GB2555851A

GB2555851A - Treatment of engine exhaust gases

Info

Publication number: GB2555851A
Application number: GB1619215.5A
Authority: GB
Inventors: Slaney Tim; Wicks Nick; Jones Alan
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2016-11-14
Filing date: 2016-11-14
Publication date: 2018-05-16

Abstract

A vehicle exhaust gas treatment apparatus comprises a gasoline particulate filter (GPF) 60, eg a catalyst coated gasoline particulate filter (cGPF). A secondary air injection (SAI) apparatus 70 injects a quantity of secondary air or oxygen into the GPF 60. Heater apparatus 80 external to the engine can increase the temperature of the exhaust gas flowing through the GPF 60 and/or of the GPF itself. Oxygen from a tank or atmospheric secondary air may be supplied by a pump 74 or by a passive injector 76, eg a venturi (176, fig.3), upstream of the GPF. The heater apparatus 80 may be electrical, eg with a heating element 81 in the filter, or microwave. Alternatively, fig.4, the heater apparatus may be located at the catalytic converter (TWC) 50 and/or in the flow path between the TWC 50 and the GPF 60. A controller 80 determines the need for regeneration and operates the SAI apparatus 70 and/or the heater 80 if it determines that passive regeneration is not possible.

Description

(71) Applicant(s):

Jaguar Land Rover Limited (Incorporated in the United Kingdom)

Abbey Road, Whitley, Coventry, Warwickshire, CV3 4LF, United Kingdom (56) Documents Cited:

CN 104847455 A

US 6185931 B1 (58) Field of Search:

INT CL F01N, F02D

Other: EPODOC, Patent Fulltext, WPI (72) Inventor(s):

Tim Slaney Nick Wicks Alan Jones (74) Agent and/or Address for Service:

Swindell & Pearson Ltd

Friar Gate, DERBY, DE1 1GY, United Kingdom (54) Title of the Invention: Treatment of engine exhaust gases

Abstract Title: Regenerating a vehicle gasoline particulate filter (57) A vehicle exhaust gas treatment apparatus comprises a gasoline particulate filter (GPF) 60, eg a catalyst coated gasoline particulate filter (cGPF). A secondary air injection (SAI) apparatus 70 injects a quantity of secondary air or oxygen into the GPF 60. Heater apparatus 80 external to the engine can increase the temperature of the exhaust gas flowing through the GPF 60 and/or of the GPF itself. Oxygen from a tank or atmospheric secondary air may be supplied by a pump 74 or by a passive injector 76, eg a venturi (176, fig.3), upstream of the GPF. The heater apparatus 80 may be electrical, eg with a heating element 81 in the filter, or microwave. Alternatively, fig.4, the heater apparatus may be located at the catalytic converter (TWC) 50 and/or in the flow path between the TWC 50 and the GPF 60. A controller 80 determines the need for regeneration and operates the SAI apparatus 70 and/or the heater 80 if it determines that passive regeneration is not possible.

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TREATMENT OF ENGINE EXHAUST GASES

FIELD OF THE INVENTION

The present invention relates to a vehicle exhaust gas treatment apparatus for a motor vehicle. Aspects of the invention relate to a vehicle exhaust gas treatment apparatus, to a control apparatus, to a vehicle, and to a method.

BACKGROUND

Engine exhaust gases contain a number of gases and particulates that it is undesirable to release to the atmosphere. The gases typically include hydrocarbons (HC), carbon monoxide (CO), carbon dioxide (CO₂) and nitrogen oxides (NOx) whilst the particulates include carbon particles.

Catalytic converters are a known way of removing certain gases from an exhaust flow. For example, a three-way catalytic converter (TWO) can reduce nitrogen oxides, carbon monoxide and unburnt hydrocarbons.

There is increasing interest in removing particulates from the exhaust gas of a gasoline engine. One approach to removing particulates is a coated filter which also performs TWO functions. This may be called a four way catalyst (FWC). A second approach to removing particulates is by providing a gasoline particulate filter (GPF) downstream of the three-way main catalytic converter.

A gasoline particulate filter traps particulate matter, such as soot particles. During operation a quantity of trapped soot particles accumulate within the filter. An accumulation of trapped particulate matter can reduce flow through the filter and cause a backpressure on exhaust gases. It is desirable that the trapped material is removed from the filter. During certain operating conditions the filter can oxidise (burn off) trapped particulate matter. This is called regeneration of the filter. Regeneration requires a minimum operating temperature, such as a temperature of around 400°C. It may be difficult to achieve the operating conditions required for filter regeneration. For example, a vehicle driven in low ambient temperatures and/or a vehicle with low engine load may not reach the temperature required for regeneration.

It is possible to operate the engine in a manner to encourage filter regeneration. This is called active regeneration. One way of active regeneration is by increasing the exhaust gas temperature and lean lambda. However, this can cause additional problems. For example, increasing exhaust gas temperature may cause a catalytic converter located upstream of the GPF to exceed its maximum temperature before the GPF has reached its operational temperature. Ensuring sufficient oxygen supply via lambda control enleanment may cause gaseous tailpipe emissions to increase (especially NO_X).

STATEMENT OF THE INVENTION

Embodiments of the invention provide a vehicle exhaust gas treatment apparatus, a control apparatus, a vehicle, and a method. Embodiments of the invention may be understood by reference to the appended claims.

In one aspect of the invention for which protection is sought there is provided a vehicle exhaust gas treatment apparatus for a motor vehicle comprising an internal combustion engine, the vehicle exhaust gas treatment apparatus comprising:

a gasoline particulate filter;

a secondary air injection apparatus configured to inject a quantity of secondary air into the gasoline particulate filter;

a heater apparatus external to the internal combustion engine configured to increase a temperature of at least one of: exhaust gas flowing through the gasoline particulate filter; the gasoline particulate filter.

Secondary air may be from the environment, from an air storage means such as a compressed gas cylinder or from another part of the powertrain such as from the air intake, from downstream of the inlet air filter.

The secondary air injection apparatus may comprise an air injector located upstream of the gasoline particulate filter.

The secondary air injection apparatus may comprise: an inlet to receive air from an external environment of the vehicle; the air injector; and a pump configured to pump air from the inlet towards the air injector.

The air injector may be a passive injector. Passive injector herein describes a means of injecting air into the exhaust without a powered pump. The passive injector may be permanently open or it may have solenoid valve switch activation.

The passive injector may be a venturi.

The secondary air injection apparatus may comprise a filter which is configured to filter secondary air before the air injector.

The heater apparatus may comprise an electrical heating element.

The heater apparatus may comprise a microwave heater wherein the microwave heater may heat a target in the exhaust gas stream, said target may be a portion of the gasoline particulate filter, said portion may be the front face of the gasoline particulate filter.

The electrical heating element may be located within the gasoline particulate filter.

The gasoline particulate filter may comprise an upstream face and the electrical heating element may be located on the upstream face of the filter.

The heater apparatus may be located in an exhaust gas flow path upstream of the filter.

The secondary air injection apparatus may be configured to receive a first control signal to selectively operate the secondary air injection apparatus and the heater apparatus may be configured to receive a second control signal to selectively operate the heater apparatus.

In a further aspect there is provided a vehicle exhaust gas treatment apparatus comprising: a catalytic converter;

the gasoline particulate filter located downstream of the catalytic converter.

In a further aspect there is provided a control apparatus for a vehicle exhaust gas treatment apparatus according to any one of the preceding claims, comprising a controller which is configured to:

determine when a regeneration of the gasoline particulate filter is required; determine if the gasoline particulate filter can regenerate; and if it is determined that the gasoline particulate filter cannot regenerate, output at least one of:

a first control signal to operate the secondary air injection apparatus; a second control signal to operate the heater apparatus.

The controller may comprise:

an electronic processor having an electrical input for receiving a signal indicative of whether regeneration of the gasoline particle filter is required; and an electronic memory device electrically coupled to the electronic processor and having instructions stored therein, wherein the processor is configured to access the memory device and execute the instructions stored therein such that it is operable to:

determine when a regeneration of the gasoline particulate filter is required;

determine if the gasoline particulate filter can regenerate; and if it is determined that the gasoline particulate filter cannot regenerate, output at least one of:

The controller may be configured to determine when a regeneration of the gasoline particulate filter is required by determining a pressure drop across the gasoline particulate filter.

The controller may be configured to determine if the gasoline particulate filter can regenerate by at least one of:

determining a temperature of the gasoline particulate filter; determining a flow rate through the gasoline particulate filter.

In a further aspect there is provided a motor vehicle comprising a vehicle exhaust gas treatment apparatus of another aspect.

In a further aspect there is provided a method of treatment of engine exhaust gases of a motor vehicle comprising:

passing the exhaust gases through a gasoline particulate filter; and at least one of:

injecting a quantity of secondary air into the gasoline particulate filter;

increasing a temperature of exhaust gas flowing through the gasoline particulate filter by heating the exhaust gas using a heater apparatus external to an internal combustion engine of the motor vehicle;

increasing a temperature of the gasoline particulate filter by a heater apparatus external to an internal combustion engine of the motor vehicle.

In an aspect of the invention for which protection is sought there is provided a non-transitory computer readable medium carrying computer readable code for controlling a vehicle to carry out the method of another aspect.

In one aspect of the invention for which protection is sought there is provided a computer program product executable on a processor so as to implement the method of another aspect.

In an aspect of the invention for which protection is sought there is provided a computer readable medium loaded with the computer program product of another aspect.

In an aspect of the invention for which protection is sought there is provided a processor arranged to implement the method of another aspect, or the computer program product of another aspect.

At least one embodiment has an advantage that regeneration of the GPF is achieved without changing operation of an engine of the vehicle to promote regeneration of the GPF.

At least one embodiment has an advantage that regeneration of the GPF is achieved without changing operating conditions at a catalytic converter upstream of the GPF.

Advantageous features of the invention are mentioned in the following description and in the claims appended hereto.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures in which:

FIGURE 1 is a schematic drawing of a vehicle with an engine exhaust gas treatment apparatus;

FIGURE 2 shows an engine exhaust gas treatment apparatus according to an embodiment of the invention;

FIGURE 3 shows an engine exhaust gas treatment apparatus with an alternative form of secondary air injection apparatus;

FIGURE 4 shows an engine exhaust gas treatment apparatus with some alternative forms of heater apparatus;

FIGURE 5 shows an example of operation of a controller.

DETAILED DESCRIPTION

Figure 1 shows an example of a vehicle 10 in which apparatus according to an embodiment of the present invention may be used. The vehicle 10 has an internal combustion engine (ICE) 21. The internal combustion engine is a gasoline engine which combusts gasoline in one or more combustion chamber. A clutch 22 couples an output of the engine 21 to a transmission 24, which is in turn coupled to a driveline 30 of the vehicle 10. The transmission 24 may be arranged to: drive only a pair of front wheels 11,12 (i.e. front wheel drive); drive only a pair of rear wheels 13, 14, (i.e. rear wheel drive); or drive all four wheels (i.e. four wheel drive). Embodiments of the invention are also suitable for vehicles having less than four wheels or more than four wheels.

Exhaust gas from the engine 21 is output to an exhaust gas treatment apparatus 50, 60.

Another name for the exhaust gas treatment apparatus is an engine aftertreatment apparatus. The exhaust gas treatment apparatus comprises a catalytic converter 50 and a gasoline particulate filter (GPF). The catalytic converter 50 may be a three-way catalytic converter (TWC) which performs the three functions of:

(1) reduction of nitrogen oxides to nitrogen and oxygen: 2NO_X —> xO₂ + N₂;

(2) oxidation of carbon monoxide to carbon dioxide: 2CO + O₂ —> 2CO₂;

(3) oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water:

CxH_2x+2 + [(3x+1 )/2]O₂ -+ xCO₂ + (x+1 )H₂O.

The GPF 60 is configured to remove particulate matter, such as soot particles, from the exhaust gas. In this embodiment the GPF 60 is located downstream of the catalytic converter 50. That is, the GPF 60 is not close-coupled with the catalytic converter 50. The GPF 60 may be called an underfloor GPF, due the location of the GPF under a floor of the vehicle.

The GPF 60 can regenerate under certain operating conditions. The term “regenerate” means the GPF can oxidise, i.e. burn off, soot trapped by the filter. The term “light off” can be used to describe the point at which the GPF meets the operating conditions (e.g. temperature, flow rate) required for soot oxidation. The term “light out” can be used to describe the point at which the GPF no longer meets the operating conditions (e.g. temperature, flow rate) at which soot oxidation will occur.

It has been recognised that the GPF may not achieve the operating conditions required for light off, and therefore may not regenerate. There are two requirements for oxidation of soot: temperature (i.e. temperature should be high enough); and oxygen (i.e. quantity of oxygen present in the exhaust gas should be high enough). If either of these requirements are not present, oxidation will not occur.

Figure 2 shows two separate sets of apparatus 70, 80 which can be operated to help the GPF achieve the operating conditions required for light off and hence regeneration. The apparatus 70, 80 is provided at a location which is at, or near to, the GPF 60.

Figure 2 shows a secondary air injection (SAI) apparatus 70. The SAI apparatus 70 can inject a quantity of secondary air into the GPF 60. The SAI apparatus 70 increases an amount of air in the exhaust gas flowing through the GPF 60 without a need to change operation of the engine. Oxygen is the gas required for oxidation. The SAI apparatus may inject pure oxygen (e.g. from a tank) but it is more practical to inject atmospheric air which contains oxygen.

Figure 2 shows a heater apparatus 80. The heater apparatus 80 may increase a temperature of at least one of: exhaust gas flowing through the gasoline particulate filter 60; the gasoline particulate filter 60 (e.g. a surface of the filter 60). The heater apparatus 80 directly heats the exhaust gas or the GPF 60 without a need to change operation of the engine. For example, there is no need to change operation of the engine to produce a hotter exhaust gas.

The SAI apparatus 70 and the heater apparatus 80 can be used independently of one another under the control of a controller 40. The controller 40 may operate:

(i) only the SAI apparatus 70;

(ii) only the heater apparatus 80;

(iii) the SAI apparatus 70 and the heater apparatus 80.

There are various ways of implementing the SAI apparatus 70. In the embodiment of Figure 2 the SAI apparatus 70 comprises an air inlet 71 to receive air from an external environment of the vehicle. The SAI apparatus 70 comprises an air injector (air outlet, or air injection point) 76 in a flow path upstream of the gasoline particulate filter 60. The SAI apparatus 70 comprises a pump 74. The pump is driven by an electrical motor 73. A filter 72 is provided in a flow path between the inlet 71 and the air injector 76. The filter 72 is configured to filter unwanted material from air received via the inlet 71. A valve 75 (e.g. a solenoid valve) may be provided in a flow path of the SAI apparatus 70. The valve 75 can open to allow a flow of secondary air from the air injector 76, or can close to prevent a flow of air from the air injector 76. The motor-driven pump 73, 74 is controlled by a control signal 41 received from the controller 40. The valve 75 is controlled by a control signal 42 received from the controller 40.

There are various ways of implementing the heater apparatus 80. In the embodiment of Figure 2 the heater apparatus 80 comprises an electrical heating element 81 which is provided within the GPF 60. For example, the heating element 81 may be located on, or near, an upstream face of the GPF. The heating element 81 may be implemented as a “slice”. The heating element 81 may be located on one or more layers of the filter structure within the GPF 60.

A number of sensors 45 are provided to monitor operating conditions of the GPF 60.

Figure 2 schematically shows a single sensor 45 but it will be appreciated that multiple sensors can be provided at various locations. The sensors 45 may monitor one or more of:

a temperature of the GPF 60; a flow rate through the GPF 60; pressure drop across the

GPF 60. The controller 40 receives inputs from the sensors 45.

Figure 3 shows another embodiment. This embodiment has a different form of secondary air injection (SAI) apparatus 170. The SAI apparatus 170 can inject a quantity of secondary air into the GPF 60. The SAI apparatus 170 increases an amount of air in the exhaust gas flowing through the GPF 60 without a need to change operation of the engine. The SAI apparatus 170 does not have a pump 74 driven by an electrical motor 74. Instead, a venturi injector 176 or another form of passive injector is provided. The venturi injector 176 is configured to draw air from a secondary flow path through apparatus 170. The secondary flow path can comprise an inlet 71 and a filter 72. Similar to Figure 2, a valve 75 (e.g. a solenoid valve) may be provided in a flow path of the SAI apparatus 170. The valve 75 can open to allow a flow of secondary air from the injector 176, or can close to prevent a flow of air from the injector 176. The valve 75 is controlled by a control signal 42 received from the controller 40.

Figure 4 shows two alternative forms of heater apparatus 180, 280. The exhaust gas treatment apparatus may use one of the heater apparatus 180, 280 in place of the heater apparatus 80 shown in Figure 2. Alternatively, the exhaust gas treatment apparatus may use a combination of two or more of the heater apparatus 80, 180, 280. The heater apparatus 180 is located upstream of the GPF 60. The heater apparatus 180 may be located at the catalytic converter 50. Exhaust gas is heated by the heater apparatus 180 at the catalytic converter 50 and the heated exhaust gas then passes to the GPF 60. The heater apparatus 180 is controlled by a control signal 143 received from the controller 40 and a switch 182. The heater apparatus 280 is located upstream of the GPF 60. The heater apparatus 280 may be located along a flow path between the catalytic converter 50 and the GPF 60. Exhaust gas is heated by the heater apparatus 280 and the heated exhaust gas then passes to the GPF 60. The heater apparatus 280 is controlled by a control signal 243 received from the controller 40 and a switch 282. In each case, the heater apparatus 180, 280 heats the exhaust gas without a need to change operation of the engine. For example, there is no need to change operation of the engine to produce a hotter exhaust gas.

Figure 5 shows an example of operation of the controller 40. The controller 40 may determine (101) if a regeneration of the GPF 60 is required. For example, the controller 40 may determine a pressure drop across the GPF 60 using inputs from sensors. The controller 40 may determine when the pressure drop across the GPF reaches a threshold value indicative of regeneration being required. If regeneration is required, the controller proceeds to block 102. The controller 40 may determine (102) if the GPF 60 can regenerate. That is, the controller 40 may determine if the operating conditions of the GPF 60 allow passive regeneration to occur. If it is determined that the GPF 60 can passively regenerate, no assistance is required. If it is determined that the GPF 60 cannot regenerate, some assistance is required. The controller proceeds to block 103. The controller can output at least one of: at least one control signal 41, 42 to operate the SAI apparatus 70; a control signal 43 to operate the heater apparatus 80. Control signal 41 may operate a switch 77 of the SAI apparatus 70, and control signal 43 may operate a switch 82 of the heater apparatus 80.

Although various sensors are described above, in some embodiments it is possible to remove the need for at least one of the sensors, e.g. remove the need for a temperature sensor. The controller may use an exhaust gas system model. The model determines temperatures across the system based on known dimensions and gas flows. If this model predicts that the temperature in the GPF is too low and/or that there is not the required oxygen, then it commands an increase in temperature from the heater apparatus and/or an injection of secondary air from the SAI apparatus.

The internal combustion engine is a gasoline engine which combusts gasoline in one or more combustion chamber. In the present embodiment, the internal combustion engine is a gasoline engine adapted to operate at stoichiometric conditions. Exhaust gases from the combustion cycle are expelled from the internal combustion engine into the exhaust system for treatment by aftertreatment systems (denoted by the reference numeral), including a catalytic converter and a gasoline particulate filter (GPF). The catalytic converter is a threeway catalyst (TWC) and is operative to combine oxygen (02) with carbon monoxide (CO) and unburned hydrocarbons (UHC); and to reduce the nitrogen oxides (NOx), particularly the mono-nitrogen oxides nitric oxide (NO) and nitrogen dioxide (NO2). The GPF collects particles of soot from the exhaust gas. The GPF in the present embodiment is a coated gasoline particulate filter (cGPF) having a catalyst coating. The GPF is regenerated by oxidising the soot. The oxidation of the GPF requires oxygen and a high temperature, which may exceed 500 °C.

Lambda (λ) is the ratio of the actual air/fuel ratio (AFR) to the stoichiometric air/fuel ratio (AFRsto/cft) and is defined by the following equation:

AFR.

A=As outlined above, the internal combustion engine is configured to operate at stoichiometric conditions, i.e. lambda (λ) is at least substantially equal to one (1).

During normal (stoichiometric) operation of the internal combustion engine, there is a small amount of oxygen available in the exhaust gas and this is used for oxidation of carbon monoxide (CO) and unburnt hydrocarbons (UHC) in the catalytic converter.

An engine control unit may be configured to modify lambda (λ) to increase soot oxidation. In particular, the engine control unit may be configured to increase lambda (λ) of the internal combustion engine. The engine control unit may thereby control the fuelling of the internal combustion engine to provide overall stoichiometric conditions across the aftertreatment system. Increasing lambda (λ) of the internal combustion engine results in a greater temperature in the system and additional oxygen being contained in the exhaust gas for oxidising soot in the GPF. The maintenance of stoichiometric conditions through the GPF allows for reduction of nitrogen oxides (NOx) and oxidation of carbon monoxide (CO) and hydrocarbons (HC) in the catalytic converter; and oxidation of the soot in the GPF. The engine control unit can be configured to improve soot oxidation, as well as gaseous emissions conversion, during stoichiometric operation of the internal combustion engine but at the cost of fuel.

In order to avoid the increased fuelling of the engine by the control unit, embodiments are described to provide an increase in temperature and an increase in oxygen downstream of the GPF to aid oxidation of soot in the GPF.

The heater apparatus 80, 180, 280 may use electrical energy supplied by a vehicle battery either a high voltage battery or a low voltage battery. The heater apparatus 80, 180, 280 being distinct from the engine may be an electric heater, a microwave heater or any other kind of heat source external to (i.e. secondary to) the engine.

Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of the words, for example “comprising” and “comprises”, means “including but not limited to”, and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

CLAIMS:

1. A vehicle exhaust gas treatment apparatus for a motor vehicle comprising an internal combustion engine, the vehicle exhaust gas treatment apparatus comprising:

a gasoline particulate filter;

2. A vehicle exhaust gas treatment apparatus according to claim 1 wherein the secondary air injection apparatus comprises an air injector located upstream of the gasoline particulate filter.

3. A vehicle exhaust gas treatment apparatus according to claim 2 wherein the secondary air injection apparatus comprises:

an inlet to receive air from an external environment of the vehicle; the air injector; and a pump configured to pump air from the inlet towards the air injector.

4. A vehicle exhaust gas treatment apparatus according to claim 2 wherein the air injector is a passive injector.

5. A vehicle exhaust gas treatment apparatus according to claim 4 wherein the passive injector is a venturi.

6. A vehicle exhaust gas treatment apparatus according to any one of the preceding claims wherein the secondary air injection apparatus comprises a filter which is configured to filter secondary air before the air injector.

7. A vehicle exhaust gas treatment apparatus according to any one of the preceding claims wherein the heater apparatus comprises an electrical heating element.

8. A vehicle exhaust gas treatment apparatus according to any one of claims 1 to 6 wherein the heater apparatus comprises a microwave heater.

9. A vehicle exhaust gas treatment apparatus according to claim 7 wherein the electrical heating element is located within the gasoline particulate filter.

10. A vehicle exhaust gas treatment apparatus according to claim 9 wherein the gasoline particulate filter comprises an upstream face and the electrical heating element is located on the upstream face of the filter.

11. A vehicle exhaust gas treatment apparatus according to any one of claims 1 to 8 wherein the heater apparatus is located in an exhaust gas flow path upstream of the filter.

12. A vehicle exhaust gas treatment apparatus according to any one of the preceding claims wherein the secondary air injection apparatus is configured to receive a first control signal to selectively operate the secondary air injection apparatus and the heater apparatus is configured to receive a second control signal to selectively operate the heater apparatus.

13. A vehicle exhaust gas treatment apparatus comprising: a catalytic converter; and the gasoline particulate filter according to any one of the preceding claims located downstream of the catalytic converter.

14. A control apparatus for a vehicle exhaust gas treatment apparatus according to any one of the preceding claims, comprising a controller which is configured to:

determine when a regeneration of the gasoline particulate filter is required;

15. A control apparatus for according to claim 14, comprising a controller, the controller comprising;

determine when a regeneration of the gasoline particulate filter is required;

16. A control apparatus according to claim 14 or 15 wherein the controller is configured to determine when a regeneration of the gasoline particulate filter is required by determining a pressure drop across the gasoline particulate filter.

17. A control apparatus according to any one of claims 14 to 16 wherein the controller is configured to determine if the gasoline particulate filter can regenerate by at least one of:

18. A motor vehicle comprising a vehicle exhaust gas treatment apparatus according to any one of claims 1 to 13.

19. A vehicle according to claim 18 further comprising control apparatus according to any one of claims 14 to 17 for the exhaust gas treatment apparatus.

20. A method of treatment of engine exhaust gases of a motor vehicle comprising: passing the exhaust gases through a gasoline particulate filter;

and at least one of:

injecting a quantity of secondary air into the gasoline particulate filter; increasing a temperature of exhaust gas flowing through the gasoline particulate filter by heating the exhaust gas using a heater apparatus external to an internal combustion engine of the motor vehicle;

21. A non-transitory computer readable carrier medium carrying a computer readable code for controlling a vehicle to carry out the method according to claim 20.

22. A computer program product executable on a processor so as to implement the method of claim 20.

5

23. A computer readable medium loaded with the computer program product of claim 22.

24. A processor arranged to implement the method of claim 20, or the computer program product of claim 22.

10

25. A vehicle exhaust gas treatment apparatus, control apparatus, a motor vehicle, method, carrier medium, computer program product, computer readable medium or processor substantially as hereinbefore described with reference to the accompanying drawings.

Intellectual

Property

Office

Application No: GB1619215.5