SE1251147A1 - Control system for a vehicle, and a method in connection with the control system - Google Patents

Abstract

A control system (2) for a vehicle (4), the control system (2) comprising an analysis unit (6) arranged in connection with a "Look-Ahead" cruise control system (LACC system) (8) for the vehicle, and at least one control unit (10) arranged in connection with at least one auxiliary system (12) for the vehicle (4). The analysis unit (6) is adapted to analyze a future velocity (7) predicted by the LACC system (8) for the vehicle with respect to available energy, using a predetermined analysis algorithm, and to generate an energy indication signal (14) depending on the result of the analysis, the energy indication signal (14) comprises at least the first energy parameter adapted to indicate the presence of available energy. The control unit is adapted to control the supply of energy to an energy storage means for the auxiliary system, with a control signal (15), depending on at least said first energy parameter and a predetermined control algorithm. (Figure 1)

Description

EP 1900588 discloses a method for a vehicle for calculating optimal driving parameters and a corresponding auxiliary system for fuel-efficient driving. The method thus calculates optimal fuel consumption taking into account so-called vehicle characteristics, driving conditions and predetermined time limits. Indications are given to the driver so that he can drive in such a way that optimal fuel consumption is achieved.

Today's trucks have various auxiliary systems, such as air compressors for the brake system, cooling system for the vehicle and power generators. These systems often include some form of energy storage.

For an auxiliary system in the form of an air compressor that is part of the vehicle's braking system, the function is controlled by a control system, a so-called “Air Processing System” (APS).

The APS is usually controlled by a control algorithm that prioritizes activation of the air compressor when the engine is towing, ie. engine brakes. Engine braking can be described as the vehicle braking by utilizing the resistance (friction) that arises when the engine is pulled around.

The activation of the air compressor to charge the compressed air tanks during engine braking then takes place, according to the control algorithm, since it is energy efficient to activate the compressor when the vehicle brakes the engine. When the vehicle has engine brakes, no fuel injection is required because the kinetic energy that the vehicle then has, among other things. a. enough to pull around the engine. From an energy perspective, the assumption made is only completely correct when there is an actual intention to brake the vehicle, which is not always the case when the vehicle brakes the engine. There may thus be times when the vehicle is engine braked even if there is no intention to brake the vehicle and if you then activate the compressor, it means that the vehicle's kinetic energy decreases more than intended, which is not optimal from a fuel consumption perspective. In today's vehicles, for example lorries, buses and cars, there is a cruise control system for automatically regulating the vehicle's speed so that it is within a speed range around an adjustable speed value.

The speed range is defined by a minimum and maximum speed value, respectively. The cruise control system is adapted to regulate if and when the vehicle needs to brake so as not to exceed the maximum permitted speed that applies in the current driving situation, for example on a downhill slope and it can also control the application of gas, such as on an uphill slope.

Today, there are so-called reference speed-controlling cruise control, such as "Look Ahead" cruise control (LACC), which are so-called strategic cruise control devices that use information about the sections of road ahead to regulate the vehicle's speed.

The information about the road section in front includes, for example, the slope and curvature of the road, the traffic situation, road work, traffic intensity and / or road conditions.

Furthermore, the information may refer to a speed limit for the upcoming road section. This information can, for example, be obtained as positioning information, such as GPS information, map information and / or topography map information, weather reports, and information communicated between different vehicles as well as information communicated via radio from, for example, a driving center.

For example, a LACC allows the maximum permitted speed to be raised in front of a steep uphill slope to a level which is above the set speed level, as the motor vehicle is assumed to lose speed on the steep uphill slope due to high train weight relative to the vehicle's engine performance.

Similarly, the LACC allows the minimum permitted speed to be lowered to a level below the set speed on a steep downhill slope, as the motor vehicle is assumed to accelerate on the steep downhill slope due to the high train weight. The idea here is that it is more fuel-efficient to take the help of the motor vehicle's acceleration downhill than to first accelerate 4 in front of the downhill and then brake downhill. In this way, the LACC can reduce fuel consumption while largely maintaining driving time.

As mentioned above, there is a general need to improve a vehicle's fuel consumption.

The object of the present invention is to further improve the vehicle's fuel consumption and at the same time to improve the energy supply for the vehicle's auxiliary system.

SUMMARY OF THE INVENTION The above objects are achieved by the invention defined by the independent claims.

Preferred embodiments are defined by the dependent claims.

Thus, the above purposes are achieved by utilizing information from the vehicle's "Look-Ahead" cruise control system to thereby identify current and future energy resources that can be utilized by the vehicle's auxiliary system without unnecessarily reducing the vehicle's kinetic energy.

This leads to optimized fuel consumption and thus the vehicle consumes less fuel overall, which makes both more cost-effective and more environmentally friendly.

Brief Description of the Drawings Figure 1 shows a block diagram schematically illustrating the present invention.

Figure 2 is a flow chart illustrating the present invention.

Figure 3 shows two graphs illustrating a predicted speed of a vehicle over a road section in front. Detailed Description of Preferred Embodiments of the Invention With reference to the accompanying drawings, the invention will now be described in detail.

This will be done first with reference to the block diagram in Figure 1.

The invention relates to a control system 2 for a vehicle 4, wherein the control system 2 comprises an analysis unit 6 arranged in connection with a "Look-Ahead" - cruise control system (LACC system) 8 for the vehicle, and at least one control unit 10 arranged in connection with at least one auxiliary system 12 for the vehicle 4.

The LACC system 8 and its function as well as the auxiliary system 12 will be described in detail below.

The analysis unit 6 is adapted to analyze a future speed 7 predicted by the LACC system 8 for the vehicle with respect to available energy, using a predetermined analysis algorithm. The analysis unit 6 is further adapted to generate an energy indication signal 14 depending on the result of the analysis, the energy indication signal 14 comprising at least a first energy parameter which is adapted to indicate the presence of available energy.

In this context, available energy refers to kinetic energy for the vehicle which is available, for example, when the vehicle is driving downhill and which, for example, would disappear as heat in connection with braking.

The first energy parameter thus represents available energy that can be recovered in connection with braking of the vehicle. Braking of the vehicle can be done with the help of auxiliary brake, retarder, engine brake and / or wheel brake.

The energy parameter can be seen as a vector that contains information about what happens during the process of controlling the energy supply.

The analysis algorithm is adapted to analyze the predicted speed and determine the first energy parameter so that it indicates that energy is available provided that: - the predicted speed of the vehicle increases or is constant, and - no fuel injection takes place.

According to one embodiment, the analysis algorithm is adapted to analyze the predicted velocity and determine a second energy parameter so that it indicates the starting point and boiling point when the energy is available.

The start point and the end point, respectively, are expressed, for example, as times in e.g. seconds, or as distances in meters. If the energy is already available, of course, the starting point is zero.

The first energy parameter thus indicates that there is available energy, and preferably also the amount of available energy, while the second energy parameter indicates when it is available.

The energy indicating signal 14 is adapted to be applied to the control unit 10, and the control unit 10 is adapted to control the energy supply 16, with a control signal 15, to an energy storage means for the auxiliary system 12 depending on at least said first energy parameter and a predetermined control algorithm.

The energy storage means is designed depending on the type of auxiliary system in question, and may be a tank or container, or a rechargeable battery.

According to one embodiment, the auxiliary system is an air compressor arranged in connection with the vehicle's braking system. The energy storage means is then realized through one or more containers with compressed air where the energy is stored by increasing the pressure in the containers.

According to another embodiment, the control unit is adapted to control the energy supply 16, with the control signal 15, for an auxiliary system which is an AC compressor.

The control unit 10 is thus adapted to control the energy supply 16 to the auxiliary system in such a way that the braking effect which the energy extraction of the auxiliary system contributes 7 entails a reduced degree of use of the vehicle auxiliary brake, retarder, engine braking and / or wheel braking.

The invention also relates to a method for a control system in a vehicle, which method will now be described with reference to the flow chart in Figure 2. In the flow chart, the first three boxes indicate the method according to the invention while the last two relate to a preferred embodiment of the invention. The method includes the steps of: - predicting a future speed of the vehicle; - analyze the predicted future speed of the vehicle with respect to available energy, using a predetermined analysis algorithm; generating an energy indication signal depending on the result of the analysis, the energy indication signal comprising at least a first energy parameter adapted to indicate the presence of available energy.

The analysis algorithm is adapted to analyze the predicted speed and determine the first energy parameter so that it indicates that energy is available provided that: - the predicted speed of the vehicle increases or is constant, and - no fuel injection takes place.

According to one embodiment, the analysis algorithm is adapted to analyze the predicted velocity and determine a second energy parameter so that it indicates the start point and end point when the energy is available.

Said starting point and end point may be times when the energy will be available. Alternatively, these can be specified as a distance or a position for the vehicle.

According to one embodiment, the energy indication signal is adapted to be applied to the control unit which is adapted to control the supply of energy to an energy storage means for the auxiliary system in dependence on at least said first energy parameter and a predetermined control algorithm. According to a preferred embodiment, the control unit is adapted to control the energy supply for an auxiliary system which is an air compressor.

According to another embodiment, the control unit is adapted to control the energy supply for an auxiliary system which is an AC compressor.

The control unit is adapted to control the energy supply to the auxiliary system, which results in a lower degree of use of the vehicle's auxiliary brake, retarder, engine braking and / or wheel braking.

The invention also comprises a computer program product adapted to carry out the method described above. The computer program product is, for example, installed in one or more of the control system 2, the analysis unit 6 or the control unit 10.

The LACC system 8 is as described above adapted to predict a future speed of the vehicle during a future so-called time horizon, which can be considered as a future time interval, or a future mileage. This future predicted speed can be based on different driving modes such as cruise control (speed controller), where the torque of the engine represents the torque required to maintain the predetermined set speed. As an alternative driving mode, the simulation can take into account engine braking, where the engine torque is based on the engine's towing torque curve.

The simulation of the future speed of the vehicle usually takes place continuously with an update interval which can be, for example, every second, or every other second.

Preferably, the predicted velocity is analyzed by means of the analysis algorithm as soon as a new predicted velocity is present, for example as often as this is determined.

The LACC system is thus adapted to simulate in a known manner a speed of the vehicle based partly on so-called predetermined vehicle parameters, for example the vehicle's weight, engine power, and the like, which determine the specific vehicle's characteristics at a driving time, and environment-related parameters. These inputs to the LACC system have generally been designated "18" in Figure 1. The ambient parameters include one or more of the following information about the current position of the vehicle, the current speed of the vehicle and / or the current slope of the road. Information on the current position of the vehicle can, for example, be obtained from a GPS arranged in the vehicle. For example, the slope of the road can be obtained from map data including information about the topology of the road, slopes, curves, and the like. Radar and camera can also be used to get information about the slope of the road and the like. This information can also come from oncoming cars or be an estimate based on the current road slope. At the top of Figure 3 is a graph representing a simulated vehicle speed v (km / h) during a future predetermined distance P (m x 104), in this case a distance that is just over 3.5 km. At the bottom of Figure 3, a curve is shown that denigrates the topography over the same distance and where the y-axis denotes the height in meters. The section comprises a downhill slope between points A and B where a reduction in height of approximately 30 meters takes place. In the top figure, the time when the simulation shown takes place is also marked with “X” and the times up to A and B, respectively, are marked with T1 and T2. Simulation is performed with the LACC system using the aforementioned predetermined vehicle parameters and information about the vehicle's current position, speed and current map data. This system can automatically, ie. without the assistance of the driver of the vehicle, pouring the speed of the vehicle below a predetermined maximum speed or within a predetermined speed range, as is the case in Figure 3. This may mean maintaining the speed of the vehicle on an uphill slope or slowing down the speed of the vehicle on a downhill slope or the like.

As shown in Figure 3, it is desirable for the vehicle to pour a first predetermined speed VSET, which in this case is determined to be 80 km / h. This predetermined speed can be, for example, the speed determined in the cruise control system, for example a LACC system, and which is the speed that the vehicle is intended to pour during normal travel when the road can be considered to be substantially flat, ie. lack major height differences. Figure 3 also shows a second predetermined speed VMAX, which is a maximum speed that the vehicle must not exceed and in this case it is set to 89 km / h. The second predetermined speed can be described as an estimated braking speed that the vehicle must maintain e.g. at a downhill slope, which is the traffic situation that the curve according to the figure is intended to represent. the interval between 80 and 89 km / h is thus a predetermined speed interval, within which the vehicle's speed is intended to be.

At point A the vehicle thus begins to accelerate and at point B the vehicle's braking process can be said to be completed. It is thus during the time that the vehicle is between points A and B, ie. T2-T1, there will be an excess of kinetic energy, ie. available energy that can benefit from an auxiliary system. In addition to braking the vehicle in a conventional manner, excess energy during the time between points A and B, according to the present invention, can be supplied to at least one auxiliary system and then this energy withdrawal can be seen as an alternative way of contributing to the braking of the vehicle. The energy withdrawal can take place, for example, by connecting the auxiliary system, for example by means of a friction coupling, a magnetic coupling or an electrically driven coupling.

The simulation of the vehicle's speed is the basis for the control algorithm to be able to define the estimated time until the next time the vehicle will exceed a predetermined speed and may need to be braked. In this way, the control algorithm can make an assessment of when, during a future distance, it is appropriate to start supplying energy to an auxiliary system.

By making a simulation of the vehicle's speed, a prediction of when the vehicle will need to be braked can be made. When there is available energy, ie. an excess of kinetic energy can be supplied to one or more auxiliary systems. An excess of energy can be present on downhills, before curves, when changing speed determination from a higher to a lower limit, before an intersection, etc. For example, when changing speed from 90 to 70 km / h, it can be seen that the supply of energy to an auxiliary system has the same effect as using a braking system because the auxiliary system indirectly loads the engine with an 11 torque, ie. the speed of the vehicle is reduced. With a reduction in speed, it is already possible at a position that is defined a certain distance before the position where the speed change is to take place to release the gas and already starting at this position, energy can be supplied to the auxiliary system. Thus, a pre-braking can be achieved even before the actual braking takes place as a result of, for example, depressing the brake pedal or activating a braking system. Even in situations where excess energy is obtained from the vehicle traveling on a downhill slope, energy supply to an auxiliary system may already take place at a position before the actual downhill slope begins. This position may be located at point X in Figure 3. This position may e.g. is determined by defining at which position a last gas application before the hill takes place or the position which is the last time when the vehicle's engine gives a positive engine torque. In the same way, this position can be determined in the event of an imminent reduction of the speed determination.

The control algorithm that controls the energy supply to the auxiliary system preferably comprises one or more threshold values for the first energy parameter. Thus, the energy supply to the auxiliary system is controlled in dependence on the energy parameter's relation to said threshold values. For example, when the energy parameter is above one of said threshold values, energy supply to the auxiliary unit will take place.

In an alternative embodiment, the control algorithm can also define a time interval during which there is available energy for several auxiliary systems. For example, when the first energy parameter exceeds a given threshold value that indicates good access to energy. The control algorithm then controls the priority order for energy supply to the various auxiliary systems during the time interval. The prioritization has been made with regard to the types of assistance systems that are available and the status and areas of use for these. Available energy can be supplied to various auxiliary systems that have some form of energy storage, eg the compressor for the air conditioning system or the generator, for refrigerated trucks that require a lot of available energy for cooling the cargo space, etc. According to a preferred embodiment, the method implemented by the control system according to the invention takes place to an auxiliary system in the form of an air compressor. When energy is supplied to the air compressor, it can be used to compress air to the vehicle's Air System in connection with the air compressor, and also to the vehicle's braking system. In a so-called regeneration of the air compressor, the compressor's desiccant is dried, the purpose of which is to dry the air coming from the activated compressor.

Such regeneration does not require energy from the engine, but takes place by using already compressed air, which is taken from a tank. The tank forms an air reservoir adjacent to the compressor and the APS. This can therefore take place before an excess of energy has been established. Thus, the regeneration cycles can be optimized. The energy supply to the air compressor can also be used to activate the compressor. In the control algorithm for the method according to this preferred application, there may also be a priority order of how this energy is to benefit the compressor. For example, when there is a large excess of available energy, regeneration of the compressor air can be prioritized and after completion of regeneration, the compressor can be activated. It is therefore appropriate to know when there will be surplus energy to have had time to complete the regeneration before this occurs or to know how long the period is during which there will be surplus energy to be able to prioritize so that there can first be a regeneration and then a supply of energy during this period.

A vehicle's air compressor can operate at different pressure intervals, which can be at different pressure levels. The pressure intervals can also be such that they overlap each other.

The control algorithm according to this embodiment allows the compressor to operate within different pressure ranges which can be, for example, 8.5-9.5 bar, 8.7-10.0 bar, and 11.0-12.0 bar, respectively. The second pressure range corresponds to normal control, which means that this pressure range is usually used, but the limits (also for the other two intervals) may change during operation.

The lowest interval is determined on the basis of safety reasons, which should be an interval at which the vehicle can brake without there being a safety risk in using the pressure in this interval. According to one embodiment, the regulation of the air compressor is effected by letting the energy parameters control which pressure range is to be used, i.e. let the predicted supply of energy, and when it occurs, be crucial.

This can be done simply by the following method steps: - determine available energy; - determine which pressure range is relevant depending on the available energy, and - decide whether the air compressor is to be activated, deactivated or whether regeneration is to take place.

Thus, according to the control system and method of the present invention, the control unit is adapted to determine a pressure range, among several different pressure ranges regarding the pressure in one or more pressure vessels adjacent to the air compressor, depending on available energy and the time when energy is available. And then to activate or regenerate the air compressor depending on the pressure range determined.

The present invention is not limited to the preferred embodiments described above. Various alternatives, modifications and equivalents can be used.

The above-mentioned embodiments are therefore not to be construed as limiting the scope of the invention, as defined by the appended claims.

Claims (15)

14 Patent claims A control system (2) for a vehicle (4), the control system (2) comprising an analysis unit (6) arranged in connection with a cruise control system (8) for the vehicle, and at least one control unit (10) arranged in connection with at least one auxiliary system (12) for the vehicle (4), characterized in that the analysis unit (6) is adapted to analyze a future speed (7) of the vehicle predicted by the cruise control system (8) with respect to available energy, using a predetermined analysis algorithm , and generating an energy indicating signal (14) depending on the result of the analysis, the energy indicating signal (14) comprising at least a first energy parameter adapted to indicate the presence of available energy. The wing system according to claim 1, wherein said analysis algorithm is adapted to analyze the predicted speed and determine the first energy parameter so as to indicate that energy is available provided that: - the predicted speed of the vehicle increases or is constant, and - no fuel injection takes place . The control system according to any one of claims 1 or 2, wherein said analysis algorithm is adapted to analyze the predicted velocity and determine a second energy parameter so as to indicate the start point and end point where the energy is available. The control system according to any one of claims 1-3, wherein said energy indication signal is adapted to be applied to said control unit (10), wherein the control unit is adapted to control the supply of energy to an energy storage means for the auxiliary system, with a control signal (15), depending on at least said first energy parameter and a predetermined control algorithm. The control system according to any one of claims 1-4, wherein said control unit is adapted to control the energy supply (16), with a control signal (15), for an auxiliary system which is an air compressor. The control system of claim 5, wherein said control unit is adapted to determine a pressure range, among several different pressure ranges regarding the pressure in one or more reservoirs adjacent to the air compressor, depending on available energy and the time when the energy is available, and to activate or regenerate the air compressor depending thereon. The control system according to any one of claims 1-4, wherein said control unit is adapted to control the power supply (16), with a control signal (15), for an auxiliary system which is an AC compressor. A method for a control system (2) in a vehicle (4), wherein the control system (2) comprises an analysis unit (6) arranged in connection with a cruise control system (8) for the vehicle, and at least one control unit (10) arranged in connection to at least one auxiliary system (12) for the vehicle (4), characterized in that the method comprises the steps of: - analyzing a future speed of the vehicle predicted by the cruise control system (8) with respect to available energy, using a predetermined analysis algorithm; generating an energy indicating signal (14) depending on the result of the analysis, the energy indicating signal (14) comprising at least a first energy parameter adapted to indicate the presence of available energy. The method of claim 8, wherein said analysis algorithm is adapted to analyze the predicted speed and determine the first energy parameter so as to indicate that energy is available provided that: - the predicted speed of the vehicle increases or is constant, and - no fuel injection takes place . The method of any of claims 8 or 9, wherein said analysis algorithm is adapted to analyze the predicted rate and determine a second energy parameter so as to indicate the start point and end point where the energy is available. The method of any of claims 8-10, wherein said energy indication signal is adapted to be applied to said control unit, the control unit being adapted to control the supply of energy to an energy storage means for the auxiliary system depending on at least said first energy parameter and a predetermined control algorithm. The method according to any of claims 8-11, wherein said control unit is adapted to control the energy supply of an auxiliary system which is an air compressor. The method of claim 12, wherein said control unit is adapted to determine a pressure range, among several different pressure ranges regarding the pressure in one or more reservoirs adjacent to the air compressor, depending on available energy and the time when the energy is available, and to activate or regenerate the air compressor depending thereon. The method of any of claims 8-11, wherein said control unit is adapted to control the power supply of an auxiliary system which is an AC compressor. Computer software product adapted to implement the method according to any one of claims 8-14.