GB2297531A

GB2297531A - Drive for Boats or Ships

Info

Publication number: GB2297531A
Application number: GB9601959A
Authority: GB
Inventors: Kurt Gutmann
Original assignee: Gutmann Messtechnik AG
Current assignee: Gutmann Messtechnik AG
Priority date: 1995-01-31
Filing date: 1996-01-31
Publication date: 1996-08-07
Also published as: ITMI960129A0; ITMI960129A1; GB9601959D0; DE19502959C1; FR2729916A1; IT1282065B1

Description

1 Drive for Boats or Ships 2297531 The invention relates to a drive for

boats or ships, including a combustion engine and an exhaust duct having its outlet below the water line, wherein a catalytic converter is provided in the run of the exhaust pipe above the water line.

In such drives the engine or engines is/are located inboard in an engine compartment and the exhaust gases coming from the combustion engine are conducted to the outside by way of an exhaust duct (exhaust pipe) and then issue under the surface of the water in order to damp the noise emission. The exhaust duct extending partly within the engine compartment and the heat it radiates cause an unwanted rise in the temperature of the engine compartment. To reduce this temperature rise it is already known to inject cooling water into the exhaust duct.

With combustion engines a pulsation of the exhaust gas flow is developed in the exhaust duct, leading particularly at low speed to intensive pressure-suction fluctuations in the exhaust. This results in water being sucked into the exhaust and then expelled again, particularly in the case of large-volume engines.

In adverse circumstances there may also be a so-called "water return shock" if water gets into the engine via the exhaust valves, possibly causing considerable damage. A further shortcoming is that boat engines are capable of being improved with respect to pollutant emission.

It would be advantageous to provide a drive of the type set forth at the outset, which has a reduced pollutant emission and avoids the further above-mentioned drawbacks, particularly the ingress of water into the exhaust duct.

According to a first aspect of the present invention, the exhaust duct has, between the exhaust outlet of the engine and the water line, a connection for a vent duct', and in the vent duct there is a check valve arranged to open at subatmospheric pressure and to close at overpressure.

The pollutant emission is effectively reduced by the catalytic converter. Further, the catalytic converter used in conjunction with the boat engine is effectively protected against the ingress of water by the vent duct with check valve. Through the air compensation, there is an intake of air instead of the considerably heavier medium of water in the time segment when underpressure prevails in the exhaust. The air supply to prevent ingress of water could also be provided for exhaust ducts not incorporating a catalytic converter and would dependably prevent water from penetrating the exhaust or engine. However, this measure is of especial significance in conjunction with the use of a catalytic converter, because water penetrating the catalytic converter would be a considerable hazard. This is so because during operation of the engine the catalytic converter can reach temperatures of above 10000 Celsius and penetrating water could lead to explosive vaporization. This is effectively and simply prevented by the first aspect of the present invention.

In the absence of the measure embodying the first aspect of the invention, the danger of water penetrating the catalytic converter is especially great because by design it is situated comparatively close to the outlet 3 end of the exhaust and thus also close to the surface of the water.

According to a second aspect of the invention, a flap or the like for closing the exhaust duct when the engine is at rest is provided in the zone situated above the water line and on the outlet side of the catalytic converter.

The catalytic converter is sealed in the direction of the water by this closing element and is thereby also protected against condensate when the engine is at rest.

According to a third aspect of the present invention, the catalytic converter has a multilayer cooling jacket with at least one air duct directly adjoining the outer jacket of the catalytic converter and at least one outwardly adjoining cooling water duct.

The measures employed heretofore for cooling the exhaust duct, for instance by injecting cooling water into the exhaust duct or by insulating the exhaust duct, are no longer possible or no longer suffice when a catalytic converter is used.

However, according to the third aspect of the invention the increased heat generated in connection with a catalytic converter can be effectively shielded outwardly by a multilayer cooling jacket. Therefore the temperature of the engine compartment and interior of the boat is not raised further if a catalytic converter is used. Tests have shown that although the catalytic converter gas a very high working temperature of e. g. 900' Celsius, the outer jacket temperature of the cooling jacket is sure to remain below the prescribed limit of 90' Celsius.

The cooling jacket is preferably three-layered with an 4 inner air cooling jacket directly adjacent to the outer jacket of the catalytic converter, an outwardly adjoining water cooling jacket and an outer solid insulating jacket. Especially effective heat insulation is thereby enabled, particularly given very high differences in temperature between the inner zone and outer zone.

is Preferred embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:

Fig. 1 Fig. 2 Fig. 3 Fig. 4 Figs. 5 to 8 is a schematic representation of a boat drive with exhaust duct, is a longitudinal section through a catalytic converter with cooling jacket, is a view of the outlet end of a catalytic converter with adjoining exhaust duct and connection for a vent duct, is a cross section of the portion of the exhaust duct and catalytic converter depicted in Figure 3, are different views of the portions of the exhaust duct and catalytic converter at the outlet end, together with a flap, Fig. 9 is a schematic representation of an exhaust duct with vent means and controlled check valves of a double exhaust system, Fig. 10 is a side view of a passage for a lambda probe, - 5 Fig. 11 is a plan view of a guide- and retaining ring for one end of the catalytic converter, Fig. 12 is a side view of the guide ring depicted in Figure 11, Fig. 13 is a longitudinal section through an exhaust duct in the region of a dividing point with inserted catalytic converter and Fig. 14 is a representation corresponding substantially to Figure 13, but here with a different fixing of the catalytic converter.

Figure 1 depicts, partly in schematic form, a drive 1 for boats or ships. The associated combustion engine is represented schematically as a function block 2 and its exhaust gas outlets 3 are connected to an exhaust duct 4 having its outlet 5 below the water line 6.

A catalytic converter 7 for reduction of toxic substances is placed in the run of the exhaust duct 4 at a location above the water line 6 in the use position of the boat.

During operation of the combustion engine 2, a pulsation of the exhaust gas flow is developed in the exhaust duct 4 with the result that at low speed, particularly during idling, alternating overpressure and underpressure are generated within the exhaust duct 4. In the overpressure phase the exhaust gases are pressed under the surface of the water 6 and expelled at the exhaust outlet 5. In the underpressure phase there has been the problem with the conventional exhaust ducts that water is taken in via the outlet 5.

For reasons of space a catalytic converter 7 is usually 6 mounted with its outlet 8 comparatively close to the surface of the water 6. When a catalytic converter 7 is used, the ingress of water would lead to it being damaged or destroyed. According to the first aspect of the invention it is therefore proposed that, between the exhaust outlet of the engine 2 and the water line 6, the exhaust duct 4 is provided with a connection 9 for a vent duct. In the run of this vent duct 10 there is a check valve 11 which opens at underpressure within the exhaust duct 4 and enables air to be admitted to the exhaust duct 4 Therefore in exhaust gas by way of an air inlet pipe 12. the suction phase of the pulsation of current, not water, but the considerable lighter medium of air is taken in. water is therefore efficiently and dependably prevented from penetrating the catalytic converter during this pulsation.

Figure 1 indicates that more than one vent duct 10 can be connected to the check valve 11 and air inlet pipe 12. It is therefore sufficient if there is one vent means with branched vent ducts 10 to a plurality of exhaust ducts 4.

To reduce the heat emission in the vicinity of the catalytic converter 7, it is surrounded by a multilayer cooling jacket 13. By means of this cooling jacket it is ensured that the temperature of the outer cover does not exceed a maximum of 90 degrees. The cooling jacket is of multilayer structure in order to achieve the high temperature drop of approx. 1000' Celsius in the region of the catalytic converter and outer cover of the cooling jacket 13. Directly adjoined to the outer jacket 14 of the catalytic converter 7 is an air cooling jacket 15 adjoined by a water cooling jacket 16, followed outwardly by a solid insulating jacket 17.

The very high temperatures of the catalytic converter 7 are cooled down stepwise by the multilayer structure of the cooling jacket 13. The air cooling jacket directly adjacent to the catalytic converter brings about a cooling to the extent that the cooling medium conducted in the outwardly adjoining water cooling jacket 16 is not heated above the boiling point. The cooling water for the cooling jacket 13 can be admitted at the inlet side of the catalytic converter and be fed into the water cooling jacket 16 coaxially surrounding the exhaust duct 4, as is marked by arrows PF1. Arrow PF2 marks the exhaust gases.

The water cooling jacket 16 and also the air cooling jacket 15 terminate in the exhaust duct 4 at the outlet side of the catalytic converter 7. In this region the catalytic converter is slidably guided within the cooling jacket 13. For this purpose the catalytic converter is guided with a pipe socket 18 substantially coaxially in a guide ring 20 which has openings 19 therethrough (cf. Fig. 11) and is connected to the exhaust duct 4. This sliding support is necessary because between ambient temperature and operating temperature the catalytic converter changes in dimension, particularly in length.

Figures 3 and 4 show a transition zone between the outlet end of the catalytic converter 7 surrounded by the cooling jacket 13 and the exhaust duct 4. The transition piece serves to adapt the shape of the outlet of the catalytic converter to the shape of the adjoining exhaust duct 4. The exhaust duct often has an oval end piece, so that the outlet end adjoining the catalytic converter also has to have a complementary outer shape. The underside view of Figure 4 shows the pipe socket 18 which belongs to the catalytic converter 7 and is guided in the guide ring 20. Also to be clearly seen are the openings 19. The guide ring 20 is externally supported against an exhaust gas pipe 21. Arranged around the latter is an oval piping section 22 for adaptation of shape, continuing in the direction of flow to the exhaust duct 4. Between the exhaust gas pipe and the oval piping section 22 there are connectors or connecting webs 23 provided as stabilizers.

The space, which is formed between the exhaust gas pipe' 21 and the oval piping section 22 and continues in the direction of flow to the gas duct 4 and outlet 5, composes an expansion chamber where the vent system of the exhaust duct enters. The connection 9 for the vent duct 10 can also be seen.

The measures illustrated in Figures 5 and 6 or 7 and 8 are proposed to protect the catalytic converter against water vapour and condensate even when the engine is at rest, this being important particularly in the case of salt water. For this purpose a flap 25 closing the exhaust duct 4 when the engine is at rest is provided in an intermediate zone situated above the water line 6 and on the outlet side of the catalytic converter 7. This flap is kept open by the exhaust gas flow during operation of the engine. A pulsation of exhaust gas flow occurring at low engine speed does not lead to the flap 25 closing either, this being prevented by inertia. The flap 25 assumes the closing position only when the engine is at rest and there is no exhaust pressure. The flap 25 is pivotable at the side of the pipe socket 18 of the catalytic converter 7 and in the exemplary embodiment of Figure 5 is externally pressurized in the closing direction by a closing weight 26. Instead of this closing weight 26, a closing spring 27 can be provided, as shown in Figures 7 and 8.

In the case of a oval piping section 22, as was described with reference to Figures 3 and 4 and is provided in Figures 5 and 8, the closing mechanism closing weight 26, closing spring 27 - can'also be arranged beside the piping section 28 in the interspace 24.

In the exemplary embodiment of Figure 1 the check valve 11 is differential pressure-controlled, the valve body 40 being held in the closing position by gravity. Thi's represents a simple and reliable device.

In certain cases it may be necessary that electromagnetically operable valves, for instance, be used as the check valve, as is indicated schematically in Figure 9. Figure 9 shows an embodiment for a double exhaust system, showing air inlet pipes 12, vent ducts 10 and control valves 11a. In addition pressure sensors 28 are provided through which the pressure conditions prevailing in the exhaust duct 4 are measured. The pressure sensors 28 and the control valves 11a are connected via signal lines 29 and control lines 30 to an electronic control unit 31. Through this electronic control unit 31 the control valves 11a are opened at underpressure in the exhaust duct 4 and are closed at overpressure. In addition, through the electronic control unit 31, the control valves 11a can be closed above a predeterminable engine speed at which the pulsation of the exhaust gas flow no longer has any detrimental consequences. Power supply lines are designated 32.

As is to be seen in Figure 2, the cooling jacket has openings 33 and 34 therethrough on the one hand for a lambda probe and on the other hand for sampling exhaust gas after the catalytic converter. A slip bushing 35 is inserted in the opening 33 for the lambda probe and is connected to the walls of the water cooling jacket 16 and air cooling jacket 15 via special seals. Welded to - 10 the catalytic converter socket 36 on the inflow side is a connecting piece 37 screwed together with the slip bushing 35.

At the opening 34 for an exhaust gas sensor, the outside wall is provided with a screw fitting 38 for closing this opening 34 and the wall of the catalytic converter is provided with a guide tube 39. Figure 10 shows in detail the component parts provided for the use of the lambda probe before they are interconnected. In particular the slip bushing 35 and the connecting piece 37 are to be separately seen.

Figures 13 and 14 show catalytic converters 7a, 7b incorporated in the exhaust duct 4a in an embodiment modified compared to Figures 1 and 2. These catalytic converters 7a, 7b are incorporated in an exhaust duct 4a where there is already a water cooling jacket 16a. The outside wall of the water cooling jacket 16a is designated 41 and the inside wall, which simultaneously constitutes the exhaust gas pipe, is designated 42.

In the run of the exhaust duct 4a there is a dividing point 43 usually located between the exhaust elbow and the continuing exhaust duct. The exhaust duct ends there are held together by stay bolts (not shown). For explanatory purposes the dividing point is depicted drawn slightly apart. The seals 44 between the front ends of the exhaust duct and water cooling jacket 16a are also to be seen.

In the case of such existing exhaust ducts with a likewise already existing water cooling jacket 16a, it is proposed - if space allows - that the catalytic convert-er be incorporated directly in this region of the existing exhaust duct. The outside diameter of the catalytic converter is dimensioned in such a way that an air or gas cooling jacket 15a is formed between the outside wall 14a of the catalytic converter and the inside wall 42 of the exhaust pipe. In conjunction with the already present water cooling jacket 16a, there is again a multilayer cooling jacket 13a. Therefore here again the high operating temperatures of the catalytic converter are reduced stepwise through the air cooling jacket 15a and the outwardly adjoining, already present water cooling jacket 16a to such an extent that a temperature within the admissible range prevails externally of the cooling jackets 13a.

In the exemplary embodiment of Figure 13, the catalytic converter 7a has at its inflow end an annular fastening flange 45 connected to the exhaust duct, particularly to the inner exhaust gas pipe, in the vicinity of the dividing point 43. The catalytic converter is fastened only at this one end, so that the expansions of the catalytic converter occuring with the high differences in operating temperature do not have any detrimental consequences.

The fastening flange 45 connected to the catalyt1c converter 7a projects radially beyond the outer jacket 14a of the catalytic converter and is supported in an annular groove 46 formed in the face of the inside wall 42 constituting the exhaust gas pipe. The annular groove 46 and the fastening flange inserted there are dimensioned in such a way that the catalytic converter is held centred within and in spaced relationship to the exhaust gas pipe. Thus between catalytic converter and existing exhaust gas pipe there is an air gap to form the air cooling jacket 15a. The axial depth of the annular groove 46 and the thickness of the fastening flange 45 are dimensioned in such a way that the dividing point 43 remains unaffected, i.e. after insertion of the catalytic converter the available seal 12 and also the other parts can be used as before. It is therefore possible for a catalytic converter to be retrofitted very cost-advantageously.

The measures already described with reference to the previous Figures for protecting the catalytic converte against penetrating water or water vapour can also be used in this embodiment.

Figure 14 shows a different embodiment of a catalytic converter 7b in which the annular fastening flange 45 is not connected at one end of the catalytic converter, but in the course of the longitudinal expanse, for instance in the central region of the converter. The ends of the catalytic converter extend on the one hand in the direction of the engine and exhaust elbow and on the other hand into the exhaust duct continuing from the dividing point 43. It is also ensured here that the thermal expansions occuring in the catalytic converter during operation and thus the changes in length are not prevented.

The annular groove 46 may also be provided in the front end of the exhaust gas pipe coming from the engine, as is indicated by dashed lines in Figure 14.

The position of the fastening flange 45 on the catalytic converter is determined primarily by the space available and by the lengths of the straight sections of the exhaust gas pipe extending from the dividing points 43. Therefore, to suit the prevailing conditions, the fastening flange 45 can be provided at practically any point along the length of the respective catalytic converter to be used.

Mention is made that no exacting demands are made on the seal between fastening flange 45 and exhaust gas pipe, 13 - because exhaust gas penetrating the air or gas cooling jacket 15a through that location does not have any negative repercussions. In the embodiment of Figure 14 the upper zone of the air cooling jacket (gas cooling jacket) is open, so that exhaust gas can penetrate here. However this has practically no detrimental effects for the cooling operation, because it only has to be ensured that in order to avoid direct heat transfer there is no metallic contact between the outer jacket 14a of the catalytic converter and the inside wall 42 of the exhaust gas pipe.

14

Claims

Claims is 1. A drive for boats or ships, including a combustion engine and

an exhaust duct having its outlet below the water line, wherein a catalytic converter is provided in the run of the exhaust duct above the water line, and wherein between the exhaust outlet of the engine and the water line, the exhaust duct has a connection for a vent duct, and in said vent duct there is a check valve arranged to open at subatmospheric pressure and to close at overpressure.
2. A drive for boats or ships, including a combustion engine and an exhaust duct having its outlet below the water line, wherein a catalytic converter is provided in the run of the exhaust duct above the water line, and wherein a flap or the like for closing the exhaust duct when the engine is at rest is provided in the zone situated above the water line and on the outlet side of the catalytic converter.
3. A drive for boats or ships, including a combustion engine and an exhaust duct having its outlet below the water line, wherein a catalytic converter is provided in the run of the exhaust duct above the water line, wherein between the exhaust outlet of the engine and the water line, the exhaust duct has a connection for a vent duct, and in said vent duct there is a check valve arranged to open at subatmospheric pressure and to close at overpressure, and wherein a flap or the like for closing the exhaust duct when the engine is at rest is provided in the zone situated above the water line and on the outlet side of the catalytic converter.
4. A drive for boats or ships as claimed in claim 1, 2 or 3, wherein the catalytic converter has a multilayer cooling jacket with at least one air duct directly adjoining the outer jacket of the catalytic converter and at least one outwardly adjoining cooling water duct.
5. A drive for boats or ships, including a combustion engine and an exhaust duct having its outlet below the water line, wherein a catalytic converter is provided in the run of the exhaust duct above the water line, wherein the catalytic converter has a multilayer cooling jacket with at least one air duct directly adjoining the outer jacket of the catalytic converter and at least one outwardly adjoining cooling water duct.
6. A drive as claimed in any of claims 1, 3 and 4, wherein the check valve is differential pressurecontrolled.
7. A drive as claimed in claim 6, wherein the check valve has a valve body assuming the closing position by gravity.
8. A drive as claimed in any one of claims 1,3, 4, and 7, wherein a valve connected to a control unit is provided as check valve and that connected to the control unit is a pressure sensor for measuring the pressure within the exhaust duct.
9. A device as claimed in claim 8, wherein the valve is electromagnetically operable.
10. A drive as claimed in claim 8 or 9, wherein the check valve is controlled as a function of speed and is closed above a predeterminable engine speed.
11. A drive as claimed in any one of claims 1, 3, 4 or 6 to 10, wherein behind the check valve, as considered in the direction of air supply, the vent duct has connecting conduits to a plurality of catalytic 16 converters.
12. A drive as claimed in any one of claims 1, 3, 4 or 6 to 11, wherein the connection for the vent duct is arranged in front of or behind the catalytic converter.
13. A drive as claimed in claim 12, wherein the vent duct is arranged outside the cooling jacket of the catalytic converter.
14. A drive as claimed in any one of claims 2, 3, 4 or any claim appendant thereto, wherein the flap which is situated at the outlet side of the catalytic converter and closes the exhaust duct when the engine is at rest is pivotable and that an actuator is provided pivoting the flap into the closing position.
15. A drive as claimed in claim 14, wherein said actuator is a weight and/or a spring.
16. A drive as claimed in claim 4 or 5 or any claim appendant thereto, wherein the cooling jacket is three-layered with an inner air cooling jacket directly adjacent to the outer jacket of the catalytic converter, an outwardly adjoining water cooling jacket and an outer solid insulating jacket.
17. A drive as claimed in claim 4 or 5 or any claim appendant thereto, wherein one end of the catalytic converter is slidably connected within the cooling jacket to the exhaust duct and that for this purpose a pipe socket of the catalytic converter is guided substantially coaxially in a guide ring which has openings therethrough for the cooling medium or media and is connected to the exhaust duct.
18. A drive as claimed in any one of claims 4 or 5 or any claim appendant thereto, wherein the cooling jacket is provided with openings for a lambda probe, an exhaust sensor or the like, and that intermediate elements allowing thermal expansion are provided between the openings and the cooling jacket or exhaust duct.
19. A drive as claimed in claim 18, wherein said openings contain slip bushings or the like.
20. A drive as claimed in claim 18 or claim 19, wherein said intermediate elements take the form of seals.
21. A drive as claimed in any preceding claim including a water cooling jacket arranged at least partially around the exhaust duct, wherein the catalytic converter is inserted in that region of the exhaust duct which is provided with the water cooling jacket and the outside diameter of the catalytic converter is dimensioned in such a way that an air cooling jacket is composed between the outside wall of the catalytic converter and the inside wall of the exhaust duct, and wherein the catalytic converter has in the course of its longitudinal expanse a fastening flange held in the region of a dividing point of the exhaust duct.
22. A drive as claimed in claim 21, wherein the flange is provided at one end of the catalytic converter.

23. A drive as claimed in claim 21 or 22, wherein a seat is provided for the fastening flange of the catalytic converter and is located at least at one end of the exhaust duct terminating at a dividing point of the exhaust duct.
23. A drive as claimed in claim 23, wherein the seat i in the form of an annular groove on an end face of the S 18 duct.
24. A drive for boats or ships, substantially as described herein with reference to Figures 1 to 4 or figures 5 and 6 or Figures 7 and 8 or Figure 9 or Figure 10 or Figures 11 and 12 or Figure 3 or Figure 14.