SE1050404A1 - Method and system for vehicles - Google Patents

Description

l0 l5 20 25 30 corresponding fuel-consuming accelerations and, in fuel-consuming behavior, kinetic energy-dissipating decelerations. This results in a large amount of energy being required to accelerate the vehicle, only to be consumed as a braking effect, often even after a relatively short time. Such scenarios are particularly common in areas with high traffic intensity and / or frequent traffic lights or, in the case of city buses, frequent bus stops.

A hybrid vehicle is a vehicle that uses two or more power and / or fuel sources. A common type of hybrid vehicle is electric hybrid vehicles, which include a first power generating source, such as e.g. an internal combustion engine, and one or more electric machines, wherein said one or more electric machines are used for generating a propulsion force acting on the drive wheels of the vehicle.

The use of an electric machine as a propulsion motor has the advantage that in certain operating conditions, such as when using the electric machine for braking, e.g. to decelerate the vehicle or maintain a constant speed in a downhill, the electric machine can regenerate electrical energy for feedback to the vehicle's electrical system. This regenerative braking has the advantage that the generated energy can be used to charge an energy storage for storage of electrical energy. Energy stored in the energy storage can be used by the electric machine during a subsequent acceleration and thereby relieve the internal combustion engine with reduced fuel consumption as a result.

This "interaction" between electric machine and internal combustion engine in electric hybrid vehicles often works so well that the driver of the vehicle in principle does not experience any difference when driving a hybrid vehicle compared to driving a corresponding conventional vehicle. Since electric hybrid vehicles are usually associated with a higher purchase cost compared to a conventional vehicle, it is therefore important for the vehicle owner to be able to confirm that the investment in hybrid vehicles also pays off financially.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method which solves the above-mentioned problems. This object is achieved by a method according to claim 1.

The present invention relates to a method for comparing a fuel consumption of a first vehicle with a second vehicle, said first vehicle comprising a first energy converter consisting of an internal combustion engine for generating a first propulsion force for propelling said first vehicle, and at least a second energy converter consisting of a first electric machine for generating a second propulsion force for propelling said vehicle, the method comprising, for a first time when said first and second vehicles are driven in the same way: - determining by means of determining means a difference in fuel consumption between said first vehicle and said second vehicle, said second vehicle comprising only an energy converter for generating propulsion for propelling said second vehicle, and said energy converter in said second vehicle constituting an internal combustion engine substantially substantial with said first internal combustion engine.

Thus, the fuel consumption of the hybrid vehicle is compared with the fuel consumption of driving the same vehicle, ie. a vehicle equipped with a substantially identical internal combustion engine, and preferably also a gearbox, and when driving along the same stretch of road, would have resulted in. 10 l5 20 25 30 By determining the difference in fuel consumption for a, apart from the hybrid part, basically identical vehicle, ie. a vehicle with otherwise substantially identical essential driveline components, ie. internal combustion engine and gearbox, and preferably the same driveline transmission, a very accurate measure of the amount of fuel saved, and thus the fuel cost saved, can be obtained, whereby the driver and / or owner of the vehicle can easily present the profitability of investing in a hybrid vehicle.

The fuel savings can be presented graphically on a display for the driver of the vehicle, whereby the driver can be informed about the fuel savings at all times, or when desired.

The fuel savings can e.g. is shown as total accumulated savings since the vehicle was first put into operation, or savings during the current journey or time period such as the current month. The fuel savings can be presented in the amount of fuel, and / or combined with fuel costs to also provide an economical measure of the savings. The fuel savings can also be divided into savings for different situations.

In addition to presenting savings data to the driver, data can also be sent, e.g. via an RTI (Road Traffic Informatics) system to the vehicle owner.

In one embodiment, the method comprises comparing a driving force emitted by the electric machine with a driving force emitted by the internal combustion engine, wherein a difference in fuel consumption is determined based on said driving force emitted by said electric machine and internal combustion engine. Said driving force can consist of delivered torque or delivered motor power.

Additional features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments and the accompanying drawings.

Brief Description of the Drawings Fig. 1a shows a driveline in a vehicle in which the present invention can be used to advantage.

Fig. 1b shows an example control unit in a vehicle control system.

Fig. 2 shows a diagram of the fuel consumption of an internal combustion engine as a function of speed and torque.

Fig. 3 shows an exemplary method according to the present invention.

Detailed Description of Preferred Embodiments The powertrain of a hybrid vehicle includes, in addition to the components present in a conventional vehicle, also a hybrid member consisting of a number of additional components, such as an electric machine, power electronics unit for driving the electric machine, energy storage, etc. These components are relatively expensive. as a natural consequence that the acquisition cost of the hybrid vehicle will be higher compared to the acquisition cost of the same vehicle without a hybrid part.

The internal combustion engine and the electric machine are controlled by the vehicle's control system, and the interaction between the internal combustion engine and the electric machine often works so well that the driver's driving experience when driving a hybrid vehicle in principle does not differ at all from a conventional vehicle. The driver thus gets no sense of the energy saving the hybrid system actually contributes.

The present invention solves this by determining the fuel saving of the hybrid vehicle in relation to a, apart from the hybrid part, conventional but otherwise identical vehicle, where the conventional vehicle is driven along the same distance as the hybrid vehicle.

This is exemplified in the following, where Fig. 1a shows a driveline in a hybrid vehicle 100 according to a first exemplary embodiment of the present invention. There are hybrid vehicles of different types, and the vehicle shown is a parallel hybrid vehicle.

The driveline of the parallel hybrid vehicle in Fig. 1a comprises an internal combustion engine 101. The internal combustion engine 101 is connected in a conventional manner, via a shaft 102 output on the internal combustion engine 101, to a gearbox 103. Gearboxes in heavy vehicles, as in the embodiment shown, often consist of an automatic (using the vehicle's steering system) geared 'manual' gearbox 103. Partly because manual gearboxes are significantly cheaper to manufacture, but also because manual gearboxes have a higher efficiency. For this reason, the vehicle 100 also includes a clutch 106 for selectively connecting the output shaft 102 of the internal combustion engine 101 to the gearbox 103.

The clutch 106 in the present example consists of a clutch automatically controlled by the vehicle control system, but can also be a manually controlled clutch, since control systems in vehicles in the presence of a manual (driver) controlled clutch can in a known manner perform shifting with closed clutch, and thus without the use of the same. The automatically controlled clutch 106 is controlled by a clutch actuator (not shown) based on control signals from a control unit 116.

The vehicle further comprises drive shafts 104, 105, which are connected to the drive wheels 113, 114 of the vehicle, and which, as in a conventional internal combustion engine system, are driven by a shaft 107 emanating from the gearbox via a shaft gear, which e.g. The vehicle may also consist of a conventional differential 108. The vehicle also includes a front pair of wheels 111, 112.

Unlike a conventional vehicle, the vehicle shown in Fig. 1a also comprises an electric machine 110, which is connected to the input shaft 109 of the gearbox 103, "downstream" of the clutch 106, i.e. the input shaft 109 of the gearbox can be driven by the electric machine 110 even in the case where the coupling 106 is open. Parallel hybrid vehicles can thus transmit power to the drive wheels 113, 114 from two separate power sources simultaneously, ie. both from the internal combustion engine 101 and the electric machine 110.

Alternatively, the vehicle can be propelled by either source of power separately, ie. either by the internal combustion engine 101 or the electric machine 110. In an alternative embodiment, the electric machine is arranged upstream of the clutch, or alternatively downstream of the gearbox. Depending on the location of the electric machine, not all of the features described below need apply.

For example. pure electric machine operation cannot be obtained in the case where the electric machine is arranged upstream of the coupling.

The vehicle can also be of a type with a conventional automatic gearbox, with the electric machine arranged upstream or downstream of the gearbox.

As is known to those skilled in the art, there are a number of types of electric machines that are applicable for use in hybrid vehicles, so the electric machine 110 may be an electric machine of any applicable type. In the example description below, however, the electric machine consists of a three-phase motor, the power supply to the electric machine 110 consisting of a three-phase power supply.

Three-phase motors can be of both so-called asynchronous and synchronous type, where the synchronous motor has the advantage that an exact speed determination can be performed. In vehicle applications, it is naturally desirable that the rotational speed of the drive wheels, and thus of the electric machine, can be varied in addition to the variation which can be obtained by conventional shifting by means of the gearbox, so that the electric machine must also be able to be speed controlled.

The rotational speed is controlled, for an electric machine in general, by the frequency of the supply voltage with which the motor is supplied with power, where the speed of the electric machine is directly proportional to this frequency. Speed control of an electric machine thus requires that the voltage supplied to the motor can be varied. In the case of an AC motor, this means that the frequency of the supply AC voltage must be variable.

The motor 110 shown in Fig. 1 is therefore powered by a three-phase variable frequency power supply, which is generated by using a power electronics unit 117.

Power electronics unit 117 operates against an energy storage 118, such as e.g. one or more batteries, supercapacitors, etc.

The energy storage can be arranged to be charged in several different ways, e.g. by regenerative braking by means of the electric machine 110 and / or via "plug-in" to an external power source, such as a conventional electricity network.

The power electronics unit 117 shown in the figure may be of a type commonly found in hybrid vehicles and is therefore not described in more detail here. In general, however, it can be said that the power electronics unit 117, in the case of an alternating current motor, converts the direct voltage of the energy storage 118 to an alternating voltage.

The conversion is performed by means of a converter device, which e.g. may comprise a plurality of IGBT (Insulated Gate Bipolar Transistor) transistors, which by means of appropriate switching can provide a three-phase voltage of desired and variable amplitude and frequency for driving the electric machine 110 and thus the vehicle's drive wheels 113, 114. 10 15 20 25 30 On In this way, the electric machine 110 can be used to propel the vehicle 100 at vehicle speeds from zero to maximum speed, or a lower speed, depending on the size of the electric machine, by controlling the frequency supplied to the motor 106 from 0 Hz to a frequency resulting in the vehicle (or, in cooperation with the internal combustion engine, its) top speed. In the case of heavy vehicles, however, a very large battery capacity is currently required, and thus a very heavy battery, in order for the vehicle to be able to be driven longer distances when only electric machine operation is performed. For this reason, the electric machine 110 is usually used only for propulsion in certain situations, at least some of which will be described below.

Furthermore, control systems in modern vehicles usually consist of a communication bus system consisting of one or more communication buses for interconnecting a number of electronic control units (ECUs), or controllers, and various components located on the vehicle. Such a control system can comprise a large number of control units, and the responsibility for a specific function can be divided into more than one control unit.

For the sake of simplicity, in Fig. 1a, in addition to the already mentioned control unit 116, only four further electronic control units 115, 119, 126, 127 are shown.

The control unit 119 controls, in this embodiment, the motor 101, while the control unit 116 controls clutch 106 and gearbox 103 respectively (two or more of motor, gearbox and clutch may alternatively be arranged to be controlled by one and the same control unit, or other, not shown control units) . The control unit 115 controls the electrical machine / power electronics unit / energy storage.

The control units 115-116, 119 can communicate with each other via said communication bus system, which is indicated by dashes between the control units in the figure.

The control unit 126 controls the vehicle's RTI (Road Transport Informatics) system, which controls functions such as traffic information and vehicle navigation. In the present example, the control unit 126 is also responsible for presenting the fuel part of the hybrid part to the owner of the vehicle in the present exemplary embodiment. The RTI control unit is normally responsible for the vehicle's communication with e.g. a fleet management portal, whereby data can be transferred to said fleet management portal for evaluation of the vehicle owner.

The control unit 127 controls the display of data on the instruments present in the cab, which, in addition to conventional pointer instruments, often include one or more displays. By means of the control unit 127, data regarding fuel consumption can be displayed on these one or more displays, alternatively a display specifically intended for the purpose, for presentation of fuel consumption data for the driver of the vehicle.

Control units of the type shown are normally arranged to receive sensor signals from different parts of the vehicle, e.g. from gearbox, internal combustion engine, electric machine, clutch and / or other control units or components on the vehicle. The control unit generated control signals are normally dependent on both signals from other control units and signals from components.

For example. the control unit 115 controls the electric machine 110 / the power electronics 117 etc. e.g. to depend on information such as received from the control units 119, 126, 127 and / or 116.

The control units are further arranged to emit control signals to various parts and components of the vehicle, such as e.g. electric machine 110 and the power electronics unit 117, for controlling them. The present invention can be implemented in any of the above control units, or in any other applicable control unit in the vehicle control system. The functions of the invention can also be divided into two or more of said or other control units.

The control is often controlled by programmed instructions. These programmed instructions typically consist of a computer program, which when executed in a computer or controller causes the computer / controller to perform the desired control, such as method steps of the present invention.

The computer program is usually a computer program product 109 stored on a digital storage medium 121 (see Fig. 1b) such as, for example: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash Memory, EEPROM (Electrically Erasable PROM), a hard disk drive, etc., in or connected to the control unit and executed by the control unit. By changing the instructions of the computer program, the behavior of the vehicle in a specific situation can thus be adjusted.

An exemplary control unit (control unit 127) is shown schematically in Fig. 1b, wherein the control unit 115 may in turn comprise a calculation unit 120, which may be constituted by substantially any suitable type of processor or microcomputer, e.g. a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC).

The computing unit 120 is connected to a memory unit 121, which provides the computing unit 120 e.g. the stored program code 109 and / or the stored data calculation unit 120 need to be able to perform calculations.

The calculation unit 120 is also arranged to store partial or final results of calculations in the memory unit 121. Furthermore, the control unit 115 is provided with devices 122, 123, 124, 125 for receiving and transmitting input and output signals, respectively. These input and output signals may contain waveforms, pulses, or other attributes, which of the input signals devices 122, 125 may be detected as information and may be converted into signals which may be processed by the computing unit 120. These signals are then provided to the computing unit 120. The devices 123, 124 for transmitting output signals are arranged to convert signals obtained from the calculation unit 120 for creating output signals by e.g. modulate the signals, which can be transmitted to other parts of the vehicle's control system and / or the component (s) for which the signals are intended. Each of the connections to the devices for receiving and transmitting input and output signals, respectively, may be one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Orientated Systems Transport), or any other bus configuration; or by a wireless connection.

An exemplary method 300 according to the present invention is shown in Fig. 3.

According to the above, the basic idea of the present invention is to compare the fuel consumption of the hybrid vehicle with the fuel consumption that driving the same vehicle without a hybrid part, when driving along the same road section, would have resulted in.

Method 300 begins in step 301 where it is determined whether the fuel consumption difference is to be determined.

The difference in fuel consumption can e.g. be arranged to be performed at regular intervals, such as every second, every 5 seconds or at any other applicable time interval. l0 l5 20 25 30 l3 The time interval can also be arranged to be varied while driving. For example. For example, the difference in fuel consumption can be determined more frequently in situations such as hard accelerations, where rapid changes in the operating point of the internal combustion engine and / or the electric machine occur. The method proceeds from step 301 to step 302, where the actual fuel consumption of the hybrid vehicle 100 is determined, after which the method proceeds to step 303, where the fuel consumption of a corresponding conventional vehicle is determined. Once fuel consumption has been determined for both vehicles, the difference in fuel consumption is determined in step 304 and presented to drivers and / or vehicle owners in step 305.

The method can then return to step 301 for the next determination (time / time interval). Instead of determining consumption explicitly for both types of vehicles, and then the difference, as in steps 302-304, steps 302-304 may be performed in a single step, as will be exemplified by the equations below.

By determining the difference in fuel consumption for a, apart from the hybrid part, in principle identical vehicle, ie. a vehicle with otherwise substantially identical essential driveline components, ie. internal combustion engine and preferably also a gearbox, a very accurate measure of the amount of fuel saved, and thus, with the aid of information regarding fuel price, also saved fuel cost, can be obtained. Thus, the driver of the vehicle, and perhaps especially the owner of the vehicle, as above can get a concrete proof that it is actually not only environmentally friendly, but also profitable to invest in hybrid vehicles.

Determining the difference in fuel consumption can be done in several ways, and a specific calculation example is exemplified below.

In the example shown, the invention is exemplified by an internal combustion engine in the form of a diesel engine, but the invention is applicable to any internal combustion engine.

In addition to the fact that fuel savings can be calculated in different ways, fuel can be saved with the help of the hybrid system in a number of different situations. Examples of such situations are exemplified below. It should be understood, however, that fuel savings in the different situations can vary greatly from situation to situation. Furthermore, it should be understood that while there is a value in presenting the total fuel savings for all fuel saving situations, there may also be a value in presenting fuel savings only for one or a subset of the situations described below.

In an exemplary embodiment, only the savings made in situations when the torque of the internal combustion engine exceeds a predetermined value is determined, as only this determination can give a good indication of saved fuel. According to an alternative embodiment, a combination of e.g. all the calculation bases exemplified below.

As mentioned above, the electric machine sits on the input shaft of the gearbox, whereby the internal combustion engine and the electric machine can drive the vehicle's drive wheels either separately or together. When the electric machine helps the internal combustion engine with the propulsion of the vehicle, the fuel demand of the internal combustion engine decreases.

Fig. 2 shows a diagram 200 which illustrates an example of how the fuel consumption of an example engine can vary with engine speed and torque delivered. Fuel consumption is shown as fuel flow in liters / hour. As can be seen in the figure, the distances between the fuel flow curves in large parts of the figure are constant, or substantially constant, especially when considering engine power changes at a certain speed.

This means that the fuel consumption of the internal combustion engine 10 15 20 25 30 15 varies in principle linearly with the engine power delivered (and thus also linearly with torque changes). Thus, the efficiency of the internal combustion engine is (substantially) constant within large parts of the working range of the internal combustion engine.

Suppose e.g. that the internal combustion engine operates at point a, ie. emits an engine power (torque is used below, but engine power could still be used, as torque and power are connected to each other through a simple and well-known mathematical relationship. In the appended claims, the term driving force is used to represent delivered torque or delivered power) Take at speed nl. If the electric machine now applies a torque Tb, the torque emitted by the internal combustion engine will drop to Ta-Tb = Tc (point c) (if the same driving force is to be obtained as would be the case without the presence of a hybrid part). Since the fuel consumption of the internal combustion engine is linear towards the power, ie. the efficiency at point c is the same as at point a (the fuel flow per kilowatt hour / newton meter developed is the same), the fuel savings obtained with the help of the electric machine will be directly proportional (linear) to the torque (the power) that the electric machine contributes. Ie. as long as the efficiency is the same, the amount of fuel injected will be linear to the torque delivered. If the torque generated by the combustion engine combustion is reduced by half, this also means that the injected fuel is reduced by half. The efficiency of an internal combustion engine is usually substantially constant at one and the same speed, and in such cases the fuel saved by means of the hybrid part can be estimated by: ElM0t0rT0rque (n) XF uelSaved = ZF uelRate (n)> <”EngíneT0rque (n) (z) eq. <1) 10 l5 20 25 l6 This equation is written as a sum, where a calculation is made for a number of measuring points / periods (n) with the duration At, where At, as above, can vary in length depending on the current driving situation.

I eq. (l) constitutes: Pheßhvaí = saved fuel, expressed in liters, accumulated during the time t during the calculation.

FUdRaæOÛ = current fuel consumption at the time of measurement, e.g. expressed in liters / second. Fuel consumption can e.g. is determined by means of a model of the internal combustion engine, which can be stored in the vehicle's control system as a mathematical expression or in tabular form, whereby the current engine control parameters can be used to determine the F uelRate (n).

E fi gme flfl qud fl) is the torque of the internal combustion engine for a specific measuring point / period (n).

E fl wbmr fl nqud fl) is the torque of the electric machine for a specific measuring point / period (n).

The equation can of course also be written as an integral, just as torque can be exchanged for delivered power or other suitable unit that represents delivered power. Eq. (l) could thus also be written as: Electric motor Pr 0pelP0w (n) X F uelSaved = A F uelRate (n)> <At (l) Engine Pr 0pelP0w (n) Where PropelPow (Propelling Power) represents driving force.

Since the fuel consumption of the internal combustion engine is, or with good accuracy can be assumed to be linear with the current torque in situations as above, the saving during the interval At 10 thus becomes equal to the contribution of the electric machine in relation to the contribution of the internal combustion engine. If the electric machine emits the same torque as the internal combustion engine, the saving will thus be as great as the current fuel consumption of the internal combustion engine. For example, if the contribution of the electric machine is 25% of the torque the internal combustion engine would have had without the presence of an electric machine, the fuel saving will thus be 1/3 of 025 glues * current consumption. (l) the method shown for calculating fuel economy can be used as long as the torque of the internal combustion engine is the same, or substantially the same at the operating point at which the internal combustion engine would operate without the contribution of the electric machine, e.g. point a above, and the operating point at which the internal combustion engine operates with contributions from the electric machine (eg point c above). Depending on how accurate a determination is desired, the efficiency difference of the internal combustion engine between points a and c can e.g. allowed to deviate with any value controlled by the desired accuracy, e.g. 1%, i.e. fuel consumption does not have to be completely linear with the power of the internal combustion engine.

The diagram shown in Fig. 2 can e.g. is stored, as appropriate, e.g. as values for different (power) torque / speed combinations, in the vehicle's control system, whereby at each occasion (s) it can be determined with the aid of said stored data on eq. (l) is applicable for use in the calculation to obtain the desired accuracy. For example. there may be certain parts of the combustion engine's working area where the application of eq. (l) is not applicable.

Furthermore, only positive electric machine torques are taken into account when using eq. (l). In the event of negative electric machine torques, EWMbwr ätts¶ que = 0 is set. Furthermore, 10 15 20 25 30 18 calculation is performed according to eq. (1) preferably only when the internal combustion engine emits a positive driveline torque. Although the combustion of the internal combustion engine emits a positive torque, p.g.a. engine friction and other losses, this still means that the torque contribution to the driveline is negative, ie. engine braking in progress. In this case, savings are not according to eq. (1) relevant.

Furthermore, eq. (1) be arranged to be used only when the torque of the internal combustion engine, Ehgme fi mque, or the torque emitted by the flywheel of the internal combustion engine, is greater than a predetermined threshold value. This e.g. due to the fact that the efficiency of the internal combustion engine at low torques can be comparatively low, therefore further compensation as below may be required.

Points where E fi gme fl wque is less than the threshold value are set to O. At the same time, another calculation method can be used in such situations, at least some of which are exemplified below.

In one embodiment, the calculation method shown is also used for purely electric driving, however, in this case power must be used because the internal combustion engine and electric machine will operate at different speeds, and torque comparison can thus not be used.

In addition, in this case, the internal combustion engine usually operates at idle, the working point of the internal combustion engine often being at a working point with inferior efficiency. Depending on where the internal combustion engine would have operated without a contribution from the electric machine, the accuracy may therefore deteriorate in this situation. If the internal combustion engine had operated at a higher efficiency working point, the equation will not be accurate (ie there is an efficiency difference for the internal combustion engine between the working points), so a compensation factor may be used if necessary. For example. the calculated value can be compensated with k. d. . . N X¶; Ešïg # ¿to take into account that the savings are not the exact effect. degree e, as large as the value obtained according to the equation. Of course, other types of conversion factors can also be used.

The vehicle can also be driven electrically without the internal combustion engine running. In this case, the saving will be the consumption that the internal combustion engine would have had at the current speed and electric machine power / torque.

The result of it in eq. (1) the sum obtained can be summed in a parameter which is preferably not reset during the service life of the truck. This means that total fuel saved so far can be presented to the driver and / or vehicle owner. The result can also be saved in a parameter representing e.g. ongoing journey to be able to compare savings for several consecutive journeys along the same route.

Furthermore, the vehicle can be provided with current fuel costs, e.g. by the driver of the vehicle entering the current fuel price when refueling. With knowledge of the fuel price, not only savings in the number of liters of fuel can be shown, but also savings in economic terms. Instead of the vehicle driver entering the fuel price, this can e.g. obtained via any suitable wireless link, such as e.g. using the RTI system.

Another example of a situation where the hybrid part of the driveline can lead to a fuel saving is when starting from a standstill. l0 l5 20 25 20 When starting from a standstill, compared to when starting with the conventional vehicle, a fuel saving occurs due to two factors. The first factor is missing energy losses during clutch grinding. The clutch normally closes at start-up to a position where the clutch is so closed that it is able to transmit the torque that the engine can emit at maximum at idle speed. This clutch position is then maintained until the input shaft of the gearbox reaches the engine idle speed, closing the clutch completely. This coupling grinder causes energy losses in the form of frictional heat.

The second factor is due to the fact that the electric machine can be used to start the vehicle, whereby the vehicle can be started completely electrically without the internal combustion engine having to be started.

The savings achieved due to reduced clutch grinding can then be calculated as follows: EngíneSpeed (n) - ElMotorSpeed (n) 60 SlípL0ss (n) => <ZH> <E lMotorT 0rque (n) (W) eq (2).

This value is then used in the equation: FuelSaved = Zn SlípL0ss (n)> where EQ§QFudFm fi is a conversion factor used to accurately compare what energy extracted from the battery corresponds to in fuel. The calculation method shown becomes somewhat generalized when the internal combustion engine does not have the same efficiency in all operating points, and when starting with an internal combustion engine can lead to starting at different operating points.

Practical tests have shown, however, that despite the generalization, very good accuracy is obtained over time. 10 15 20 25 21 Another situation where a large saving can be made is when the internal combustion engine is switched off at a stop.

In this case, the sum of the normal idle consumption of the internal combustion engine, FUdRaæh fl e, is simply determined for the time intervals it would normally have been running, ie.

FueISaVedIdIe = Z Fueueafeldze> <Off (z).

It can be advantageous to report this value separately, as an economically minded driver of a conventional vehicle can actually switch off the internal combustion engine automatically at longer shorter and / or longer stops, whereby the actual saving may be lower than the calculated one. Another situation that results in fuel savings, albeit in relatively small amounts, such as e.g. 5 Wh per start, constitutes an internal combustion engine start with the electric machine. In a parallel hybrid, the electric machine can be used instead of the usual starter motor for starting the internal combustion engine. This means that there is a saving when the energy is taken from decelerated energy, and no generator needs to load the internal combustion engine to charge a standard starter battery.

So far, only fuel-saving measures have been reported. However, there are also situations where the hybrid part of the driveline gives rise to energy losses. The greatest loss occurs when the batteries are charged from positive internal combustion engine torque.

The energy storage can, in order to obtain a long service life, e.g. are used only within a certain range of the total capacity of the energy storage, such as e.g. within 40-60% of fully charged battery. This means that if the charge level becomes too low, e.g. drops to 35%, the battery must be charged using the internal combustion engine. This is achieved by loading the internal combustion engine with the electric machine, whereby the increased load gives rise to an increased fuel consumption.

This increased fuel consumption can be calculated as: - E lMotorT 0rque (n) X At F uelLost = Z F uelRate (n)> <e kv. (4) EngíneTorque fi a) There are also additional factors that can give rise to energy losses for the hybrid vehicle.

For example. fan and pump functions may be required by the hybrid part of the driveline (eg for cooling the electric machine / energy storage), which leads to electrical losses from the vehicle's conventional electrical system (usually a 24V system in heavy vehicles).

This energy loss can be compensated for in the case of positive internal combustion engine torques (in the event of "negative" internal combustion engine torque requirements, charging can take place free of charge by braking with the help of the electric machine). The power consumption that arises during operation of such units can be calculated in conventional and known ways. The total power consumption from these units can then be converted to a corresponding internal combustion engine torque by division by 2 * n * Ehgma¶waí, where E fi gma fi waí constitutes the speed of the internal combustion engine. Fuel losses can then be calculated using eq. (1) above, where E fl wbmr fl uqud fl) is replaced by the calculated torque. The extra rolling resistance that arises due to the increased weight of the hybrid vehicle should also be taken into account. The rolling resistance can also be converted to an effect in a known manner, and is summed with the unit losses above when using eq. (1) above. l0 l5 20 25 30 23 The increased weight due to driveline hybrid part (weight varies from vehicle to vehicle, and depending on energy storage capacity, but can in an example consist of about 200 kg) also means an increased energy consumption during acceleration, and when driving in slopes. As long as no active braking takes place, however, this energy is stored as extra kinetic energy, which can be used in e.g. downhills to accelerate the vehicle, or to charge the energy storage using the electric machine. If, on the other hand, the stored kinetic energy is slowed down, these losses can also be taken into account.

Another aspect that can be taken into account is that in hybrid vehicles, the electric machine can be used to move the internal combustion engine's operating point to improve emission properties. In some cases, this saves fuel compared to using traditional methods. An example is that diesel is often used to burn clean particulate filters. By moving the combustion engine's operating point, the exhaust temperatures can be raised without the need to use diesel to burn the particulate filter. In this case, the amount of diesel that would normally have been consumed to burn the filter can be added to the above.

Each individual emission strategy has its own calculation algorithm for saved fuel.

All in all, a very good estimate of the total fuel savings for the hybrid vehicle can be determined and presented to the driver of the vehicle in an applicable manner, e.g. via a display as above.

For example. fuel savings can be displayed as fuel saved during the current journey, average fuel savings per hour or distance, total fuel saved since reset.

Preferably, the driver can reset trip data in the usual 10 15 24 24 24 manner. In the control unit, however, the parameters are not reset, but the vehicle's trip computer only determines new reference points at reset.

Calculated parameters can, as above, also be sent to e.g. a fleet management portal, whereby the owner of the vehicle can follow up on saved fuel. Furthermore, statistics can be calculated on which distances, which / which drivers, type of driving where the hybrid system benefits most, and thus saves the increased purchase cost the fastest.

The invention has so far been described in connection with a parallel hybrid system. However, the invention is also applicable to other types of hybrid systems, as long as an internal combustion engine is present, and as long as fuel consumption is compared with a vehicle equipped with a substantially identical internal combustion engine.

As mentioned above, it should be noted that an internal combustion engine equipped with a starter motor / generator, which is otherwise the same as the internal combustion engine of the hybrid vehicle, is in this context considered to be identical to the internal combustion engine of the hybrid vehicle. The same applies to such other small changes that may be required by the hybrid system.

However, the internal combustion engine must be the same with respect to cylinder volume, etc. to be considered the same according to the present invention.

Claims (21)

10 15 20 25 25 P A T E N T K R A V A method of comparing a fuel consumption of a first vehicle with a second vehicle, said first vehicle comprising a first energy converter consisting of an internal combustion engine for generating a first propulsion force for propelling said first vehicle, and at least one second energy converter consisting of a first electric machine for generating a second propulsion force for propelling said vehicle, the method comprising, for a first time where said first and second vehicles are driven in the same manner: - determining by means of determining means a difference in fuel consumption between said first vehicle and said second vehicle, said second vehicle comprising only an energy converter for generating driving force for propelling said second vehicle, and said energy converter in said second vehicle constituting an internal combustion engine substantially identical to said first internal combustion engine. The method of claim 1, wherein said first and second vehicles comprise a respective driveline with substantially identical driveline gear ratio. A method according to claim 1 or 2, wherein said first vehicle and second vehicle comprise substantially identical internal combustion engine and gearbox, and wherein in said first vehicle said first electric machine is arranged between said internal combustion engine and said gearbox. A method according to any one of claims 1-3, wherein said determination is performed at least in part based on a driving force emitted by said electric machine. l0 l5 20 25 26 A method according to any one of claims 1-4, wherein the propulsion contribution of the electric machine at said first time is compared with the propulsion contribution of the internal combustion engine at said first time, and wherein said difference in fuel consumption between said first vehicle and said second vehicle is determined at least in part based on said comparison. A method according to any one of claims 1-5, wherein the method comprises comparing at least one driving force emitted by the electric machine with a driving force emitted by the internal combustion engine, wherein a difference in fuel consumption is determined based on said driving power of said electric machine and internal combustion engine. driving force. A method according to claim 6, wherein said difference in fuel consumption for a given time / time interval is determined by means of an equation equivalent to: E lmotor Pr opelPom / (n) X At F uelSaved = F uelRate> <(l), Engine Pr 0pelP0w (n) where PropelPow (Propelling Power) represents driving force. A method according to claim 6 or 7, wherein, if the efficiency of said internal combustion engine in said first vehicle, in the case of propulsion contribution from said electric machine, differs from the efficiency of the internal combustion engine in said second vehicle by more than a first value, a compensation factor is used in said determination of a difference in fuel consumption, and wherein said compensation factor depends on said difference in efficiency. Method according to any one of the preceding claims, wherein said difference in fuel consumption is determined only at times with energy withdrawal from an energy storage connected to said electric machine. 10 15 20 25 30 27 A method according to any one of the preceding claims, wherein said determined difference in fuel consumption is combined with a fuel cost to obtain an economic measure of said difference in fuel consumption. A method according to any one of the preceding claims, wherein said determination is performed for a number of consecutive times, said determined difference in fuel consumption accumulating in at least one parameter. A method according to any one of the preceding claims, wherein said determining is performed for a number of consecutive times, said determined difference accumulating in a plurality of parameters, each parameter representing a type of situation. A method according to any one of claims 11-12, wherein said one or more accumulated differences in fuel consumption are accumulated for a plurality of consecutive vehicle journeys with said vehicle. A method according to any one of the preceding claims, wherein said determined difference in fuel consumption is presented to the driver of the vehicle via a display. A method according to any one of the preceding claims, wherein said method is performed in said first vehicle, and wherein said second vehicle is represented by the sum of the propulsion contribution from said internal combustion engine at said first vehicle and the propulsion contribution from said electric machine. Method according to any one of the preceding claims, wherein in said determination of difference in fuel consumption, determination of difference in fuel consumption is performed for one or more of the group: - vehicle start with the aid of an electric machine, - shut down the internal combustion engine when stationary, - increased fuel consumption when charging energy storage. A method according to any one of the preceding claims, further comprising performing said determination while driving with said vehicle. A computer program comprising program code, which when said program code is executed in a computer causes said computer to perform the method according to any one of claims 1-17. A computer program product comprising a computer readable medium and a computer program according to claim 18, wherein said computer program is included in said computer readable medium. A system for comparing a fuel consumption of a first vehicle with a second vehicle, said first vehicle comprising a first energy converter comprising an internal combustion engine for generating a first propulsion force for propelling said first vehicle, and at least one second energy converter consisting of a first electric machine for generating a second propulsion force for propelling said vehicle, characterized in that the system comprises determining means for, for a first time where said first and second vehicles are driven in the same way: - determining a difference in fuel consumption between said first vehicle and said second vehicle, said second vehicle comprising only an energy converter for generating driving force for propelling said second vehicle, and said energy converter in said second vehicle constituting an internal combustion engine substantially identical to said first internal combustion engine. 29 Vehicle, characterized in that it comprises a system according to claim 20.