SE534647C2 - Cruise control for a motor vehicle and a method for controlling it - Google Patents

Abstract

The present invention relates to a cruise control for a motor vehicle, which motor vehicle (1) comprises a driveline arranged to assume different driveline gears for driving the motor vehicle (1), the driveline comprising at least one engine (10) and at least one gearbox (20); wherein the cruise control (40) is arranged to be controlled based on a first parameter RF defined and a second driving force F and the first as a difference between a first driving force FD,, Max driving force F Max is a maximum driving force for the motor vehicle (1) available on a current driveline transmission and the second driving force F Dr is a current driving resistance of the motor vehicle (1). Furthermore, the invention relates to a method, a date program and a date program product; and a motor vehicle comprising such a cruise control. (Figure 9)

Description

534 B11? is to provide a cruise control which helps to reduce the fuel consumption of the motor vehicle compared to cruise control according to the prior art. A further object of the present invention is to provide an alternative cruise control for motor vehicles.

According to one aspect of the invention, the above-mentioned object is achieved with a cruise control for a motor vehicle, which motor vehicle comprises a driveline arranged to assume different driveline gears for driving the motor vehicle, the driveline comprising at least one engine and at least one gearbox; wherein the cruise control is arranged to be controlled based on a thirst parameter R defined as a difference between a first driving force F Mu, and a second driving force fl Fn,, and the first driving force F Max is a maximum driving force for the motor vehicle available at a current driveline transmission and the second driving force FD, is a current driving resistance of the motor vehicle.

According to an embodiment of the invention, the cruise control is further arranged to: operate with an automatic distance control to a motor vehicle in front, the automatic distance control means that the motor vehicle is accelerated, decelerated or maintains a constant speed to maintain a given distance T; D to the motor vehicle in front, so that a current distance T ,,; D, between the motor vehicle and the motor vehicle in front is allowed to deviate from the given distance T; D based on the first parameter R ,, and / or a second parameter R m., The second parameter R m, being fi nier as the ratio between the first parameter R m. and a normalization factor.

According to another embodiment of the invention, the cruise control is further arranged to: operate in a first mode in which an automatic distance control to a motor vehicle in front takes place, whereby the automatic distance control means that the motor vehicle is accelerated, decelerated or maintains a constant speed. ; D to the motor vehicle in front; and operate in a second mode in which a current distance Tp; D, between the motor vehicle and the motor vehicle in front is allowed to deviate from the given distance T; D based on the first parameter R ,, and / or the second parameter RACC. 53-5 B47 Further embodiments of the above-mentioned cruise control are found in the dependent claims attached to the cruise control.

Furthermore, the invention relates to a motor vehicle, such as a car, truck or bus, comprising at least one cruise control as above.

According to another aspect of the invention, the above-mentioned object is achieved with a method for controlling a faith holder for a motor vehicle, which motor vehicle comprises a driveline arranged to assume different driveline gears for driving the motor vehicle, the driveline comprising at least one engine and at least one gearbox; the method comprising the steps of: - determining a first pair of networks R defined as a difference between a first driving force F Mm and a second driving force fi FD,, the first driving force fi an F M0, is a maximum driving force for the motor vehicle l available on a current driveline gear ratio and the second driving force 1 ~ ',,, is a current driving resistance for the motor vehicle; and - controlling the cruise control based on the first parameter R ,, - and / or a second parameter R m., the second parameter R M, being fi denied as the ratio between the first parameter RF and a normalization factor.

According to an embodiment of the method above, the cruise control is further arranged to operate with an automatic distance control to a motor vehicle in front, the distance control means that the motor vehicle is accelerated, decelerated or maintains a constant speed to maintain a given distance T; D to the motor vehicle in front; wherein the method further comprises the step of: - allowing a current distance TP; D, between the motor vehicle and the motor vehicle in front deviates from the given distance T; D based on the first parameter R ,, - and / or the second parameter R Acc 'The invention also relates to a computer program and a computer program product related to the above method. 534 E47 The present invention provides a cruise control and a method which utilize information about the maximum available driving force and driving resistance of the motor vehicle. Thus, the speed of the motor vehicle, by means of a cruise control according to the invention, can be set so that the fuel consumption can be reduced for the motor vehicle compared with the use of a cruise control according to the prior art.

In addition, the invention provides an adaptive cruise control which uses information about the motor vehicle's maximum available driving force and driving resistance to determine a current distance to a motor vehicle in front, which can be varied in relation to a given desired distance between the vehicles depending on the driving force and driving resistance. Even in this case, the fuel consumption of the motor vehicle can be reduced.

Additional advantages and applications of a cruise control and a method according to the invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed description of the present invention, embodiments of the invention will be described with reference to the accompanying figures, in which: Figure 1 schematically shows a part of a driveline for a motor vehicle; Figure 2 shows a graph of maximum engine torque as a function of engine speed for an engine; Figure 3 shows a graph of a mapping function which translates values of a motor vehicle's acceleration capacity into virtual accelerator pedal values; Figure 4 shows a graph of a mapping function which translates values of a motor vehicle's acceleration capacity into virtual accelerator pedal values with respect to a cruise control setting; Figure 5 shows when a current distance between a motor vehicle and a motor vehicle in front is substantially equal to a given distance; Figure 6 shows when a current distance is greater than a given distance; Figure 7 shows when a current distance is less than a given distance; Figure 8 shows a fate diagram for calculating acceleration capacity to be used in a cruise control application; figure 9 shows a fate diagram for controlling an adaptive cruise control according to the invention; 534 E47 - figure 10 shows a condition diagram for an adaptive cruise control according to the invention; figure 1 1 shows a control unit to be included in a motor vehicle according to the invention; Figure 12 shows how a first driving force and a second driving force act on a motor vehicle on an uphill slope; and - fi Figure 13 shows how a first drive fi and a second drive fl act on a motor vehicle on a level surface.

Detailed Description of the Invention A cruise control 40 for a motor vehicle 1 according to the present invention is arranged to be controlled based on a first parameter R ,,, the first parameter R ,, being defined as a difference between a first driving force fi F Mm and a second driving force E , the first driving force FMG, being a maximum driving force for the motor vehicle 1 available on a current driveline transmission and the second driving force FD, being a current driving resistance of the motor vehicle 1.

More specifically, the first parameter R, _. is interpreted as a difference between a first driving force F Ma, which represents the maximum sum of the available driving forces that "help" to propel the motor vehicle 1 in its direction of travel on the current driveline gear ratio, i.e. the available driving force of the motor vehicle 1, minus a second driving force F 1, which is the sum of the driving forces which act on the motor vehicle 1 in its direction of travel or the direction opposite to the direction of travel, and is the current driving resistance of the motor vehicle 1.

For a deeper understanding of the invention, the following is a brief description of the driveline of a motor vehicle 1 and the torque curve of the engine 10 of a motor vehicle 1 with reference to Figures 1 and 2, respectively.

Figure 1 schematically shows parts of a driveline ßr a motor vehicle 1. The driveline comprises a motor 10, which in this case is mechanically connected by means of a shaft to a first end of a gearbox 20 via a coupling device 40. Furthermore, the gearbox 20 is at its second end mechanically connected to a differential gear 30 arranged at a rear axle by means of a PTO shaft 50. The rear axle in turn comprises the left and right drive shafts 60, respectively, which drive the drive wheels of the motor vehicle 1 (not shown in the figure). 5234 Bil? With this well-known arrangement, the mechanical work of the motor 10 is transmitted via a number of transmission devices, such as clutch device 40, gearbox 20, cardan shaft 50, differential gear 30 and drive shafts 60, to the drive wheels for driving the motor vehicle 1.

The gearbox 20 is a transmission device which has a number of forward gears for propelling the motor vehicle 1 and usually also one or two reverse gears. The number of forward gears varies, but 12 forward gears are e.g. commonly found in modern trucks.

The gear ratio of a driveline can vary, so the driveline can assume different driveline gears (i.e. different gear configurations). The different gears depend on e.g. on the currently engaged gear in the gearbox 20 and the differential gear 30 gear. Furthermore, it can be stated that there are drivelines which can assume a number of different discrete driveline gears and drivelines which have continuous gear, for example automatic gearboxes 20 with so-called converters or other types of gearboxes 20 with continuously variable transmission.

In addition, most motor vehicles have a control system comprising one or more electronic control units 110 (also called "Electronic Control Unit", ECU). The purpose of said control system is to control / regulate one or more functions in the motor vehicle 1 by means of, for example, one or more actuators, which may be related to different functions in the motor vehicle 1, such as motor control, shifting, cruise control, suspension configuration, etc., said control system using of a number of different parameters, such as current engine speed, current accelerator pedal position, current engine torque, and data from various sensors to control the various functions of the motor vehicle 1.

Furthermore, Figure 2 shows a graph of a maximum torque curve for a motor 10 as a function of the motor speed for motor 10. The points P1-P3 in the graph show different breakpoints for the maximum torque curve. The graph also shows an example of a situation when an engine 10 has an engine quarter RI with an engine torque M1, so the engine 10 in this situation operates below its maximum torque curve with a difference equal to M2-M1, as illustrated by the arrow in Figure 2 Maximum driving force fi means the driving force which, via the driveline, drives the motor vehicle 1 in its direction of travel if the motor 10 were to act on its maximum torque curve at a current engine speed. 534 E11? With a basic understanding of the driveline and engine torque curve 10 as described above, the first driving force F m, according to an embodiment of the invention defined as: FMax = Engïul x iTOI where Engm denotes an available torque at maximum engine torque for engine 10 at current engine speed, and in , denotes a current driveline gear ratio for the driveline up to and including the drive wheels including the wheel radius of the motor vehicle 1.

According to another embodiment, the second driving force is FD, a driving force fi which can assume a positive (eg uphill) or negative (eg downhill) value and act in the opposite direction to the direction of travel of the motor vehicle 1. Figures 12 and 13, respectively, show how the first F Ma, and second FD, driving force acts on a motor vehicle 1 on an uphill slope and on a flat surface, respectively. The second driving force FD, depends on one or fl your parameters belonging to the group comprising: luñ resistance, rolling resistance, friction in said driveline, moment of inertia, mass of said motor vehicle 1, road inclination, i.e. depends on the factors that affect the current driving resistance. However, topographical map data and the like can also be used in determining the second driving force F ", since, for example, the road slope can be determined from relevant map data.

More specifically, the second driving force FD, according to an embodiment of the invention defined as: Fi »= F / e /" mxa (2), where FR, denotes a current actual driving force for the engine 10, m the mass and a the acceleration of the motor vehicle 1. The actual driving force of the engine 10 is in the example in Figure 2 equal to M1.

In the most fall cases, the second driving force FU, will be the driving force fi that varies the most because e.g. the influence of the road slope is included as a parameter in the second driving force F ,,,. 534 E47 However, the first driving force FM "will also vary as the gear ratio of the driveline varies depending on such factors as the current gear ratio of the gearbox 20, the wheel radius of the motor vehicle 1, variations of the maximum torque curve of the engine 10, and so on.

According to a further embodiment of the invention, the first parameter is determined according to: RF = FMax _ Fl »i.e. the first parameter R, is defined as a difference according to equation (3) and will assume a negative value, a positive value or the value zero. If the difference is negative, it means that the motor vehicle 1 cannot accelerate on the current driveline gear ratio, i.e. the motor vehicle 1 is in a power deficit and will lose speed (ie decelerate), if the difference is equal to zero it means that the motor vehicle 1 is in a state of power equilibrium, which means that the motor vehicle 1 can maintain the current speed but not accelerate up to a higher speed; and finally, if the difference is positive, it means that the motor vehicle 1 has the possibility to accelerate, at least if the motor 10 were to act on its maximum torque curve for a given engine speed, as shown in Figure 2, i.e. the motor vehicle 1 has a surplus of power.

The first parameter R F gives an absolute measure of the current driving capacity / acceleration capacity of the motor vehicle 1 because it is related to the current characteristics and driving situation of the motor vehicle 1, which sometimes means that in order for the first parameter R should be useful, the first parameter R ,, should be related to said characteristics and driving situation. Examples of properties are vehicle weight, engine power, driveline configuration; and examples of driving situations are road slope and road surface. Since the first parameter RF is an absolute measure, e.g. a value of R ,, = 10000 N give a large acceleration capacity of a motor vehicle 1 which has a vehicle weight of 1000 kg and a very small acceleration capacity of a motor vehicle 1 which has a vehicle weight of 100000 kg.

A normalization of the difference according to equation (3) with respect to the motor vehicle 1's currently available propulsion capacity ger on the other hand gives a relative measure of a motor vehicle 1's current acceleration capacity (acceleration can of course also be derived from the first 534 Bil? Parameter RF using the relationship between acceleration and kra according to the laws of physics, as will be appreciated by those skilled in the art), which is to be understood as the ability of the motor vehicle 1 to accelerate. Thereby a dimensionless unit is obtained containing information about the motor power of the motor vehicle 1, the road inclination, rolling resistance, wind resistance, etc.

The advantage of a relative measure as above is that a value is obtained which indicates how much of the available engine power will be required to be able to accelerate the motor vehicle 1. This in turn means that said value can advantageously be used directly or indirectly in various applications related to various functions, such as control strategies for, for example, gear selection, generator operation, air compressor operation, etc. If the calculation of R m. Gives the result that the engine power of the motor vehicle l will not be sufficient to accelerate the motor vehicle I, the control system may try to “manage” the resources that use energy (eg lu fi compressor, generator, etc.) while the control system attempts to run the engine 10 at an engine speed that provides maximum driving force. This means that the control system tries to use as much as possible of the engine l0 torque to drive the motor vehicle 1 instead of e.g. fill the air tanks with air because the system strives to do this in situations where the system has the opportunity to get energy "for free", e.g. when the motor vehicle l engine brakes on downhill slopes. It will therefore be appreciated that said parameter is useful in many different functions of a motor vehicle 1 and will in the following description be referred to as a second parameter R Au.

Thus, a further embodiment of the invention relates to a cruise control 40 arranged to be controlled based on a second parameter R Ace, which in turn is based on the first parameter R

The second parameter R Ace represents an acceleration capacity of a motor vehicle 1, which is determined as a ratio between the first parameter R, and a normalization factor. In a preferred embodiment, the second parameter is determined according to: RACC = F Max _ E »___ Iflf Max F Max (4), where the term in the denominator is a normalization factor, the motor vehicle l having an acceleration surplus of R ACE> 0, an acceleration deficit of RACL . <0 and a 534 E11? l0 acceleration equilibrium of R m. = 0. Furthermore, if R m.> l, all motor power can be used to accelerate the motor vehicle l, whereby the motor vehicle l increases in speed without the need to supply power from the engine l0 (for example in case of steep descents).

As mentioned above, the first R or other R Aw parameters can also be used to determine a virtual accelerator pedal value. In this context, the term virtual accelerator pedal value is understood to mean a theoretically calculated value which can be, and usually is, a lower value than the actual accelerator pedal value, the latter value being the actual value the accelerator pedal assumes when a driver depresses the accelerator pedal when driving the motor vehicle .

If the second parameter R m. Is used to calculate such a virtual accelerator pedal value, this can be done by means of a mapping function as shown in the graph in Figure 3, where virtual accelerator pedal values (y-axis), Pv, are shown as a function of the second parameter R m. . (x-axis) representing the acceleration capacity of the motor vehicle l.

Figure 3 shows how the virtual accelerator pedal value with said mapping function is translated to 100%, which corresponds to full throttle, when the second parameter R m. Assumes a value less than 0, and is translated to 0%, which corresponds to no gas, when RACL assumes a value greater than 1. Such a mapping of the second parameter R m means that the virtual accelerator pedal value is translated to 100% at power balance and power deficit, ie. when R Au. 5 0, and somewhere between 0-100% when the motor vehicle 1 has a large excess (in Figure 3, the function is linear in this range).

When the entire engine power can be used to accelerate the motor vehicle 1, i.e. when R Aw = 1, the accelerator pedal value is translated to 0%, and in such a situation an application may be to try to mimic an accelerator pedal movement that a real driver has when he / she drives economically and wants to keep a constant speed, e.g. releases the gas on the crest and downhill slopes, as well as gases at entrances into slopes and in the slopes. Thus, a real driver is modeled with a virtual one according to this application. It is therefore understood that the virtual accelerator pedal value can be used in a variety of applications which depend on an accelerator pedal value, such as modeling a virtual driver to give driver tips, steering the unit, indicating driver tips, and so on. Furthermore, it should be understood that the virtual accelerator pedal value can either be used as the only input parameter in said applications or in combination with other input parameters, such as for example the actual accelerator pedal value. 534 B47 ll Figure 4 shows an example of a mapping function of a virtual accelerator pedal value using the first R 1 or second R m. Parameter in a cruise control 40 according to the invention. The y-axis represents permissible values for a virtual accelerator pedal and the x-axis represents a difference between a desired locked speed of the cruise control (i.e. the set desired speed of the cruise control) and the current actual speed of the motor vehicle 1.

This difference between the two speeds will define permissible values that the virtual accelerator pedal may assume, and between these extreme values the virtual accelerator pedal value will be determined by the second parameter R (for example by means of a mapping function Ace shown in figure 3). For example, when driving with cruise control, the control system knows the speed at which the driver wants the motor vehicle 1 to run and therefore the deviation (offset) from Vse can be taken into account, where V86 is the desired speed corresponding to an offset value of 0 in Figure 4. If the speed drops below Vse, the freedom of movement of the pedal value decreases and the pedal value is forced towards the maximum value (Max in figure 4). Correspondingly, if the speed increases over VM, the freedom of movement decreases in this case as well and the pedal value is forced towards the minimum value (Min in Figure 4) in order to keep the motor vehicle 1 at the desired speed VSM.

In such an embodiment of the invention, it means that the second parameter R m. Will be an input parameter in the accelerator pedal calculation coupled to a cruise control application when the system tries to maintain a constant speed on the motor vehicle 1 due to different driving conditions, Lex. road slope, and the limitations of the accelerator pedal value indicate whether the system wants to increase / decrease in speed. In an application such as this, the system attempts to model a real driver with a virtual driver, where the real driver tries to maintain a constant speed, which means that if the motor vehicle 1 is above or below the target speed, this is compensated by decreasing or increasing the speed. If, on the other hand, the motor vehicle 1 is at the desired speed, then it is environmental factors, such as road slope, wind resistance, vehicle weight, etc. which determine the accelerator pedal value (R m, in the model).

As previously described, it has become increasingly common with so-called adaptive cruise control 40 arranged in motor vehicles 1. The first R or the second R m, the parameter can also be used to control such a type of cruise control 40. 534 E47 12 For this reason, an embodiment of the invention relates to a cruise control 40, which is further arranged to operate with an automatic distance control to a motor vehicle in front 30 The automatic distance control means that the motor vehicle l is accelerated, decelerated or maintains a constant speed to maintain a given distance T; D to the front motor vehicle 30 either by accelerating the motor vehicle 1 by means of its engine 10 or decelerating it by engine braking or by using brakes, such as wheel brakes and / or auxiliary brakes, and so on. In addition, the adaptive cruise control 40 is arranged so that the current distance T D, between the motor vehicle 1 and the forward motor vehicle 30 is allowed to deviate from the given distance T; D based on the first parameter R ,, and / or the second parameter R ACC 'By the term "permitted" is meant in this context that the cruise control 40, depending on the first R ,, or second R m. Parameter, allows the current distance T, of the motor vehicle 1, ; D, to the forward motor vehicle 30 occasionally deviate from the given distance T; D before the flag holder 40, for example, decelerates or accelerates the motor vehicle 1 to the current distance T D, shall be equal to the given distance T; D, whereby this permissible deviation can be in time or distance. For example, assuming that the front motor vehicle 30 maintains a constant speed (eg with a conventional cruise control 40 according to the prior art), the motor vehicle 1 can be driven on a uphill slope to allow the distance between the vehicles to increase (allow the current distance T ,; D,> given distance T; D) and then in a subsequent downhill slope "roll over" the existing motor vehicle 30 (allow the current distance T,; D, <given distance T; D) to be "freewheeling" on a flat road (driveline disconnected ) or that the engine 10 is towed (engine brake) for a long time before the cruise control 40 starts accelerating the motor vehicle 1 to the current distance T1; D, shall be equal to the given distance T; D. Thus, additional fuel in the motor vehicle 1 can be saved.

According to an embodiment of the invention, a current distance T D, assume a value that is greater than a minimum value and / or less than a maximum value. The maximum and minimum value can depend on a number of different factors and can be considered to constitute the outer limits of a permissible distance variation between the current distance T 1; D, between the motor vehicle 1 and the forward motor vehicle 30. For example, it is not desirable for the motor vehicle 1 to be so close to the front motor vehicle 30 that it becomes dangerous to drive or is perceived as "nasty" to the driver. 5311 B47 13 If the motor vehicle l drives at high speed, the minimum distance will usually be greater because a certain distance at low speed means a shorter "time slot" if the same distance were to be used at a higher speed. Furthermore, it is also not desirable that a current distance TP; The DP of the fi stationary motor vehicle 30 is so large that the distance detection (eg radar) risks losing contact with the vehicle in front 30.

In addition, the maximum and minimum value may depend on a detected acceleration capacity of the front motor vehicle, which could mean, for example, small allowable distance variations of the allowable distance if the advancing motor vehicle 30 has greater acceleration capacity (and / or propulsion capacity) than the motor vehicle 1 and greater allowable distances. if the motor vehicle l has a greater acceleration capacity (and / or propulsion capacity) than the front motor vehicle 30. Furthermore, the distance variation may depend on the prevailing traffic situation so that if the motor vehicle 1 is driven in heavy traffic, the permissible distance variation may be reduced so as not to cause irritation. Variations in the speed of the motor vehicle 1 also mean that the vehicle behind must more or less vary / adapt its speed to the speed of the motor vehicle 1.

According to another embodiment of a cruise control 40 according to the invention, it is further arranged to operate in a first mode C1 in which an automatic distance control to a stationary motor vehicle 30 takes place. The automatic distance control means, as previously mentioned, that the motor vehicle 1 is accelerated, decelerated or maintains a constant speed to maintain a given distance T; D to the front motor vehicle 30. In addition, the adaptive cruise control 40 is arranged to operate in a second mode C2 in which a current distance TP; D, between the motor vehicle 1 and the front motor vehicle 30 is allowed to deviate from the given distance T; D based on the first parameter R ,, and / or the second parameter R Au ..

The cruise control 40, which is arranged to operate in a first C1 or second C2 mode, may further be arranged to, if the cruise control 40 operates in said first mode C1, switch to operate in said second mode C2 if the first parameter R / or the second parameter R m. assumes a value greater or less than zero. In addition, if the cruise control 40 operates in said second mode C2, switch to operate in said first mode C1 if the first parameter R1 and / or the second parameter RAC assumes a value which is zero. 534 84? In a practical application of a cruise control 40 according to the invention, a tolerance value T can be used, which means that an interval around zero, i.e. 0 +/- T is defined, the first R, _. or the second R m. parameter is considered to be zero in a cruise control application if said parameters assume a value within the range. The tolerance value T can preferably be obtained by calibration and will vary for different types of motor vehicles 1.

The choice of value of the tolerance value T will affect how often the motor vehicle 1 will vary in speed. If the tolerance value T is large, the distance set by the driver as the desired distance to the motor vehicle 30 in front will be maintained more often and the distance variation to the in-train motor vehicle 30 will for this reason be smaller. A smaller tolerance value T therefore means that the control system of the motor vehicle 1 allows deviations from the given distance T; D on more occasions. When selecting a large tolerance value T, the given distance T is prioritized; D which the driver has set and a small tolerance value means that reduced fuel consumption is prioritized because the control system will then vary the speed of the motor vehicle l more often depending on the driving resistance of the motor vehicle l. Thus, the tolerance value T can be used as an input parameter for controlling e.g. experienced driving experience ("comfort parameter"), fuel consumption, etc.

By distance is meant in this description a time distance or a distance between a motor vehicle 1 and a motor vehicle 30 in front, unless otherwise stated. With a current distance TP; D, between the motor vehicle I and the motor vehicle 30 in front means the instantaneous distance between them; and at a given distance T; D between the motor vehicle 1 and the front motor vehicle 30 refers to the distance that the cruise control 40 is set to try to maintain between the motor vehicle 1 and the front motor vehicle 30.

According to an embodiment of an adaptive cruise control 40 according to the invention, the current distance TP is allowed; D, be greater than the given distance T; D if the first R 1, or second parameter Rim, assumes a value less than zero. According to another embodiment of the invention, the current distance TP is allowed; D, be less than the given distance T; D if the first R, _. or the second parameter R m. assumes a value greater than zero. 534 G4? In a preferred embodiment of the invention, the cruise control 40 is arranged to be a combination of the two embodiments above, so that the current distance TP; D, is allowed to be greater or less than the given distance T; D depending on the value of the first R, .- and / or the second parameter R me.

Figures 5-7 show examples of how an adaptive cruise control 40 according to the invention can function where Figure 5 shows how a motor vehicle 1 maintains a given distance T; D to the nearest motor vehicle 30, i.e. the current distance TP; Dp between the motor vehicle 1 and the nearest motor vehicle 30 is equal to the given distance T; D e ersom if the value of the first R F and / or the second R m. The pair parameter is zero, e.g. due to the surface / road being flat. In Figure 6, the current distance T ,, is allowed; D, be greater than the given distance T; D since the first R, _. and / or the second R m. the parameter assumes a value less than zero, e.g. in a situation such as in an uphill slope and the motor vehicle in front 30 maintains a constant speed as shown in Figure 6. Contrary to the situation shown in Figure 6, the current distance TP is allowed; D, be less than the given distance T; Figure 7 because the value of the first R ,, and / or the second R m. Parameter assumes a value greater than zero, e.g. when the motor vehicle 1 is located on a downhill slope.

From the above, it is sometimes or often advantageous from a fuel consumption point of view to increase the distance between the vehicles instead of slavishly "following" the motor vehicle in front 30, for example on an uphill slope. In addition, it is at least possible to make up for an increased current distance TP; D, following an uphill slope by the cruise control 40 allowing the current distance TP; D ,, is less than the given distance T; Di a subsequent downhill (fi gur 7), e.g. by using the brakes later than what happens with an adaptive cruise control according to the prior art. Thus, additional fuel in the motor vehicle 1 can be saved.

It should therefore be understood that it is advantageous that a current distance T ,,; D ,, is allowed to be varied in relation to a given distance T; D depending on the first R ,, and / or the second R Act parameter in an adaptive cruise control 40, which the inventor has discovered. 534 E47 16 In more detail, the control of a cruise control 40 according to the invention can take place, for example, according to the fate diagrams in Figs. 8 and 9, respectively. In Fig. 8, in this example, the second parameter R m is calculated, i.e. the acceleration capacity of the motor vehicle 1 as follows: 1. Reading of sensors and other information and / or data, such as, for example, the current currently engaged, the given cruise control speed, etc .; 2. Reading of vehicle data, such as, for example, the maximum available engine number for the motor vehicle 1, the total gear ratio of the motor vehicle 1, etc .; 3. Calculation of the driving resistance of the motor vehicle 1, which can be done by means of parameters such as current engine torque, road inclination, motor vehicle 1 acceleration, etc .; 4. Calculation of the maximum driving force of the motor vehicle 1, which can be done by using parameters, such as the maximum available engine torque, the total gear ratio of the motor vehicle 1, etc .; and 5. Calculation of the acceleration capacity R m, for the motor vehicle 1 according to any of the embodiments described above.

Given the calculation in the fate diagram in Figure 8, an adaptive cruise control 40 according to the invention can be controlled according to the fate diagram in Figure 9 as follows: 6. Determine in which mode (C1 or C2) the cruise control 40 should operate in the given calculation above where the cruise control 40 operates in the first mode Cl om R Au. is zero, and in the second mode C2 if R m. is separated from zero; 7. If the cruise control 40 operates in the first mode C1, the cruise control 40 strives to maintain the current distance TP; D, between the vehicles the same as the given distance T; D, i.e. the holder 40 does not allow deviation from the given distance in this mode; and 8. If the cruise control operates in the second mode C2, the current distance TP is allowed; D ,, deviate from the given distance T; D depending on the value of the acceleration capacity R m, where: 534 B47 17 8a. the current distance TP; D ,, is allowed to be greater than the given distance T; D if the acceleration capacity R m, is less than zero, and 8b. the current distance TP; Dp is allowed to be less than the given distance T; D if the acceleration capacity R is greater than zero.

Figure 10 shows a state diagram of an adaptive cruise control 40 according to the invention, in which conditions for when the transition takes place between the two respective modes C1 and CZ in which the adaptive cruise control 40 operates are illustrated.

Preferably, a cruise control 40 according to the invention is mounted, alternatively implemented, in a motor vehicle 1 comprising one or fl your control units 1 10, which may for example be an electronic control unit (ECU) arranged to control one or funktioner your functions in the motor vehicle 1, e.g. shifting, engine speed, braking, acceleration. Furthermore, the control unit 110 is arranged to control the cruise control 40 by calculating the first R 1 and / or the second R 1 parameter in real time.

Figure 10 schematically shows a control unit 1 described above. The control unit 11 may comprise a calculation unit 11, 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 calculation unit 11 is connected to a memory unit 112 arranged in the Control Unit 110, which provides the calculation unit 11, e.g. the stored program code and / or the stored data calculation unit ll 1 need to be able to perform calculations.

The calculation unit 1 1 1 is also arranged to store partial or final results of calculations in the memory unit 112.

Furthermore, the control unit 110 is provided with devices 113, 114, 115, 116 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 13, 116 may be detected as information and may be converted into signals which may be processed by the computing unit 111. These signals are then provided to the computing unit 11 The outputs 14, 115 for transmitting output signals are arranged to convert signals 534 B47 18 obtained from the computing unit 111 for creating output signals by e.g. modulate the signals, which can be transmitted to other parts of the system. One skilled in the art will appreciate that the above-mentioned computer may be the computing unit III and that the above-mentioned memory may be the memory unit 12.

Each of the connections to the devices for receiving and transmitting input and output signals, respectively, may be one or two 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. The connections 70, 80, 90, 100 in ñgur 1 may also be one or more of these cables, buses, or wireless connections.

The invention further relates to a method for controlling a cruise control 40 for a motor vehicle 1, which motor vehicle 1 comprises a driveline arranged to assume different driveline gears for driving the motor vehicle 1, the driveline comprising at least one engine 10 and at least one gearbox 20; the method comprising the steps of: determining a first parameter RF defined as a difference between a first driving force F Mu, and a second driving force F ,,,, the first driving force F Ma, being a maximum driving force for the motor vehicle 1 available on a current driveline gear ratio. and the second driving force FD, is a current driving resistance of the motor vehicle 1; and controlling the cruise control 40 based on the first pair R 1 and / or a second pair R Au, the second pair RAM being defined as the ratio between the first pair R 1 and a normalization factor.

In addition, the invention relates to a method as above, wherein the cruise control 40 is further arranged to operate with an automatic distance control to a motor vehicle in front 30, the distance control means that the motor vehicle 1 is accelerated, decelerated or maintains a constant speed to keep a given distance T; D to the front motor vehicle 30; further comprising the step of: allowing a current distance TP; D, between the motor vehicle 1 and the front motor vehicle 30 deviates from the given distance T; D based on the first R, and / or the second parameter R m ..

The person skilled in the art further understands that the method according to the invention can be modified so that it corresponds to the different embodiments of a cruise control 40 as above. 534 B47 19 As will be appreciated by those skilled in the art, a method of controlling a cruise control according to the present invention may also be implemented in a computer program, which when executed in a computer causes the computer to perform the method. The computer program is included in a computer readable medium of a computer program product, said computer readable medium consisting of a suitable memory, 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.

Finally, it should be understood that the present invention is not limited to the embodiments of the invention described above but relates to and encompasses all embodiments of the invention within the scope of the appended independent claims.

Claims (20)

A patent holder for a motor vehicle, which motor vehicle (1) comprises a driveline arranged to assume different driveline gears for driving the motor vehicle (1), the driveline comprising at least one engine (10) and at least one gearbox (20). ; characterized in that the cruise control (40) is arranged to be controlled based on a first parameter RF defined as a difference between a first driving force F Max and a second driving force FD, the first driving force F Mu, being a maximum driving force for the motor vehicle (1). available on a current driveline transmission and the other drivetrain fi an FD, is a current driving resistance of the motor vehicle (1). Cruise control according to claim 1, wherein the first driving force F Ma, is a driving force which, via the driveline, drives the motor vehicle (1) in its direction of travel at the current maximum available engine torque for the motor (10); and the second driving force F ,,, is a driving force fl which can assume a positive or a negative value and acts on the motor vehicle (1) in its direction of travel, which second driving force FU, depends on one or fl your parameters belonging to the group comprising: air resistance, rolling resistance, friction in said driveline, moments of inertia, topographic map data, road slope, and a mass for the motor vehicle (1). Cruise control according to claim 2, wherein the first driving force FM 'is defined as: F Ma, = Engm xim, wherein Engm denotes an available maximum motor torque for the motor (10) at current motor speed, and i,. ,,, denotes a current driveline transmission for the driveline up to and including the drive wheels including the wheel radius; and the second driving force E), they are denoted as: FD, = F R, - - m x a, where F 'denotes a current actual driving force for the engine (10), m a mass and a an acceleration for the motor vehicle (1). 534 B47 21 Cruise control according to any one of the preceding claims, wherein the first parameter R F is determined by the equation: R 1. FMux - FD,, wherein the motor vehicle (1) has a driving force om excess of R,> 0, a driving force deficit of R, <0 and a driving force fl iron weight of R ,, = o. The cruise control according to claim 1, wherein the cruise control (40) is controlled based on a second parameter R m, the second parameter R m. Being defined as the ratio between the first parameter R m and a non-analyzing factor. Cruise control according to claim 5, wherein the second parameter R m. Is determined by the 'F Max _ E »RI *' '° equation: R Au = _17- = F_-, wherein the motor vehicle (1) has an acceleration excess Max Max if R m,> 0, an acceleration deficit of R AW <0 and an acceleration equilibrium of RAcc = Cruise control according to claims 1-6, further arranged to: - operate with an automatic distance control to a motor vehicle in front (30), wherein the automatic distance control means that the motor vehicle (1) is accelerated, decelerated or maintains a constant speed to maintain a given distance (T; D) to the front motor vehicle (30), so that - a current distance (T ,,; Dp) between the motor vehicle (1) and the front motor vehicle (30) is allowed to deviate from the given distance (T; D) based on the first parameter R, _. and / or the second parameter R Ace ' Cruise control according to claims 1-6, further arranged to: - operate in a first mode (Cl) in which an automatic distance control to a motor vehicle in front (30) takes place, wherein the automatic distance control means that the motor vehicle (1) is accelerated, decelerated or maintains a constant speed to maintain a given distance (T; D) to the motor vehicle in front (30); and - operating in a second mode (C2) in which a current distance (T ,,; Dp) between the motor vehicle (I) and the remaining motor vehicle (30) is allowed to deviate from the given distance (T; D) based on 534 B47 22 the first parameter R ,, and / or the second parameter R m,. The cruise control according to claim 8, wherein the cruise control (40) is further arranged that the OIIII cruise control (40) operates in said first mode (C1), switching to operate in said second mode (C2) about the first parameter R1. and / or the second parameter R Au. assumes a value greater than or less than zero; and - the cruise control (40) operates in said second mode (C2), switching to operate in said first mode (C1) if the first parameter R1 and / or the second parameter Rm. assumes a value which is zero. Cruise control according to claim 9, wherein the cruise control (40) is further arranged to use a tolerance value Tmed with which an interval 0 +/- T is defined around zero, which first RF or second R m, parameter is considered to be zero in the cruise control (40) if the first R 1, or second R m, the parameter assumes a value in the range 0 +/- T, A cruise control according to claims 7-10, wherein the current distance (T ,,; Dp) is allowed to be greater than the given distance (T; D) but less than or equal to a maximum distance of the first parameter R, , and / or the second parameter R m. assumes a value less than zero, the maximum distance depending on one or more of the following factors: the motor vehicle's current speed, road safety, propulsion capacity and / or acceleration capacity of the motor vehicle in front (30), traffic situation, and experienced driving experience. Cruise control according to claims 7-11, wherein the current distance (T ,; DP) is allowed to be less than the given distance (T; D) but greater than or equal to a minimum distance if the first parameter RF and / or the second parameter R m. assumes a value greater than zero, which minimum distance depends on one or more of the following factors: the motor vehicle's current speed, road safety, propulsion capacity and / or acceleration capacity of the previous motor vehicle (30), traffic situation, and perceived driving experience. 534 Bil? 23 Cruise control according to claims 7-12, wherein the given distance (T; D) and the current distance (T ,,; Dp) are a time distance or a distance. Cruise control according to claims 7-13, wherein the forward motor vehicle (30) is the nearest forward motor vehicle. A motor vehicle (1), such as a car, truck or bus, comprising at least one cruise control (40) according to any one of claims 1-14. A motor vehicle (1) according to claim 15, further comprising a control unit (1 10), such as an electronic control unit (ECU), arranged to control one or more of your functions in the motor vehicle (1), such as shifting, engine speed, braking, acceleration, which control unit (110) is further arranged to control the cruise control (40) by calculating the first R 1 or the second R m. parameter in real time. A method of controlling a cruise control for a motor vehicle, the motor vehicle (1) comprising a diivine line adapted to assume different driveline gears for driving the motor vehicle (1), the driveline comprising at least one engine (10) and at least one gearbox (20); characterized by comprising the steps of: - determining a first parameter R ,, defined as a difference between a first driving force FMU, and a second driving force F} ,,, the first driving force F Max being a maximum driving force fi for the motor vehicle (1) available on a current driveline gear ratio and the second driving force FD, is a current driving resistance for the motor vehicle (1); and - controlling the cruise control (40) based on the first parameter R ,, and / or a second parameter R An, the second parameter R m, being defined as the ratio between the first parameter R, and a normalization factor. A method of controlling a cruise control according to claim 17, wherein the cruise control is further arranged to operate with an automatic distance control to a motor vehicle in front (30), the distance control means that the motor vehicle (1) is accelerated, decelerated or maintains a constant speed to maintain a given distance (T; D) to the existing motor vehicle (30); further comprising the step: 534 E47 24 - allowing a current distance (T ,,; D ,,) between the motor vehicle (1) and the remaining motor vehicle (30) to deviate from the given distance (T; D) based on the first parameter R , and / or the other parameter R m,. 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 claims 17-18. A computer program product comprising a computer readable medium and a computer program according to claim 19, wherein said computer program is included in said computer readable medium.