GB2564431B

GB2564431B - A system and method for heating a vehicle catalytic converter

Info

Publication number: GB2564431B
Application number: GB1711036.2A
Authority: GB
Inventors: Gregory Jonathan; Mehring Jan; Lineham Owen; David Bunn Matthew; Sarah Williams Kirsty
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2017-07-10
Filing date: 2017-07-10
Publication date: 2019-07-17
Anticipated expiration: 2037-07-10
Also published as: GB2564431A; GB201711036D0; DE102018114504A1

Description

A SYSTEM AND METHOD FOR HEATING A VEHICLE CATALYTIC CONVERTER Technical Field

This disclosure relates generally to a system and method for heating a vehicle catalytic converter and particularly, although not exclusively, relates to a system and method for heating a vehicle catalytic converter comprising heat transfer from the vehicle exhaust gas to the catalytic converter.

Background

Catalytic converters are used in the exhaust systems of automobiles and cause a reaction in the exhaust gases to turn harmful emissions into more environmentally friendly and inert emissions.

Catalytic converters on petrol engines require a working temperature of 400 degrees Celsius or above in order to efficiently convert polluting exhaust gases into inert ones. A common problem with catalytic converters is that when the engine is first switched on the catalyst is cold and requires a period of time to warm up in order to attain a working temperature. Below BOO degrees Celsius conversion efficiency of the catalyst is typically less than ten percent and vehicles fitted with catalytic converters typically emit their most polluting emissions during the first five minutes of engine operation before the catalytic converter has warmed up. This situation is made even worse during cold weather.

Gasoline and diesel particulate filters suffer from the same issues in that they need to attain a working temperature to function efficiently. When the engine is first switched on the particulate filter is cold and requires a period of time to warm up to attain the working temperature. During the warming up phase the engine burns additional fuel to provide extra heat to the filter to help facilitate regeneration. This extra fuel requirement negatively affects the efficiency of the system. Once the required temperature has been reached then regeneration can occur without the need for the engine to burn extra fuel and a system efficiency is established.

Additional heating of the catalytic converter to reduce the time taken to achieve working temperature has been suggested. Catalytic converter heating can be achieved by maximizing heat transfer to the exhaust passage using a large amount of spark retard and late injection timing to reduce the combustion efficiency and increase the amount of hot exhaust gas flow. However, this method negatively affects fuel economy and noise, vibration and harshness (NVH) and a fuel economy penalty over the New European Driving Cycle (NEDC). A further common problem suffered by catalytic converters is overheating once a working temperature has been achieved. When the temperature within the catalytic converter continues to rise, and reaches a certain point, the catalytic converter will cease to work efficiently and may become progressively compromised.

It is therefore necessary to provide a system and method for reducing the time taken for a catalytic converter to reach a working temperature without the aforementioned problems.

Statements of Invention

According to a first aspect of the present disclosure, there is provided an apparatus for establishing or maintaining the temperature of a catalytic converter within a predetermined temperature range, wherein the apparatus comprises an exhaust passage for the flow of exhaust gas from an engine, a catalytic converter disposed in the exhaust passage, a heat exchanger in thermal communication with the exhaust passage, and a flow passage that at least partially surrounds the catalytic converter and is in thermal communication with the heat exchanger, wherein a heat transfer fluid is disposed within the flow passage and the apparatus is configured to enable the heat transfer fluid to flow in a cycle around the heat exchanger and the catalytic converter and thereby transfer heat between the heat exchanger and the catalytic converter.

The heat exchanger comprises a conduit configured to allow exhaust gas to flow there through; and the heat exchanger further comprises at least one heat exchanger valve configured to be reversibly deployed to prevent the flow of exhaust gas within the conduit.

According to a second aspect of the present disclosure, there is provided a system for heating a catalytic converter, wherein the system comprises an exhaust passage for the flow of exhaust gas from an engine, a catalytic converter disposed in the exhaust passage, a heat exchanger in thermal communication with the exhaust passage, and a flow passage that at least partially surrounds the catalytic converter and is in thermal communication with the heat exchanger, wherein a heat transfer fluid is disposed within the flow passage and the system is configured to enable the heat transfer fluid to flow in a cycle around the heat exchanger and the catalytic converter and thereby transfer heat from the heat exchanger to the catalytic converter.

The system may further comprise an insulating jacket disposed around the catalytic converter. At least part of the flow passage may be disposed within the insulating jacket. The insulating jacket can retain heat in and around the catalytic converter over an extended period of time.

The insulating jacket may be spaced radially outwardly from the outer surface of the catalytic converter. By providing a space or gap between the jacket and the outer surface of the catalytic converter then unwanted or uncontrollable direct heat transfers can be avoided. Preferably the spacing is maintained by a least one isolation collar.

The heat transfer fluid may be a liquid. The liquid may have a high specific heat capacity. The liquid may have a high maximum fluid operating temperature.

The catalytic converter may further comprise insulation adjacent at least one of an exhaust gas entry point or an exhaust gas exit point, the insulation being capable of retaining heat during engine off. The catalytic converter may comprise the insulation at both the exhaust gas entry point and the exhaust gas exit point. The insulation may be in the form of an insulating sleeve or cap.

The heat exchanger may be downstream from the catalytic converter.

The system may further comprise at least one valve disposed within the flow passage, the valve may be configured to be reversibly deployed to prevent the heat transfer fluid from flowing in a cycle around the heat exchanger. The flow passage valve could be used to stop the transfer of thermal energy when the catalytic converter is determined to be overheating.

The heat exchanger valve could be used to stop the transfer of thermal energy when the catalytic converter is determined to be overheating.

The system may further comprise a cooling system comprising a further heat exchanger in thermal communication with the flow passage, a cooling means, and a further flow passage in thermal communication with the further heat exchanger and the cooling means, and a further heat transfer fluid is disposed within the further flow passage, the cooling system may be configured to enable the further heat transfer fluid to flow in a cycle around the further heat exchanger and the cooling means and thereby transfer heat from the heat exchanger to the cooling means. The cooling system could be used when the catalytic converter has overheated and must be cooled in order to return to an efficient working temperature.

According to a further aspect of the invention there is provided a vehicle comprising the above mentioned system for heating a vehicle catalytic converter.

According to a further aspect of the invention there is provided a method of heating a catalytic converter, the method comprising disposing a catalytic converter in a vehicle exhaust passage, disposing a heat exchanger in thermal communication with the vehicle exhaust passage, and providing a flow passage that at least partially surrounds the catalytic converter and is in thermal communication with the heat exchanger, and disposing a heat transfer fluid within the flow passage and enabling the heat transfer fluid to flow in a cycle around the heat exchanger and the catalytic converter and thereby transfer heat from the heat exchanger to the catalytic converter.

The method further comprises providing the heat exchanger with at least one conduit configured to allow the exhaust gas to flow there through; and configuring the heat exchanger valve to be reversibly deployed to prevent the flow of exhaust gas within the conduit.

The method may also comprise disposing an insulating jacket around the catalytic converter and may also comprise spacing the insulating jacket radially outwardly from an outer surface of the catalytic converter.

The method may further comprise disposing at least one valve in the flow passage, and configuring the valve to be reversibly deployed to prevent the heat transfer fluid from flowing in a cycle around the heat exchanger.

The method may further comprise providing a further heat exchanger in thermal communication with the flow passage, providing a cooling means, and providing a further flow passage in thermal communication with the further heat exchanger and the cooling means, and disposing a further heat transfer fluid within the further flow passage, and enabling the further heat transfer fluid to flow in a cycle around the further heat exchanger and the cooling means and thereby transfer heat from the further heat exchanger to the cooling means.

To avoid unnecessary duplication of effort and repetition of text in the specification, certain features are described in relation to only one or several aspects or embodiments of the invention. However, it is to be understood that, where it is technically possible, features described in relation to any aspect or embodiment of the invention may also be used with any other aspect or embodiment of the invention.

Brief Description of the Drawings

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

Figure 1 is a schematic view of a system according to an arrangement of the present disclosure;

Figure 2 is a schematic view of a system according to the arrangement of the present disclosure;

Figure 3 is a schematic view of a system according to the arrangement of the present disclosure; and

Figure 4 is a schematic view of a system according to the arrangement of the present disclosure.

Detailed Description

Figure 1 shows a system 10 for heating a vehicle catalytic converter. The system 10 includes an exhaust passage 20 of the vehicle engine which is used to direct exhaust gases away from the vehicle engine towards a silencer. A catalytic converter 30 is situated within the exhaust passage 20 of the vehicle. The catalytic converter 30 has an entry point 32 whereby untreated exhaust gases enter the catalytic converter 30, and an exit point 34 whereby treated exhaust gases exit the catalytic converter 30. A main body section 36 houses the catalyst and is situated between the entry point 32 and the exit point 34. Within the main body 36 a catalyst causes a reaction in the exhaust gases to turn harmful emissions into inert emissions. A heat exchanger 40 is also situated within the path of the exhaust passage 20. The heat exchanger 40 comprises an entry point 44 within the exhaust passage 20. The entry point 44 is connected to and open with the exhaust passage 20 and allows a portion of the exhaust gases flowing within the exhaust passage 20 to be directed away from the main travel path and into the entry point 44. The entry point 44 is connected to a main channel 42 of the heat exchanger. The main channel 42 is a conduit for the flow of exhaust gas. The main channel 42 has a large surface area to volume ratio in order to allow an extensive area over which the exhaust gas may contact its side walls. At the end of main channel 42 is a discharge point 46 which is connected to and open with the exhaust passage 20. The discharge point 46 allows the exhaust gases travelling along the main channel 42 to be discharged back into the exhaust passage 20. The walls of the heat exchanger are made of a material that would provide for good heat exchange across their surfaces.

The system 10 also comprises a flow passage 50 that is in thermal communication with both the catalytic converter 30 and the heat exchanger 40. A heat exchanger section 52 of the flow passage 50 is situated around at least the main channel 42 of the heat exchanger 40 and is in thermal communication with almost the entirety of the main channel 42 outer walls. The heat exchanger section 52 of the flow passage 50 comprises an entry port 54 at one end and this entry port 54 is situated in close proximity to the entry port 44 of the heat exchanger. The heat exchanger section 52 also has an exit port 56 at another end and this exit port is situated in close proximity to the discharge point 46 of the heat exchanger. The heat exchanger section 52 of the flow passage 50, between the entry port 54 and the exit port 56, comprises an elongate conduit that surrounds and envelops the main channel 42 of the heat exchanger. The heat exchanger section 52 of the flow passage 50 is wide enough to provide a good flow path along and around the heat exchanger 40. The walls of the heat exchanger section 52 of the flow passage 50 are made of a material that would allow good heat exchange across the surfaces. A catalytic converter section 60 of the flow passage 50 surrounds and envelops the catalytic converter 30 and substantially matches the shape of the outer surface of the main body 36. The catalytic converter section 60 of the flow passage has an entry port 62 on one side of the catalytic converter 30 and an exit port 64 on the other side of the catalytic converter 30. The section of the flow passage 50 between the entry port 62 and the exit port 64 provides a flow path that substantially matches the outer surface of the main body 36 of the catalytic converter 30.

The exit port 56 from the heat exchanger section 52 of the flow passage 50 is connected by a conduit 58 to the entry port 62 of the catalytic converter section 60 of the flow passage. The exit port 64 from the catalytic converter section 60 of the flow passage 50 is connected by a conduit 66 to the entry port 54 of the heat exchanger section 52 of the flow passage 50. In this manner the flow passage 50 provides a continuous flow path that forms a loop from the heat exchanger section 52, through exit port 56, along the conduit 58 to the entry port 62, around the catalytic converter section 60, and then out of exit port 64, through the conduit 66 to the entry port 54 and back to the heat exchanger section 52.

Within the flow passage 50 is a heat transfer fluid 68 that is capable of transferring heat between the heat exchanger 40 and the catalytic converter 30. The fluid 68 fills the flow passage 50 and is able to move around the flow passage 50 in the above described cycle under the action of natural circulation. Additionally or alternatively a pump may be used. The fluid 68 can be any fluid that is capable of transferring heat between the catalytic converter 30 and the heat exchanger 40 but preferably it is a fluid with a specific heat capacity and maximum fluid operating temperature that will allow the fluid to work effectively at the 400+degrees Celsius temperatures that are achieved by the system. The fluid may be a liquid or a gas. A thermally insulating jacket 70 sits around and encapsulates the catalytic converter 30 and at least the catalytic converter section 60 of the flow passage 50. The jacket 70 extends from a point adjacent to the entry point 32 and surrounds the main body 36 down to a point adjacent to the exit point 34 of the catalytic converter 30. The jacket 70 further comprises apertures through which the entry port 62 and the exit port 64 of the flow passage 50 can extend. The insulating jacket 70 is designed to retain and preserve heat and it may comprise a vacuum system, tank, or insulating material.

The insulating jacket 70 and the catalytic converter section 60 of the flow passage 50 are held at a distance and separated from the outside surface of the main body 36 of the catalytic converter 30 such that they are not in direct contact. In this manner, the inner surface of the jacket 70 and the inner surface of the catalytic converter section 60 of the flow passage 50 do not directly contact the outside surface of the catalytic converter 30 thereby minimising conductive heat transfer.

To maintain the distance and separation the insulating jacket 70 and catalytic converter section 60 of the flow passage 50 are mounted around the catalytic converter 30 by means of a thermal isolator collar 80 placed around the entry point 32 of the exhaust passage 20. Additionally or alternatively a thermal isolator collar 80 may be placed around the exit point 34 of the exhaust passage. The thermal isolator collar 80 supports the jacket 70 and the flow passage 50 so that both maintain their position. The thermal isolator collar 80 can also prevent heat transfer from the jacket 70 to the exhaust passage 20 when the engine is turned off.

The system may further comprise one or more insulating sleeve or cap 90 situated near the entry point 32 to the catalytic converter 30 and/or the exit point 34 of the catalytic converter. The insulating sleeve or cap 90 is formed of materials designed to retain and preserve heat. The insulating sleeve or cap 90 can trap hot exhaust gases within the main body 36 of the catalytic converter 30 when the engine is switched off and the flow of gases from the engine stops. The insulating sleeve or cap 90 may sit around the exhaust passage 20 or cover the end of the isolator collar 80, preferably without contacting the collar 80 itself. By preventing leakage of the hot stagnant gas from within the catalytic converter 30 the temperature of the catalytic converter can be maintained over an extended period of time during engine off. This residual heat within the catalytic converter 30 will subsequently reduce the time taken for the catalytic converter 30 to once again achieve a working temperature from engine start up.

With reference to Figure 2, operation of the system 10 as explained above will be described. To begin operation of the system 10 the vehicle engine is switched on and a continuous supply of hot exhaust gas 100 begins to flow from the engine and along the exhaust passage 20. As the hot exhaust gas 100 flows along the exhaust passage 20 it flows through entry point 32 and in to the main body 36 of the catalytic converter 30.

If the engine has been turned off for an extended period of time, and the system has become cold, then the catalytic converter 30 will not initially be at a working temperature. The heat from the hot exhaust gas 100 will begin to increase the temperature of the catalytic converter 30. The hot exhaust gas 100 will flow through the main body 36 of the catalytic converter 30 towards exit point 34. Once the hot exhaust gas 100 has passed through the exit port 34 it will continue to flow through the passage 20 and on towards the silencer.

As the hot exhaust gas 100 continues to flow along the exhaust passage 20 it will flow past entry point 44 to the heat exchanger 40. As the hot exhaust gas 100 flows past the entry point 44 a portion the hot exhaust gas 100 will flow from the exhaust passage 20 and into the entry point 44. The hot exhaust gas 100 will then flow from the entry point 44 and on through the main channel 42 of the heat exchanger 40. The hot exhaust gas 100 will continued to flow through the main channel 42 of the heat exchanger 40 until it reaches and flows through the discharge point 46 where it will re-join the hot exhaust gas 100 flowing through the exhaust passage 20.

As the hot exhaust gas 100 flows through the heat exchanger 40 some of the thermal energy of the exhaust gas 100 will be transferred from the exhaust gas 100 to the heat transfer fluid 68 within the heat exchanger section 52 of the flow passage 50. The heat transfer fluid 68 within the heat exchanger section 52 of the flow passage 50 will start to increase in temperature.

The heated heat transfer fluid 68 begins to flow through the heat exchanger section 52 of the flow passage 50 out of exit port 56 and in to conduit 58. Once the heated heat transfer fluid 68 is within conduit 58 it will then flow along conduit 58 until it reaches the entry port 62 to the catalytic converter section 60 of the flow passage 50. From entry port 62 the heated heat transfer fluid 68 will continue to flow around the catalytic converter section 60 of the flow passage and surround the main body 36 of the catalytic converter 30. In doing so, the heated heat transfer fluid 68 will transfer some of its thermal energy to the main body 36 of the catalytic converter 30.

Once the heated heat transfer fluid 68 has passed around and along the catalytic converter section 60 of the flow passage 50 it will reach exit port 64. The heat transfer fluid 68 will then flow out of exit port 64 and into conduit 66 and leaving the catalytic converter section 60 of the flow passage. The heat transfer fluid 68 will then flow through conduit 66 until it reaches entry port 54 of the heat exchanger section 52 of the flow passage 50. The heat transfer fluid 68 will then cycle back through the heat exchanger section 52 of the flow passage 50 where it will again be heated by the transfer of heat from the hot exhaust gas 100.

In the above described manner the heat transfer fluid 68 can continue to flow in a cycle within the flow passage 50 and the fluid 68 will continue to be heated and, in turn, transfer thermal energy to the catalytic converter 30. This continuous heating of the catalytic converter 30 in the described manner will allow it to reach a working temperature faster than by heating from the normal passage of hot exhaust gas 100 alone.

During the initial stages of the flow of hot exhaust gas 100, following engine start up, the catalytic converter 30 may increase in temperature faster than the fluid 68 within flow passage 50. Therefore, in the initial stages following engine start up, the thermal energy within the catalytic converter 30 may pass to the fluid 68 and increase the temperature of that fluid 68. With this additional heating the fluid 68 will quickly increase in temperature as it flows within the flow passage 50. This additional heating will further reduce the time taken for the catalytic converter 30 to reach a working temperature.

Furthermore, during the initial stages of the flow of the hot exhaust gas 100 following engine start up, the insulating jacket 70 will retain the thermal energy that is building up both within the catalytic converter 30 and within the heat transfer fluid 68 in the catalytic converter section 60 of the flow passage 50. The retention of this thermal energy by the jacket 70 will also further reduce the time taken for the catalytic converter 30 to reach a working temperature.

If the engine has been turned off for a short period of time then the insulating jacket 70 will have retained the built-up thermal energy already within the catalytic converter 30. This retained heat will also reduce the time taken from engine start up for the catalytic converter 30 to achieve a working temperature. Additionally, any insulating sleeve or cap 90 at the entry point 32 and/or exit point 34 will have prevented the hot exhaust gases 100 from leaving the main body 36 of the catalytic converter 30. The retention of the hot gases 100 within the catalytic converter 30 will also allow the catalytic converter 30 to retain heat thereby reducing the time needed for it to achieve a working temperature from engine start up.

The heat exchanger 40 is shown in the Figures and described as situated in the after treatment section of the exhaust passage 20, however it will be appreciated that the heat exchanger 40 could also be in the pre-treatment section of the exhaust passage 20 or indeed anywhere in the system that would allow effective heat exchange between the heated exhaust gas 100 and the exhaust passage 20.

It will further be appreciated that the heat exchanger 40 could also direct heat away from the heat transfer fluid 68 and into the channel 42 of the heat exchanger, thereby providing a means for removing excess heat from the system. This is particularly useful if the catalytic converter 30 gets too hot and there is a risk of catalyst damage.

Figure 3 shows a system 300 that can be used if the catalyst 30 or the heat transfer fluid 68 become too hot. The system 300 may employ a by-pass flow passage 302 to prevent the heat transfer fluid 68 from passing through the heat exchanger 40. By way of example, a flow passage valve 304 can be selectively employed at a position at or near to the entry port 54 to the heat exchanger section 52 of the flow passage 50. The flow of the heat transfer fluid 68 would be re-directed so as not to pass through the section 52 in the vicinity of the heat exchanger 40 thereby avoiding further heating of the fluid 68. A single valve 304 could be used. Additionally or alternatively, a further flow passage valve can also be selected to be employed in a position at or near to the exit port 54 to the heat exchanger section of the flow passage 50. Although in system 300 a valve 304 is situated at or near to the entry port 54 and/or exit port 56 it may, in practice, be located anywhere that would facilitate the heat transfer fluid 68 by-passing the heat exchanger.

The system 300 includes a heat exchanger valve 306 that may be selectively employed at the entry point 44 to the main channel 42 of the heat exchange 40. The valve 306 would prevent the heated exhaust gases 100, flowing in the exhaust passage 20, from entering in to the main channel 42 of the heat exchanger 40. A single valve 306 could be used. Additionally or alternatively, a further heat exchanger valve could also be selectively employed in to a position at or near to the discharge point 46 to the heat exchanger 40. Although in system 300 the valve 306 is shown to be situated at or near to the entry point 44 or discharge point 46 it may, in practice, be located anywhere that would prevent the heated exhaust gas 100 from entering the heat exchanger 40.

The system 300 may also comprise a single valve in either the flow passage 50 or the heat exchanger 40 that could be reversibly employed to prevent the flow of hot exhaust gas 100 in the heat exchanger 40 or the flow of the heat transfer fluid 68 in the flow passage 50 thereby preventing the exchange of heat between the heated exhaust gas 100 and the heat transfer fluid 68.

Use or not of the system 300 can be controlled once a certain temperature, operating factor or further characteristic has been detected which is indicative of the catalyst or the fluid being deemed to be too hot or too cold. The system 300 may also be manually employed based on user criteria.

Figure 4 shows a system 400 for cooling a vehicle catalytic converter. The system 400 may be used in addition to system 10 and may be selectively employed when the catalytic converter 30 or the heat transfer fluid 68 become too hot. The system 400 comprises a further flow passage 402 through which can flow a further heat transfer fluid 404. The further heat transfer fluid 404 comprises a coolant. The coolant may be a gas or a liquid. The liquid coolant may be water based, comprise antifreeze or may be an oil.

The further flow passage 402 comprises a radiator 406. The radiator has at least one exit port 408 to a conduit 410 which is connected by at least one entry port 412 to a further heat exchanger 414. The further heat exchanger 414 is in thermal communication with at least one section of flow passage 50. The further heat exchanger 414 comprises at least one exit port 416 connected to a further conduit 418. The further conduit 418 is connected by at least one entry port 420 to the radiator 406.

The further flow passage 402 provides means for the further heat transfer fluid 404 to flow from the radiator 406, through exit port 408 and along conduit 410 until it enters the further heat exchanger 414 through entry port 412. In the further heat exchanger 414 the further heat transfer fluid 404 undergoes a heating stage. In the further heat exchanger 414 the further heat transfer fluid 404 may increase in temperature as a result of the transfer of thermal energy from heated heat transfer fluid 68 within the flow passage 50. The walls of the further heat exchanger 414 are made of a suitable material to allow the transfer of thermal energy and the further heat exchanger 414 has a sufficiently large surface area, in contact with the flow passage 50, to facilitate good heat exchange.

The heated further heat transfer fluid 404 moves out of the further heat exchanger 414 through exit port 416 and in to conduit 418. The heated further heat transfer fluid 404 then moves along conduit 418 until it reaches entry port 420 and flows in to radiator 406. In radiator 406 the heated further heat transfer fluid 404 undergoes a cooling stage. In the radiator the heated further heat transfer fluid 404 loses its thermal energy and the temperature of the fluid 404 reduces. Once the further heat transfer fluid 404 has reduced in temperature sufficiently then it will begin to flow through exit port 408 once more and the cycle of the fluid 404 will continue. The fluid 404 can be caused to move in a cycle through the further flow passage 402 by natural circulation. Additionally or alternatively, a pump may be used by system 400.

Use or not of the system 400 can be controlled once a certain temperature, operating factor or further characteristic has been detected which indicative of the catalyst 30 or the fluid 68 being deemed to be too hot or too cold. The system 400 may be manually employed based on user criteria. Use of the system 400 could be controlled through the employment of at least one further flow passage valve 430 within the system to prevent the flow of the further heat transfer fluid 404 within the further flow passage 402.

The transfer of thermal energy from the heat transfer fluid 68 in flow passage 50 to the further heat transfer fluid 404 in further flow passage 402 will reduce the temperature of the heat transfer fluid 68. If the temperature of the heat transfer fluid 68 is reduced sufficiently then, in turn, thermal energy with be transferred from the catalytic converter 30 to the heat transfer fluid 68 which will in turn result in a reduction of the temperature of the catalytic converter 30. The exchange of thermal energy from the hot exhaust gas 100 to the heat transfer fluid 68 in heat exchanger 40 could be stopped when system 400 is employed in order to increase the cooling effect on the catalytic converter 30.

It will be appreciated by those skilled in the art that although the invention has been described by way of example, with reference to one or more examples, it is not limited to the disclosed examples and alternative examples may be constructed without departing from the scope of the invention as defined by the appended claims.

Claims

1. A system for heating a catalytic converter, wherein the system comprises: an exhaust passage for the flow of exhaust gas from an engine, a catalytic converter disposed in the exhaust passage, a heat exchanger in thermal communication with the exhaust passage, and a flow passage that at least partially surrounds the catalytic converter and is in thermal communication with the heat exchanger, wherein a heat transfer fluid is disposed within the flow passage and the system is configured to enable the heat transfer fluid to flow in a cycle around the heat exchanger and the catalytic converter and thereby transfer heat from the heat exchanger to the catalytic converter; and wherein the heat exchanger comprises a conduit configured to allow the exhaust gas to flow there through; and the heat exchanger further comprises at least one heat exchanger valve configured to be reversibly deployed to prevent the flow of exhaust gas within the conduit.

2. A system according to claim 1, further comprising an insulating jacket disposed around the catalytic converter.

3. A system according to claim 2, wherein at least part of the flow passage is disposed within the insulating jacket.

4. A system according to claim 2 or claim 3, wherein the insulating jacket is spaced radially outwardly from the outer surface of the catalytic converter.

5. A system according to claim 4, wherein the spaced relationship between the insulating jacket and the outer surface of the catalytic converter is maintained by at least one isolation collar.

6. A system according to any preceding claim, wherein the heat transfer fluid is a liquid.

7. A system according to any preceding claim, wherein the catalytic converter further comprises insulation adjacent at least one of an exhaust gas entry point or an exhaust gas exit point, the insulation being capable of retaining heat within the catalytic converter during engine off.

8. A system according to claim 7, wherein the insulation comprises an insulating sleeve or cap.

9. A system according to any preceding claim, wherein the heat exchanger is downstream from the catalytic converter.

10. A system according to any preceding claim, further comprising at least one valve disposed within the flow passage, wherein the valve is configured to be reversibly deployed to prevent the heat transfer fluid from flowing in a cycle around the heat exchanger.

11. A system according to any preceding claim, wherein the system further comprises a cooling system, the cooling system comprising; a further heat exchanger in thermal communication with the flow passage, a cooling means, and a further flow passage in thermal communication with the further heat exchanger and the cooling means, wherein a further heat transfer fluid is disposed within the further flow passage and the cooling system is configured to enable the further heat transfer fluid to flow in a cycle around the further heat exchanger and the cooling means and thereby transfer heat from the heat exchanger to the cooling means.

12. A vehicle comprising a system according to any preceding claim.

13. A method of heating a catalytic converter, the method comprising: disposing a catalytic converter in a vehicle exhaust passage, disposing a heat exchanger in thermal communication with the vehicle exhaust passage, and providing a flow passage that at least partially surrounds the catalytic converter and is in thermal communication with the heat exchanger, and disposing a heat transfer fluid within the flow passage and enabling the heat transfer fluid to flow in a cycle around the heat exchanger and the catalytic converter and thereby transfer heat from the heat exchanger to the catalytic converter; wherein the heat exchanger comprises a conduit configured to allow the exhaust gas to flow there through; and the heat exchanger further comprises at least one heat exchanger valve configured to be reversibly deployed to prevent the flow of exhaust gas within the conduit.

14. A method according to claim 13, the method further comprising disposing an insulating jacket around the catalytic converter.

15. A method according to claim 14, the method further comprising spacing the insulating jacket radially outwardly from an outer surface of the catalytic converter.

16. A method according to any one of claims 13 to 15, the method further comprising disposing at least one valve in the flow passage, and configuring the valve to be reversibly deployed to prevent the heat transfer fluid from flowing in a cycle around the heat exchanger.

17. A method according to any one of claims 12 to 16, the method further comprising providing a further heat exchanger in thermal communication with the flow passage, providing a cooling means, and providing a further flow passage in thermal communication with the further heat exchanger and the cooling means, and disposing a further heat transfer fluid within the further flow passage, and enabling the further heat transfer fluid to flow in a cycle around the further heat exchanger and the cooling means and thereby transfer heat from the further heat exchanger to the cooling means.

18. An apparatus for establishing or maintaining the temperature of a catalytic converter within a predetermined temperature range, wherein the apparatus comprises an exhaust passage for the flow of exhaust gas from an engine, a catalytic converter disposed in the exhaust passage, a heat exchanger in thermal communication with the exhaust passage, and a flow passage that at least partially surrounds the catalytic converter and is in thermal communication with the heat exchanger, wherein a heat transfer fluid is disposed within the flow passage and the apparatus is configured to enable the heat transfer fluid to flow in a cycle around the heat exchanger and the catalytic converter and thereby transfer heat between the heat exchanger and the catalytic converter; wherein the heat exchanger comprises a conduit configured to allow the exhaust gas to flow there through; and the heat exchanger further comprises at least one heat exchanger valve configured to be reversibly deployed to prevent the flow of exhaust gas within the conduit.