FR2959292A1 - Method for determining energy efficient rolling speed of e.g. hybrid vehicle, involves seizing rolling speed according to actual rolling state and specific information of vehicle, where actual state is actual energy consumption of vehicle - Google Patents

Abstract

The method involves seizing energy efficient rolling speed (102) according to an actual rolling state and specific information of a vehicle, where the actual rolling state is actual speed and actual energy consumption of the vehicle. The actual energy need from the actual power of the engine and inclination of an actual roadway are determined (104). The specific information of the vehicle is provided with an energy consumption curve and a transmission characteristic curve. Independent claims are also included for the following: (1) a Device for determining energy efficient rolling speed of a vehicle, comprising a determination unit (2) a computer program product comprising a set of instructions to perform a method for determining energy efficient rolling speed of a vehicle.

Description

FIELD OF THE INVENTION The present invention relates to a method for determining the energy-efficient running speed of a vehicle as well as a device for its implementation and a computer program product. State of the art Current vehicles are often equipped with a fuel consumption indicator which displays for the driver the current fuel consumption related to a journey, for example in 1/100 km.

Actual or instantaneous fuel consumption depends on the speed due to rolling resistance, coefficient of adhesion and air resistance, acceleration and load as a function of weight and slope as well as gear ratio chosen. There are also gear ratio selection indicators indicating to the driver the optimum gear ratio for the current driving situation with respect to the fuel consumption. DE 10 2007 044 401 A1 describes the use of engine and transmission information to determine switching points optimized for consumption. For this, there are limit thresholds for the minimum and maximum torque and speed. The switching point recommendation (shift ratio) is based on the energy demand that remains momentarily constant. DESCRIPTION AND ADVANTAGES OF THE INVENTION The object of the present invention is to develop in this context a method for determining the energy-saving running speed of a vehicle as well as a device applying the method and a computer program product for the implementation of the method. Thus, a subject of the invention is a method for determining a fuel-efficient running speed of a vehicle comprising the following steps: - seizing the energy-saving running speed according to the current driving condition and vehicle-specific information, - the current driving status being the current speed and the current energy consumption of the vehicle.

In other words, the invention relates to a system that provides the driver with a speed at which the vehicle has the lowest consumption compared to the current consumption. At the same time, the system determines the effects of this lower speed and displays them. According to the invention, one or more speeds of taxiing with respect to the current speed as well as a current consumption and an alternative consumption compared to a path and the optimum gear ratio, corresponding to this fuel consumption, will be determined and presented to the driver. The vehicle is equipped with an internal combustion engine or an electric vehicle or a hybrid vehicle. The energy-efficient driving speed is a vehicle speed optimized from the point of view of the vehicle's energy consumption while corresponding to a deviation from the speed currently used which remains acceptable to the driver. The energy consumption is the fuel consumption or the consumption of electrical energy. If potential energy savings occur, the corresponding energy-saving speed deviates from the current speed used.

In the optimum case, there will be significant savings only for small variations in speed, usually it is speed reductions. Information on the energy saving speed thus defined, can be displayed for the driver so that he can adapt the speed of the vehicle. The energy-saving speed can be determined from a prescription based on the current speed of the vehicle and the current energy consumption by the vehicle. It is also possible to determine a number of alternative energy-saving speeds which differ, for example, in the resulting energy consumption or in the selection of the gear ratio of the vehicle gearbox. The current energy consumption may represent a current state of charge of the vehicle. If information is available concerning the current speed as well as the current energy demand in an already used form, this information can be used in the method of the invention. Alternatively, the information can be

Corresponding 3 mations using appropriate sensors or receive such information. The current energy requirement can be determined from the current engine power and additionally or alternatively from the road gradient. The engine power is determined from the current engine speed and the actual torque provided by the engine. This makes it possible to determine very precisely the current energy requirement. If the current energy requirement is determined from the slope of the road, the mass of the vehicle is taken into account. This allows for a simple assessment of the current energy requirement. In addition, the current acceleration, current speed, current position, accelerator pedal, and current transmission ratio of the transmission can be used to determine the energy requirement. The vehicle-specific information may consist of at least one energy consumption curve and / or a transmission characteristic curve. The corresponding curves can be recorded in the vehicle control electronics and can be read to determine the energy saving running speed or used for this determination. Starting from the current operating point defined by the current speed, it will be possible, using a characteristic curve, to determine a more advantageous operating point for the energy consumption and to select a speed associated with this operating point more advantageous as an energy efficient running speed. The vehicle-specific information can be extracted from memorized stored-path consumption characteristic fields as well as consumption characteristic curves and consumption characteristic fields. The characteristic curves or characteristic fields can be in the form of tables.

According to one characteristic, the energy-saving running speed is defined within a tolerance window associated with the current speed. The tolerance window defines a minimum speed and a maximum speed. Thus, it avoids too much difference between the energy saving speed and the current speed. The extension of the tolerance window can be predefined in a fixed manner or adapted to a magnitude of

4 the current speed. The tolerance window may also take into account a minimum or maximum recommended driving speed, for example a driving speed. The method according to the invention comprises a step for determining an advantageous gear ratio of the vehicle gearbox. The preferred gear ratio is set according to the current driving condition and the vehicle-specific information. The advantageous transmission ratio defines an optimum gear ratio for the energy-saving running speed. If the optimum gear ratio does not correspond to the gear ratio currently selected, a shift request is sent to the driver or the optimum gear ratio will be selected automatically in the case of an automatic gearbox. .

Correspondingly, information can be provided regarding the energy efficient running speed and / or the preferred gear ratio and / or the current driving condition by the interface with a display facility. The display installation may be an optical display facility or an acoustic display facility, i.e., for example an image screen or a speaker. If, for the driver, both information concerning the current driving situation and information concerning one or more driving conditions corresponding to the energy-efficient driving speeds thus obtained are displayed, the driver will have a good opportunity to comparison and will be able to decide for or against a speed of running energy saving. Alternatively or additionally, the above information may be provided at an interface for the control apparatus of the transmission line providing switching. In the embodiment using the tolerance window, this window can be adjusted according to the class of the road currently used. Alternatively or additionally, the tolerance window can be adjusted according to the current speed limit. This avoids, for example, exceeding or exceeding a maximum speed or a minimum speed to recommend the energy-saving running speed. In this case, the current class of the road and / or the speed limit will be determined from a digital map and the current position of the vehicle. The method according to the invention can be integrated in a navigation system and the position data and those of the class of the road can be provided by the navigation system at the interface for the method of the invention. The class of the road or the speed limits may be determined by an object recognition and in particular a recognition of traffic signals. An image capture facility such as a video camera can cooperate with an image exploitation system. The present invention further creates a device comprising means for performing the steps of the method of the invention. This variant of the invention in the form of a device makes it possible to solve the problem posed within the scope of the invention quickly and efficiently. The device according to the invention is an electrical apparatus processing signals supplied by sensors and generating control signals from these sensor signals. The device may comprise an interface made by a circuit and / or by a program. In the case of an embodiment by a circuit, the interfaces may for example be part of a system called ASIC (dedicated circuit) which contains the various functions of the device. It is also possible that the interfaces comprise integrated circuits that are clean, or at least partially constituted by discrete components. In the case of a realization in the form of a program, the inter-faces may be existing program modules for example on a microcontroller next to other program modules. The invention also advantageously relates to a computer program product with a program code recorded on a machine readable medium such as a semiconductor memory, a hard disk or an optical memory and used to apply the method. as described above when the program is executed by a device.

The program code can also be provided by a server to be downloaded by an appropriate data link, for example the Internet. The downloading of programs can be done by the user against the payment of a fee. It is thus a program or computer program product constituting an industrial and commercial product as such. Drawings The method for determining an energy-saving running speed according to the invention will be described hereinafter by way of example with the aid of the appended drawings in which: FIG. 1 shows a flow diagram of an example of embodiment of the invention; FIG. 2 is a block diagram of an exemplary embodiment of the invention; FIG. 3 shows a distance / consumption curve for a certain state of charge, and FIG. possible display of information according to the present invention. DESCRIPTION OF EMBODIMENTS OF THE INVENTION FIG. 1 shows a simplified flowchart of a method for determining an energy-efficient running speed for a vehicle according to an exemplary embodiment of the invention. In step 102, information relating to the current driving condition and vehicle specific information is collected.

The information relating to the current driving state is information on the current speed as well as information on the current energy requirement or the current state of charge of the vehicle. This information is collected by appropriate interfaces with sensors, operating facilities, or memory installations.

In step 104, one or more energy-saving, alternative speeds are determined. This can be done on the basis of the information received regarding the current driving status and vehicle-specific information. To determine an energy efficient running speed, an appropriate algorithm is applied.

In step 106, information concerning an energy-efficient running speed is provided and displayed, for example, to the driver of the vehicle. The display can be linked to the current speed, the current consumption, and the current gear ratio, as well as to the energy saving consumption associated with the energy-saving running speed and the economy-efficient gear ratio. Energy associated with the speed of running energy saving. Fig. 2 shows a block diagram of a device 200 for determining an energy efficient running speed for a vehicle corresponding to an embodiment of the invention. The device 200 is shown with a controller 202 and a display facility 204. In this embodiment, the device is in the form of a driver assistance system 200 for selecting the speed. This may include a driver assistance system for selecting a speed corresponding to a lower power consumption. The driving assistance system 200 applies the method described in FIG. 1. The control 202 is the control of the engine and / or the control of the transmission (gearbox) of the vehicle. The controller 202 transmits the current speed, current consumption, current speed and / or current load or instantaneous load to the driver assistance system 200. The driver assistance system 200 is based on the data received from control 202 to determine alternate speed, alternating power, and alternate speed gears. The gear ratio currently selected is determined for example from the current speed and the current speed. The alternative speed can be compared to the current speed to allow the operation of the vehicle more energy efficient. The driver assistance system 200 provides current speed and alternative speed information, current consumption information and alternative fuel consumption as well as information on the current gear ratio and an alternate gear ratio. As a variant, only a selection of the information indicated is determined or applied to it.

8 display installation 204. In addition, several alternative speeds with associated consumption as well as information relating to gear ratios can be determined and provided. The display facility 204 displays the data received from the driver assistance system 200. For this, the display facility 204 is coupled to the driver assistance system 200 through an appropriate interface. In order to determine the optimum alternating speed ratio and the optimum alternative consumption, the exemplary system shown in Figure 2 can take the vehicle-specific data as well as the actual data of the current driving situation. Vehicle-specific data are, for example, con-summation curves, consumption characteristic fields, or transmission / transmission characteristic fields. Current data is eg speed or load. Alternative speeds are proposed which offer a significant advantage of consumption without, however, speeds being too low compared to the current driving speed. The consumption advantage and the speed disadvantage must also be within acceptable and comparable orders of magnitude. It is assumed that the driver wishes in principle to travel at a speed which corresponds to the order of magnitude of the current speed, that is to say that he will accept only "small" deviations if the advantage of the consumption is significant. The method is particularly advantageous if small variations in speed result in a relatively large saving while the driver was not aware of it. In order to determine the alternative speed and the corresponding consumption as well as the gear ratio, it is possible to use, for example, consumption curves giving the consumption for certain load situations corresponding to the weight of the vehicle and the slope of the road as a function of speed. rolling. Another possibility for determining the values is to use the motor characteristic fields, ie the consumption according to the

9 load and the speed as well as the gearbox, that is to say the transmission ratio (gear ratio). In both cases, the most advantageous operating points in the curves or the fields of characteristics are searched for. Curves or characteristic fields may be stored in the control unit or be removed from the engine control or transmission or transmission control unit.

Figure 3 shows a consumption curve 312 for a certain load situation according to an exemplary embodiment of the invention. As a function of the consumption curve and based on the current speed v 0, a speed v 1 that is energy efficient is determined. In this graph, the abscissas represent the speed v and the ordinates represent the consumption c referred to a distance. Depending on the load situation presented, the consumption reported at a distance for a low speed is relatively high then falls as the speed increases to go through a minimum and then increase again with speed. For the current speed vO, the consumption curve 312 gives a reported consumption at a distance cO. Starting from the current speed vO, another increase of the speed results in a consumption brought to the distance, higher. This is not desirable. On the other hand, a reduction in speed to reach the minimum value of the consumption in relation to the path results in a lower consumption compared to the path. Thus the reduction of the current speed vO gives a saving of energy. The reduction of the speed must be done only to the extent that it is acceptable to the driver, for example up to the indicated speed v1. The speed v1 corresponds to a consumption with respect to the distance and which is certainly greater than the minimum value but lower than the consumption with respect to the distance cO. The value of the alternative speed v1 may correspond to a minimum value of a tolerance window in which the alternative speed must be situated. A maximum value of the tolerance window may correspond to the current speed v0 or to a higher speed. The alternative speed is determined by detecting the consumption curve 312 from the current speed in the direction of the higher speeds and / or towards the lower speeds until finding an alternative speed which has a minimum consumption compared to the distance . The detection is done for example according to a predefined step. It is also possible to select different alternative speeds by a random command and compare the consumption referred to the distance with the current consumption c0 compared to the distance or compare them to determine in this way the lowest possible consumption compared to the distance and the associated speed. Only the speeds within the tolerance window will be taken into account. According to this exemplary embodiment, it is assumed that the instantaneous speed v 0 of the vehicle corresponds to the consumption c 0 and the driver will be offered as an alternative the lower speed v 1 or the lower consumption c 1. At the consumption c0 for the speed v0 is associated an optimum speed ratio associated with the point of the consumption curve. If in the instantaneous driving situation another gear ratio is used, the optimum gear ratio will be displayed for the driver. The selection of an attractive alternative speed may depend on the class of the road used at that time. For example, it is not interesting on a motorway to propose a speed much lower than 100 km / h because it would hinder the circulation since the trucks which are the slowest vehicles circulate at least 80 km / h. This is why, according to an extension of the system, a navigation system with a digital map containing the recording of the classes of roads, such as for example auto-routes, national roads or urban traffic lanes, as well as the limitations of speeds. To determine the alternative speed, a minimum speed and a maximum speed can be set for this reason.

11 as a limitation. For example, the speed v1 shown in Figure 3 is a minimum speed limit. In other load situations, other characteristic curves will be used. The current load situation is determined for example by using current engine data or the slope of the road. Figure 4 shows a possible presentation, for example on the display installation of Figure 2, and corresponding to an exemplary embodiment of the invention. According to this embodiment, the display is in the form of a table. In a first column 421, velocity values in km / h are indicated; the second column 422 gives the consumption values in 1/100 km and the third column 423 gives the gear ratios. In the first line 431, we have the current values; the second line 432 gives a first alternative value proposition; the other line 423 gives other alternative values corresponding to a second pro-position. According to this embodiment, the current speed is 100 km / h. Current consumption is 8.5 l / 100 km and the fifth gear is used. These present values are indicated in the first line 431. In order to reduce the consumption, it is possible, in the current load situation, to go from the fifth to the sixth ratio. This is determined for example according to a characteristic gearbox curve. As a first proposal, the second gear 432 can be displayed as an alternative gear ratio, the sixth gear ratio. At this ratio is linked a reduced consumption of 8.0 1/100 km for an unchanged speed of 100 km / h. In order to further reduce fuel consumption, in addition to the selection of the sixth gear ratio, the current load situation can be further reduced to, for example, 92 km / h. This is done, for example, according to the characteristic curve presented in FIG. 3. As the second proposition in the third line 433, the alternative ratio is indicated as the sixth ratio and, moreover,

12 as an alternative speed, we have 92 km / h. This translates into a con-summation reduced to 7.5 1/100 km. The display in the form of a table allows the driver to compare the current operating status of the vehicle and the alternate states. By appropriate treatments, for example by a gear ratio change or an adaptation of the rolling speed, the driver can switch from the current operating state of the vehicle to an alternating state. In the case of an automatic or semi-automatic control of the vehicle, the driver can select one of the displayed alternating states and adapt the control of the vehicle according to the selection of the operating state of the vehicle by the driver. According to another development, the rolling control will ensure small variations in the operating state without intervention of the driver.

Claims (1)

CLAIMS 1 °) A method for determining a fuel-efficient running speed of a vehicle comprising the following steps: - enter (104) the energy-efficient running speed according to the current driving condition and vehicle-specific information - the current driving condition being the current speed and the current energy consumption of the vehicle. 2) Method according to claim 1, characterized in that the current energy requirement is determined from the current engine power and / or inclination of the current roadway. Method according to claim 1, characterized in that the vehicle-specific information comprises at least one energy consumption curve (312) and / or a transmission characteristic curve. 4) Method according to claim 1, characterized in that it determines the speed of running energy-saving within a tolerance window associated with the current speed. The method of claim 1, characterized by the step of: determining the most advantageous transmission ratio of a vehicle gearbox according to the current driving condition and the vehicle-specific information. Method according to Claim 1, characterized in that information concerning the energy-saving running speed and / or the advantageous transmission ratio and / or the current driving status are provided by an interface with a display installation (204) 14 and / or at an interface of a control apparatus of the transmission line for application. The method of claim 4, comprising the step of: setting the tolerance window according to the class of the current road and / or the current speed limitation. Method according to Claim 7, characterized in that the current road class is determined on the basis of a digital map and the current position of the vehicle. Device for carrying out the steps of the method according to any one of claims 1 to 8, characterized in that - it comprises means for determining (104) the energy-saving running speed on the basis of current driving status and vehicle-specific information, - the current driving status being the current speed and the current energy consumption of the vehicle. 10) Computer program product comprising a program code, in particular recorded on a machine-readable medium for implementing the method according to any one of claims 1 to 8 when the program is executed by a device.