GB2172386A

GB2172386A - An exhaust gas disposal system

Info

Publication number: GB2172386A
Application number: GB08606268A
Authority: GB
Inventors: Horst Fleischer
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1985-03-14
Filing date: 1986-03-13
Publication date: 1986-09-17
Also published as: GB2172386B; FR2578909A1; JPH0527759B2; NL185793B; NL8600403A; NL185793C; GB8606268D0; JPS61282600A; FR2578909B1; DE3509156C1

Abstract

An exhaust gas disposal system, for a tunnel through which vehicles can be driven, comprises an extraction duct (9) which is located above the vehicle (3) and follows the direction of the traffic lane and to which the exhaust gas (5) is conducted from the vehicle via a transfer pipe (8) which is shuttle-shaped in cross-section. The transfer pipe (8) slides through a pair of sealing lips (11) which seal a longitudinal slot (10) on the underside of the extraction duct (9). To reduce friction between the sealing lips (11) and transfer pipe (8) the non-rigid and flexibly designed sealing lips (11) are firstly held together magnetically by embedded magnetic strips (13, 13') with different polarities and secondly expanded magnetically by magnetic forces of the opposite polarity on the transfer pipe (8). According to a modified embodiment, the sealing lips (11) are expanded pneumatically in the contact area by an air jet arrangement integrated in the transfer pipe. An air gap between the sealing lips and transfer pipe allows ambient air having a cooling effect to be sucked in and a cushion of air to built up. <IMAGE>

Description

SPECIFICATION Exhaust gas disposal system for a driving section, such as a tunnel The invention relates to an exhaust gas disposal system for a driving section, particularly but not exclusively a tunnel, through which vehicle can travel. Such a system comprises an extraction duct which follows the direction of the traffic lane and a longitudinal slot which runs along a point on the circumference of the extraction duct and which can be sealed by a pair of mirror-image flexible sealing lips in contact with one another, and further comprising a transfer pipe of shuttle-shaped crosssection which moves with the vehicle and which extends from outside between the sealing lips and into the extraction duct and travels along the length of the sealing lips and then causes them to spread open momentarily at the point where it passes through the lips.A system of this type is also known for example from German Patent Specification 31 43 236.

With the previously known disposal system, exhaust gases can be disposed of economically in terms of investment costs and running costs for example in tunnels, as well as other driving sections, for example in town centres having heavy pedestrian traffic. Exhaust gas disposal in assembly and production bays is also conceivable in this way. The sealing lips and the shuttle-shaped transfer pipe which cooperates with these lips constitute a central problem with this method of exhaust gas disposal, that is particularly when used in public suburban passenger transport where the transfer pipe notionly slides between the sealing lips at relatively high speeds, but is also subjected to considerable heating at the exhaust gas end because of relatively high controlled engine loadings.This heating by exhaust gases and the heating caused by friction result in wear on the sealing lips and in the sealing lip material sticking to the transfer pipe, whereby the sliding properties are considerably impaired and the heating due to friction is even further increased.

The invention seeks to provide measures which enable trouble-free operation of the exhaust gas disposal system, on which the invention is based, to be maintained uninterruptedly over prolonged periods of time and also in the event of higher sliding speeds and engine performance.

According to the invention, there is provided an exhaust gas disposal system for a driving section, particularly a tunnel, through which vehicles can travel, comprising an extraction duct which follows the direction of the traffic lane and a longitudinal slot which runs along a point on the circumference of the extraction duct and which can be sealed by a pair of mirror-image flexible sealing lips in contact with one another, and further comprising a transfer pipe of shuttle-shaped cross-section which moves with the vehicle and which extends from outside between the sealing lips and into the extraction duct and travels along the length of the sealing lips and then causes them to spread open momentarily at the point where it passes through the lips, wherein flexible magnetic strips which have different polarities and are in the form of permanent magnets are embedded in respective areas of the free longitudinal edges lying adjacent to one another on the sealing lips, and magnets having the opposite polarity to that of each of the magnetic strips on the lips are attached to the lateral faces of the transfer pipe.

In an advantageous embodiment of the invention, a compressed air jet arrangement is provided in the side wall of the transfer pipe.

When the sealing lips are spread open magnetically, the magnetic force can be increased to such an extent that the sealing lips slide, at a distance therefrom, over the outer circumference of the shuttle-shaped transfer pipe and combine with this transfer pipe to form an air gap through which cooling ambient air can be drawn in. In addition, the magnetic expanding action of the sealing lips also has the advantage that the sealing lips are also held together by magnetic force, as a result of which they can have a particularly non-rigid design because they no longer need to support their own weight.

This also leads to a further reduction of frictional force. Where the compressed air jet is incorporated in the transfer pipe, the sealing lips are spread open pneumatically, and an air cushion builds up in the area where the sealing lips bear against the transfer pipe, which cushion largely prevents a direct sliding contact between the sealing lips and transfer pipe and moreover produces an intensive cooling effect.

Practical embodiments of the invention will now be described by way of examples and with reference to the accompanying drawings, in which: Figure 1 shows a longitudinal view of a trackforming traffic lane having an exhaust gas disposal system above the vehicle, Figure 2 shows a cross-section through and an oblique view of, the extraction duct shown in Figure 1, Figure 3 shows a cross-section, on an enlarged scale, through the sealing lips of the extraction duct of Figures 1 and 2, showing the embedded magnetic strips, but not the intermediate transfer pipe, Figure 4 shows the sealing lips illustrated in Figure 3, but with the lips spread open by the magnetic outer walls of the shuttle-shaped transfer pipe passing between the lips, Figure 5shows an oblique view of the shuttleshaped transfer pipe seen in Figure 4, Figure 6 shows a detail of a shuttle-shaped monolithic magnet as a modification of the transfer pipe of Figure 5, Figure 7 shows a further modification of a magnetic transfer pipe having embedded electromagnets, Figures 8 and 9 show, respectively, a side view (Figure 8) and a plan view (Figure 9) of a further embodiment of a transfer pipe having an embedded air jet arrangement, and Figure 10 shows a further embodiment of a transfer pipe having an integrated air jet arrangement.

The track-forming traffic lane 1 shown in Figure 1 has, at the sides, transverse guide surfaces 2 which cooperate with transverse guide rollers 4 of the vehicle 3 and predetermine mechanically a precise directional guidance for the vehicle. In the roof or ceiling area of the driving section, which can be for example a tunnel, an extraction duct 9 is suspended and connected at various points to extraction fans (not shown in the drawing).

In order to conduct the exhaust gases from the internal combustion engine-driven vehicle 3 into the extraction duct 9, the exhaust 5 of the vehicle extends through the vehicle interior up to and above the roof. At this point the exhaust is directed into a tiltablefunnel 7, the surface of which is attached to a transfer pipe 8, 18 or 28 having a shuttle-shaped cross-section, shown for example in Figure 2. The tilt axis 6 of the funnel 7 and transfer pipe 8, 18 or 28 lies in the longitudinal direction of the vehicle and is approximately on a level with the end section of the exhaust 5.

Because the transfer pipe is tiltable, it is possible to compensate for lateral rolling movements of the vehicle body in the extraction duct area.

The underside of the extraction duct 9 has a longitudinal slot 10 which runs along the entire length of the extraction duct. The longitudinal slot is in turn sealed by a pair of flexible sealing lips 11 which are in a mirror image arrangement and the tips of the longitudinal edges 12 forming a seal against one another.

In the embodiment shown in Figures 1 to 4, the sealing lips 11 are in the form of thin, one-layer lips.

Even though, in the fitted position, they hang down with a relative steepness when in the closed state, there is nevertheless still a relatively great gravitational force acting on the sealing lips which tends to draw the lips apart. In order that the sealing lips 11 may still be kept closed in opposition to the gravitational action even without a vacuum occurring inside the extraction duct 9, flexible magnetic strips 13 or 13' having different polarities are embedded in respective areas of the free longitudinal edges 12 lying adjacent to one another on the sealing lips 11.

In this case they are flexible magnetic strips which may be deflected laterally corresponding to the shuttle-shaped contour of the transfer pipe without any appreciable force being applied. The magnetic strips hold the two free longitudinal edges 12 firmly together magnetically, thereby making it possible for the sealing lips to have a relatively non-rigid design as a result of which the frictional force on the shuttle-shaped transfer pipe sliding through the channel can be very low.

In the embodiments shown in figures 4 to 7 the side walls of the transfer pipe 8 or 18 are also magnetic, but with opposite polarity to that of the respective magnetic strips 13, 13' so that the contact forces between the free longitudinal edges 12 and a transfer pipe are reduced magnetically.

in the embodiment shown in Figures 4 and 5 a pair of curved magnetic plates 14 or 14' in the form of permanent magnets having the opposite polarity to that of the corresponding magnetic strips 13' or 13 are placed around the shuttle-shaped transfer pipe 8.

Since the curvature of the shuttle-shaped transfer pipe is relatively long in the longitudinal direction of the vehicle, relatively weak magnetic forces are sufficient to curve the sealing lips around the shuttle-shaped transfer pipe with the minimum possible frictional force. When the permanent magnets 14 or 14' or the magnetic strips 13' and 13 are sufficiently magnetized, even a small air gap 16 is formed between, on one side, the lateral surface of the transfer pipe or corresponding magnetic plates and the inner side qf the free longitudinal edges 12 on the sealing lips. Ambient air can be drawn vertically through this air gap, which has the effect of, firstly, cooling the surfaces and, secondly, also causing the build-up of a hydrodynamically effective air cushion between the surfaces sliding one over the other.If, despite this, a slight contact still occurs in places between the surfaces moving relative to one another, friction can be reduced by a low-friction slideway lining 21 made preferably of polytetrafluoroethylene.

In contrast to the two plate-shaped magnets 14, 14' illustrated in Figure 4 or Figure 5, the embodiment of Figure 6 shows a shuttle-shaped monolithic magnet 15 in which the interior is also in the form of a pipeshaped and shuttle-shaped passage. This monolithic permanent magnet can be slipped over the transfer pipe 8 in place of the screw-on magnetic plates 14 or 14'. This monolithic design of the permanent magnet has the advantage of making the magnet more easily interchangeable and pivotable.

It is actually conceivable that not only the traffic lanes, but also if the exhaust and extraction duct 9 are arranged centrally-the extraction duct can be used in both directions of travel. In order that the magnets on the vehicle side may still be provided with the correct polarity, i.e. the opposite polarity to that of the magnetic strips on the lip side, in such cases where the shuttle-shaped transfer pipe occupies a position turned through 180 between the sealing lips, the magnet 15 in a case such as mentioned above would have to be turned or pivoted in such a manner that the polarity of the magnet 15 is in each case opposite to the polarity of the magnetic strips 13 or 13' in both directions of travel.

Such pivotability is more likely to be achieved with a monolithic and pipe-shaped permanent magnet.

Electromagnetic magnetization of the plateshaped magnetic shoes 17 is provided in the case of the transfer pipe shown in Figure 7, that is, between the two curved plate-shaped magnetic shoes 17 in the illustrated embodiment there are arranged a total ofthree exciting coils 20 or 20' which extend along the surface generating lines and can be fed by an electrical system on the vehicle. Ribs 19, which are made of a non-magnetic material, for example ceramic material, and which are moreover wearresistant and have good sliding properties, are fitted in the area of the points of the electromagnet having a shuttle-shaped cross-section. Again, it is conceivable in this case to provide a friction-reducing slideway lining. The actual transfer pipe 18 in the embodiment shown in Figure 7 is formed by a pair of pipes 18 of trapezoidal cross-section extending between the exciting coils 20 and 20'; these two trapezoidal pipes 18 are arranged as a mirror image of one another and form approximately a pipeshaped 'shuttle'. The advantage of the electromag netically designed transfer pipe according to Figure 7 is that, firstly, the magnetic force can be controlled by an appropriate power supply, that secondly it is possible to compensate for a drop in magnetization due to temperature, and that finally the polarity of the electromagnet is reversible, which may become necessary in the example of use mentioned above.

In the embodiments shown in Figures 8 to 10 a different solution is used to reduce friction between the sealing lip and transfer pipe, that is, in these embodiments air jets are integrated in the transfer pipes. This method of designing the transfer pipes is not dependent on having embedded magnetic stirps in the free longitudinal edges of the sealing lips even though this is suitable for a non-rigid design of the sealing lips.

In such a case it is advantageous for at least the outer wall 22 or 22' of the double-walled transfer pipe 28 or 28' to be designed in non-magnetic or non-magnetizable material, for example stainless steel. This prevents the sealing lips from sticking magnetically to the transfer pipe. The inner wall 23 or 23' of the transfer pipe is also advantageously composed of non-magnetic material in order to counteract this with particular effect. The air jet arrangement is formed by designing the transfer pipe 28 or 28' with a double wall in it shuttle-shaped cross-sectional area and providing the outer wall 22 or 22' with a large number of air outlet holes 27; the intermediate space enclosed by the double wall is connected to a compressed air source inside the vehicle via a connecting line 24.By forcing compressed air out of the air outlet holes a cushion of air is built up in the relatively large area between, on the one side, free longitudinal edges of the sealing lips and, on the other side, the outer wall of the transfer pipe, this air cushion guiding the sealing lips around the shuttle-shaped transfer pipe almost without any contact taking place. In addition, the transfer pipe and also the sliding gap are intensively cooled by the injected compressed air.

In the transfer pipe shown in Figures 8 and 9 there are provided in the intermediate space a plurality of small distributing pipes 25 which are in a comb-like arrangement and extend parallel to the surface generating lines of the shuttle-shaped transfer pipe.

In fluidic terms they are in parallel connection with one another and are each associated with a group of air outlet holes 27 lying vertically one below another.

In the embodiment of the transfer pipe 28' shown in Figure 10 the plate forming the inner wall 23' is provided with spacer bosses 26 which are directed towards the intermediate space and are stamped in the inner wall plate in large numbers and in accordance with a regular pattern. A communicating intermediate space between the inner wall 23 and the smooth-faced outer wall 22' is created by these spacer bosses. By means of appropriate beading or bordering in the upper end area of the transfer pipe 28 or by appropriate seal welding to the funnel 7, the intermediate space is sealed on the outside. Only the air outlet holes 27 which are arranged at regular intervals in the area of the smooth-faced wall allow air to escape from the intermediate space. The embodiment shown in Figure 10 consists of a particularly small number of individual parts and can therefore be manufactured economically. For the sake of completeness it should also be mentioned that a low-friction slideway lining 21 can also be provided in the case of pneumatically operating friction-reducing transfer pipes 28 or 28'.

Claims

1. An exhaust gas disposal system for a driving section, particularly a tunnel, through which vehicles can travel, comprising an extraction duct which follows the direction of the traffic lane and a longitudinal slot which runs along a point on the circumference of the extraction duct and which can be sealed by a pair of mirror-image flexible sealing lips in contact with one another, and further comprising a transfer pipe of shuttle-shaped crosssection which moves with the vehicle and which extends from outside between the sealing lips and into the extraction duct and travels along the length of the sealing lips and then causes them to spread open momentarily at the point where it passes through the lips, wherein flexible magnetic strips which have different polarities and are in the form of permanent magnets are embedded in respective areas of the free longitudinal edges lying adjacent to one another on the sealing lips, and magnets having the opposite polarity to that of each of the magnetic strips on the lips are attached to the lateral faces of the transfer pipe.

2. An exhaust gas disposal system according to Claim 1, wherein the polarity of the magnets of the transfer pipe can be reversed.

3. An exhaust gas disposal system according to Claim 1 or Claim 2, wherein the magnets of the transfer pipe can be tilted through 180" either independently or together with the transfer pipe.

4. An exhaust gas disposal system comprising an extraction duct which follows the direction of the traffic lane and a longitudinal slot which runs along a point on the circumference of the extraction duct and which can be sealed by a pair of mirror-image flexible sealing lips in contact with one another, and further comprising a transfer pipe of shuttle-shaped cross-section which moves with the vehicle and which extends from outside between the sealing lips and into the extraction duct and travels along the length of the sealing lips and then causes them to spread open momentarily at the point where it passes through the lips, wherein a compressed air jet is set into the side wall of the transfer pipe.

5. An exhaust gas disposal system according to Claim 4, wherein the transfer pipe has a doublewalled design in the area of its shuttle-shaped cross-section, that the outer wall is provided with a plurality of air outlet holes, and the intermediate space enclosed by the double wall is connected to a compressed air source.

6. An exhaust gas disposal system according to Claim 5, wherein there are provided, in the intermediate space, a plurality of small distributing pipes which are in a comb-like arrangement and supply compressed air to the air outlet holes which are associated in groups with each distributing pipe.

7. An exhaust gas disposal system according to Claim 5, wherein one of two plate-like members forming the double wall, is provided with spacermembers which are directed towards the intermediate space.

8. An exhaust gas disposal system according to Claim 7, wherein the spacer members are provided on the inner of the two plate-like members.

9. An exhaust gas disposal system according to any one of Claims 4 to 8, wherein flexible magnetic strips which have different polarities and are in the form of permanent magnets are embedded in respective areas of the free longitudinal edges lying adjacent to one another on the sealing lips.

10. An exhaust gas disposal system according to any one of Claims 1 to 8, wherein the shuttle-shaped transfer pipe is provided on the outer side with a friction-reducing lining.

11. An exhaust gas disposal-system according to any one of claims 1 to 10, wherein the frictionreducing lining is made of polytetrafluoroethylene.

12. An exhaust gas disposal system substantially as hereinbefore described and with reference to the accompanying drawings.