Method for reducing emissions in a vehicle having a combustion engine

Abstract

The present invention relates to a method for reducing emissions in a vehicle having a combustion motor, the method comprising: acquiring road section-related data, the road section-related data at least partially including data related to an estimated required driving power of the combustion motor on a predetermined driving section, and controlling the combustion motor according to the acquired road section-related data while or before driving on the predetermined driving section, so as to heat the exhaust gas aftertreatment system of the combustion motor.

Description

Technical Field

[0001] The invention relates to a method for reducing emissions in a vehicle having a combustion engine by using predictive route-related data, a system for implementing the method, and a computing unit and a computer program for implementing the method. Background Art

[0002] In order to comply with the emission limits for various pollutants prescribed for vehicles with combustion engines, exhaust gas aftertreatment is necessary. However, exhaust gas aftertreatment systems require a certain operating temperature in order to ensure the necessary conversion rates for complying with the prescribed emissions, and exhaust gas aftertreatment systems only work optimally within a certain temperature range. Exhaust gas aftertreatment systems are usually heated by the exhaust gas flow.

[0003] However, in various situations in a vehicle, the engine power of the combustion engine is reduced or switched off, so that the temperature of the connected catalytic converter also drops. This is the case, for example, when stopping at traffic lights, generally when the vehicle is decelerating, or when driving downhill. This includes a power cut-off, that is, a targeted interruption of the fuel supply to the combustion engine when the vehicle is operating in coasting mode.

[0004] If the combustion engine is then ignited again with a higher power, the catalytic converter, which has cooled down in the meantime, can only convert the harmful gases to a limited extent. In addition, an excess of oxygen can occur in the catalytic converter due to the fact that the catalytic converter is filled with fresh air during the thrust cut-off. At the beginning of combustion, this has the effect that in particular NOx components are not fully converted and enter the environment. Increased particle emissions can also occur. Similar situations also occur in hybrid vehicles, for which only the electric motor is sometimes used without the combustion engine and the combustion engine is disconnected. Summary of the invention

[0005] According to the invention, a method, a system, a computing unit and a computer program for carrying out the method are provided. Advantageous embodiments are the subject of the following description.

[0006] According to one aspect of the present invention, a method for reducing emissions in a vehicle having a combustion motor is proposed, the method comprising acquiring road section-related data, the road section-related data at least partially comprising data on an estimated required drive power of the combustion motor on a predetermined driving section, wherein the combustion motor is controlled based on the acquired road section-related data during or before driving on the predetermined driving section in order to heat an exhaust gas aftertreatment system of the combustion motor.

[0007] The control of the combustion motor can include, for example, prematurely ending the operating phase in which the combustion motor is switched off and reactivating the combustion motor. Here, the operating phase in which the combustion motor is switched off can be, for example, a parking phase or a stop phase of the vehicle, a thrust switching-off phase or a regeneration phase. In another embodiment of the present invention, the control of the combustion motor can include at least temporarily limiting the power of the combustion motor. As with the limitation of the motor power, the premature reactivation of the combustion motor can limit emissions in the vehicle by heating the exhaust gas aftertreatment system.

[0008] According to an exemplary embodiment, the control of the combustion engine includes the following steps: determining whether the vehicle is currently in a thrust cut-off phase; determining the expected stopping duration in the expected stopping phase of the vehicle with the help of route-related data; and determining on the basis of the expected stopping duration whether the thrust cut-off phase should be terminated prematurely or the combustion engine should be reactivated prematurely in the expected stopping phase. Optionally, the control can also determine that neither of these two options is executed. In this way, the optimal control in terms of power technology and emission technology can be determined depending on the expected duration of the previous stopping phase.

[0009] In all examples, the route-related data can be obtained from a central server, wherein one or more vehicles collect measurement data while driving on a predetermined route and transmit the measurement data to a central server, and wherein the central server at least partially analyzes the measurement data and processes it into route-related data for the predetermined route. Thus, even vehicles without their own sensors can obtain prediction values ​​and route-related data for applying a suitable driving strategy, for example as an extension of a navigation map.

[0010] According to one embodiment of the present invention, the data related to the road section includes at least one of the following data: position data, navigation data, slope data, parking points on the road section, expected parking duration at the parking points of the road section, expected motor power, expected rotation speed. Similarly, the measured data and / or data related to the road section can include at least one of the following data: vehicle position data, vehicle speed, vehicle acceleration, slope of the road section, user requirements, lambda value of the oxygen sensor, temperature of the exhaust gas aftertreatment system, motor temperature, motor torque, motor speed, engaged gear. Other examples of data and measured data related to the road section are derived from the detailed description of the embodiment. The data can also be combined in a mutually dependent manner, for example in the form of an indicator of the motor speed at a specific position or in the form of a function of other measured values.

[0011] A computing unit according to the present invention, for example a control unit of a motor vehicle, is configured, in particular in terms of programming, to carry out the method according to the present invention.

[0012] It is also advantageous to carry out the method according to the invention in the form of a computer program or computer program product with a program code for carrying out all method steps, since this results in particularly low costs, in particular if the executing controller is also used for other tasks and is therefore already present. Suitable data carriers for providing the computer program are in particular magnetic, optical and electrical memories, such as, for example, hard disks, flash memories, EEPROMs (electrically erasable programmable read-only memories), DVDs (digital versatile disks), etc. The program can also be downloaded via a computer network (Internet, intranet, etc.).

[0013] Furthermore, according to one embodiment of the present invention, a system is proposed, which includes: another remotely arranged computing unit, which is configured to receive measurement data about a predetermined driving route, wherein the remotely arranged computing unit is further configured to at least partially analyze the measurement data and process it into route-related data; and a computing unit or a controller in a vehicle as described above, which is designed to obtain route-related data from the remotely arranged computing unit. Furthermore, the system can include one or more vehicles, which are equipped with at least one sensor and a control device, wherein the control device is configured to collect measurement data of at least one sensor on a predetermined route and transmit the measurement data to a central server.

[0014] In this case, the term remotely arranged computing unit naturally also includes any arbitrary processing location, server, cloud or other element which is able to collect, analyze and forward data from a plurality of vehicles and comprises corresponding interfaces or communication connections.

[0015] Further advantages and embodiments of the invention are apparent from the description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention is schematically illustrated in the drawings by means of exemplary embodiments and is described below with reference to the drawings.

[0017] Figure 1 A schematic diagram shows a driving situation in which a method according to one specific embodiment of the present invention can be used;

[0018] Figure 2 The centralized collection of road segment data according to one embodiment of the present invention is exemplarily shown;

[0019] Figure 3A driving situation is shown in which a method for ending a thrust cut-off according to an exemplary embodiment of the present invention is used; and

[0020] Figure 4 A driving situation is shown in which a method for early engine starting according to a further specific embodiment of the present invention is used. DETAILED DESCRIPTION

[0021] Data collection and forecasting

[0022] Figure 1 The speed profile of a vehicle on a predetermined route is shown by way of example, wherein the speed v is plotted over the distance d covered. The route can be divided into two areas B1 and B2, wherein, for example, a node can be a stop 10 at a traffic light or a bend. This is a typical situation in which a coasting mode and a thrust cut-off can be used in the vehicle. Another typical situation is downhill driving.

[0023] The figure shows three different speed changes F1, F2, F3, which can represent, for example, the changes of three vehicles on a predetermined driving route or three trips of the same vehicle. In area B1, the vehicle first moves at a uniform speed, wherein the starting speed is different, and then the speed is reduced to the minimum speed. This minimum speed can be 0, but not necessarily 0. It can be seen that the parking points with the lowest speed are located at different points of the route. In this example, the braking process also starts at different positions in each trip; trip 1 shows the highest starting speed and the longest deceleration distance. The exact change process is only shown as an example.

[0024] After the parking point 10 or the point with the minimum speed, the acceleration phase is shown in the area B2. The course for each travel is different again, the travel F1 here shows the minimum acceleration, while the travel F3, for example, represents a strong acceleration. This area can be, for example, the acceleration after parking, for example starting after a traffic light.

[0025] However, instead of a speed course as shown, similar situations can also represent high dynamics in the driving behavior, i.e. strong acceleration or braking behavior, or also generally increased loads (even if the speed remains constant), such as, for example, driving uphill on a slope without stopping. In all these cases, due to the increased load, a higher emission load to be borne by the exhaust gas aftertreatment system also occurs.

[0026] Different conclusions about the route section can be drawn from different travel courses by collecting and analyzing these and other data.

[0027] Figure 2 The components involved in one specific embodiment of the invention are shown, in which route data are collected and learned in order to adapt the driving and operating strategy of the vehicle. A vehicle 100 is shown here as a representative example, which collects and uses different data during operation. This can be data related to the vehicle itself, such as, for example, data related to existing components and components that have an impact on driving performance and engine operation; data collected during driving operation, such as, for example, speed, acceleration, lambda value of an oxygen sensor (before or after the catalytic converter), temperature of the catalytic converter, engine temperature, engine torque, engine speed, engaged gear; and collected data related to the environment, such as, for example, position data collected by GPS or other positioning systems, altitude measurement data, slope data, speed limit or average speed, turns and parking positions in traffic, weather data such as thin ice or humidity. For example, the vehicle can record how the speed changes on a specific specified route, which engine speeds occur at a selected speed on a short slope and from which area the user (or the vehicle automatic control system) usually changes gears while the user is driving along the route.

[0028] A suitable vehicle 100 can therefore collect at least a portion of this data by suitable sensors in the vehicle and then transmit it via a communication device, 110. For this purpose, the vehicle can be equipped with a mobile radio connection, for example. Nowadays, vehicles are often networked in one or more ways for other applications. A connection can exist with at least one remote computing unit 120, such as a central server or computing center, with a storage system such as a cloud or a decentralized storage system, with other vehicles and / or with a traffic infrastructure. The connection 110 can be established here, for example, via a data connection of a mobile radio network or a separate data connection. Other interfaces that can be used locally or remotely, such as a WLAN connection or a Bluetooth interface and other common low-energy interfaces, are also possible.

[0029] As an alternative, the vehicle can also use a communication connection that is only temporarily available in conjunction with a local storage, which is always used, for example, when a mobile radio connection is temporarily or permanently not available. In this case, it is also possible to first store more extensive data in the vehicle 100 by means of a suitable storage system and then, for example, synchronize the data accordingly or retrieve the data and transmit them to the central server 120 when arriving home. Figure 2 The collection of data in an online central system in the form of a remote computing unit which collects and processes data from a large number of vehicles is shown by way of example.

[0030] All the elements used can be integrated or connected at different locations in the vehicle; therefore, the data can be collected by the motor control unit through different sensors, integrated in the on-board computer or infotainment system. It can involve a separate system or a control unit or microprocessor that has already assumed other tasks in the vehicle. The system can be fixedly integrated in the vehicle, or can be installed or removed and provided with corresponding interfaces with the vehicle's sensors and on-board devices. There is no mandatory clear boundary between these different systems in the vehicle, and these systems can also be connected to each other in different ways, for example, via a bus system. It goes without saying that any possible combination of these and other elements is possible, as long as they can assume the tasks of data collection, data transmission and / or data analysis according to requirements.

[0031] Then, corresponding combined route-related data can be compiled from the collected data in conjunction with the position data. For the position data, common systems such as GPS or other positioning systems present in the vehicle can be analyzed.

[0032] It goes without saying that improved predictions can also be achieved with a larger number of measurement data. In this case, the system can, for example, median all the measurement data acquired for a route section, if this makes sense; however, it is also possible to record and store all route section data or a portion of the acquired data separately, for example for each vehicle type, since the operating data of different vehicles on the same route section can differ greatly.

[0033] The acquired and analyzed data are then assigned in turn to the vehicle systems used in the desired processing phase. Figure 2 130. For this purpose, the vehicle 140 can, for example, receive regular updates of its navigation map, wherein the map is combined with such route-related operating data. The same applies to the connections and communication means of the vehicle 140 as described above with respect to the data-collecting vehicle 100. Preferably, a correspondingly equipped vehicle can both collect and transmit data and also receive the collected route data for the driving strategy, or the vehicle can assume only one of the two roles 100, 140.

[0034] According to an embodiment, a part of the data can already be processed and analyzed in the collecting vehicle 100, and only the results of the analysis, for example the route data of multiple days within the scope of the same driving route, are averaged and then sent to the remote computing unit 120. However, as an alternative, all raw data can also be transmitted separately or in addition to the analyzed data. When using the data, it is also applicable that the driving or operating strategy can already be calculated and prepared at the central location 120 and thus be forwarded to the vehicle for use in a prepared state, for example in the form of a navigation map with a prepared driving strategy, or that the raw measurement data or only partially processed data are also transmitted to the vehicle 140, and the corresponding control system in the vehicle 140 can then respectively formulate an adapted driving and operating strategy for the vehicle used from these data (for example using suitable software).

[0035] According to one embodiment of the invention, the previously collected data thus allow the pure map data to be enriched with different information about the route and the expected behavior of the vehicles moving on it. Thus, the map can be provided with additional information about the gradient, about the duration of the traffic light state or about the route sections with temporarily restricted speeds, for example. These data can be specified as desired depending on the desired depth of prediction; thus, for example, different route characteristics can be stored for different clock times.

[0036] It is also possible to extrapolate the data stored and analyzed specifically for a specific route segment to other route segments. If, for example, the vehicle characteristics at different traffic lights are recorded and known by the vehicle, corresponding rules or driving strategies can be derived and stored therefrom, which apply to all traffic lights or parking points, even if there is no data for the traffic lights or parking points. If new data are available later that allow a more accurate analysis (for example, there is a deviation in the duration of the traffic light state at a traffic light that is unknown so far), the stored data can be improved. Similar processing methods can be envisioned for slopes or turns and downhills on the road segment. Therefore, by applying the stored model situations to other situations, it is also possible to easily configure the following map areas with data on driving and operating strategies: for the map areas, there is no or only a small amount of measurement data for analysis so far.

[0037] The stored data and rules about the driving strategy can also be combined with the data measured dynamically during driving operation in order to work as efficiently as possible. In addition to the data currently measured in the vehicle, systems such as Car-2-Infrastructure (Car2x) can also be used here if corresponding interfaces and systems are available. In this case, the elements of the infrastructure, such as traffic lights and specially provided transmission points, are provided with communication means in order to exchange information directly with the vehicle, for example via WLAN (Wireless Local Area Network) or mobile radio networks. This can be information such as the status of traffic lights, road closures, decelerations due to congestion and changing speed limits. A similar concept is v2v (vehicle to vehicle) communication or car2car (vehicle to vehicle) communication, in which vehicles in the surrounding area communicate directly with each other in order to display lane changes, emergency braking, the end of congestion or other unexpected events on the road section that can be significant for other vehicles. In one embodiment, the vehicle according to the invention can incorporate such data into the current driving strategy or modify the map-based rules.

[0038] Driving and operating strategies

[0039] According to one specific embodiment of the invention, the knowledge about the route obtained from the collected data, which can be present, for example, in the form of separate route data, combined map data or situation-based rules, is used to limit emissions during driving operation as effectively as possible. In this case, the motor can be ignited to a greater extent than would be required based on other drive control components in the drive train, in particular based on route-related data. In this case, the data can be used not only for the operating strategy, i.e. the operating mode of the combustion engine in a specific situation, but also for the entire driving strategy (acceleration, speed).

[0040] The temperature of the cooled catalytic converter can be increased again within 20 to 30 seconds, for example. Oxygen balance is usually established more quickly and can be achieved within about 5 seconds. However, the exact time depends of course on the type of exhaust gas aftertreatment used and primarily on the operating point of the combustion engine. As already described, the oxygen balance plays a greater role in pure combustion drives than in hybrid drives, in which a regeneration phase is usually used instead of a thrust cut-off, in which the combustion engine is completely disconnected from the drive and does not have an increased air flow. In principle, however, all methods described by way of example for thrust cut-off can also be used for hybrid vehicles, in which a regeneration phase is carried out instead, for example.

[0041] A first possibility is to stop the thrust cut-off. Figure 3 Again according to Figure 1 The example of is shown with a deceleration (area B1), a stopping phase and a subsequent acceleration (area B2). That is, if the operating phase starts with a coasting operation (B1) and a thrust cut-off is applied, that is, the fuel injection to the combustion engine is interrupted, then the control device of the vehicle 140 can determine from the acquired route-related data how the driving behavior and the required motor power are expected to change over the upcoming route section. On this basis, the control unit can then actively terminate the thrust cut-off in advance at an appropriate time 15, that is, at least re-establish fuel injection and ignite the engine at a lower level, in order to avoid further cooling and ventilation of the catalytic converter. The line course shown below the diagram should show the course of the thrust cut-off (S, upper line) and the course of the ignition of the engine (M, lower line); that is, it can be seen that the thrust cut-off is applied for a certain time and then also obviously terminated and the engine is ignited again before the end of the speed reduction and before the stopping point.

[0042] According to another embodiment, when a phase with a thrust cut-off is detected, in contrast to the previous option, the thrust cut-off is maintained and the combustion engine is restarted prematurely during the subsequent shutdown phase in order to achieve sufficient heating. Figure 4 With the help of Figure 1 and 3. The stopping phase is again determined from the acquired route-related data. Here, the time for starting the motor is determined according to which data about the expected stopping time are present in the current route section. If, for example, there are collected, stored or otherwise acquired data for the route section, which show that the red traffic light state will continue for another 20 seconds after the vehicle reaches the traffic light, then the thrust cut-off in area B1 can be fully utilized and the motor can be started during the subsequent stopping phase at the traffic light, for example 10 seconds before the green traffic light signal. The line below the speed diagram shows this process; the thrust cut-off S and the cut-off of the combustion engine are maintained until the stopping point between these two areas, 25, and only then is the motor ignited again during the stopping phase (line M below the diagram), of course, before starting. Here, it is preferred to operate the motor at low power during this time, because the driving power is not yet required and the emissions should be kept as low as possible. This operating mode is particularly suitable for re-establishing the oxygen balance in the exhaust gas aftertreatment system. By taking into account the travel time to be expected at the current speed or the speed prevailing on the route, the analysis and prediction can already be carried out significantly before reaching traffic lights or generally reaching an area with reduced speed.

[0043] Should the thrust cut-off be terminated early? Figure 3 ) or can it anticipate a sufficiently long subsequent stopping phase during which the motor is started in advance ( Figure 4 ), it is also possible to judge on the basis of predictive data about the route section. For example, a threshold value for the expected stopping time can be determined, so that the thrust cut-off is terminated prematurely when the expected stopping time is shorter than the threshold value, and when the expected stopping time exceeds the threshold value, the above-mentioned use of the thrust cut-off together with the early connection of the combustion engine can be selected only during the stopping phase. With the help of the above-mentioned example, the threshold value can be determined at 8 seconds, for example, so that the thrust cut-off is terminated prematurely when the expected stopping phase is only 2 seconds (below the threshold value) and the motor is already re-ignited in the coasting operation and is instead operated, for example, in idling. If, however, a stopping phase of 20 seconds is expected as in the second example, the system can decide to restart the motor only during the stopping time. Of course, any other values ​​and combinations can also be used as determining factors. Similarly, based on known route-related data, not only the optimal time for terminating the thrust cut-off is determined, but also the optimal time for starting the motor during the stopping phase, or the motor can be reactivated immediately.

[0044] Another possible situation in which the method according to the invention can work is downhill driving. Thus, area B1 in the figure corresponds to a downhill slope, in which coasting occurs, while area B2 represents the flat road section or uphill slope that follows. It is not mandatory to set a parking point or parking phase between the areas. Deceleration does not necessarily occur in area B1. The characteristics of the road section, i.e. uphill, downhill, continuous driving operation and the expected speed can be prepared as road section-related data for the road section section. Here, the vehicle control unit can therefore terminate the thrust cut-off of the motor in advance, especially at the downhill slope, so that the exhaust gas aftertreatment system does not cool too much. Since the driving section and its characteristics are known from the road section-related data in an ideal situation, the time for terminating the thrust cut-off can be optimized accordingly.

[0045] The route data can also be used to reduce the general driving dynamics, that is, to avoid strong acceleration, acceleration with a cold engine, and / or too frequent power cut-offs. This prevents oxygen imbalances in the catalytic converter and improves emission values. Similarly to the control of the power cut-off, route-related data such as, for example, uphill slopes, parking spots, bends, speed limits can then be used to limit and regulate the engine power and the maximum possible acceleration permanently or in specific sections. This is possible in particular when the vehicle is operated in combination with a speed control device (e.g., adaptive cruise control, ACC), in which the vehicle automatically tries to maintain a speed predefined by the user, or in the case of an assistance system that can also adjust different speeds with the help of map data or other features (e.g., "CountryRoadAssist").

[0046] The system can be provided with further features, such as a distance sensor. This allows the acceleration to be adapted more flexibly and more proactively. If the exhaust gas aftertreatment system is cold, that is to say, for example, after a long parking or coasting phase in which the combustion engine is switched off, such a system can predetermine a maximum value for the acceleration or torque requirement for a limited time (until actual or estimated heating). This can be used alone or in combination with the previously described limitation of the thrust cut-off or parking phase, so that, for example, the thrust cut-off is terminated prematurely in area B1 and the possible acceleration is still maintained with restrictions at the beginning in area B2. Since the driver then does not have all the desired power available, this difference can optionally be compensated, for example, by the electric machine, in particular in hybrid vehicles. The expected power can be estimated or calculated by means of a catalyst model, so that the driving strategy can be optimized with respect to power and emissions.

[0047] For all these strategies, route-related data can be used, as already described, in order to adapt the duration and extent of the acceleration limitation, the control of the driving dynamics and other features to the actual route conditions. As for the thrust cut-off, measurement data are first collected by one or more vehicles, stored locally or centrally, and analyzed, and then combined with map data to form route-related data, which can predict the necessary engine power, the expected speed course and other requirements for the engine operation for a specific route section.

Claims

1. A method for reducing emissions in a vehicle having a combustion engine, comprising: Acquiring data related to a road section, the data related to the road section at least partially including data related to an estimated required driving power of the combustion motor on a predetermined driving section; and According to the acquired route-related data, the combustion engine is controlled before or during driving on a predetermined driving route in order to heat an exhaust gas aftertreatment system of the combustion engine. The control of the combustion motor includes: ascertain whether the vehicle is currently in a thrust cut-off phase; if this is the case, The estimated stopping time during the expected stopping phase of the vehicle is then determined based on the route-related data, and On the basis of the predicted shutdown duration, it is determined whether the thrust cut-off phase is to be terminated prematurely or whether the combustion engine is to be reactivated prematurely during the anticipated shutdown phase.

2. The method according to claim 1, wherein the controlling of the combustion motor comprises: The operating phase in which the combustion engine is switched off is terminated prematurely and the combustion engine is reactivated. 3 . The method according to claim 2 , wherein the operating phase in which the combustion motor is shut down is a parking phase, a thrust shut-off phase or a regeneration phase of the vehicle.

4. The method according to any one of claims 1 to 3, wherein the control of the combustion motor comprises: The power of the combustion motor is at least temporarily limited.

5. A method according to any one of claims 1 to 3, wherein the road section-related data is acquired from a computing unit remote from the vehicle, wherein one or more vehicles collect measurement data while traveling on a predetermined road section and transmit the data to the computing unit remote from the vehicle, and wherein the computing unit remote from the vehicle at least partially analyzes the measurement data and processes the measurement data into road section-related data for a predetermined road section.

6. A method according to any one of claims 1 to 3, wherein the data related to the road section includes at least one of the following data or a combination thereof: position data, navigation data, slope data, a parking point on the road section, an expected parking time at the parking point of the road section, an expected motor power, and an expected rotation speed.

7. The method according to claim 5, wherein the measurement data and / or the data related to the road section include at least one of the following data: vehicle position data, vehicle speed, vehicle acceleration, slope of the road section, user requirements, lambda value of the oxygen sensor, temperature of the exhaust gas aftertreatment system, motor temperature, motor torque, motor speed, and the engaged gear. 8 . A computing unit configured to carry out all method steps of the method according to claim 1 .

9. System, including: a remote computing unit, which is configured to receive measurement data about a predetermined driving route, wherein the remote computing unit is further configured to at least partially analyze the measurement data and to process the measurement data into route-related data, and The computing unit according to claim 8 in the vehicle is designed to acquire the route-related data from the remote computing unit.

10. The system according to claim 9, further comprising: One or more vehicles, each of which is equipped with at least one sensor and a control device, wherein the control device is configured to acquire measurement data of the at least one sensor on a predetermined route and to transmit the measurement data to the remote computing unit. 11 . A computer program product comprising a computer program which, when executed on a computing unit, causes the computing unit to carry out all method steps of the method according to claim 1 . 12 . A machine-readable storage medium having a computer program stored thereon which, when executed on a computing unit, causes the computing unit to carry out all method steps of the method according to claim 1 .

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