WO2015076728A1

WO2015076728A1 - Method and system for adaptation of at least one injector at an internal combustion engine

Info

Publication number: WO2015076728A1
Application number: PCT/SE2014/051354
Authority: WO
Inventors: Magnus GRANSTRÖM
Original assignee: Scania Cv Ab
Priority date: 2013-11-21
Filing date: 2014-11-14
Publication date: 2015-05-28
Also published as: SE540690C2; DE112014004957T5; SE1351380A1

Abstract

The present invention pertains to a method at the adaptation of at least one injector (201-206} in a combustion engine (101), wherein said combustion engine (101) comprises a number n of combustion chambers (c1-c6), and wherein fuel may be injected into said number n of combustion chambers (c1-c6) with the use of at least one respective injector (201-206). The method comprises, at said adaptation: - to inject a first amount of fuel to a first subset X of said number n of combustion chambers (c1-c6), where the number of combustion chambers x in said subset X consists of x = n-y; y ≥ 1, and - to control the injection of fuel into combustion chambers comprised in a second subset Z of said number of combustion chambers (c1-c6), so that the injection of fuel amounts to a second amount of fuel, wherein the combustion chambers comprised in said, second subset Z of combustion chambers are different from the combustion chambers comprised in said first subset X of combustion chambers.

Description

METHOD AND SYSTEM FOR ADAPTATION OF AT LEAST ONE INJECTOR AT AN INTERNAL COMBUSTION ENGINE

Field of the invention

The present invention pertains to combustion engine systems , and in particular to a method for the adaptation of at least one injector for a combustion engine according to the preamble of claim 1. The invention also relates to a system and a vehicle, as well as a computer program and a computer program product, which implement the method according- to the

inventio .

Background of the invention

Modern combustion engines are usually equipped with injectors for supply of fuel to the combustion engine's combustion chambers, e.g. one or several cylinders, in order to generate propulsive force on an output shaft from the combustion engine by combustion.

The amount of fuel which must actually be supplied to a combustion engine at any given point in time is usually determined by a control device in the vehicle's internal control system, which determines a fuel amount for injection, e.g. based on the prevailing operating conditio s of the vehicle. The injectors for injection of fuel are then

controlled based on signals from the control device.

These injectors are usually controllable in such a way, that a relatively accurate and specific fuel amount may be supplied to the combustion process, and additionally at a desired point in time in the combustion, cycle.

However, in order for the desired fuel amount to actually be supplied to the combustion process, and for the combustion engi e to thus operate as desired/designed, k owledge is required about the inj ector' s specific features , i.e. how much fuel that actually passes through the injector, and thus is supplied to the combustion chamber, when the injector is open. The fuel amount that passes through the injector when it is open, and. which is actually supplied to a combustion chamber at the opening of an injector, is impacted e.g. directly by the opening time during which the injector is open, as well as by the pressure at which the fuel is pressurised.

The amount of fuel which passes through the injector also depends on the design of the injector, e.g. the design of the hole (s) through which the fuel is injected. The injector's specific design may, however, va y f om one injector to another, e.g. because of manufacturing tolerances. For the above reasons, a mapping is often created, e.g. at manufacture or assembly of the combustion engine, as for example a lookup table, where the amount, of fuel actually supplied, by the injector is specified for specific injection parameters, e.g. opening times/fuel pressure. The injectors may be individually calibrated, at the manufacture of an injector and/or combustion engine, so that the mapping may be adapted to each individual injector .

With the use of said mapping, it. may be ensured that, the actual fuel amount which is supplied to the combustion

engine's combustion chamber is also consistent with the intended amount of fuel for injection.

The characteristics of an injector may, however, change over time. For this reason, an adaptation of the injectors is usually carried out, either regularly or as and when needed, so that parameters for control of the injectors are corrected when needed. One objective of the present invention is to provide a method for adaptation of at least one injector for a combustion engine in a vehicle. This objective is achieved with a method according to claim 1 ,

The present invention pertains to a method at the adaptation of at least one injector in a combustion engine, wherein said combustion engine comprises several n combustion chambers, and wherein fuel may be injected to said several n combustion chambers with the use of at. least one respective injector. The method comprises, at said adaptation:

- to inject a first amount of fuel to a first subset X of said several n combustion chambers, where the number of combustion chambers x in said subset. X consists of x = n-y; y ≥ 1, and.

- to control the injection of fuel into combustion chambers forming part of a second subset Z of said several combustion chambers, so that the injection of fuel amounts to a second, amount of fuel, different from, said first amount of fuel, so that the combustion chambers comprised in said second subset Z of combustion chambers are different from the combustion chambers comprised in. said first subset X of combustion chambers .

Said second amount of fuel may consist of an amount of fuel that falls below said first amount of fuel, and may also be such that no fuel is injected into the combustion chambers comprised in said second subset Z of combustion chambers.

As mentioned above, at the operation of a combustion engine it is important that the fuel amount being supplied to the combustion engine's combustion chamber is consistent with the intended amount of fuel for injection. Since, e.g. because of wear, the characteristics of an injector usually change over time, a. new calibration or adaptation of the injectors is usually carried out, either regularly or as and when needed, so that the injectors' injection parameters such as opening t imes are corrected hen eeded . This adaptation may be carried out in different ways, where e.g. different adaptation, methods may be applied depending on. the fuel amounts to be adapted. Thus, different types of adaptation methods may be used for different operating areas (combustion engine loads) for one and the same combustion engine, e.g. depending on the size of fuel amounts injected in the various operating areas, e.g. high/low combustion engine loads .

One way of carrying out an adaptation is to apply a. known load to the combustion engine, wherein the fuel injection is subsequently adjusted until the combustion engine's operation corresponds to the load setting. When the load is maintained, parameters for fuel injection, are determined and stored, e.g. opening time and injection pressure, i.e. mapping according to the above is updated, whereby later settings of these

injection parameters thus entail that the combustion engine will deliver work corresponding to the load applied at the adaptat ion .

One way of achieving said known and thus determined load is to use an exhaust brake, with which the exhausts generated, from. the combustion engine are throttled. With the use of such exhaust brakes, the load may be controlled very accurately. A known load may also be applied to the combustion in. another applicable manner, e.g. with the use of an electric motor in the case of hybrid vehicles. At the application of a known load, however, this is normally limited with respect to the maximum force that may be applied. This also entails that the adaptation may not implemented for work achieved by the combustion engine, above the amount of load. This in turn means that only a part, sometimes only a small part, of the combustion engine's operating- area may be adapted in this manner. According to the present invention, a greater part of the combustion engine's work may be adapted, even if the maximum applicable load remains the same.

This is achieved by way of injecting fuel o ly in a subset of the combustion engine's combustion chambers. By proceeding in this manner, the work which corresponds to the load applied will be generated by only a part of the combustion engine's combustion chambers, and as a result these combustion chambers must perform a larger amount of work. This represents work which, if all the combustion chambers carried out this larger amount of work, would constitute a total amount of work representing a significantly greater force than the force applied, so that the invention also allows for adaptation of work representing this greater load.

The smaller the number of combustion chambers to which fuel is supplied, the greater a load may thus be simulated.

According to one embodiment, fuel is also injected into one or several of the combustion chambers which form part of said second subset. Z of combustion chambers, as per the above. In this case, a smaller amount of fuel may be injected in one or several of these combustion chambers. This may e.g. have positive effects regarding the combustion engine's operation.

According to one embodiment, fuel is injected into all the combustion chambers comprised in said second subset Z of combustion chambers. The amount of fuel that is injected into these combustion chambers is different from the amount that, is injected into the combustion chambers comprised, in said, first subset X, and according to one embodiment it is smaller than the amount injected into the combustion chambers comprised in said firsts subset X.

The fuel injected into the combustion chambers comprised in said second subset Z preferably consist of previously adapted fuel amounts, so that the force (torque) contribution from these fuel amounts is known.

Further, different amounts of fuel may be injected into different combustion chambers which are not comprised in said first subset of combustion chambers, e.g. with the objective of impacting the combustion engine ' s operation.

The adaptation may be arranged to be carried out with the combustion engine disconnected from the vehicle's driving wheels, in order to avoid impact by forces which are hard to estimate and which may impact the vehicle when it is in movement. The adaptation may also be arranged to be carried, out at a standstill.

The adaptation may be carried, out for several loads and for different injection conditions, e.g. for several different fuel injection pressures and/or other injection parameters. The adaptation may also be arranged to be carried, out several times for the same load./parameters , wherein a higher accuracy at the adaptation may be obtained.

Further characteristics of the present invention and

advantages thereof will be described in the detailed

description of example embodiments set out below and in the enc1.osed d.rawings .

Brief description of the drawings

Fig. 1A shows a powertrain in a vehicle, in which the present invention may advantageously be used.

Fig. IB shows a control device in. a vehicle control system. Fig. 2 schematically shows an injection system in the vehicle displayed in Fig. 1.

Fig. 3 schematically s ows an example method according- to one em odiment of the present in ent ion .

Detailed description of preferred embodiments

Fig. 1.A schematically shows a powertrain in a vehicle 100, according to an embodiment of the present invention. The vehicle 100 shown schematically in Fig. 1A comprises a powertrain with a combustion engine 101, which in a customary manner, via. an output shaft on the combustion engine 101, usually via a flywheel 102, is connected to a gearbox 103 v a a clutch 106. The combustion engine 101 is controlled by the control system of the vehicle 100 via a control device 115.

An output shaft 107 from the gearbox 103 drives the driving wheels 113, 114 via a final gear 108, e.g. a customary

differential, and the drive shafts 104, 105 connected to said final gear 108. Fig. 1A thus shows a shifting system of a type with automatically shifted manual gearboxes, but the invention is equally applicable in all types of powertrains, such as manual gearboxes, double clutch boxes, conventional automatic boxes, etc. Likewise, the invention is equally applicable in all types of vehicles where a combustion engine is used, such as a hybrid vehicle.

Combustion engines in vehicles of the type shown in Fig. 1A are often equipped with controllable injectors for supply of the desired amount of fuel to the combustion engine's

combustion chamber at the desired point in time during a combustion cycle.

Fig. 2 schematically shows an example of a fuel injection system for the combustion engine 101, exemplified in Fig. 1A. The fuel injection system consists of a so-called Common Rail system, but the invention is equally applicable in other types of injection systems where controllable fuel injection is used. The combustion engine 101 consists of, in the displayed example., a 6-cylinder combustion engine with an injector for each combustion chamber (cylinder) , schematically indicated in the figure with 201-206.

Each injector 201-206 is thus responsible for injecting

(supplying) fuel into the combustion chambers cl-c6,

schematically indicated with dashed lines. Obviously, the combustion engine may consist of an engine with any number of combustion chambers. According to the present invention, however, at least two. Also, the injection system may comprise two or more injectors per combustion chamber cl-co. The injectors 201-206 are individually controlled by respective actuators (not shown) arranged at the respective injectors, which, based on received control signals, control the

opening/closing of the injectors 201-206.

The control signals for the control of the actuators'

opening/closing of the injectors may be generated by some applicable control device, e.g. by the engine control device 115 in the example displayed. The control device 115 thus determines the amount of fuel which is to be injected into the respective combustion chambers cl-co at any given time, e.g. based on prevailing- operating conditions in the vehicle.

Obviously, this determination may be carried out often, e.g. every time a change with respect to the work requested from the combustion engine occurs. Specifically how the required amount of fuel is determined is well described in prior art technology, and will not be described in further detail herein. The control device 115 uses a mapping according to the q above to translate a desired fuel amount into a corresponding opening time for the injectors.

The injection system shown in Fig. 2 consists of a so-called Common Rail system, which means that all injectors (and therefore all combustion chambers} are supplied by a common fuel conduit 207 (Common Rail), which, with the use of a fuel pump 208, is filled, with fuel simultaneously with the fuel in the conduit 207 being pressurised with a certain pressure, also with the help of the fuel pump 208. The pressurised fuel in the common conduit 207 is then injected into the combustion chamber of the combustion engine 101 with the use of the respective injectors 201-206, The exhausts resulting during combustion are in the customary way led away from the

combustion engine 101 via an exhaust conduit 209, An exhaust brake 210 is arranged in the exhaust pipe. The exhaust brake 210 is controlled, by the cont ol system of the vehicle 100, with the help of a control device 116 (see Fig, 1A) .

Injection of fuel into a combustion chamber may occur in various ways, where the fuel may e.g. be supplied in the form of a longer injection or of an injection divided into several consecutive injections during- one and the same combustion cycle. Several openings/closings of a specific injector may thus be carried out during one and the same combustion cycle. Regardless of how the injection of fuel occurs during a combustion cycle, it is important that the injected fuel amount is consistent with the intended amount, of fuel for injection. If the actually injected amount of fuel becomes too small in relation to the amount of injected fuel wanted, the combustion engine's performance will be lower than intended, with poorer d iveability as a consequence. Conversely, if t e injected fuel amount becomes too igh in relation to the intended fuel amount, the combustion engine may deliver a higher torque/output than intended. This may in turn lead to damages to the combustion engine and/or other components in the vehicle, if these are not dimensioned for the higher output .

Injection of the correct amount of fuel may, according to the above, be ensured by way of carrying out an adaptation at the manufacture/assembly of the combustion engine and/or

injectors. This may be carried out for each injector, with the objective of having regard to individual differences among injectors. The adaptation may also be carried out individually for each injector, but the injectors may also be arranged to be handled as a group, i.e. the adaptation is carried out so that the injectors jointly achieve injection of the desired total amount of fuel, though individual differences may still occur .

The characteristics of an injector may, according to the above, change over time, whereby a certain injection parameter setting no longer ensures injection of the intended, amount of fuel. For example, the injectors' characteristics may change in such a way that a higher amount of fuel than desired is injected for a given opening/ in ection pressure ratio, with the disadvantages set out above as a consequence. For this reason, an adaptation of the injectors is usually carried out, either regularly or as and when needed, after the combustion engine has been brought into operation, where the injectors' injection parameters, e.g. opening times, are corrected, so that the amount of fuel actually delivered to the combustion is equal to the amount of fuel intended to be supplied.

An adaptation of the injectors for injection of fuel may be carried out in various ways. For example, the adaptation may be arranged to be carried out according to various methods. depending on whether the adaptation relates to high or low combustion engine loads. The present invention may be applied in different types of adaptation methods, but it is perhaps particularly applicable in adaptation methods where a known load is appl ed to the combustion engine. The invention will therefore be described in connection with such a method, i.e. a method where a known load is applied to the combustion engine at the adaptation.

At such an adaptation a known load is applied to the

combustion engine, so that the fuel injection is adjusted until the work delivered corresponds to the set load, i.e. the combustion engine's speed is kept constant at some applicable speed. This speed, may consist of some applicable speed and may, e.g. at adaptation in a vehicle at a standstill, consist of an idling speed or a proximate speed in order to avoid causing unnecessary speed, increases, unexpected by the driver. This adaptation may then, in a prior art manner, be deemed valid for higher speeds, potentially with the use of a

compensation factor. Alternatively, the adaptation may be arranged, to be carried out for different speeds. When the load is maintained pa ameters for fuel injection, e.g. opening times, are determined, so that existing parameters in the mapping may be replaced with the parameters determined at the adaptation . This therefore means that operation of the

combustion engine with said, determined parameters will entail the combustion engine delivering work corresponding to the load applied at the adaptation. The adaptation may be carried out for several loads and for different injection conditions, e.g. for severa1 different fuel injection pressures arid/or other injection parameters.

One way of achieving said determined/known load is to use an exhaust brake with which the exhausts generated by the combustion engine are throttled, with the result that, a back pressure is formed, in turn resulting in an increased load on the combustion engine. With the use of such exhaust brakes, the load may be controlled very accurately, and. as a result a careful adaptation of the combustion chamber ' s injectors may also be carried out.

A known load, may also be applied to the combustion engine in another applicable manner, e.g. with the use of an electric motor in the case of hybrid vehicles, The load, that may be applied is, however, often, limited, in size and, according to the present invention, adaptation for higher loads may be achieved even though these higher loads are not really available. One example embodiment 300 according to the present invention is displayed in Fig. 3. The method according to the present invention is arranged to be carried out by some applicable control device in the vehicle's control system, and may e.g. be implemented in the engine control device 115 (displayed in. Fig. 1A) or any other applicable control device in the vehicle. The control device may thus consist of any suitable control device in the

vehicle's control system. For example, the function to carry out the adaptation may be arranged in. the control device where adaptation is normally carried out. The invention may also be implemented in a control device dedicated to the present invention.

Generally, control systems in today's vehicles consist of a communications bus system, consisting of one or several communication buses to connect a number of electronic control devices (ECUs) , such as the control devices, or controllers 115, 116, and different components arranged in the vehicle 100. Such a control system may comprise a large number of control devices, and the responsibility for a specific function may be distributed among more than one control device. For the sake of simplicity, in Fig, 1A only a very limited number of control devices are displayed.

The function of the control device 115 (or the control device (s) at which the present invention is implemented) may e.g. depend on signals from the control device 116 which controls the exhaust brake, e.g. to obtain knowledge about the braking force setting. Also, exhaust braking force may be requested by a request to the control device 116. Generally, control devices of the type displayed are normally arranged to receive sensor signals from different parts of the vehicle 100, as well as from, different control devices arranged on the vehicle 100.

The control is often controlled by programmed instructions. These programmed instructions typically consist of a computer program which, when executed in a computer or control device, causes the computer/control device to carry out the desired control action, as a method, step in the process according to the present invention.

The computer program is usually a part of a computer program product, ^"where the computer program product comprises an applicable storage medium 121 (see Fig. 13), with the computer program stored on. said storage medium 121. Said digital storage medium 121 may e.g. consist of any from the following group: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory) , EPROM (Erasable PROM) , Flash, EEPROM (Electrically- Erasable PROM), a hard disk unit, etc., and. may be set up in or in. combination with the control device, where the computer program is executed by the control device. By changing the computer program's instructions, the vehicle's behaviour may thus be adjusted in a specific situation. An example control device (control device 115) is shown schematically in Fig. IB, and the control device in turn may comprise a calculation unit 120, which may consist of e.g. a suitable type of processor or microcomputer, e.g. a circuit for digital signal processing (Digital Signal Processor, DSP) , or a circuit with a predetermined specific function

(Application Specific Integrated Circuit, ASIC) . The

calculation unit 120 is connected to a memory unit 121, which provides the calculation unit. 120 with e.g. the stored program code and/or the stored data that the calculation unit 120 needs in order to be able to carry out calculations. The calculation unit 120 is also set up to store interim or final results of calculations in the memory unit 121.

Further, the control device is equipped with devices 122, 123, 124, 1.25 for receiving and sending of input and. output

signals . These input, and output signals may contain waveforms, pulses or other attributes which may be detected, by the devices 122, 125 for the receipt of input signals, as

information for processing by the calculation unit 120. The devices 123, 124 for sending output signals are arranged to convert the calculation result from the calculation unit 120 into output signals for transfer to other parts of the

vehicle's control system and/or the component (s) for which the signa.Is a.re intended. Each one of the connections to the devices for receiving and sending of input and output signals may consist of one or several of the following: a cable; a data bus, such as a CAN (Controller Area Network) bus, a MOST (Media Oriented. Systems Transport) bus, or any other bus configuration; or of a wireless connection.

Reverting to Fig, 3, an example embodiment 300 according to the present invention is displayed. In step 301, it is

determined whether an adaptation of the fuel injection should be carried out. If so, the method continues to step 302. The adaptation may e.g. be arranged to be carried out with

applicable intervals, e.g. after a certain time has lapsed, when the vehicle has been driven a certain distance or when the vehicle's combustion engine has been in operation a certain time since the previous adaptation. The adaptation may also be arranged to be carried out as soon as an opportunity is provided. For example, the adaptation may be arranged to be carried out only when the vehicle is at a standstill, since a determined load may then be applied to the combustion engine with good accuracy. Accordingly, a criterion for transition from step 301 to step 302 may be that the vehicle is at a standstill. Generally, reference is made to prior art

technology as regards applicable terms for the start of t e adaptation .

At the transition from step 301 to step 302, a parameter i = 1 is set, representing the sequenced adaptation that is to be carried out. For example, a greater or smaller number of adaptations may be arranged to be carried out. For example, adaptation may be carried out for several different loads of the combustion engine, as well as several different, injection pressures. In cases where other parameters may be adjusted, e.g. the injection area, the adaptation may be carried out for additional combinations of injection parameters. Also, the adaptation may be arranged to be carried out at different, combustion speeds.

According to the example displayed in Fig. 3, the parameter i =1 is set. at the transition from, step .301 to 302, but.

according to one embodiment the parameter i is set at a value representing an adaptation following after the adaptation i, which was most recently carried out at a previous occasion. For example, the adaptation may for different reasons be interrupted, before all the adaptations have been carried out, e.g. because the vehicle is set into motion from a standstill.

In this case, the adaptation may be resumed at a later

applicable occasion, so that the adaptation may thus be resumed where it was previously ended..

According to the present example, the combustion

chambers/injectors that participate in the adaptation i are defined for the adaptation i, and. in step 302 the adaptation i is then carried out. This is carried out by applying a load applicable for the adaptation i, e.g. with the use of the exhaust brake 210. With the use of the exhaust brake 210, a very accurate loading- of the combustion engine 101 may be carried out, where this load may be known for different settings of the exhaust brake, i.e. for different throttles and different combustion engine speeds.

The load that may be applied with the use of e.g. the exhaust brake 210 is usually relatively limited in relation to the maximum force that may be developed by the combustion engine 101. According to the present invention, adaptation for a.

larger interval of the force that, may be delivered by the combustion engine 101 is facilitated through, at adaptation, applying a fuel supply where different fuel amounts are supplied, to the combustion engine's combustion chamber at the generation of a force corresponding to the load applied by the exhaust brake 210.

According to one embodiment of the present invention, fuel is supplied only to a subset X of the combustion engine's

combustion chambers cl-c6, while no fuel is thus supplied to the remaining combustion chambers. In e.g. the case of a 6- cylinder combustion engine 101, fuel may be arranged to be supplied, to 3 of the combustion engine ' s 6 combustion

chambers, e.g. cl, c3, c5 in Fig, 2. By e.g. carrying out the 1 adaptation by way of injection of fuel into only 3 of 6 combustion chambers, a significantly greater, approximately doubled, amount of fuel will be required in the 3 combustion chambers cl, c3, c5 participating in the adaptation, compared to if all of the combustion chambers cl-c6 had been used at the adaptat ion .

By proceeding in this manner, in this example, a load twice as great as the one actually applied, may thus be simulated, so that the adaptation may also be used for combustion engine work that is twice as great compared to what actually

corresponds to the force applicable by the exhaust brake. The present invention thus facilitates an adaptation of the combustion chambers' injectors over a greater working area for the combustion engine 101, than what may be achieved when all the injectors participate in the adaptation. This in turn entails that the combustion engine 101 in operation may be driven more accurately over a larger working area.

During the adaptation, the injected amount of fuel is adjusted for the combustion chambers/injectors participating in the adaptation, until the work, delivered by the combustion engine 101 corresponds to the load applied, i.e. the combustion engine's speed is kept constant at the desired speed. In step 303 it is therefore determined whether the adaptation i is completed, and as long as this is not the case, the injection parameter is adjusted via step; 302 in a prior art manner, until the desired conditions have been met. These conditions may be set in a prior art manner and are therefore not

described in further detail here. When the adaptation i is completed, the method continues to step 304 where the

injection parameters for the adaptation i are stored. These may e . . consist of an opening time for in ectors at the injection pressure that has been applied at the adaptation, or other applicable parameters . The method then continues to step 305 at the same time as the parameter i is increased by one, i = and in step 305 it is determined whether the parameter i falls below a parameter j, where j represents the total number of adaptations to be carried out. As long as i is smaller than j, the method reverts to step 302 for the

performance of the next adaptation, while the method is ended at step 306 when all the adaptations have been completed.

In the above example, the combustion engine comprises an even number of combustion chambers, and an adaptation where half of the combustion engine's combustion chambers (injectors) participate is carried out. This adaptation may, according to one embodiment, be assumed to be applicable also for the combustion chambers/injectors that do not participate in the adaptation. According to one embodiment, however, an

adaptation of a first half of the combustion chambers is carried out first, to be followed by an adaptation of the second half of the combustion chambers. In this manner, a better adaptation of the fuel injection may be achieved.

The present invention may thus be applied in order to inject fuel only into e.g. half of the combustion engine's combustion chambers, such as 2 cylinders in a 4-cylinder engine, 3 cylinders (in a 6-cylinder engine}, 4 cylinders (8-cylinder engi e), 6 cylinders (12 -cylinder e gine). The present

invention may also be applied in combustion engines with an odd number of cylinders, e.g. 5, wherein fuel may e.g. be supplied to 2 or 3 of the 5 cylinders of the combustion engine. The number of cylinders applied, may e.g. be selected based on whether the combustion engine may be made to operate in a desired manner at the respective reduced number of c linders . If the combustion engine consists of a 5---cyli der engine, 3 cylinders may e.g. be adapted first, to be followed by an adaptation of the 2 remaining cylinders if possible.

The number of combustion chambers to which fuel is supplied, may also consist of any applicable number of combustion chambers, e.g. 3 of a total of 8 combustion chambers, 5 of a total of 8 combustion chambers, 2 of a total of 6 combustion chambers, 4 of a total of 6 combustion chambers, etc., as long as the combustion engine is able to, to the extent desired, maintain a desired speed without the operation becoming undesirably uneven. The cylinders selected for application at the adaptation may e.g. be selected based on firing order and/or other applicable criteria, in order to facilitate an operation as even as possible for the combustion engine at the adaptation, when it is operated with fewer than all cylinders. Generally, the fewer combustion chambers to which fuel is supplied, the greater the fuel amounts that may be supplied, to such combustion chambers. According to one embodiment, fuel is supplied only to one combustion chamber.

It is also possible to adapt an applicable number of

combustion chambers at a time, e.g. one, two, or three, in a 6-cylinder engine, where adaptation may be carried out first for a first subset of combustion chambers, and then, for the other subset (s), so that, one subset at a time may be adapted. For example, two combustion chambers at a time may be adapted, so that three adaptations are thus required to adapt all the combustion chambers.

It is also possible to adapt an applicable number of

combustion chambers at a time, e.g. one, two, three, four or five, in a 6-cylinder engine, where adaptation may be carried, out cyclically for all possible or applicable combinations of the reduced number of combustion chambers. By proceeding in this way, adaptations may be compared with each other, so that data with respect to individual injectors may be extracted from such comparisons .

According to the present invention, adaptation of larger fuel amounts is thus allowed for an individual combustion chamber, with the result that a good adaptation is obtained for a larger part of the combustion engine's working area. According to the present invention, the adaptation may advantageously be combined ^"with an adaptation according to prior art where the same amount of fuel is injected simultaneously into all of the combustion chambers, so that adaptation according to the prior- art technology may be used for lower loads. Further, the injectors are often non-linear at operation i the areas adapted according to the present invention, i.e. the amount of injected fuel does not increase linearly with the opening time. The invention thus has the advantage that, since a larger part of the injector's working area may be adapted with good accuracy, the negative impact of such non-linearity is reduced, which means that the vehicle may be driven with more accurate control over a larger working area.

The smaller the number of combustion chambers to which fuel is supplied, the more uneven the operation of the combustion engine will probably be. The smallest number of combustion chambers to which fuel is supplied may thus be arranged to be controlled by the combustion engine's operation. If the speed of the combustion engine becomes too uneven, unwanted cylinder pressure variations may arise, with the consequence that the exhaust back pressure also varies. This variation may require that a compensation factor is used to ensure correct

adaptation .

Above, the invention has been described in a manner, where fuel is supplied to one or a subset of the total number of combustion chambers, but where no fuel is supplied to the remaining combustion chambers. According to one embodiment of the present invention, a larger amount of fuel is supplied to at least one of the combustion engine's combustion chambers or to all of the combustion chambers to which fuel is supplied according to the above, while another amount, e.g. a smaller amount, of fuel is supplied to one or several of the other combustion chambers. This smaller amount of fuel may e.g. be arranged to constitute a maximum, of 50% of said, first amount of fuel, a maximum of 30% of said first amount of fuel, or a maximum of 10% of said first amount of fuel. This has the advantage that one or a few combustion chambers may be used to generate the greater part of the work required, with the consequence that larger amounts of fuel may be adapted, while simultaneously injection into the one or several or all of the remaining combustion chambers may be used, e.g. to ensure a more even operation of the combustion engine.

The smaller fuel amount supplied to non-adapted cylinders may also be used to provide a better soundstage and thus a better driving experience when, the adaptation is ongoing-. Generally, when driving a vehicle, excessive deviations from what is normal may be experienced by the vehicle's driver as

disturbing. By supplying a small amount to e.g. all the combustion chambers except one, where such amounts may

advanta.geou.sly already be adapted, and thus allowing for the total resulting force contribution from these combustion chambers to be determined with good accuracy, and thus subtracted from the total work of the combustion engine, the force contribution obtained from the combustion chamber to which a greater amount of fuel is supplied may be determined with good accuracy. Also, different amounts of fuel may be injected into different combustion chambers that are not adapted, e.g. if this is advantageous for the combustion engine's operation. In this case as well, the injected amounts may already be well adapted, so that the force contribution may be taken into consideration as per the above. This method may also be applied where a larger amount of fuel is supplied to more than one combustion chamber according to the above, and thus in all of the cases exemplified above, where fuel has been supplied to a subset of the engine's combustion chambers.

Further, during an adaptation of the above type, in general all unknown loads that that are applied to the combustion engine should be shut off, so that the method according to the present invention may, in a prior art manner, be arranged to shut off all or as many as possible of the loads applied to the combustion engine, such as power take-off, air

conditioning, etc. The method for implementing this at adaptation is, however, well known and is therefore not described in further detail here.

In summary, the present invention thus provides a method for the adaptation of fuel injectors with several advantages compared to prior art technology, and wherein the adaptation may e.g. be used at shifting in order to be able to relieve a powertrain correctly or on other occasions to control the desired force from the combustion engine.

Further, the present invention has hitherto been described in connection with an exhaust brake in order to achieve a desired load of the combustion engine. The combustion engine may, however, also be loaded in another applicable manner, e.g. with the use of an electric motor in a hybrid vehicle or another applicable element with which a known load may be applied to the combustion engine. Addi.tiona.lly, the present invention has been exemplified above in relation to vehicles. The invention is, however, also applicable to any vessels/processes where after-treatment systems as set out above are applicable, e.g. watercrafts or aircrafts with combustion processes as per the above.

There are also combustion engines where elements to achieve a specific load are missing. Such engines may e.g. consist of industrial engines or marine engines. The present invention may, however, be applied in such engines as well, e.g. to obtain an even idling. In this case, adaptation may be carried out as above, but instead of varying the load e.g. the number of cylinders to which fuel is supplied may be varied. In this manner, an adaptation may be obtained for at least the

combustion engine's internal losses or for prevailing constant loads, so that e.g. a more even idling may be obtained.

Other embodiments of the method and the system according to the invention are available in the claims enclosed hereto. It should also be noted that the system, may be modified according to various embodiments of the method according to the

invention (and vice versa) and that the present invention is in no way limited to the above embodiments of the method according to the invention, but relates to and comprises all embodiments within the scope of the enclosed independent claims .

Claims

C<X..

1. Method at adaptation of at least one injector (201-206) in a. combustion engine (101), wherein said combustion engine (101) comprises a number n of combustion chambers <cl-c6) , and wherein fuel may be injected into said number n of combustion chambers (cl-c6) with the use of at least one respective injector (201-206) , characterised in that the method comprises, at said adaptation:

- to inject a first amount of fuel into a first subset X of said number n of combustion chambers (cl--c6), where the number of combustion chambers x in said subset. X consists of x = n-y; y > 1, and

- to control the injection of fuel into combustion chambers comprised in a second subset Z of said number of combustion chambers (cl--c6), so that the injection of fuel amounts to a second, amount of fuel, wherein the combustion chambers comprised in said second subset Z of combustion chambers are different from the combustion chambers comprised in said first subset of combustion chambe s .

2. Method according to claim 1, also comprising to control injection of fuel into combustion chambers comprised, in said second subset Z of combustion chambers, so that, no fuel is supplied to the combustion chambers comprised in said second subset Z of combustion chambers.

3. Method according to claim 1, also comprising to control injection of fuel into combustion chambers comprised in said second subset Z of combustion chambers, so that said second amount of fuel is supplied to at least one

combustion chamber comprised, in said, second subset Z of combustion chambers.

4. Method, according to claim 3, wherein i jection of fuel into combustion chambers comprised in said second subset Z of combustion chambers is controlled, so that said second amount of fuel is supplied to a number of

combustion chambers comprised in said second, subset Z of combustion chambers,

5. Method according- to any one of the previous claims, also comprising to control injection of fuel into combustion chambers comprised in said second subset Z of combustion chambers, so that the injection of fuel amounts to, at a maximum, said second, amount of fuel, and. said second, amount of fuel consists of an amount of fuel that falls below said first amount of fuel,

6. Method according to any one of the previous claims,

wherein said second amount of fuel constitutes a maximum of 50% of said first amount of fuel,

7. Method according to any one of the previous claims,

wherein said second amount of fuel constitutes a

previously adapted amount of fuel,

8. Method according to any one of the previous claims,

comprising, when a. first adaptation with injection of said, first amount of fuel into said first subset X of said number n of combustion chambers (cl-c6) has been carried out:

- to carry out a. second adaptation with injection of said first amount of fuel into at least one combustion chamber, separate from the combustion chambers comprised in said first subset X.

9. Method, according to any one of t e previous claims, also comprising to carry out a number of adaptations with injection of said first amount of fuel into a subset of said combustion chambers, wherein at each adaptation said first subset consists of different subsets of said, number n of combustion chambers (cl~c6). , Method according to any one of the previous claims, wherein said first fuel amount is supplied, to each one of the combustion chambers (cl-c6) comprised in said first subset X of combustion chambers. , Method according to any one of the previous claims, wherein said injection of said first fuel amount is carried out during a combustion cycle. , Method according to any one of the previous claims, also comprising to apply to said combustion engine a first load at said adaptation, wherein said combustion engine is controlled to deliver work corresponding to said first load , , Method according to claim 12, wherein said first load is applied at least partly with an exhaust brake system and/or an electric motor. , Method according to any one of the previous claims, wherein said first amount of fuel exceeds the total amount of fuel injected into the combustion chambers separate from said, first, subset X of combustion chambers. , Method according to any one of the ^"previous claims, also comprising, at the determination of injection parameters for the combustion chambers in said first subset. X of combustion chambers, to take into consideration force contributions from combustion chambers comprised in said second subset Z of combustion chambers. , Method according to any one of the previous claims, also comprising, based on said adaptation, to store injection parameters for combustion chambers comprised in a first subset X of said number n of combustion chambers.

17. Method according to claim 15 or 16, wherein said

injection parameters at least comprise a representation of an opening time for an injector associated with a respective combustion chamber (201-206) .

18. Method according to any one of claims 1-17, wherein

combustion chambers comprised in said second subset Z of combustion chambers consist of all of the combustion chambers not comprised in said first subset X of

combustion chambers.

19. Computer program comprising a program code which, when said program code is executed in a computer, achieves that said computer carries out the method according to any one of claims 1-18.

20. A computer program product comprising a computer-readable medium and a computer program according to claim 19, said computer program being comprised in said computer- readable medium.

21. System for adaptation of at least one injector (201-206) in a combustion engine (101), wherein said combustion engine (101) comprises a number n of combustion chambers (cl-c6), and wherein fuel may be injected into said number n of combustion chambers (cl-c6) with t e use of at least one respective injector (201-206) , characterised in that the system comprises elements, at said

adaptation :

- to inject a first amount of fuel to a first subset X of said number n of combustion chambers (cl-c6), where the number of combustion chambers x in said subset X consists of x = n-y; y ≥ 1, and

- to control the injection of fuel into combustion chambers comprised, in a second, subset Z of said number of combustion chambers (cl-c6), so that the injection of fuel amounts to a second amount of fuel, wherein the combustion chambers comprised in said second subset Z of combustion chambers are different from the combustion chambers comprised in said first subset X of combustion chambe s . , Vehicle (100), characterised in that it comprises a system according- to claim 21.