GB2060054A - Internal combustion engine with a liquid-cooled exhaust system, and a vehicle including such an engine - Google Patents

Abstract

An exhaust pipe 1 cooled by non- recirculating raw water drawn from, for example, the sea. Should the raw water inlet become blocked, water will no longer be drawn into the mixing chamber 3, to mix with exhaust gases and the temperature of the exhaust pipe will rise. A bi-metallic temperature sensor is wrapped around the exhaust pipe and expands to close contacts 6 and 7 of a relay including a battery 8 and thus operates a warning light 4. In a further embodiment the raw water may be passed around the exhaust pipe and not mixed with exhaust gases. The sensor may be located interiorly of the exhaust pipe and may operate a temperature gauge by a direct mechanical action, and/or operate an audible alarm. <IMAGE>

Description

SPECIFICATION Internal combustion engine with a liquidcooled exhaust system, and a vehicle including such an engine.

Technical Field This invention relates to an internal combustion engine with a liquid-cooled exhaust system, and is particularly of a type in which liquid coolant is supplied to cool the exhaust system but does not recirculate around the system.

Background Art Such engines are particularly, but not exclusively, employed on boats, and the exhaust system is cooled by non-recirculating raw water drawn from the sea or river on which the boat floats. A pump, which may be in the form of an impeller, may be used to draw raw water in through an inlet, usually fitted with a filter, and hence to the exhaust system from where it is exhausted to the sea or river.

The engine block may be cooled by nonrecirculating raw water or it may be cooled by a separate, recirculating, freshwater supply. In the former case raw water may be drawn in through the aforementioned inlet and passed round the engine block before being supplied to the exhaust system.

The raw water may be mixed with exhaust gases emitted from the engine, in which case it will be mixed with the exhaust gases in a mixing chamber upstream of an exhaust outlet to cool the exhaust gases and additionally to muffle noise caused by the gases in the system. A U-bend may then be provided between the engine block and the exhaust system to prevent water in the exhaust system being sucked back into the block.

Where the raw water cools both the engine block and the exhaust, a thermostat may be provided on the engine to either admit or prevent the flow of raw water through the engine block, according to the temperature of the latter. A bypass arrangement allows the water to flow to the exhaust system whether the thermostat is open or closed. The raw water may pass from the engine block to the exhaust manifold to cool the manifold, before being mixed with the exhaust gases in the exhaust system.

If the engine block is cooled by a freshwater recirculating supply, then cooling raw water for the exhaust system may be employed to cool the recirculating fresh water by heat exchange. The raw water may be drawn into a mixing chamber in the exhaust system, where the raw water mixes with the exhaust gases and is passed out of the exhaust outlet; again, provision will usually be made to prevent raw water from being sucked back into the engine.

Where muffling of noise from the exhaust system by the raw water is considered unimportant, the raw water may not be mixed with the exhaust gases at all, but may, for example, be passed through a heat exchanger in the form of a tube coiled around the exhaust system.

It is acknowledged that the raw water inlet can easily become clogged with weed, even if it has a filter, thereby preventing raw water from being supplied to cool the exhaust system. Where the' engine block is cooled by a recirculating system, the lack of exhaust coolant may not affect the engine temperature to any marked extent for a considerable time, so that there may be no indication from an engine temperature gauge that the exhaust temperature is excessive. An excessively hot exhaust system may cause substantial damage to bodywork around the exhaust system, and can be particularly dangerous in a boat. It is an object of the present invention to alleviate the likelihood of such damage and danger arising.

Statement of Invention and Advantages According to the present invention there is provided: an internal combustion engine including an exhaust system; means capable of supplying a liquid in a non-recirculating manner to cool the exhaust system; means capable of sensing an increase in temperature of the exhaust system, and indicating means responsive to the sensing means for indicating the increase or a predetermined increase in temperature of the exhaust system.

By the present invention a temperature increase in the exhaust system may be brought to attention before a substantial increase in engine block temperature occurs or before damage is caused to the exhaust system or any structure close to the exhaust system.

The sensing means may be located so that it is in the path of the exhaust gases or, preferably, it may be provided on the exterior of, for example, an exhaust pipe of the exhaust system. Where the liquid coolant is mixed with the exhaust gases in, for example, a mixing chamber, the sensor is conveniently located at or adjacent the downstream end of the mixing chamber.

Alternatively, where the liquid coolant is maintained separate from the exhaust gases, such as by supplying the coolant through flow means within or surrounding the exhaust pipe, to cool the exhaust gases by heat exchange, the sensor is conveniently located immediately downstream of such heat exchange position.

Particularly where the internal combustion engine of the present invention is located in a boat, the non-recirculating liquid coolant may comprise raw sea or river water. When the coolant is mixed with the exhaust gases, it will pass out of the exhaust system through the exhaust outlet. A separate coolant outlet will be provided if the coolant does not mix with the exhaust gases.

The internal combustion engine of the present invention may be used when the engine block is cooled either by a non-recirculating liquid or by a recirculating liquid. However, in the former case, the non-recirculating liquid cooling the engine block will generally also cool the exhaust system so that a blockage of the coolant inlet will likely also cause a substantial increase in engine temperature which may be monitored on an engine temperature gauge. In this case, the exhaust system temperature sensing means may cause the indicating means to give a clearly visible or audible signal at a predetermined increase in temperature to give additional warning of the general increase in temperature in the engine.

The indicating means may be a temperature measuring gauge and/or may comprise means which is capable of emitting a visual and/or audible warning signal in response to the predetermined increase in temperature of the exhaust system. The indicating means may be located some distance away from the exhaust system, perhaps in the cockpit of a vehicle housing the engine. The indicating means may be powered by a battery, and be capable of emitting a warning signal when sensing means, for example in the form of a bi-metallic strip or liquid (mercury) temperature sensor, expands and closes a contact relay connecting the battery to the indicating means. A fluid temperature sensor such as a bellows-type sensing means may alternatively be used.

Conveniently, where the indicating means is adapted to emit a warning signal, the sensing means may be connectable to a relay circuit including the indicating means and a power source and, upon sensing the predetermined rise in temperature, connects the indicating means to the power source.

Figures in the Drawings Two embodiments of an internal combustion engine in accordance with the invention will now be described by way of example only, with reference to the accompanying diagrammatic drawings, in which: FIGURE 1 shows one way of cooling an exhaust system of a liquid-cooled internal combustion engine, and shows sensing means, and indicating means for the exhaust system, and FIGURE 2 shows a second way of cooling an exhaust system of an internal combustion engine, and shows the sensing means and indicating means for this exhaust system.

Detailed description of the Drawings FIGURE 1 shows an exhaust pipe 1 of the exhaust system of the liquid-cooled internal combustion engine. The sensing means is generally indicated at 2 and is in the form of a bimetallic strip wrapped around the exterior of the exhaust pipe located downstream of a mixing chamber 3. The indicating means is in the form of a light bulb and is designated by the reference numeral 4.

A liquid coolant, such as raw sea or river water, can be drawn from an inlet, for example by an impeller (not shown), and passed into the mixing chamber through inlet pipe 5, directly from the sea or river. Alternatively, raw water in the inlet pipe 5 may have passed from the engine block (not shown) if the block is cooled by the raw water, or from the exhaust manifold (not shown) if this is cooled by the raw water. The raw water is mixed with exhaust gases flowing in the exhaust pipe, and the mixture passed further downstream along the exhaust pipe, in the direction shown in the FIGURE, to an exhaust outlet back into the sea or river.

If the temperature of the exhaust pipe increases, for instance if the supply of the raw water to the exhaust pipe is cut off or drastically reduced, the bimetallic strip bends, and closes contacts 6 and 7 if a predetermined increase in temperature is reached. When the cdntacts are closed, a power source in the form of a battery 8 is connected to the bulb 4, and the bulb emits a warning light. The bulb is conveniently mounted on the facia 9 in the cockpit of a boat housing the internal combustion engine and may thus give out a warning signal if a filter at the inlet for the raw water becomes clogged with weed. The bulb is disconnected from the battery (which may be 12 or 24 volts D.C.) as soon as the exhaust temperature falls again and the bi-metallic strip opens the contacts.That is to say, once the filter (not shown) at the inlet for the raw water has been unblocked, the warning light goes out automatically. However, there is no reason why the indicating means should not be switched off before the filter is unblocked by means mounted on the facia.

FIGURE 2 is similar to FIGURE 1 except that no mixing chamber is provided. Instead liquid coolant is passed through a heat exchanger 10, in the form of a tube coiled around the exhaust pipe 1.

The number of coils of the tube may be chosen to suit cooling requirements. The liquid coolant is not mixed with the exhaust gases and is passed out of an outlet separate to the outlet for the exhaust gases. The liquid coolant coils are in direct contact with the exterior of the exhaust pipe, and heat from the pipe is dissipated to the coolant, thereby cooling the exhaust.

If preferred, sensing means in the form of a direct-acting heat-sensitive fluid sensor may be wrapped around the exhaust pipe. In this case a temperature measuring gauge may be used to read the exhaust temperature continuously and thereby detect an increase in temperature of the exhaust. Where such a gauge is used, a power source such as a battery may or may not be required, and there is no reason why, in addition to a continuous temperature reading, a warning alarm signal should not be emitted when a predetermined temperature rise has been reached.

It will be appreciated that the scope of the invention extends to more sophisticated sensing and indicating means suitable to be employed on or in exhaust systems of engines of the general category mentioned. As alternatives to the described embodiment, the temperature sensing means may be located within the exhaust pipe to measure the temperature of the exhaust gases or gas/coolant mixture, or it may, for example, be located in a recess or other housing in the exhaust system. Further, while it is preferred that the indicating means is responsive to an electrical signal from the temperature sensing means, it will be appreciated that a mechanical connection may be suitable. If desired, the temperature sensing means or the indicating means may be employed to shut down the engine automatically upon a predetermined increase in temperature of the exhaust system.

Claims (17)

1. An internal combustion engine including an exhaust system; means capable of supplying a liquid in a non-recirculating manner to cool the exhaust system; means capable of sensing an increase in temperature of the exhaust system, and indicating means responsive to the sensing means for indicating the increase or a predetermined increase in temperature of the exhaust system.

2. An internal combustion engine as claimed in claim 1 in which the liquid coolant is introduced into the exhaust system in use to be mixed with exhaust gases in the system.

3. An internal combustion engine as claimed in claim 2 in which the exhaust system comprises a mixing chamber in which the liquid coolant is mixed with the exhaust gases, and wherein the sensing means is located at or adjacent the downstream end of the mixing chamber.

4. An internal combustion engine as claimed in claim 1 in which the means capable of supplying non-recirculating liquid coolant to cool the exhaust system comprises a heat exchanger in heat exchangeable relationship with the exhaust system, and through which the liquid coolant is capable of passing to cool the exhaust system, the sensing means being located downstream of the heat exchanger.

5. An internal combustion engine as claimed in any one of the preceding claims in which the sensing means is located exteriorly of the exhaust system.

6. An internal combustion engine as claimed in any one of the preceding claims in which the sensing means is connectable to a relay circuit including the indicating means and a power source to power the indicating means.

7. An internal combustion engine as claiined in claim 6 in which the sensing means is capable of expanding to close two contacts together, to cause the power source to actuate the indicating means.

8. An internal combustion engine as claimed in any preceding claim in which the sensing means comprises a bi-metallic strip.

9. An internal combustion engine as claimed in any one of claims 1 to 7 in which the sensing means comprises a fluid temperature sensor.

10. An internal combustion engine as claimed in claim 9 in which the fluid is mercury.

11. An internal combustion engine as claimed in claim 6 and any claim dependent thereon in which the power source comprises a battery.

12. An internal combustion engine as claimed in any one of the preceding claims in which the indicating means comprises a temperature measuring gauge.

13. An internal combustion engine as claimed in any one of the preceding claims in which the indicating means is capable of emitting an audible warning signal in response to a predetermined increase in temperature of the exhaust system.

14. An internal combustion engine as claimed in any one of claims 1 to 12 in which the indicating means is capable of emitting a visual warning signal in response to a predetermined increase in temperature of the exhaust system.

1 5. An internal combustion engine as claimed in claim 14 in which the indicating means comprises a light bulb.

1 6. An internal combustion engine as claimed in any one of the preceding claims in which the liquid coolant is water.

17. A liquid-cooled internal combustion engine including sensing means and indicating means substantially as herein described with reference to the accompanying drawings.

1 8. A vehicle, such as a boat comprising an internal combustion engine as claimed in any preceding claim.