WO2014058383A2

WO2014058383A2 - Identification and use of free energy

Info

Publication number: WO2014058383A2
Application number: PCT/SE2013/051191
Authority: WO
Inventors: Fredrik Roos; Martin Svensson; Axel Eriksson
Original assignee: Scania Cv Ab
Priority date: 2012-10-10
Filing date: 2013-10-10
Publication date: 2014-04-17
Also published as: SE539394C2; SE1351200A1; WO2014058383A3; DE112013004514T5

Abstract

The present invention proposes a method and a system for identification of cost-free energy and utilisation of said cost-free energy in at least one vehicle-borne system. The method comprises simulation of at least one future speed profile v _sim along a section of road ahead of a vehicle on the basis of information related to the section of road. The method comprises identification, on the basis of at least one future speed profile v _sim, of whether cost-free energy will be available for the vehicle along the section of road. Available cost-free energy is defined here as surplus energy which the vehicle has during a simulated period of rolling roll _Sim and during a simulated active braking process brake _Sim if the simulated period of rolling roll _Sim is followed by the simulated braking process brake _Sim. The method comprises also utilisation of this available cost-free energy for replenishment of at least one energy store in at least one vehicle-borne system which obtains energy from a power train of the vehicle.

Description

IDENTIFICATION AND USE OF FREE ENERGY

Technical field

The present invention relates to a method for identifying cost-free energy and utilising said cost-free energy in at least one vehicle-borne system according to the preamble of claim 1. The present invention relates also to a system adapted to identifying cost-free energy and utilising said cost-free energy in at least one vehicle-borne system

according to the preamble of claim 31, and a computer

programme and a computer programme product which implement the method according to the invention.

Background

The following background description represents a description of the background to the present invention and therefore need not necessarily represent prior art.

The cost of fuel for motor vehicles, e.g. cars, trucks and buses, represents a significant expense for their owner or user. In the case for example of a haulage company, apart from the procurement cost of a vehicle, the main expense items for its routine operation are pay for the driver, repair and maintenance costs and the cost of fuel for the vehicle's propulsion. The fuel cost may here very greatly affect the company's profitability. A wide variety of different systems have therefore been developed for reducing fuel consumption, e.g. fuel-efficient engines and fuel-economising cruise controls .

There are prior art methods for making engines more economical on fuel and vehicles more energy-efficient. Some of these methods utilise a vehicle's kinetic energy by feeding it back to various systems on board, e.g. during the vehicle's

braking . Some examples are described below of previous methods and devices intended to connect consumer units to a vehicle's brake system and/or to control a vehicle's brake system in an optimised way. DE 10 2010 005730 refers to a method for powering a compressor for a motor vehicle. The compressor is activated when the vehicle's brake device is activated. Connecting the

compressor to the brake device will therefore depend on when activation of the brake device takes place, making it possible for the kinetic energy built up in the system to be used for the compressor.

DE 10 2006 049760 refers to a freight vehicle with a brake system. Various consumer units such as air compressor, cooling installation or electricity generator can be connected to the vehicle's engine. The consumer units are with

advantage connected when a braking process of the vehicle is taking place, with the object of allowing the operation of the consumer units to be reduced when a braking process is not taking place, and thereby potentially saving fuel. EP 1900588 refers to a method pertaining to a vehicle for calculating optimum operating parameters and to a

corresponding auxiliary system for fuel-economical operation. The method therefore calculates optimum fuel consumption on the basis of so-called vehicle characteristics, driving conditions and predetermined time limits. The driver is provided with indications to enable him/her to drive in such a way as to achieve optimum fuel consumption.

Brief description of the invention The abovementioned known methods do not work satisfactorily in that they cannot make vehicles sufficiently fuel-economical and energy-efficient.

It is generally the case that there is a need for intelligent propulsion of a vehicle which is fuel-economical and energy- efficient, results in emissions which are small in amount and not harmful, and/or causes minimum vehicle wear. It is therefore an object of the present invention to propose a method and a system which result in such intelligent

propulsion of the vehicle.

This object is achieved by the aforesaid method according to the characterising part of claim 1. It is also achieved by the aforesaid system according to the characterising part of claim 31 and by the aforesaid computer programme and computer programme product.

According to the present invention a simulation is conducted, e.g. by a simulation unit, of at least one future speed profile v_slm for an actual vehicle speed v_act along a section of road ahead of the vehicle. The simulation is based on

information related to this section of road ahead.

This is followed by conducting, e.g. by means of an

identification unit, an identification of whether cost-free energy will be available for the vehicle along the section of road. The identification of available cost-free energy is based on the at least one simulated future speed profile v_slm.

The available cost-free energy takes according to the

invention the form of surplus energy which the vehicle has during a simulated period of rolling roll_Si_m and during a simulated active braking process brake_Sim if the simulation shows that the simulated period of rolling roll_s±m is followed by the simulated active braking process brake_Sim-

The available cost-free energy identified is then utilised, e.g. by a utilisation unit, to replenish at least one energy store in at least one vehicle-borne system which obtains energy from the vehicle's power train.

The present invention thus results in the identified available cost-free energy being stored/saved in one or more energy stores on board the vehicle, potentially for subsequent utilisation. The energy store may for example take the form of a tank, a container, a confined space, a compressor or a chargeable battery.

If the cost-free energy which according to the present

invention is available when a simulated period of rolling rollsim is followed by a simulated active braking process brake_Sim was not taken advantage of by applying the present invention, it would be braked away during the actual active braking process brake_act which corresponds to the simulated active braking process brake_sim. The present inventions thus uses simulations of one or more future speed profiles v_slm to spot cost-free energy which can be utilised without adversely affecting the vehicle's

propulsion. The available cost-free energy identified

according to the invention takes the form of kinetic energy for the vehicle, e.g. on a downhill run, which would disappear in the form of heat during the vehicle's active braking. Thus surplus energy which really is cost-free in that it would be lost if not utilised by the present invention can be

identified and utilised to replenish energy stores in the vehicle-borne systems. The present invention therefore results in energy-optimised fuel consumption in that energy stores are replenished without increasing fuel consumption. The overall cost-effective and environmentally friendly effect is that the vehicle consumes less fuel.

According to the present invention a pre-braking may be effected already before the active braking, since the

simulation shows that the active braking will subsequently be required, allowing the transfer of energy to energy stores to commence before the active braking. The energy transfer to energy stores is thus maximised while at the same time causing a braking action which results in this pre-braking.

The optimised fuel consumption achieved by the present

invention has also a positive effect upon emissions from the vehicle. The ever tougher requirements currently being set for emissions and amounts of emissions from vehicles make the reduced fuel consumption and the consequently reduced

emissions from the vehicle highly advantageous.

Reducing vehicle wear, e.g. on brake linings, brakes and/or brake systems, may also lower vehicle operating costs while at the same time the reduced wear also reduces the amount of time which vehicles spend off the road on workshop visits.

Intelligent propulsion of the vehicles which is fuel- economical, results in emissions which are small in amount and not harmful and causes minimum vehicle wear may generally be said to be desirable.

Brief list of drawings

The invention is explained in more detail below with reference to the attached drawings, in which the same reference

notations are used for similar items, and in which Figure 1 depicts an example of a vehicle,

Figure 2 is a flowchart for a method according to an

embodiment of the present invention,

Figure 3 depicts an example of a driving situation for which an embodiment of the present invention may be employed,

Figure 4 depicts an example of a driving situation for which an embodiment of the present invention may be employed,

Figure 5 depicts an example of a driving situation for which an embodiment of the present invention may be employed, Figure 6 depicts an example of a pressure range for a

compressor,

Figure 7 depicts a control unit according to an embodiment of the present invention.

Description of preferred embodiments Figure 1 depicts schematically a power train of a vehicle 100 in which the present invention may be implemented. The power train comprises a combustion engine 101 which in a

conventional way is connected, via an output shaft 102 from the engine, usually via a flywheel, to a gearbox 103 via a clutch 106. The gearbox 103 is here illustrated schematically as a unit but might physically also take the form of a

plurality of interacting gearboxes, e.g. a range gearbox, a main gearbox and a split gearbox, which are situated along the vehicle's power train. The vehicle 100 further comprises driveshafts 104, 105 which are connected to its tractive wheels 111, 112 and are driven by an output shaft 107 from the gearbox 103 via an axle gear 108, e.g. a conventional differential. The vehicle further comprises wheels 113, 114 which may or may not be tractive and may be arranged for steering of the vehicle.

The vehicle 100 further is provided with various different brake systems 150 which may comprise a conventional service brake system, e.g. in the form of wheel brakes 151, 152, 153, 154 comprising brake discs and/or brake drums with associated brake linings or the like, situated adjacent to the vehicle's wheels 111, 112, 113, 114. The brake system 150 may also comprise one or more supplementary/auxiliary brakes, e.g. a brake 155 acting upon the vehicle's power train, e.g. a retarder, an electromagnetic brake and/or a decompression brake, or an exhaust brake. A retarder may take the form of a primary retarder situated before the gearbox and/or a

secondary retarder situated after the gearbox. An

electromagnetic brake may be situated at any suitable location where it can act upon the vehicle's power train. A

decompression brake may be integrated in the engine.

Supplementary/auxiliary brakes may also comprise an exhaust brake which uses a damper fitted in the exhaust outlet to increase the engine's pumping losses and thereby its braking torque in order to provide braking action. The exhaust brake may also be regarded as integrated in the engine 101 or at least in the engine and its exhaust treatment system 170. The brakes 155 which act upon the power train are here

schematically depicted as acting upon the gearbox output shaft 107, but they might be situated substantially anywhere along the power train and act at substantially any location where a braking action can be provided.

The engine 101 may be controlled on the basis of instructions from a cruise control 120 in order to maintain a constant actual vehicle speed and/or to vary the actual vehicle speed, e.g. so as to achieve fuel consumption which is optimised within reasonable vehicle speed limits. The function of the cruise control is described in more detail below.

The vehicle 100 is also provided with at least one control unit 130 adapted to controlling various different functions of the vehicle, e.g. the engine 101, the brake system 150 and one or more vehicle-borne systems 160 which obtain energy from the vehicle's power train. These one or more systems 160 are schematically depicted in Figure 1 as acting upon the gearbox output shaft 107 but might be situated substantially anywhere along the vehicle's power train and act at substantially any location where energy can be obtained and/or taken advantage of from the power train. These systems 160 might also be situated separately from the power train, with an energy- conducting device between the power train and them. An example of such a separately situated vehicle-borne system is illustrated schematically in Figure 1 in the form of the brake system 150.

As described in more detail below, the control unit 130 of the system for identifying and utilising cost-free energy

according to the present invention comprises a simulation unit 131, an identification unit 132 and a utilisation unit 133.

One skilled in the art will appreciate that the control unit might also be arranged to operate one or more further units on board the vehicle, e.g. the clutch 106 and/or the gearbox 103 (not depicted in the diagram) .

The at least one control unit 130 is depicted in the diagram separately from the cruise control 120, but they can exchange information with one another. They may also be logically separated but be physically implemented as a single unit or be jointly situated/implemented both logically and physically. Today' s vehicles therefore often have one or more systems provided with one or more energy stores which can be

charged/replenished with energy obtained from the vehicle's power train. Such vehicle-borne systems using energy stores may comprise at least one auxiliary system which has an energy store, e.g. an auxiliary system comprising a compressor which is part of the brake system 150, a compressor which is part of an air conditioning system, a temperature regulator which is part of an air conditioning system, a battery, a cooling system adapted to cooling the engine 101 and/or a cooling system adapted to cooling the brake system 150.

Auxiliary systems comprise in this specification supporting systems on board the vehicle, i.e. systems which are not directly used for its propulsion. They take for example the form of various cooling systems. The present invention may be employed on an auxiliary system which uses an energy store.

Vehicle-borne systems which use energy stores may also

comprise at least one power-using system (power take-off, PTO) , e.g. a cooling or freezing device for transport of, for example, foods or other frozen goods. There may also be other types of power-using systems whereby various different

machines may be connected to, and be powered by, the vehicle. Power-using systems using one or more energy stores which can be charged/replenished with energy obtained from the vehicle's power train may employ the present invention.

In a hybrid vehicle, a hybrid ancillary unit may store energy in an energy store and be used to produce electrical energy from the motion of the power train, for subsequent utilisation in the vehicle's propulsion. In this specification, the invention is often exemplified for use in auxiliary systems with energy stores, but it might be used for substantially all the various types of vehicle-borne systems described above which use energy stores, i.e. systems which have some kind of ability to store/save and keep energy in any form. The energy stored/saved may be utilised by the vehicle-borne system to perform a function. For example, an auxiliary system comprising air compressors for the brake system 150 may store energy by building up the air pressure in a container by means of the air compressor. An auxiliary system comprising electricity generators may for example store energy in a battery. In the case of cooling and/or air conditioning installations, the energy store takes the form of the actual space which is cooled/heated, i.e. the air which is contained in the space and whose temperature is to be regulated. The energy store may thus for example take the form of the air contained in a driving cab or in a refrigerator or freezer. The present invention then makes it possible for example for the temperature of this air to undergo extra cooling when cost-free energy is available and thus make it possible to at least partly avoid having to use energy which is not cost-free for subsequent cooling.

The present invention may be employed in the case of

substantially all types of vehicle-borne systems with energy stores and is for example particularly suitable for vehicle- borne systems which provide a relatively slight braking effect compared with that required to brake the vehicle.

Figure 2 is a flowchart for a method 200 according to an embodiment of the present invention.

The method pertains to identifying cost-free energy for a vehicle and also to utilising this identified cost-free energy in at least one system with which the vehicle is fitted. As a first step 201 of the method, a simulation of at least one future speed profile v_slm is conducted, e.g. by a

simulation unit 131, for an actual vehicle speed v_act along a section of road ahead of the vehicle 100. The simulation is here based on information related to this section of road which is still ahead of the vehicle at the time of the

simulation. The simulation of the at least one future speed profile v_slm is described in more detail below.

As a second step 202 of the method, an identification of whether cost-free energy will be available for the vehicle along the section of road covered by the simulation is

conducted, e.g. by an identification unit 132. The

identification is based here on the at least one simulated future speed profile v_slm. The present invention defines the available cost-free energy as an amount of surplus energy which the vehicle 100 has during a simulated period of rolling roll_Si_m and during a simulated active braking process brake_Sim if the simulation shows that the simulated period of rolling roll_slm is followed by the simulated active braking process brake_slm. In other words, available cost-free energy can be identified if the simulations show that the vehicle will undergo a simulated period of rolling roll_slm followed by a simulated active braking process brake_slm. This cost-free energy would then be simulated as being available during the simulated period of rolling roll_Si_m and during the simulated active braking process brake_s±m- The simulations of roll_slm and brake_slm are described in more detail below.

Available cost-free energy means in this specification kinetic energy which is available for the vehicle, e.g. on a downhill run, and which would disappear in the form of heat during active braking of the vehicle.

As a third step 203 of the method, the available cost-free energy identified in the second step 202 is utilised, e.g. by a utilisation unit 133, to replenish at least one energy store in at least one vehicle-borne system which obtains energy from the vehicle's power train. The cost-free energy spotted is therefore stored/saved here in one or more energy stores on board the vehicle, for possible subsequent utilisation. The form of the energy store depends on the type of vehicle- borne system by which it is used. It may for example comprise a tank, a container, a confined space, a compressor or a chargeable battery of any kind suitable for the purpose.

The present inventions thus uses simulations of one or more future speed profiles v_slm to spot cost-free energy which can be utilised without adversely affecting the vehicle's

propulsion. The cost-free energy which according to the present invention is available when a simulated period of rolling roll_slm is followed by a simulated active braking process brake_s±m would, if not taken advantage of by employing the present invention, be braked away during the actual active braking process brake_act which corresponds to the simulated active braking process brake_s±m. Thus surplus energy which really is cost-free in that it would be lost if not utilised by the present invention can be identified and utilised to replenish energy stores in the vehicle-borne systems.

It is also possible for more cost-free energy to be taken advantage of by employing the present invention than when applying prior art, since the energy is also taken advantage of during the period of rolling before the brakes are actually activated, and not only during the braking. This makes it possible to take advantage of a larger proportion of the existing surplus energy. This is easy to appreciate in the case of an auxiliary system with a constant connection power such that the stored energy is equal to power multiplied by time (E=sum (P*dt) ) . The present invention lengthens the period of cost-free energy as compared with prior art, making it possible to take advantage of more cost-free energy.

This specification describes the present invention on the basis inter alia of simulated speed profiles v_si_m, actual vehicle speeds v_act, simulated periods of rolling roll_slm, actual periods of rolling roll_act, simulated active braking processes brake_s±m and actual active braking processes brake_act. These parameters and their mutual relationships will now be defined . The at least one simulated speed profile v_slm represents at least one simulation of at least one corresponding respective actual vehicle speed v_act along the section of road. In one embodiment it is assumed that the cruise control is used to control the actual vehicle speed v_act and that at the time of the simulation the section of road is still ahead of vehicle. The actual vehicle speed v_act is then a parameter which

corresponds to an actually resulting speed for the vehicle when the simulated speed profile v_slm is converted to a

practical driving situation for an actual section of road. In another embodiment the cruise control is assumed to be switched off and the vehicle's speed to be controlled

manually, e.g. by an accelerator pedal. The simulated speed profile v_slm may then be based on an assumption that a current vehicle speed corresponds to the speed desired by the driver for the section of road ahead, which may also be regarded as corresponding to the cruise control's set speed v_set . The simulated period of rolling roll_s±m for the at least one simulated speed profile v_slm is matched by an actual period of rolling roll_act for the at least one respective actual vehicle speed v_act which corresponds to the at least one simulated speed profile v_slm. In other words, the actual period of rolling roll_act is a parameter which corresponds to an actually resulting period of rolling for the vehicle when the simulated period of rolling roll_Si_m is converted to a practical driving situation for an actual section of road. The simulated active braking process brake_Sim for the at least one simulated speed profile v_s±m is matched by an actual active braking process brake_act for the at least one respective actual vehicle speed v_act which corresponds to the at least one simulated speed profile v_s±m. In other words, the actual active braking process brake_act is a parameter which

corresponds to an actually resulting braking process for the vehicle when the simulated active braking process brake_Sim is converted to a practical driving situation for an actual section of road. Many vehicles today are equipped with cruise control 120. One object of cruise control is to achieve a uniform predetermined vehicle speed. This is done either by adjusting the engine torque to avoid deceleration, or by applying braking action on downhill runs where the vehicle is accelerated by its own weight. A more general object of cruise control is to achieve convenient driving and greater comfort for the vehicle's driver .

A driver of a motor vehicle with cruise control usually chooses a set speed v_set as the speed which he/she wishes the vehicle to maintain on level roads. A cruise control then provides an engine system of the vehicle with a reference speed v_ref which is used for controlling the engine. The set speed v_set may therefore be regarded as an input signal to the cruise control, and the reference speed v_ref as an output signal from the cruise control, which is used for controlling the engine, resulting in regulation of the vehicle's actual speed v_act .

Traditional cruise controls (CC) therefore maintain a constant reference speed v_ref corresponding to the set speed v_set chosen by the driver. The value of the reference speed v_ref is here altered only when the user him/herself adjusts the set speed v_Set during the journey.

There are today cruise controls, so-called economical cruise controls, e.g. Ecocruise and similar cruise controls, which are intended to estimate current running resistance and also have knowledge of historical running resistance. An

experienced driver using a vehicle without cruise control can reduce fuel consumption by adapting his/her driving to the characteristics of the road ahead so that unnecessary braking and/or fuel-consuming accelerations can be avoided. A further development of these economical cruise controls tries to mimic the experienced driver' s adaptive driving on the basis of knowledge of the road ahead, so that fuel consumption can be kept as low as possible, since this very greatly affects profitability for an owner of the vehicle, e.g. a haulage company or the like.

An example of such a further development of an economical cruise control is a "look ahead" cruise control (LACC) , i.e. a strategic cruise control which uses knowledge of sections of road ahead, i.e. knowledge of the nature of the road in front, to determine the configuration of the reference speed v_ref.

Here the reference speed v_ref is therefore allowed, within a speed range v_min-v_max, to differ from the set speed v_set chosen by the driver, in order to operate in a way which saves more fuel .

Knowledge of the road section ahead may for example comprise prevailing topology, road curvature, traffic situations, roadworks, traffic density and state of road. It may also comprise a speed limit for the road section ahead and/or a traffic sign beside the road. These various kinds of

knowledge are for example avialable from location information, e.g. GPS (global positioning system) information, information obtained from one or more out of GNSS (global navigation satellite system) , GLONASS, Galileo and Compass, or

information obtained from a relative positioning system using optical sensors, map information and/or topographical map information, weather reports, information communicated via wireless communication, e.g. radio. Information about

vehicles in front may also form part of knowledge about the road section ahead, possibly using for example radar and/or camera equipment to determine the information about vehicles in front and locations of the host vehicle.

All this knowledge may be used in various ways. According to the present invention it may be used in predicting whether an active braking process will occur. For example, knowledge of a speed limit ahead may also be used for fuel efficiency by lowering the vehicle's speed before the speed limit zone is reached. Similarly, knowledge of a road sign conveying information about, for example, a roundabout or intersection ahead may also be used for fuel efficiency by braking before reaching the roundabout or intersection. Basing cruise control on location information in combination with

topographical map information makes it possible to avoid incorrect decisions due to a driver' s misperception of a road gradient .

A look-ahead cruise control (LACC) does for example allow the reference speed v_ref to be raised, before a steep uphill run, to a level above the set speed v_set, since the vehicle is

calculated to lose speed on the steep climb owing to high train weight relative to engine performance. Time is thus saved, which means that the LACC may be regarded as improving drivability. Similarly, the LACC allows the reference speed v_ref to be lowered to a level below the set speed v_set before a downhill run on which the vehicle is calculated to be

accelerated by its high train weight. The concept here is that it is better fuel economy to derive benefit from the vehicle's acceleration by its own weight downhill than to initially accelerate before the declivity and then brake downhill. The LACC can thus reduce fuel consumption without greatly affecting journey time.

There are also cruise controls which use a current running resistance as a basis for deciding how the vehicle's speed should vary. In such cruise controls, the reference speed v_ref may be allowed to deviate from the set speed v_set, within a speed range v_m±n - v_max, on the basis of at least one

characteristic of the running resistance, e.g. its magnitude and/or pattern over time. As mentioned above, there are also cruise controls which use radar and/or cameras to obtain information about vehicles in front. According to the present invention information about vehicles in front may be used in predicting whether an active braking process will occur, since the information may be used to prevent the host vehicle from running into a vehicle in front. On the basis of this knowledge the cruise control may also control the vehicle's actual speed v_act, within a speed range v_mln - v_max, e.g. to maintain a substantially constant distance from vehicles in front. On for example downhill runs or in situations where the vehicle has to reduce its actual speed, fuel savings have also historically been made by reduced demand for positive engine torque or by dragging.

Reduced demand for positive engine torque means that the propulsive force in the direction of travel delivered by the engine via tractive wheels is reduced, e.g. by reduced fuel injection in the engine, thereby reducing fuel consumption.

In this specification, dragging is a form of rolling whereby the vehicle travels with the power train closed, i.e. with the combustion engine connected to the vehicle's tractive wheels while at the same time the fuel supply to the engine is switched off, the vehicle thus being propelled by its kinetic energy. An advantage of this type of operation is that since the fuel to the engine is switched off the engine's

consumption will likewise be zero. This type of operation also means that the engine will be driven by the vehicle's tractive wheels via the power train, a state called

"dragging", whereby the engine's inertia results in a braking action, i.e. the vehicle being engine-braked.

Another form of rolling in this specification is freewheeling, which is a way of lowering fuel consumption by having the vehicle's kinetic energy propel the vehicle with the power train open. Freewheeling results in even lower fuel

consumption than dragging, since engine braking is eliminated while at the same time the engine speed is lowered to a minimum. Freewheeling may take place with the engine running or switched off, i.e. with fuel injection switched off or with the engine idling. Freewheeling in this specification means that the vehicle's engine is disconnected from its tractive wheels, so the power train is open. This disconnection of the tractive wheels from the engine, also called opening of the power train, may for example be effected by putting the gearbox into a neutral state or by opening the clutch. This means that during freewheeling substantially no power is transmitted from the engine to the tractive wheels. In this specification, freewheeling also covers one of a plurality of prime movers of a vehicle, e.g. in a hybrid vehicle, being driven by the tractive wheels. It thus covers for example a mode of

operating a hybrid vehicle whereby a combustion engine is disconnected from the tractive wheels but an electric motor may continue to transmit power to the tractive wheels. Freewheeling considerably reduces the forces which work against the vehicle's movement, since the engine friction F_eng then decreases to a value substantially equal to zero (0) . Freewheeling can therefore considerably lower fuel consumption by this decrease in the resistance to the vehicle. In certain freewheeling situations, however, idling fuel has to be supplied to the engine to prevent its stopping, whereas in other situations it may be allowed to stop.

The present invention thus identifies and utilises cost-free energy which is available for the vehicle. An example of a driving situation in which there may be cost-free energy is when the actual active braking process brake_act is initiated, either by a driver of the vehicle or by a control system of the vehicle, because an actual speed v_act for the vehicle along the section of road reaches a value greater than or equal to a speed v_max which is the maximum permissible on that section of road . The maximum permissible speed v_max may depend on one or more parameters, e.g. a downhill control speed v_dhsc determined for the vehicle, a distance from at least one vehicle in front, a gradient of the section of road, a curvature of the section of road, a speed limit for the section of road and/or an

operability limitation, e.g. queuing or an accident, for the section of road.

If the vehicle travels with pedal operation to control its speed, the maximum permissible speed v_max may for example be assumed to be 5 km/h higher than a current vehicle speed.

Alternatively, in the case of pedal operation the system may adaptively learn at what speed the driver usually brakes the vehicle, and may use this adaptive braking speed as a maximum permissible speed v_max. In one embodiment of the present invention the available cost- free energy arises in relation to a downhill portion of the section of road. If for example a downhill control speed v_dhsc is determined for the vehicle, the system knows according to the present invention that vehicle will be braked when the active braking process brake_act is initiated when the vehicle's actual speed v_act reaches a value greater than or equal to the maximum permissible speed v_max. If it is anticipated that this active braking process brake_act will be preceded by a period of rolling, i.e. if the simulations show the simulated period of rolling roll_Si_m being followed by the simulated active braking process brake_Sim, available cost-free energy may according to the invention be identified both during the simulated period of rolling and during the simulated active braking process. Figure 3 depicts schematically an example of a driving

situation in which an embodiment of the present invention may be used to identify available cost-free energy, in a case where a set speed v_set for a cruise control is chosen and there is a defined maximum permissible speed v_max.

At different times, e.g. every second, the vehicle's future speed v_s±m is simulated. Two examples of such times when the simulations are conducted are marked XI, X2 in the diagram.

In one embodiment of the present invention the identification of the available cost-free energy comprises determining that a simulated active braking process brake_Si_m will occur after a simulated period of rolling roll_Si_m- The simulated period of rolling roll_Si_m is simulated to occur when the simulated speed profile v_s±m has a higher value than a reference speed v_ref used by the cruise control 120. In this example the reference speed is equal to the set speed, i.e. v∑ef=v.set- This occurs at a first time Tf_ree__energy, which

therefore denotes a time at which an actual period of rolling roll_act corresponding to the simulating period of rolling rollsim will begin.

An actual active braking process brake_act for the vehicle will start when the actual vehicle speed v_act reaches a value greater than or equal to the maximum permissible speed v_max. In the diagram this is at a fourth time T_start__braker which therefore also denotes a time when the actual period of rolling roll_act corresponding to the simulated period of rolling roll_slm will end. The actual active braking process brake_act then ends at a second time T_end__0f__free__energy when an actual vehicle speed v_act, after the actual active braking process brake_act has been initiated, is again at a lower value than the maximum

permissible speed v_max. Thus in one embodiment of the present invention cost-free energy is available in the period Tf_ree__energy__lntervai between the first and second times Ί_free__energy and _end_₀f__free__eTiergy, the period marked "Gratis energy" in the diagram. It should be noted that Figure 3 has been simplified for greater clarity. For example, a number of "X" markings for simulation times have been omitted.

Each simulation determines one or more of the above times

Tfree_nergyr T_start_brake , T_end_of_free_energy and/ΟΓ Corresponding periods ^r^tlme_to_free_energyr ^'-^time_to_start_brake r ^'-^time_to_end_of_free_energy during which the vehicle travels from locations XI, X2 until these times are reached. It is for example therefore possible for a first simulation XI to determine a remaining period T_t±_me_to_free_energy which indicates how much time from this simulation will elapse before cost-free energy becomes available. It is similarly possible for the first simulation XI to determine a remaining period T_time_to_start_brake and/ΟΓ Ttime_to_end_of_free_energy (not depicted in the diagram) . At this first simulation XI, the period

Ttime_to_free_energy is greater than ΖΘΓΟ; i.e.

which means that at the first simulation XI it is too early to try to begin to utilise energy, since cost-free energy is not yet available.

The vehicle therefore travels on for a certain distance or period and then conducts another simulation. This second simulation X2 determines that the period T_t±_me_to_free_energy is equal to zero, i.e.

which means that cost- free energy is available at the second simulation X2 ,

whereupon utilisation of cost-free energy with advantage commences . A non-limitative example of how the determination of the above times Tfree_energyr T_start_brake , T_end_of_free_energy and/ΟΓ Corresponding GJTlOdS Ttime_to_free_energyr '-^time_to_start_brake r '-^time_to_end_of_free_energy may be implemented is described below.

The period T_t±_me_to_free_energy may be calculated on the basis of the simulated vehicle speed v_s±m by first determining the period T_time_to_free_energy which Corresponds tO the first time Tf_ree__energy when the simulated vehicle speed v_slm exceeds the reference speed v_ref for the first time. This value is saved as

Ttime_to_free_energy If the simulated vehicle speed v_slm later reaches the maximum permissible speed v_max, which may for example correspond to a calculated braking speed v_dhsc (downhill control speed) for a constant-speed brake, the saved value of

Ttime_to_free_energy IS kept, Otherwise Ttime_to_free_energy IS given a largest possible value ("not available") . If the simulated vehicle speed v_s±m has reached the maximum permissible speed Vmaxr the period Ttime_to_end_of_free_energy IS alSO Saved,

corresponding to the time T_end_₀f_f_ree__energy when the simulated vehicle speed v_slm is for the first time again below the maximum permissible speed v_max.

It should be noted that the driving situation in Figure 3 may also occur when the vehicle speed is for example being

controlled by the accelerator pedal or some other acceleration control. The vehicle speed v_slm is then simulated as described above in the case of pedal operation. The times Tf_ree__energy, T_start_braker Tend_of_free_energ_y and/or corresponding periods

r^tlme_to_free_energyr '-^time_to_start_brake r '-^time_to_end_of_free_energy may then be determined on the basis of the simulated vehicle speed v_slm and assumptions about when the vehicle's actual active braking process brake_act will start, which may here be assumed to be when the actual vehicle speed v_act reaches a value greater than or equal to the maximum permissible speed v_max. Figure 4 depicts schematically another example of a driving situation in which an embodiment of the present invention may be used to identify available cost-free energy, in a case where a set speed v_set for a cruise control is chosen and there is a defined maximum permissible speed v_max. The cruise control function depicted in Figure 4 may vary the reference speed v_ref as described above in the case of

intelligent/strategic cruise controls. Figure 4 may here for example illustrate the vehicle approaching a downhill run, whereupon the strategic cruise control uses its knowledge of the coming declivity to lower the reference speed v_ref before the slope in order to save fuel, since the vehicle will still be accelerated by its own weight downhill. The method for conducting simulations in Figure 4 and the values in Figure 4 correspond to those described above for Figure 3.

The vehicle's future speed v_slm (broken curve in Figure 4) is therefore simulated, e.g. every second.

As described above, identifying the available cost-free energy comprises determining that a simulated active braking process brake_s±m will occur after a simulated period of rolling roll_slm.

The simulated period of rolling roll_slm is simulated to occur when the simulated speed profile v_slm has a higher value than the reference speed v_ref used by the cruise control 120 and when at the same time the vehicle undergoes an actual

acceleration a_act. In the driving situation illustrated in

Figure 4, i.e. in the example of a downhill run, the rolling occurs when the actual acceleration a_act is positive. The positive actual acceleration a_act therefore here represents an increase in the actual speed v_act (continuous curve in Figure 4) . This happens at a first time T_free__enerqy, which therefore denotes a time at which an actual period of rolling roll_act corresponding to the simulated period of rolling roll_s±m will begin. In this example the reference speed may therefore differ from the set speed, i.e. v_ref≠v_set.

It should be noted that in certain other driving situations, e.g. when rolling before a speed limit, the rolling is

simulated to occur when the simulated speed profile v_slm has a higher value than a reference speed v_ref while at the same time the actual acceleration a_act is negative.

An actual active braking process brake_act for the vehicle will start at a fourth time T_start_brake when the actual vehicle speed v_act reaches a value greater than or equal to the maximum permissible speed v_max. This fourth time also denotes the time when the actual period of rolling corresponding to the

simulated period of rolling roll_Si_m will end. The actual active braking process brake_act then ends at a second time T_end_₀f_f_ree__energy when an actual vehicle v_act, after the actual active braking process brake_act has been initiated, is again at a lower value than the maximum permissible speed

^max · Cost-free energy is therefore available in the period

Tfree_energy_intervai between the first and second times T_free__energy and Tend_of_free_energy, the period marked "Gratis energi" in the diagram.

Figures 3 and 4 above refer to a general driving situation in which the maximum permissible speed v_max may depend on a variety of different factors, e.g. a downhill control speed, vehicles in front, speed limits, queues, traffic accidents, intersections or other obstacles on the road.

Figure 5 illustrates in particular the situation where there is in a section of road a downhill run on which the maximum permissible speed v_max is limited by the downhill control speed

Vdhsc r I.e. Vmax Vdhsc ·

The top part of Figure 5 is a graph representing an actual vehicle speed v_act (km/h) over a future predetermined distance P (m x 10⁴) , in this case a good 3.5 km. The bottom part of the diagram is a curve representing the topography over the same distance, the y axis denoting altitude in metres. There is between the times Tf_ree__energy and T_end_₀f_f_ree__energy a downhill run representing a decrease in altitude of about 30 metres. In the top part of the diagram the time when a simulation of the vehicle speed v_s±m corresponding to the actual vehicle speed v_act is conducted is marked "X" and the periods to the times

Tfree_energy and 1'end_of_free_energy are marked Ttime_to_free_energy and

Ttime_to_end_of_free_energy The simulation is conducted as described above.

In the example in Figure 5 the maximum permissible speed v_max is set at 89 km/h, corresponding to the downhill control speed v_dhsc, i.e. v_max = v_dhsc, which may be regarded as a calculated braking speed which the vehicle has to maintain, e.g. on a downhill run.

At the time T_free__energy the vehicle therefore begins to

accelerate and at the time T_end_₀f__free__energy its braking process may be said to have ended. It is therefore during the period when the vehicle is between T_free__energy and T_end__of__free__energy that there will be a surplus of kinetic energy, i.e. available cost-free energy which can be utilised by a vehicle-borne system with energy stores.

As a supplement to only braking the vehicle in conventional ways, it is therefore possible in one embodiment of the present invention for a surplus of energy during the period between T_free__energy and T_end__of__free__energy to be supplied to at least one vehicle-borne system, in which case this energy offtake may also be regarded as a supplementary way of contributing to the vehicle's braking. In all the embodiments described in this specification, the energy offtake from the power train may for example be effected by connecting the vehicle-borne system to the power train, e.g. by means of a friction clutch, a magnetic clutch or an eletrically operated clutch.

The simulation of the vehicle speed v_slm serves for example as a basis for determining the periods T_t±_me_to_free_energy and

Ttime_to_end_of_free_energy · This enables the system to determine when on a section of road ahead it is appropriate to start

supplying energy to one or more energy stores in vehicle-borne systems .

Supplying energy to an energy store which is part of a

vehicle-borne system has a similar effect to using a braking system of the vehicle, since the vehicle-borne system then indirectly loads the engine with a torque which causes the vehicle's speed to decrease.

According to the present invention a pre-braking may be obtained automatically already before the active braking is initiated, the initiation of the active braking being for example effected by depressing the brake pedal or activating a brake system. This is possible in that the simulation shows that the active braking will subsequently be required. The energy transferred to energy stores is thus maximised.

In one embodiment of the present invention the energy supply to the various energy stores takes place in an order of priority determined on the basis of the types of systems with energy stores with which the vehicle is fitted and their status and areas of use. The vehicle's actual active braking process brake_act, which in Figure 3 takes place between the fourth time T_start_brake and the second time T_end_₀f_f_ree__energy, may be effected by a driver and/or a control system for brakes actively using a wheel brake 151, 152, 153, 154 and/or a supplementary brake 155, the latter possibly in the form of a retarder, an exhaust brake, a decompression brake and/or an electromagnetic brake.

When the available cost-free energy has been identified, it may then be utilised to replenish one or more energy stores which are part of the vehicle-borne systems 160.

In one embodiment the replenishment of the at least one energy store is postponed to the first time T_free__enerqy which denotes a time when cost-free energy is available. The system thus ensures that energy stores are replenished when their

replenishment really is cost-free, e.g. on a downhill run during which active braking takes place, instead of when the energy is produced at a cost, e.g. on an uphill run before a crest followed by a downhill run.

In one embodiment of the present invention the replenishment of the at least one energy store commences at the first time

Tfree_energy when the cost-free energy is available, if the period Tfree_energy_intervai during which cost-free energy is available, i.e. the period between the first time Tf_ree__energy and the second time T_end_of_free_energy, is long enough to enable the energy store to be appreciably replenished.

In this specification, appreciable replenishment means in one embodiment an increase in the energy store corresponding to 20-100%, and preferably 50-90%, of its total capacity.

If an appreciable replenishment of the energy store is not possible with the available cost-free energy, i.e. if the available cost-free energy is insufficient for replenishment to appreciably affect the energy store, further surplus energy may be required. Replenishment of the at least one energy store is then deferred to a third time T_pre_f_ree__energy which precedes the first time T_free__enerqy when cost-free energy is available, if the period Tf_ree__energy__lntervai during which cost-free energy is available is long enough for the replenishment to appreciably affect the energy store.

In one embodiment, if cost-free energy is identified before the first time T_free__enerqy when cost-free energy is available, the at least one vehicle-borne system can consume existing energy in its energy stores. This may be regarded as the system being prepared to drain energy stores in cases where it is predictable that cost-free replenishment of the energy store will be possible immediately.

Replenishment of the at least one energy store results in an increased braking effect imparted by the vehicle's power train as a result of the vehicle-borne systems 160 taking energy from the power train. This increased braking effect therefore occurs during the vehicle's actual period of rolling roll_act and/or during its actual active braking process brake_act. This results in an increased total braking action or means that an actual braking effect provided by at least one brake system 150 may be decreased, thereby reducing wear on the constituent parts of the brake system 150.

In one embodiment of the present invention the vehicle takes the form of a hybrid vehicle provided with at least one auxiliary system, which may for example as above comprise compressors, temperature regulators, batteries or cooling systems. The replenishment of the at least one energy store in the auxiliary system then takes place before replenishment of the at least one energy store in the hybrid ancillary unit. The hybrid ancillary unit is therefore only replenished if there is spare cost-free energy for such replenishment after the energy stores of the one or more auxiliary systems have been replenished.

The function of an auxiliary system in the form of an air compressor which is part of the vehicle's brake system is controlled by a control system, a so-called "air processing system" (APS) . The activation of the air compressor to charge the compressed air tanks during engine braking takes place according to the present invention when cost-free energy is available, i.e. when activation of the compressor is energy-efficient.

When the vehicle is rollling as described above, cost-free energy is available if there is an actual intention to

thereafter actively brake the vehicle. However, a period of rolling of the vehicle is not always followed by an active braking process. There may therefore be situations where the vehicle is for example engine-braked even if there is no intention to brake it actively after the engine braking. If the compressor is then activated, i.e. when there is no subsequent active braking process, it means that the vehicle's kinetic energy decreases more than intended, which is not optimum from a fuel consumption perspective. The present invention may therefore be employed to identify the periods of time in which cost-free energy really is available.

As mentioned above, the energy store may take for example the form of a tank, a container, a confined space, a compressor or a chargeable battery. In one embodiment the energy store takes the form of an air compressor associated with the vehicle's brake system. The energy storage then uses one or more compressed-air containers in which energy is stored by increasing the pressure in them. Similarly, energy storage may be effected in an air conditioning (AC) system by an AC compressor increasing the pressure in one or more AC-related containers .

Where energy storage is in energy stores, the braking action resulting from the energy offtake by the vehicle-borne system contributes to the vehicle's total braking action. It is thus possible for example to achieve a reduced amount of use of the vehicle's auxiliary brakes, retarders, engine braking and/or wheel braking in order to provide a predetermined total braking action for the vehicle when the energy offtake takes place .

Energy supplied to an air compressor may therefore be used to compress air in the vehicle's air systems connected to the compressor, and/or to compress air for the vehicle's brake system. A so-called regeneration of the air compressor involves drying of the compressor' s drying medium whose function it is to dry the air which comes from the activated compressor. Such regeneration requires no energy from the engine but is conducted by using already compressed air taken from a tank which serves as an air reservoir associated with the compressor.

One embodiment of the present invention makes it possible for this regeneration to take place before or during the period when cost-free energy is available. The regeneration cycles may thus be optimised in that a maximised supply of energy to the air compressor is obtainable through the present

invention. As the available cost-free energy is maximised by the present invention and as it is possible to precalculate the time at which this cost-free energy is available, Tfree_energy, and alSO the period Tfree_energy_interval during which it is available, the regeneration can be optimally postponed so that it only, or substantially only, consumes cost-free energy during the air compression pertaining to the regeneration. In other words, it is thus possible to ensure that the

regeneration is completed before cost-free energy is

available, with the possibility thereafter of a cost-free pressure increase by using the compressor.

Figure 6 depicts a schematic non-limitative example of a diagram of tank pressures and pressure ranges for a

compressor. A compressor may work in different pressure ranges, e.g. a first range " Tryckintervall_l", a second range " Tryckintervall_2", and a third range "Tryckintervall_3", which may be at different pressure levels. The pressure ranges may also overlap, although for better readability the diagram illustrates them as mutually separate or not

overlapping .

The first pressure range illustrated in the diagram may for example be 8.5-9.5 bar, the second 8.7-10.0 bar and the third 11.0-12.0 bar. These values are merely non-limitative

examples which may also change during operation. The limit values which appear in the diagram, "Start_l", "Stop_l";

"Start_2", "Stop_2" and "Start_3", "Stop_3" are for the respective first, second and third pressure ranges. In this case Start_KStart_3 and Stop_KStop_3. Stop_l bears no particular relationship to Start_2. Stop_2 bears no

particular relationship to Start_3. In addition, each of Start_l, Stop_l; Start_2, Stop_2, Start_3 and Stop_3 are greater than 0 bar. The second pressure range covers pressures for normal

regulation, which means that this is the range usually employed. The limit values of the first pressure range are determined for safety reasons and intended to result in a range within which the vehicle can brake without safety risk in using the pressure within the first pressure range. This mode may typically be activated immediately before a road section where there is cost-free energy, to make it possible to take advantage of as much of the available cost-free energy as possible.

The third pressure range covers a pressure band which may be used in order to utilise cost-free energy. If cost-free energy is available, this band is therefore activated, which means that the compressor starts if the pressure is below Start_3.

In one embodiment of the present invention the compressor is controlled on the basis of availability of cost-free energy. For example, it may then be operated in such a way that the second pressure range is employed during normal movement of the vehicle when cost-free energy is not available, the first pressure range is employed immediately before cost-free energy becomes available, and the third pressure range is employed during the period T_free__energy__lnterval in which cost-free energy is available .

This may also be expressed as follows:

A. The third pressure range is employed if

Ttirne_to_free_energy 0 and Ttirne_to_end_of_free_energy^O/

B. The first pressure range is employed if

0<T_time_to_free_energy<x, where x is a predetermined period of time greater than zero, i.e. x>0; C. The second pressure range is employed if a) and b) above are not fulfilled, i.e. in normal driving situations .

One embodiment of the present invention takes into account whether the compressor is running by using a hysteresis, which means that the compressor runs across a whole pressure range even if the cost-free energy is not sufficient to run it right up to the upper limit value "Stop_l", "Stop_2", "Stop_3" .

One aspect of the present invention proposes a system adapted to identifying cost-free energy and utilising said cost-free energy in at least one vehicle-borne system. The system according to the invention comprises a simulation unit 131 arranged for simulation 201 of at least one future speed profile v_slm for an actual vehicle speed v_act along a section of road ahead of a vehicle. The simulation unit 131 is adapted to basing the simulation on embodiment related to the section of road. The system comprises also an identification unit 132 arranged for using at least one future speed profile v_slm as a basis for identification 202 of whether cost-free energy will be available for the vehicle along the section of road.

Available cost-free energy is here defined as surplus energy which the vehicle 100 has during a simulated period of rolling roll_slm and during a simulated active braking process brake_s±m if the simulated period of rolling roll_slm is followed by the simulated active braking process brake_Sim- The system

comprises also a utilisation unit 133 arranged for utilisation 203 of this available cost-free energy in order to replenish at least one energy store in at least one vehicle-borne system 160 which obtains energy from a power train of the vehicle 100. One skilled in the art will appreciate that a method for identifying cost-free energy and utilising said cost-free energy according to the present invention may also be

implemented in a computer programme which, when executed in a computer, causes the computer to conduct the method. The computer programme usually takes the form of a computer programme product 703 which comprises a suitable digital storage medium on which the computer programme is stored.

Said computer-readable medium comprises a suitable memory, e.g. ROM (read-only memory), PROM (programmable read-only memory) , EPROM (erasable PROM) , flash memory, EEPROM

(electrically erasable PROM), a hard disc unit, etc.

Figure 7 depicts schematically a control unit 700 provided with a calculation unit 701 which may take the form of

substantially any 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 701 is connected to a memory unit 702 which is situated in the control unit 700 and which provides the calculation unit with, for example, the stored programme code and/or stored data which the calculation unit needs to enable it to do calculations. The calculation unit is also adapted to storing partial or final results of calculations in the memory unit 702.

The control unit 700 is further provided with respective devices 711, 712, 713, 714 for receiving and sending input and output signals. These input and output signals may comprise waveforms, pulses or other attributes which the input signal receiving devices 711, 713 can detect as information and which can be converted to signals which the calculation unit 701 can process. These signals are then supplied to the calculation unit. The output signal sending devices 712, 714 are arranged to convert calculation results from the calculation unit 701 to output signals for conveying to other parts of the

vehicle's control system and/or the component or components for which the signals are intended.

Each of the connections to the respective devices for

receiving and sending input and output signals may take the form of one or more from among a cable, a data bus, e.g. a CAN (controller area network) bus, a MOST (media orientated systems transport) bus or some other bus configuration, or a wireless connection.

One skilled in the art will appreciate that the aforesaid computer may take the form of the calculation unit 701 and that the aforesaid memory may take the form of the memory unit 702.

Control systems in modern vehicles generally comprise a communication bus system consisting of one or more

communication buses for connecting together a number of electronic control units (ECUs) , or controllers, and various components onboard the vehicle. Such a control system may comprise a large number of control units and the

responsibility for a specific function may be divided between two or more of them. Vehicles of the type here concerned are therefore often provided with significantly more control units than depicted in Figure 7 and Figure 1, as one skilled in the art will surely appreciate.

In the embodiment depicted, the present invention is

implemented in the control unit 700 but might also be

implemented wholly or partly in one or more other control units already on board the vehicle or a control unit dedicated to the present invention.

The system according to the present invention may be adapted to effecting all of the method embodiments described above, whereby the system for each embodiment achieves the advantages described above for the respective embodiment.

One skilled in the art will also appreciate that the above system may be modified according to the various embodiments of the method according to the invention. The invention relates also to a motor vehicle 100, e.g. a truck or a bus, provided with at least one system for identifying and utilising cost- free energy.

One skilled in the art will also appreciate that there will be locations corresponding to the various times indicated in this specification and that there will be distances corresponding to the periods of time indicated in the specification, in accordance with very well-known relationships for distances, times and speeds.

The present invention is not restricted to its embodiments described above but relates to and comprises all embodiments within the protective scope of the attached independent claims .

Claims

1. A method (200) for identification of cost-free energy and utilisation of said cost-free energy in at least one vehicle-borne system (160), characterised by

- simulation (201) of at least one future speed profile v_slm for an actual vehicle speed v_act along a section of road ahead of a vehicle (100), which simulation is based on information related to said section of road;

- identification (202), on the basis of said at least one future speed profile v_s±m, of whether cost-free energy will be available for said vehicle along said section of road, said available cost-free energy being defined as surplus energy which said vehicle (100) has during a simulated period of rolling {roll_Si_m ) and during a simulated active braking process (brake_slm ) if said simulated period of rolling (roll_slm ) is followed by said simulated active braking process

(brakes±m,' ) and

- utilisation (203) of said available cost-free energy for replenishment of at least one energy store in at least one vehicle-borne system (160) which obtains energy from a power train of said vehicle (100) .

2. A method (200) according to claim 1, in which said at least one vehicle-borne system (160) comprises at least one auxiliary system.

3. A method (200) according to claim 2, in which said at least one auxiliary system comprises one or more of the following :

- a compressor which is part of a brake system (150),

- a compressor which is part of an air conditioning system, - a temperature regulator which is part of an air conditioning system,

- a battery,

- a cooling system adapted to cooling an engine (101), and - a cooling system adapted to cooling a brake system (150) .

4. A method (200) according to any one of claims 1-3, in which said at least one vehicle-borne system comprises at least one power-using system (PTO) .

5. A method (200) according to any one of claims 1-4, in which said vehicle (100) is a hybrid vehicle provided with at least one hybrid ancillary unit.

6. A method (200) according to claim 5, in which

replenishment of said at least one energy store in said auxiliary system is effected before replenishment of an energy store in said hybrid ancillary unit.

7. A method (200) according to any one of claims 1-6, in which said replenishment of said at least one energy store results in an increased braking effect caused by a power train of said vehicle (100) during an actual period of rolling

(roll_act ) of said vehicle (100) and/or during an actual active braking process {brake_act ) for said vehicle (100), making it possible for an actual braking effect provided by at least one brake system (150) of said vehicle to be reduced.

8. A method (200) according to any one of claims 1-7, in which an actual active braking process {brake_act ) for said vehicle (100) comprises active use by a driver and/or by a control system of one or more of the following: - a wheel brake (151, 152, 153, 154) and

- a supplementary brake (155) .

9. A method (200) according to claim 8, in which said supplementary brake comprises one or more of the following:

- a retarder,

- an exhaust brake,

- a decompression brake, and

- an electromagnetic brake.

10. A method (200) according to any one of claims 1-9, in which said identification (201) of said available cost-free energy comprises

- determining that said simulated active braking process

{brake_Sim ) will take place after said simulated period of rolling (roll_slm ) and

- determining a first time (Tf_ree__energy ) which denotes a time at which an actual period of rolling (roll_act ) corresponding to said simulated period of rolling (roll_slm ) will occur.

11. A method (200) according to claim 10, in which said simulated period of rolling (roll_slm ) is simulated as

occurring when said simulated speed profile (v_slm ) has a higher value than a reference speed (V_ref ) for a cruise control device used in the vehicle.

12. A method (200) according to claim 11, in which said simulated period of rolling {roll_Si_m ) is simulated as

occurring when said vehicle is also undergoing an actual acceleration (a_act) ·

13. A method (200) according to claim 12, in which said actual acceleration {a_act ) is either of the following: - positive, and

- negative.

14. A method (200) according to any one of claims 11-13, in which said reference speed (V_ref ) is determined for said section of road by said cruise control device on the basis of a chosen set speed (V_set ) and at least one of the following:

- a gradient of said section of road,

- a distance from at least one vehicle in front,

- a curvature of said section of road, and

- a speed limit for said section of road.

15. A method (200) according to any one of claims 1-14, in which said identification (201) of said available cost-free energy comprises

- determining that said simulated active braking process {brake_Sim ) will take place after said simulated period of rolling (roll_slm) , and

- determining a second time ( T_eTld_₀f__free__eTiergy ) which denotes a time when an actual active braking process (brake_act )

corresponding to said simulated active braking process

(brake_sim ) ends .

16. A method (200) according to claim 15, in which said actual active braking process {brake_act ) ends when an actual vehicle speed (v_act), after said actual active braking process (brake_act ) has been initiated, is again at a lower value than a maximum permissible speed (v_max) .

17. A method (200) according to any one of claims 1-16, in which an actual active braking process [brake_act ) for said vehicle (100) starts when an actual vehicle speed ( v_act ) reaches a value greater than or equal to a maximum permissible speed (v_max) .

18. A method (200) according to either of claims 16 and 17, in which said maximum permissible speed (v_max) is related to one of the following:

- a downhill control speed (v_dhsc ) for said vehicle (100),

- a distance from at least one vehicle in front,

- a gradient of said section of road,

- a curvature of said section of road,

- a speed limit for said section of road, and

- an operability limit for said section of road.

19. A method (200) according to any one of claims 1-18, in which said cost-free energy is identified close to a downhill run on said section of road.

20. A method (200) according to any one of claims 1-19, in which said replenishment of said at least one energy store is deferred to a first time (T_free__eriergy ) which denotes a time when said cost-free energy is available.

21. A method (200) according to any one of claims 1-19, in which said replenishment of said at least one energy store commences at a first time (T_free__energy ) which denotes a time when said cost-free energy is available, if a period

( Tf_ree__energy__intervai ) between said first time ( Ί_free__energy ) and a second time (T_end of free energy ) which denotes a time when said cost-free energy ceases to be available, is long enough for said replenishment to appreciably affect said energy store.

22. A method (200) according to any one of claims 1-19, in which said replenishment of said at least one energy store is deferred to a third time (T_pre free energy ) which precedes a first time (Tf_ree__energy ) which denotes when said cost-free energy is available, if a period (Tf_ree__energy__lntervai ) between said first time ( T_free__eriergy ) and a second time (T_enci_of_free_energy ) which denotes a time when said cost-free energy ceases to be available, is not long enough for said replenishment to appreciably affect said energy store.

23. A method (200) according to either of claims 21 and 22, in which appreciable effect upon said energy store means an increase in the energy store corresponding to 20-100% of said store and preferably corresponding to 50-90% of said store .

24. A method (200) according to any one of claims 1-19, in which, if said cost-free energy is identified, said at least one vehicle-borne system is caused to consume existing energy in said energy store before a first time (Tf_ree__energy ) which denotes a time when said cost-free energy is available.

25. A method (200) according to any one of claims 1-24, in which said simulated period of rolling (roll_slm ) comprises one of the following:

- forward propulsion of said vehicle (100) by utilisation of kinetic energy for said vehicle (100) when a power train of said vehicle (100) is closed and fuel injection to a

combustion engine (101) of said vehicle is switched off;

- forward propulsion of said vehicle (100) by utilisation of kinetic energy for said vehicle (100) when a power train of said vehicle (100) is open and fuel injection to a combustion engine (101) of said vehicle is switched off;

- forward propulsion of said vehicle (100) by utilisation of kinetic energy for said vehicle (100) when a power train of said vehicle (100) is open and said engine (101) of said vehicle is idling.

26. A method (200) according to any one of claims 1-25, in which said simulated speed profile (v_slm ) represents a simulation of said corresponding actual vehicle speed (v_act) along said section of road when a cruise control (120) is assumed to be used for controlling said actual vehicle speed ( act ) r said simulation being conducted when said section of road is still ahead of said vehicle (100) .

27. A method (200) according to any one of claims 1-26, in which said simulated period of rolling {roll_Si_m ) for said simulated speed profile (v_slm ) is matched by an actual period of rolling (roll_act ) for said actual speed profile ( v_act ) corresponding to said simulated speed profile (v_slm.)

28. A method (200) according to any one of claims 1-27, in which said simulated active braking process

(brake_sim ) for said simulated speed profile (v_sim ) is matched by an actual braking process (brake_act ) for said actual speed profile ( v_act ) corresponding to said simulated speed profile

( ^sim · )

29. A computer programme which comprises programme code and which, when said programme code is executed in a computer, causes said computer to conduct the method according to any one of claims 1-28.

30. A computer programme product comprising a computer- readable medium and a computer programme according to claim 29, which computer programme is contained in said computer- readable medium.

31. A system adapted to identifying cost-free energy and utilising said cost-free energy in at least one vehicle-borne system (160), characterised by

- a simulation unit (131) arranged for simulation (201) of at least one future speed profile (v_slm ) for an actual vehicle speed ( v_act ) along a section of road ahead of a vehicle (100), which simulation unit is adapted to basing said simulation on information related to said section of road;

- an identification unit (132) arranged for identification (202), on the basis of said at least one future speed profile (Vsim) of whether cost-free energy will be available for said vehicle along said section of road, said available cost-free energy being defined as surplus energy which said vehicle (100) has during a simulated period of rolling {roll_Si_m ) and during a simulated active braking process {brake_Sim ) if said simulated period of rolling {roll_Si_m ) is followed by said simulated active braking process {brake_Sim) ; and

- a utilisation unit (133) arranged for utilisation (203) of said available cost-free energy for replenishment of at least one energy store in at least one vehicle-borne system (160) which obtains energy from a power train of said vehicle (100) .