GB2045859A

GB2045859A - A shielded exhaust pipe system for an internal combustion engine

Info

Publication number: GB2045859A
Application number: GB8005644A
Authority: GB
Original assignee: Kloeckner Humboldt Deutz AG
Current assignee: Kloeckner Humboldt Deutz AG
Priority date: 1979-03-07
Filing date: 1980-02-20
Publication date: 1980-11-05
Also published as: GB2045859B; DE2908878A1; CH648637A5; NL8000592A; FR2438160A1; FR2438160B1

Abstract

One or a plurality of exhaust pipes is/are shielded by means of: a heat insulating wall (3) surrounding and spaced from the pipe(s); an outer housing (7) surrounding the wall (3); an air gap (6) between the outer housing and heat insulating wall (3); and ventilation openings (8) (9) in the housing (7) permitting air to flow through and ventilate the air gap (6). <IMAGE>

Description

SPECIFICATION A shielded exhaust pipe system for a multi-cylinder reciprocating-piston internal combustion engine This invention relates to a shielded exhaust pipe system. Such a system may be used, for example, with a multi-cylinder reciprocating-piston internal combustion engine having at least one row of cylinders, the engine cylinder head or heads being connected to an exhaust pipe orto a bundle of exhaust pipes (extending for example parallel to the row of cylinders) by a bend in the pipe or pipe bundle, the pipe system being surrounded by shielding comprising a heat insulating wall disposed within an outer housing.

In a known exhaust pipe system of the construction described above, (see Ha nsa - Schiffahrt Schiffbau - Hafen, Volume 110, 1973, No. 6, page 448, Figure 11) a bundle of exhaust pipes is directly surrounded by the heat insulating wall, which in turn is surrounded by an insulating housing. The exhaust pipe system should have adequate shielding, particularly in marine engines, in order to reduce heat radiation, to provide a screen against any sprayed fuel and lubricating oil, and to reduce the risk of injury through contact. However, this known system only partly meets these requirements even if the heat insulating wall between the outer housing and the exhaust pipes is very thick, which inevitably produces an undesirably bulky shielded exhaust pipe system.In the known arrangement the temperature at the outside of the outer housing can rise far above 200on, since heat delivered to the insulating wall by the exhaust pipes can be discharged to atmosphere only via the outer surface of the outer housing.

The present invention therefore aims to provide a shielding arrangementforthe exhaust pipe system of an internal combustion engine which is efficient, compact and relatively simple to manufacture. With this aim in view, the invention is directed to a shielded exhaust pipe system for an internal combustion engine, the exhaust pipe system comprising an exhaust pipe or a bundle of exhaust pipes running alongside one another, wherein the shielding comprises a heat insulating wall surrounding the pipe or pipes and spaced therefrom, an outer housing surrounding the heat insulating wall, an air gap between the outer housing and the heat insulating wall, and ventilation openings in the outer housing permitting air to ventilate the air gap between the outer housing and the insulating wall.

The heat transfer to the insulating wall from the exhaust pipe system is considerably reduced by spacing the wall at a distance from the exhaust pipe system, and furthermore the heat produced at the outer surface of the wall can be efficiently dissipated by the air flow produced in the air gap between the wall and the outer housing. The ventilation openings preferably comprise air inlet and outlet openings in the outer housing disposed so that air can enter at the bottom and escape at the top of the housing, thus producing a flow of air and preventing the accumulation of heat. This results in a relatively low temperature at the outer surface of the outer housing even in the case of modern reciprocating-piston internal combustion engines having high output and high exhaust-gas temperatures.

The outer housing could be supported from the heat insulating wall, but it is much preferred to support the heat insulating wall from the outer housing, for example by spacers and screws and/or clamps. The screws can be offset relative to the spacers to prevent heat bridges being formed in this region. Preferably the air inlets and outlets are covered by spray guards disposed at a distance therefrom, the guards making it difficult for inflammable fluids to penetrate inside the outer housing, e.g.

if the fluids are sprayed as a result of a technical fault in the engine-room.

Optionally, a protective plate can be mounted on the spray guards or on the outer housing so as to form a cavity between the plate and housing or splash guards at a region where maintenance and repair work has to be carried out. The air flow in the air gap can be enhanced by force-ventilation of the air gap between the heat insulating wall and the outer housing. Additionally, the ventilation outlet openings can be connected to a vent system, so that the strongly heated air does not reach the engineroom but, if required, is discharged directly to the atmosphere, parallel to the exhaust gases.

A preferred embodiment of a shielded exhaust pipe system according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a cross-section through an exhaust pipe system surrounded according to the invention by shielding comprising a heat insulating wall and an outer housing; Figure 2 is a partial longitudinal section through the outer housing and the insulating wall, along line Il-Il in Figure 1, and Figure 3 is a general perspective view of the exhaust pipe system for a multi-cylinder reciprocating-piston internal combustion engine.

Figure 1 shows an exhaust pipe system consisting of a bundle of exhaust-gas pipes connected by pipe bends 2 to a multicylinder reciprocating-piston internal combustion engine. The system 1 is surrounded at a distance by a heat insulating wall 3 comprising a heat-insulating layer 5 enclosed in a sheet-metal jacket 4. The wall 3 is, in turn, surrounded by an outer housing 7, an air gap 6 being formed between the wall 3 and housing 7. The housing 7 has air inlet openings 8 in its bottom region and air outlet openings 9 at its top region, the ventilation openings 8 and 9 being covered by spray guards 10 connected to the housing but spaced from the region of the housing where the ventilation openings are formed.

The spray guards 10 co-operate with housing 7 to form ducts 14 from guiding the streams of incoming and outgoing air. A protective plate 11 is secured to the housing 7 or to one or more spray guards 10 at a place which must be protected from contact, thus forming a space or cavity 15 between the housing or splash guards and the plate 11. The spray guards 10 also strengthen the outer housing 7 and secure itto bends 2 of the exhaust pipes, which bends are preferably water-cooled.

Figure 2 shows how the wall 3 is supported from and secured to housing 7 by a screw-threaded connection 12 and a spacer 13. The screw-threaded connections 12 can be offset from the spacers 13, to reduce heat transfer between the wall 3 and the housing 7.

Figure 3 is a perspective view showing how the exhaust-pipe system is insulated according to the invention. The spray guards 10 extend along the entire length of the housing 7 and cover the air inlets 8 and outlets 9, which are disposed at uniform intervals at the bottom and top regions of housing 7.

The spray guards 10, inlets s and outlets 9 are similarly disposed at the end-faces of housing 7. In order to illustrate the air flow and the arrangement of openings 8 and 9 more clearly, the spray guards 10 are removed from one portion of the drawing.

The temperature at the outer surface of the insulating wall 3 is considerably reduced by disposiny wall 3 at a distance from the pipe system 1. The heat Is then efficiently dissipated from the outer surface of the wall 3 by the flow of air, which enters gap 6 via spray guards 10 and inlets 8 and comes out via outlets 9 and guards 10. Since the guards 10 co-operate with housing 7 to form ducts 14, the air gap 6 force-ventilated, e.g. by a fan (not shown) driven by the reciprocating-piston internal combustion engine. In addition, in the case of engines incorporated in ships, the exhaust air can be discharged to atmosphere parallel to the exhaust pipe system, by means of the ducts defined by the spray guards 10. This prevents any undesirable heating of the engine-room.

The means to force ventilate the air gap 6 can comprise an engine component having fan blades, which component is, for example, a flywheel or vibration damper disposed in a protective device constructed as an air collecting housing, the component being part of the engine using the exhaust pipe system. In another embodiment the means to force ventilate the air gap comprises a source of compressed air from the engine using the exhaust pipe system, said source being for example part of a stream of cooled air charge or super-compressed starting air.

Claims

1. A shielded exhaust pipe system for an internal combustion engine, the exhuast pipe system comprising an exhaust pipe or a bundle of exhaust pipes running alongside one another, wherein the shielding comprises a heat insulating wall surrounding the pipe or pipes and spaced therefrom, an outer housing surrounding the heat insulating wall, an air gap between the outer housing and the heat insulating wall, and ventilation openings in the outer housing permitting air to ventilate the air gap between the outer housing and the insulating wall.

2. A shielded exhaust pipe system according to claim 1, in which the ventilation openings are formed in the bottom region of the outer housing and also in the top region thereof.

3. A shielded exhaust pipe system according to claim 1 or claim 2, in which spray guards are mounted to shield the ventilation openings, the spray guards being disposed outside the outer housing and spaced from the region of the housing where the ventilation openings are formed.

4. A shielded exhaust pipe system according to claim 3, in which air ducts for guiding ventilating air entering and leaving the outer housing are defined between the outer housing and the splash guards.

5. A shielded exhaust pipe system according to claim 4, in which at least one duct contains a baffle plate or plates for guiding air towards an air inlet ventilation opening.

6. A shielded exhaust pipe system according to any preceding claim, in which the insulating wall is supported from the outer housing, for example by means of spacers and screws or clamps.

7. Ashielded exhaust pipe system according to any preceding claim, in which the outer housing is secured to a bent region of the exhaust pipe or exhaust pipe bundle, which region is preferably water cooled.

8. A shielded exhaust pipe system according to any preceding claim, in which an outermost protective plate is mounted either on the outer housing or on one or more splash guards for the ventilation openings, a cavity being formed between the outer protective plate and the outer housing or splash guard or guards.

9. A shielded exhaust pipe system according to any preceding claim having means to force-ventilate the air gap between the outer housing and the heat insulating wall.

10. A shielded exhaust pipe system according to claim 9, in which the means to force-ventilate the air gap comprises a fan driven by the internal combustion engine using the exhaust pipe system.

11. A shielded exhaust-pipe system according to claim 9, in which the means to force-ventilate the air gap comprises an engine component having fan blades, which component is, for example a flywheel or vibration damper disposed in a protective device constructed as an air collecting housing, the component being part of the engine using the exhaust pipe system.

12. A shielded exhaust pipe system according to claim 9, in which the means to force ventilate the air gap comprises a source of compressed air from the engine using the exhaust pipe system, said source being for example part of a stream of cooled air charge or super-compressed starting air.

13. A shielded exhaust pipe system according to any preceding claim, in which the insulating wall comprises a heat insulating layer disposed within a sheet metal jacket.

14. A shielded exhaust pipe system according to any preceding claim, in which the pipe system comprises a bundle of exhaust pipes extending for example parallel to a row of cylinders of the engine having the exhaust pipe system, the pipes of said bundle being connected to the engine cylinder head or heads by bent pipe end regions.

15. A shielded exhaust pipe system substantially as described herein with reference to the accompanying drawings.