotates with respect to the housing and the filter does not seat properly when returning to the filtering position.

Preferably, the vehicle brake line coupling has a spring element for urging the filter towards the filtering position. The strength of the spring element determines the threshold inlet pressure and hence the amount of dirt necessary in the filtration medium so that the filter moves from the filtering position to the bypass position.

Different strength spring elements may be used to determine different threshold inlet pressures.

When the known devices for filtering air in pneumatic braking systems become blocked with dirt, often the filter is replaced. In order to replace the filter in the known devices for filtering air in pneumatic braking systems the devices must be disassembled. The inventors have realised that when the known devices are disassembled, the internal parts (e.g. spring elements and plates in the in-line filter) are liable to be ejected from the housing of the devices because the spring elements are under compression.

Reassembly of the known devices for filtering air in pneumatic braking systems requires that the internal parts are replaced in the correct order. Often incorrect assembly of the known devices for filtering air in pneumatic braking systems occurs because truck maintenance personnel can confuse the different internal parts (e.g. the orientation of the filter) . For example, during reassembly of the in-line air filter the force required to compress the first and second spring elements may exceed 90N. Often the truck maintenance personnel need a combination of strength and dexterity in order to replace the slide in the slot to hold the internal parts in place, which makes the assembly of the in-line air filter time consuming and difficult.

Preferably, the vehicle pneumatic brake line coupling has a retainer for engaging the spring element. More preferably, the retainer engages the spring element S against the filter in compression. Even more preferably, the retainer has a thread for screwing into a threaded bore of the housing. In this way, the retainer provides access to the filter and the screw thread provides a mechanical advantage when reassembling / compressing the spring element.

Additionally or alternatively, the retainer may be partially or fully tightened in the threaded bore of the housing. This means that the threshold inlet pressure may be adjusted without replacing the spring.

Preferably, the retainer has a projecting portion for projecting through the spring element to locate the spring element with respect to the retainer. This ensures that the spring element does not move out of alignment when the vehicle pneumatic brake line coupling is assembled or during operation of the vehicle pneumatic brake line coupling.

Preferably, the retainer has a shaped head for engaging with a tool for providing torque. In this way, additional mechanical advantage can be obtained when tightening the retainer with a spanner, wrench or similar tool.

Preferably, the retainer has an has a sealing member for sealing with the housing of the coupling. More preferably, the retainer has a groove for accommodating the sealing member. In this case, the sealing member provides a seal between the retainer and the housing of the vehicle pneumatic brake line coupling and movement of the sealing member is limited such that the sealing member does not snag on other parts of the coupling.

Preferably, the spring element and the filter are coaxial such that transverse movement of the filter with respect to the spring element is limited. More preferably, the filter fits snugly inside the spring element. In this case the spring element and an outlet side of the filtering surface are flush and no transverse movement between the spring element and filter may occur.

Preferably, the filter has a groove and / or lip for cooperating with the spring element. More preferably, the groove is on the rim of the filter. In this way, the groove/lip engages with the spring element and also prevents movement between the spring element and the filter. Furthermore, the groove provides a visible guide when reassembling the vehicle pneumatic brake line coupling, therein preventing incorrect orientation of the filter in the vehicle pneumatic brake line coupling.

Preferably, the filter is removable for replacement and / S or maintenance. The filter may be a cartridge to aid assembly and replacement.

Preferably the coupling has an pneumatic valve actuating means for actuating a valve when the coupling is connected such that air flows from the valve to the inlet port. In this case, the coupling can be connected to a coupling on a truck with a one way valve and the coupling activates the one way valve, providing a supply of compressed air to the inlet port.

Preferably the filter abuts against a ledge portion of the housing. In effect, the filter forms a complete or partial seal against the ledge portion of the housing.

Typically, the ledge portion is formed by virtue of the outlet port end of the housing being wider than the inlet port end of the housing. More preferably, the inlet side of the filtering surface overlaps with the ledge portion.

This provides a better seal between the filter and the ledge portion.

The coupling may have only one spring element for urging the filter towards the filtering position. This reduces the force required to compress the spring and reassemble the coupling. In this case, the vehicle pneumatic brake line coupling only has one spring element. This means reassembly and disassembly is easier because there are less parts. Since there are less parts, there is less potential for truck maintenance personnel to incorrectly assemble the vehicle pneumatic brake line coupling.

In a second aspect, the present invention provides a vehicle pneumatic brake line coupling having a housing; an inlet port; an outlet port, the inlet port and the outlet port being aligned along a longitudinal axis of the coupling; and a first element of a quick-release locking means, the first element arranged to be releasably lockable with a second element of the quick-release locking means, the second element being mounted on another coupling; wherein the coupling further has a filter mounted in the housing between the inlet port and the outlet port.

In a third aspect, the present invention provides a vehicle pneumatic brake line coupling having a housing; an inlet port; an outlet port, the inlet port and the outlet port being aligned along a longitudinal axis of the coupling, a cleanable filtration medium mounted in the housing between the inlet port and the outlet port; a filtering configuration in which a first airflow passes through the cleanable filtration medium from the inlet port to the outlet port; and a cleaning configuration in which a second airflow passes through the cleanable filtration medium from the outlet port to the inlet port such that matter is dislodged from an inlet surface of the cleanable filtration medium.

In this way, the vehicle brake line coupling has a self-cleaning mechanism. When the coupling is disconnected from a compressed air supply, there is a residual amount of compressed air, at a pressure above atmospheric pressure, in the pneumatic brake line downstream of the outlet surface of the filtration medium. This means when the vehicle brake line coupling is disconnected, the residual amount of compressed air equalizes with the air at atmospheric air pressure at the inlet port. The air flows from the outlet surface of the filtration medium to the inlet surface of the filtration medium, dislodging previously filtered matter in the filtration medium. The vehicle brake line coupling is open to the environment when disconnected and the force of the air flowing from the outlet port to the inlet port in the cleaning configuration discharges the dislodged matter clear of the coupling. The alignment of the inlet and outlet port promotes the discharge of the dislodged matter when the coupling is in the cleaning configuration. In this way, the dislodged matter may even be transported to the environment outside the pneumatic brake system.

In a fourth preferred aspect the present invention provides a vehicle pneumatic brake line coupling system having a first coupling; and a second coupling, the first and second couplings being connectable to each other; wherein the first coupling and/or the second coupling is a coupling according to any of the above mentioned aspects.

Preferably, the first coupling and the second coupling of the vehicle pneumatic brake line coupling system are male and female portions respectively. To this effect, the male portion slots into the female portion and provides an air seal between the two portions.

In a fifth preferred aspect, the present invention provides a vehicle pneumatic braking system having a vehicle pneumatic brake line coupling system according to the third preferred aspect.

In a sixth preferred aspect, the present invention provides a towing vehicle and trailer having a vehicle pneumatic braking system according to the fourth preferred aspect.

In the foregoing, the vehicle pneumatic brake line coupling of each aspect is described as having a housing, the filter being mounted in the housing. It is to be understood that in one or more preferred embodiments, this housing may be formed in more than one part. For example, the housing may comprise a coupling portion and a filter housing portion. These portions may be releasably connectable. The filter housing portion may hold the filter and the coupling portion may provide at least a first element of a quick-release locking system, as discussed above. It is possible that the coupling portion and the filter housing portion need not be directly attached to each other. For example, these portions may be in pneumatic communication with each other via an intermediate portion. It is preferred that such an intermediate portion, if present, forms part of the vehicle. For example, the intermediate portion may form a bulkhead (or part of a bulkhead) on the vehicle (e.g. trailer) It is to be understood that any of the preferred and/or optional features may be applied separately or in conjunction with any of the aspects of the invention, unless the context demands otherwise. Indeed the present invention includes a combination of each aspect with one or more other aspects. Thus, the invention provides another aspect which includes the combination of any aspect with one or more aspect(s) Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 shows a side sectional view of a vehicle pneumatic brake line coupling according to a first embodiment of the present invention.

Fig. 2 shows a side sectional view of a vehicle pneumatic brake line coupling according to a second embodiment of the present invention.

Fig. 1 shows a vehicle pneumatic brake line coupling 100 according to a first embodiment of the present invention.

The coupling 100 has an inlet port 101, an outlet port 102 and an air conduit 103 that is in fluid communication there between.

A filter 104 is mounted between the inlet port 101 and the outlet port 102 in housing 126. The filter 104 is aligned with the inlet port 101 and the outlet port 102 along a longitudinal axis A-A of the coupling 100. The filter 104 has top-hat shape with a protruding rim 107 and a recess 106 extending towards the outlet port 102.

A base portion 108 and side wall portions 109 of the recess 106 comprise the filtration medium 110 which is an air permeable material. The filtration medium 110 is a plastics material mesh. The plastics material mesh has suitably fine holes for filtering dirt and other particulate matter. Typically, the plastics material mesh filters particulate matter having a size greater than 50 microns. (That is, the particles having a length, width or height greater than 50 microns.) The filter 104 has struts ill extending from the rim 107 to the base 108 to provide a window frame structure. Windows of the filtration medium 110 are arranged in the window frame structure.

The coupling has a filtering configuration, in which the filter 104 is in a filtering position and a bypass configuration, in which the filter 104 is in a bypass position (not shown) . The filter 104 is arranged to move between the filtering position and the bypass position.

Fig. 1 shows the filter 104 in the filtering position, in which the filter 104 abuts a ledge portion 105 of the housing 126. The ledge portion 105 is formed by virtue of the housing 126 widening between the inlet port 101 and the outlet port 102. The housing 126 widens to accommodate the filter 104 in chamber 104a.

The filter 104 is urged against the ledge portion 105 by spring element 112. A first end 113 of spring element 112 abuts against the rim portion 107 of the filter 104.

A second end 114 of the spring element 112 abuts against a first end 115 of a retainer 116. Transverse movement of the spring element 112 is limited by virtue of the first end 113 of the spring element 112 engaging with a groove 117 and a concentric lip 118, extending around the rim, and the second end 114 of the spring element 112 engaging with projection portion 119.

The retainer 116 has an outer thread 120 and an inner bore (not shown) for accommodating air flow. The outer thread 120 engages with a threaded bore 121 of the housing 126. Retainer 116 has a hexagonal head 122 for engaging with a tool for providing torque such as a spanner or wrench. The retainer 116 is arranged to screw into the threaded bore 121 of the housing 126 until the hexagonal head 122 abuts an end 123 of the housing 126.

The retainer 116 has a groove 124 for accommodating an 0-ring 125, which when the retainer 116 is screwed tightly in the coupling 100, forms a seal between the end 123 of the housing 126 and the retainer 116.

In order to replace the filter 104, the retainer 116 is unscrewed by using e.g. a spanner until the retainer is free of the housing 126. The spring element 112 is then removed and the filter 104 may then be replaced. On reassembly, the spring element 112 slides over the filter 104 until the spring element 112 slots into the groove 117. The rim 107 of the filter is then placed in the chamber lO4a such that the rim 107 abuts the ledge portion 105. The retainer 116 is then rethreaded and the projecting portion 119 projects through the spring element 112 and aligns the spring element 112 and the filter 104 In use, unfiltered air enters the coupling through the inlet port 101. The unfiltered air then flows through the air conduit 103 towards the filter 104. During normal (filtering) operation, the spring element 112 urges the filter 104 towards the ledge portion 105 such that a seal is formed between the rim portion 107 and ledge portion 105. The unfiltered air then passes through the filtration medium 110. Dirt and particulate matter are then filtered from the airflow and are collected on the inlet surface (not shown) of the filtration medium 110. Clean air flows from the outlet surface of the filtration medium to the outlet port 102.

The clean air then flows to pneumatic braking system downstream of the outlet port 102. The pneumatic braking system is connected to the outlet port by pneumatic lines (not shown) If the filter 104 becomes blocked with dirt or other foreign bodies, then the filter is arranged to move from the filtering position to the bypass position. Once the pressure incident at the inlet surface exceeds the threshold inlet pressure, then the spring element 112 compresses and the filter 104 no longer abuts the ledge portion 105. Unfiltered air may then bypass the filter 104, by flowing between the ledge portion 105 and the rim portion 107. The unfiltered air can then flow downstream of the filter 104 into the pneumatic braking system. Some air may pass from the inlet surface to the outlet surface if the air filter is not completely blocked.

Typically, the coupling 100 as shown in Fig. 1 is one half of a coupling system. Indeed, Fig. 1 shows a male portion which interconnects with a reciprocal female portion. Typically the filter 104 is incorporated into either the male portion or the female portion. In an alternative embodiment, there may be an filter 104 incorporated into both the male and female portions.

Fig. 2 shows a sectional view of a vehicle pneumatic brake line coupling according to a second embodiment of the present invention.

The vehicle pneumatic brake line coupling 200 as shown in Fig. 2 has similar moveable filter arrangement as to the embodiment shown in Fig. 1 except that it is mounted in a female coupling. The filter operates in exactly the same way as described previously and is not described in detail in this embodiment.

Coupling 200 additionally has a valve lifter 201. The valve lifter 201 is a standard device for actuating compressed air valves in a towing vehicle. That is, when the coupling 200 is connected to a truck side coupling (not shown) with a one way valve, the valve lifter 201, actuates the one way valve and a supply of compressed air flows to an inlet port 203 of the coupling 200.

The respective coupling connecting portions 126, 202 of the couplings 100, 200 are previously known. The couplings 100 and 200 are designed to comply with dimensions and fittings as specified British Standards BS AU 138b:2000 and BS AU 138a: 1980, which are incorporated by reference inthis specification. The air conduit 103 of the male portion, e.g. as shown in Fig 1 has a diameter of 14.25mm. The housing of the male portion tapers towards the inlet port 101. The tapered portion 127 helps locate the male portion in the female portion when coupling the male portion to the female portion. A circumferential groove 128 is located on the male portion adjacent to the tapered portion 127. The depth of the circumferential groove 128 is 3.25mm. The distance from the inlet port 101 to the circumferential groove 128 is 30.50mm and the length of the male portion which is tapered is 29.75mm. The diameter of the tapered portioned 127 at its thickest is 23.7mm. The incline of the tapered portion 127 is 13.0 . The female portion has a reciprocal tapering (e.g. shown in Fig 2) . The circumferential groove 128 is arranged to receive ball bearings 204 of a locking mechanism 205 mounted in the female portion. The ball bearings 204 are 5.5mm in diameter. The ball bearings are locked into position with a slide collar 206, the slide collar 206 being mounted coaxially on the coupling and adjacent to the housing of the female portion at the inlet port 203. The slide collar 206 may move from a position in which the ball bearings 204 cannot move to a position where the ball bearings 204 can move. The slide collar 206 is biased to the position where the ball bearings 204 cannot move (i.e. locked) by a spring element 207. The slide collar 206 permits movement of the ball bearings 204 by virtue of a circumferential groove 208 on an inside surface of the slide collar 206, adjacent to the housing.

During connection of the male portion to the female portion, the slide collar 206 is slid towards the outlet port and the tapered portion 127 of the male portion is inserted into the female portion. The tapered portion 127 of the male portion engages the ball bearings 204, which move into the circumferential groove 208 on the inside surface of the slide collar 206. Once the male portion is fully inserted in the female portion, the ball bearings 204 engage with the circumferential groove 128 on the male portion. The slide collar 206 is then slid back towards the inlet port 203, locking the ball bearings 204 in place which locks the male portion with the female portion. In this way the locking mechanism provides a quick release locking mechanism such the pneumatic lines can be easily and quickly connected without screwing/unscrewing the pneumatic lines to the male and female portions.

In alternative embodiments, the couplings comply with European standards, e.g. Iso 1728-1980(E) or indeed other standard dimensions for vehicle pneumatic brake line couplings.

The present invention has been described with reference to preferred embodiments. For example, the filtration medium may be a foam based filter and the dirt is collected on the inlet surface of the foam and also on the inlet side within the foam. As another example of a modification, the housing 126 may be formed in two parts -a filter housing portion and a coupling portion. These may be connected via a bulkhead on the trailer. On

reading this disclosure, modifications of these

embodiments, further embodiments and modifications thereof will be apparent to the skilled person and as such are within the scope of the invention.

Claims

Claims 1. A vehicle pneumatic brake line coupling having a housing; an

inlet port; an outlet port; a filter having a filtration medium with inlet and outlet surfaces, the filter being mounted in the housing between the inlet port and the outlet port; wherein the coupling further has: a filtering configuration in which the majority airflow passes through the filtration medium; and a bypass configuration in which a bypass airflow bypasses the inlet surface of the filtration medium above a threshold inlet pressure at the filter.
2. A vehicle pneumatic brake line coupling according to claim 1 wherein the filter is moveable between a filtering position, in which the coupling is in the filtering configuration, and a bypass position, in which the coupling is in the bypass configuration, and when the inlet pressure at the filter is above the threshold pressure, the filter is arranged to move from the filtering position to the bypass position.
3. A vehicle pneumatic brake line coupling according to claims 1 or 2 wherein the filter has a recess, the recess projecting away from the direction of the airflow.
4. A vehicle pneumatic brake line coupling according to claims 1, 2 or 3 wherein the inlet port and the outlet port are aligned along a longitudinal axis of the coupling.
5. A vehicle pneumatic brake line coupling according to claim 4 wherein the filter is axially aligned with the inlet port and the outlet port.
6. A vehicle pneumatic brake line coupling according any one of claims 2 to 5 having a spring element for urging the filter towards the filtering position.
7. A vehicle pneumatic brake line coupling according to claim 6 wherein the vehicle pneumatic brake line coupling has a retainer engaging the spring element.
8. A vehicle pneumatic brake line coupling according to claim 7 wherein the retainer engages the spring element against the filter in compression.
9. A vehicle pneumatic brake line coupling according to claims 7 or 8, wherein the retainer has a thread for screwing into the housing of the coupling.
10. A vehicle pneumatic brake line coupling according to claims 7 or 9 wherein the retainer has a projecting portion for projecting through the spring element to locate the spring with respect to the retainer.
11. A vehicle pneumatic brake line coupling according to any one of claims 7 to 10 wherein the retainer has a shaped head for engaging with a tool for providing torque.
12. A vehicle pneumatic brake line coupling according to claims 7 to 11 wherein the retainer has a sealing member for sealing with the housing of the coupling.
13. A vehicle pneumatic brake line coupling according to any one of claims 5 to 12 wherein the filter and the spring are coaxial such that transverse movement of the filter with respect to the spring element is limited.
14. A vehicle pneumatic brake line coupling according to claim 13 wherein the filter fits snugly in the spring element.
15. A vehicle pneumatic brake line coupling according any one of the claims 5 to 14 wherein the filter has a groove and/or lip for cooperating with the spring element.
16. A vehicle pneumatic brake line coupling according any one of the preceding claims wherein the filter is removable for replacement and / or maintenance.
17. A vehicle pneumatic brake line coupling according to any of the preceding claims wherein the coupling has an pneumatic valve actuating means for actuating a valve when the coupling is connected such that air flows from the valve to the inlet port.
18. A vehicle pneumatic brake line coupling according any of the preceding claims wherein the filter abuts against a ledge portion of the housing so as to provide a seal between the housing and the filter when the filter is in the filtering position.
19. A vehicle pneumatic brake line coupling having a housing; an inlet port; an outlet port, the inlet port and the outlet port being aligned along a longitudinal axis of the coupling; and a first element of a quick-release locking means, the first element arranged to be releasably lockable with a second element of the quick-release locking means, the second element being mounted on another coupling; wherein the coupling further has a filter mounted in the housing between the inlet port and the outlet port.
A vehicle pneumatic brake line coupling according to claim 19, wherein the quick-release locking means is coaxial with the inlet port and the outlet port.
21. A vehicle pneumatic brake line coupling according to claims 19 or 20 wherein the first element of the quick-release locking means comprises: a moveable locking element arranged to move from a locking position to an unlocking position; and a slidable collar mounted adjacent to the housing, the slidable collar operatively engageable with the moveable locking element and the slidable collar is arranged to move from a first position to a second position, whereby the moveable locking element moves from the locking position to the unlocking position when the slidable collar moves from the first position to the second position.
22 A vehicle pneumatic brake line coupling according to any of claims 19 to 21 wherein the second element is a circumferential groove for receiving the movable locking element.
23. A vehicle pneumatic brake line coupling having a housing; an inlet port; an outlet port, the inlet port and the outlet port being aligned along a longitudinal axis of the coupling, a cleanable filtration medium mounted in the housing between the inlet port and the outlet port; a filtering configuration in which a first airflow passes through the cleanable filtration medium from the inlet port to the outlet port; and a cleaning configuration in which a second airflow passes through the cleanable filtration medium from the outlet port to the inlet port such that matter is dislodged from an inlet surface of the cleanable filtration medium.
24. A vehicle pneumatic brake line coupling according to claim 23 wherein the second airflow is residual air at a pressure above atmospheric air pressure at the outlet port equalizing with air at atmospheric air pressure at the inlet port.
25. A vehicle pneumatic brake line coupling according to claim 24 wherein the residual air pressure equalizes with atmospheric air pressure when the coupling is disconnected from another coupling.
26. A vehicle pneumatic brake line coupling according to any of claims 23 to 25 wherein the dislodged matter is discharged outside the coupling when the coupling is in the cleaning configuration.
27. A vehicle pneumatic brake line coupling according to claim 26 wherein the dislodged matter is transported to the outside environment when the coupling is in the cleaning configuration.
28. A vehicle pneumatic brake line coupling system having a first coupling; and a second coupling, the first and second couplings being connectable to each other; wherein the first coupling and/or the second coupling is a coupling according to any of the preceding claims.
29. A vehicle pneumatic brake line coupling system according to claim 28 wherein the first coupling is a male portion and the second coupling is a female portion.
30. A vehicle pneumatic brake line coupling system according to claim 29 wherein the male portion has a tapered end.
31. A vehicle pneumatic brake line coupling system according to claim 30 wherein the female portion has a tapered bore so as to accommodate the tapered end of the male portion.
32. A vehicle pneumatic brake line coupling system according to any of claims 29 to 31 wherein the first element of the quick-release locking means is mounted on the female portion and the second element of the quick-release locking means is mounted on the male portion.
33. A vehicle pneumatic braking system having a vehicle pneumatic brake line coupling system according to any of claims 28 to 32.
34. A towing vehicle and trailer having a vehicle pneumatic braking system according to claim 33.
35. A vehicle pneumatic brake line coupling substantially as hereinbefore described with reference to either of the accompanying drawings.