GB2516690A

GB2516690A - Vehicle emission control

Info

Publication number: GB2516690A
Application number: GB1313603.1A
Authority: GB
Inventors: Javier Castellano
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2013-07-30
Filing date: 2013-07-30
Publication date: 2015-02-04
Anticipated expiration: 2033-07-30
Also published as: GB201313603D0; GB2516703B; GB2516703A; GB201317360D0; GB2516690B; DE102014214277A1

Abstract

A vehicle navigation device calculates plans a route to a destination and an optimum driving cycle (ODC) or style that the vehicle should take over that route in order to reduce its emissions; the emission reduction is achieved through limiting the torque output 16 of the engine during the journey. The vehicle may estimate the outputted emissions of the journey and further may compare those to recorded emissions when the journey is complete (recorded using an exhaust gas sensor). The torque limit 16 may vary over the driving cycle and the ODC may also require particular gear selection 18 over the route. A prompt may be generated to alert the driver to the torque profile 16 and/or gear selection profile 18 along the route and this alert may be made via a screen 30. The limiting means may be overridden by a switch 32 or via a particular throttle position (or accelerator angle) 36. The device may automatically switch on upon entering a controlled emission zone.

Description

M

VEHICLE EMISSION CONTROL

This invention relates to a method of operating a driver-controlled vehicle in a manner to minimise harmful emissions from the engine of the vehicle. The invention is also concerned with apparatus in a driver-controlled vehicle for carrying out the method.

Hazardous or harmful vehicle emissions are a serious environmental problem and a wide range of techniques have been developed to reduce such emissions from internal combustion engines. While engine manufacturers have made significant progress in designing engines with reduced emissions, driver behaviour continues to have a major impact on the emissions generated in everyday driving. Although a careful driver may be able to drive a vehicle in a way which generates very low emissions, unnecessarily rapid acceleration and unsuitable gear selection can dramatically increase the emissions actually generated during a journey.

It is well known to provide to the driver of a vehicle an indication, such as a visual indication, of the instantaneous or cumulative fuel consumption. It is also known to provide an indication to the driver of suitable gear change points which, if adopted, lead to efficient operation of the vehicle from a fuel consumption point of view. However, there is not a direct correlation between fuel consumption and emissions generated.

An engine operating point at which fuel consumption is minimised may lead to imperfect combustion of the fuel, resulting in a less than optimal generation of one or more substances which are hazardous to the environment.

It is also known, for example from EP 2166309, to use route calculation map data, in conjunction with specific data relating to the vehicle, to calculate an estimated emission value for a particular journey. The calculated emission value serves to highlight to the driver the environmental cost of any particular journey, and so to provide a general incentive to the driver to adopt an environmentally friendly driving style, or not use the vehicle at all. The calculated emission value can also be used as a basis for emissions based road charging.

According to a first aspect of the present invention there is provided a method of operating a driver-controlled vehicle provided with a route calculating processor, the method comprising: a) determining in the processor a route from a start point to a destination; b) generating in the processor a driving cycle over the determined route which is optimised for the reduction of emissions; and c) limiting the output torque of the vehicle engine during progress along the determined route to conform to the optimised driving cycle.

The method may also include estimating in the processor the emissions to be generated by the vehicle following the route. This estimation may be based on the optimised driving cycle.

The expression "optimised driving cycle" means a driving cycle which aims to minimise the emissions generated over the determined route while remaining practical in normal driving conditions on public roads. The optimised driving cycle will represent a compromise between achieving the lowest possible emissions and keeping up with normal traffic. Thus, when accelerating, the optimised driving cycle will allow the vehicle to accelerate up to the local speed limit following a pattern which is brisk enough not to impede following traffic, but not much faster. Similarly, the optimised driving cycle will enable the vehicle to reach the local speed limit quickly enough to be safe, for example when entering a motorway, even though emissions might be minimised if a lower rate of acceleration, or a lower eventual cruising speed, were adopted.

The optimised driving cycle may be generated by any suitable process, for example by applying an algorithm or an iterative process. A speed profile over the determined route may be established, using speed limits obtained from map data and any known traffic conditions, with the objective of generating a speed profile which minimises engine emissions subject to the compromises referred to above. From the speed profile, an estimated torque requirement and/or a gear selection profile can be generated over the determined route. These profiles can be used, while driving over the determined route, to provide acceleration prompts and/or gear selection prompts to the driver to encourage the driver to follow, as closely as possible, the optimised driving cycle.

In one embodiment of a method in accordance with the present invention, the limitation of the output torque of the vehicle engine is a variable limit corresponding to the varying estimated torque requirement profile along the route. In order to provide the option for the driver to override the torque limitation, for example in the event of an emergency, or a need to overtake slower-moving traffic, the torque limitation may be disabled by driver intervention, for example by depression of the accelerator pedal beyond a predetermined extent.

6 The method may include the steps of determining the actual emissions generated by the vehicle when following the route, and providing an emission generation signal to the driver based on a comparison of the estimated and actual emissions. The emission generation signal and/or the accelerator position and/or gear selection prompts may be provided to the driver as respective visual signals. Other forms of signalling, such as audible or tactile signalling, may be employed.

The visual signals may be provided on a display screen in a position visible to the driver. The display screen may be an LCD or similar screen, or may be a head-up display projected on to the vehicle windscreen. The display screen may display, in addition to the prompts and emission generation signal referred to above, data such as current emission rate, estimated emissions, and a graphical indication to the driver representing the extent to which the actual emissions exceed or fall below the estimated emissions for the optimised driving cycle. The display may thus serve to motivate the driver to adopt an emission-reduction style of driving, intervening when necessary, by limiting the output torque of the engine, to avoid excessive emissions.

According to a second aspect of the present invention, there is provided apparatus in a driver controlled vehicle for carrying out a method in accordance with the first aspect of the present invention, the apparatus comprising the route calculating processor, and torque limiting means for limiting engine torque to a value corresponding to an estimated engine torque requirement for the optimised driving cycle.

The route calculating processor may be configured to estimate the emissions to be generated by the vehicle over the determined route, and means may be provided for determining the actual emissions generated by the vehicle. Signal generating means may be provided for generating an emission generation signal to the driver based on a comparison of the estimated and actual emissions.

Means such as an exhaust gas sensor may be provided for determining the actual emissions generated by the vehicle, although alternatively the actual emissions may be calculated from an emissions mode! on the basis of the operating conditions of the engine.

A display screen may be provided for displaying the emission generation signal The processor is configured to generate a driving cycle over a determined route which is optimised for the reduction of emissions. The processor may be configured to estimate the emissions based on the optimised driving cycle.

13 The engine torque may, for example, be limited by the torque limiting means to the actual instantaneous value of the optimised driving cycle. Alternatively, the engine torque may be limited to a value slightly greater than the estimated engine torque requirement of the aptimised driving cycle, for example 5% or 10% above the estimated engine torque requirement. In such a case, the driver retains the freedom to exceed the torque required by the aptimised driving cycle without entirely deactivating the torque limitation.

The signal generating means may be configured to display prompts relating to the output torque of the engine and/or gear selection based on the optimised driving cycle.

Means may be provided for disabling the torque limitation and/or the signal generating means, in order to provide the driver with the option of adopting a driving style consistent with emission reduction, or a driving style adopted for other purposes, for example to achieve a shorter travelling time.

Thus, the disabling means may be a manual switch, but it is possible also to provide means for activating the torque limitation and/or the signal generating means automatically, when disabled, upon entry of the vehicle into an emission sensitive zone, such as a natural park, a city centre, or any other built up area with transient high levels of environmental contamination. For example, the location of the vehicle may be constantly monitored using GPS equipment associated with the route calculating processor, and the disabling of the system may be overridden when the location is determined to be within an emission sensitive zone.

The disabling means may he responsive to accelerator position. For example, the disabling means may be operable to disable the torque limiting means upon movement of the accelerator through a predetermined extent.

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 drawing, which shows, in schematic form, a process for encouraging an environmentally friendly driving style.

The Figure shows a process that is performed in a vehicle, such as a passenger car powered by an internal combustion engine, in order to assist and encourage the driver to adopt a driving style which minimises the generation of hazardous emissions. Such emissions typically comprise carbon monoxide (CO), unburnt total hydrocarbons (THC) including non-methane hydrocarbons (NMHC), nitrogen oxides (NO) and particulates (such as soot).

A route calculation process 2 is performed in a processor of the vehicle, which may be a modified GPS device. The processor may be a portable unit, or it may be integrated with the vehicle.

The route calculation process 2 receives various inputs from which an appropriate route from a starting point (such as the current position of the vehicle) to a destination is calculated. Thus, the process is based on the current position 4 (or a selected starting point), a manually input destination 6, map data 8 stored in a memory of the GPS unit, and real time traffic data 10, which may be transmitted to the GPS unit by any suitable means, for example using the mobile telephone network.

The processor also receives inputs relating to vehicle and environmental data 12. This data 12 may comprise, for example, the mass of the vehicle (which may be either a fixed value taken from the vehicle specification or a value derived by onboard sensors so as to take account of the weight of vehicle occupants, luggage and fuel), vehicle engine coolant temperature, engine oil temperature and the ambient air temperature.

Based on the various inputs 4, 6, 8, 10, 12, the process 2 calculates a preferred route from the starting point to the destination, according to preferences set by the driver (for example shortest route, fastest route, avoiding motorways, etc). Once the preferred route has been calculated, the processor 2 generates an optimised driving cycle over the calculated route. The optimised driving cycle is determined using the map data 8, traffic data 10 and vehicle data 12 with the objective of minimising emissions without significant effect on the flow of traffic. Thus, the map data & provides information relating to gradients and speed limits, while the traffic data 10 enables an estimate to be made of the speed profile 14 of the vehicle over the calculated route. From the speed profile 14, and using the vehicle data 12 and in particular the mass of the vehicle, it is possible to estimate the torque requirement 16 of the engine at each stage of the route, in order to achieve or maintain the speed established by the speed profile 14. Subsequently, the processor can establish a gear change profile 18 in order to provide the required torque while generating minimal emissions.

The optimised driving cycle thus provides a sequence of gear changes over the calculated route to match the gear change profile 18, and a varying maximum output torque to achieve the torque requirement profile 16 over the entire route.Based on this information, the processor can calculate at 20 an estimated rate of generation of vehicle emissions at each point during the optimised driving cycle, as well as a cumulative value for the emissions generated up to that point in the journey. The vehicle and environmental data, and in particular the engine oil and coolant temperatures and the ambient temperature, can be used in the processor to modify the rate of emissions generation during the warm-up cycle of the engine.

The speed profile 14, the torque profile 16 and the gear change profile 18, along with the estimated emissions values 20, are input to a driver interface 22 which receives, as additional inputs, an actual emissions value 24 obtained from an exhaust gas sensor, a selected gear signal 26 and an actual output torque signal 28. The driver interface 22 outputs to a driver display 30.

In the driver interface 22, the actual gear position and output torque selected by the driver are compared throughout the journey with the corresponding values of the optimised driving cycle. The display 30 provides a visual comparison between the actual values and the corresponding optimised values, to provide assistance to the driver in maintaining a driving style which minimises the generation of emissions.

Furthermore, the display may provide a specific prompt to the driver to change gear in order to conform to the gear change profile 18 of the optimised driving cycle. The gear change prompt may comprise up/down arrows. As a supplement to the visual gear S change prompt, a torque or speed limitation may be imposed if a gear change prompt is ignored. For example, if a prompt to change up from third gear to fourth is ignored for a predetermined time, the speed of the vehicle may be limited to 35 mph.

Alternatively, fourth gear or higher must be selected before a speed in excess of 35 mph can be achieved.

A determination is made at 36 as to whether or not the accelerator position is below a threshold (X%, for example 90%) of full travel. The accelerator is normally a pedal, but may have other forms, such as a hand-operated control lever. If the accelerator position is below the threshold, a signal 38 is transmitted to the engine control module (ECM) of the vehicle to restrict the maximum engine torque that can be delivered, regardless of the actual accelerator position. As a result, the maximum torque normally available to the driver at any point in the journey is that set in the optimised driving cycle for that point. The system will prevent the driver from accelerating more briskly than allowed by the acceleration pattern employed in the generation of the optimised driving cycle.

However, if the accelerator pedal is depressed far enough to exceed the threshold, this signifies that the driver is deliberately seeking the full power delivery of the engine, for example in an emergency or when seeking to overtake slow-moving traffic. The torque limit is then overridden at 40, so that the full power of the engine is available The driver interface also outputs signals representing the estimated rate of generation of vehicle emissions in the optimised driving cycle and the actual rate of generation of emissions taken from the exhaust gas sensor. The result is represented in graphical or numeric form on the display 30 to provide an indication to the driver of the extent to which he or she is conforming to the optimised driving cycle, and the effect that this has on the emissions generated. In addition, the display may include a field in which a score or rating can be presented, to indicate to the driver how well he or she has adopted the optimised driving cycle and so minimised emissions.

If required, all or part of the system can be disabled at 32, for example by way of a manual driver-controlled switch. Thus, the driver can deactivate the torque limitation feature. If the system is disabled, it can be reactivated automatically at 34 if the current position data 4 indicates that the vehicle is in an emission sensitive zone, where it is highly desirable, or legally required, for emissions to be minimised. Such zones may, for example, be natural parks, city centres and other regions of high traffic congestion or high transitory levels of environmental pollution.

A system as described above thus provides the driver with the option of driving the vehicle in an "ECO" mode in which guidance in the form of gear change prompts, and intervention in the form of torque limitation, are provided to assist the driver in adopting a highly effective reduced emission driving style. Since the optimised driving cycle takes account of specific characteristics of the individual vehicle, the driver will be assisted in adopting a driving style tailored to that particular vehicle.

Furthermore, the assistance provided by the system will make it easier for the driver to achieve published or advertised emissions figures, and for those concerned with emissions legislation to appreciate that such published figures are in fact achievable in practice.

Claims

CLAIMS1 A method of operating a driver-controlled vehicle provided with a route calculating processor, the method comprising: a) determining in the processor a route from a start point to a destination; b) generating in the processor a driving cycle over the determined route which is optimised for the reduction of emissions; and c) limiting the output torque of the vehicle engine during progress along the determined route to conform to the optimised driving cycle.

2. A method as claimed in claim 1, in which step (b) comprises estimating in the processor the emissions to be generated by the vehicle over the determined route.

3. A method as claimed in claim 2, in which the estimate of the emissions is based on the optimised driving cycle.

4. A method as claimed in any one of the preceding claims, in which the optimised driving cycle comprises an estimated torque requirement profile over the determined route.

5. A method as claimed in claim 4, in which the maximum output torque of the vehicle engine is limited to a value corresponding to the estimated torque requirement profile.

6. A method as claimed in any one of the preceding claims, in which the optimised driving cycle comprises a gear selection profile over the determined route.

7. A method as claimed in any one of claims 4 to 6, in which an output torque prompt and/or a gear selection prompt is provided to the driver on the basis of the respective torque requirement profile and gear selection profile.

8. A method as claimed in any one of the preceding claims, further comprising the steps of determining the actual emissions generated by the vehicle when following the route, and providing an emission generation signal to the driver based on a comparison of the estimated and actual emissions.

9. A method as claimed in claim 7 or 8, in which the emission generation signal and/or the output torque and/or gear selection prompts are provided to the diiver as respective visual signals.

10. A method as claimed in claim 9, in which the or each visual signal is provided on a display screen.

11. A method of operating a driver-controlled vehicle as claimed in claim 1 and substantially as described herein.

12. Apparatus in a driver-controlled vehicle for carrying out a method in accordance with any one of the preceding claims, the apparatus comprising the route calculating processor, and torque limiting means for limiting engine torque to a value corresponding to an estimated engine torque requirement for the optimised driving cycle.

13. Apparatus as claimed in claim 12, in which the route calculating processor is configured to estimate the emissions to be generated by the vehicle over the determined route, and in which means is provided for determining the actual emissions generated by the vehicle, signal generating means being provided for generating an emission generation signal to the driver based on a comparison of the estimated and actual emissions.

14. Apparatus as claimed in claim 13, in which the means for determining the actual emissions generated by the vehicle comprises an exhaust gas sensor.

15. Apparatus as claimed in claim 13 or 14, in which a display screen is provided, and in which the emissions generation signal is a visual signal presented on the display screen.

16. Apparatus as claimed in any one of claims 13 to 15, in which the signal generating means is configured to display prompts relating to output torque requirement and/or gear selection based on the optimised driving cycle.

17. Apparatus as claimed in any one of claims 12 to 16, in which means is provided for disabling the torque limiting means. Ii

1& Apparatus as claimed in claim 17, in which the disabling means is a manual switch.

19. Apparatus as claimed in claim 17 or 18, in which means is provided for activating the signal generating means, when disabled by the manual switch, upon entry of the vehicle into an emission sensitive zone.

20. Apparatus as claimed in any one of claims 17 to 19, in which the disabling means is responsive to accelerator position.

21. Apparatus as claimed in claim 20, in which the disabling means is operable to disable the torque limiting means upon movement of the accelerator through a predetermined extent.

22. Apparatus in a driver-controlled vehicle substantially as described herein with reference to, and as shown in, the accompanying drawings.