DE102014204763A1 - Cruise control system for controlling the speed of a vehicle - Google Patents

Abstract

The invention relates to a speed control system for controlling the speed of a vehicle to a predetermined target speed, wherein the control unit for reaching and holding the target speed sends corresponding drive signals to a drive unit or brake unit. According to the invention, when the cruise control is activated and the speed is manually reduced as a function of the difference between the actual speed and the target speed of the vehicle, the control unit sends either to a drive unit a signal for initiating a sailing operation or a signal for initiating a pushing operation. or to the brake unit, a signal for initiating a braking operation.

Description

The invention relates to a speed control system for controlling the speed of a vehicle according to the preamble of claim 1.

Motor vehicles with cruise control systems have long been known. Most currently available speed control systems regulate the speed of the motor vehicle to a predetermined desired speed by a corresponding intervention in the drive control or brake control. In addition to these cruise control systems, speed control systems (so-called ACC systems) that have been extended by a distance control can already be purchased from some manufacturers today. In principle, the well-known speed control, which complies with a certain predetermined target speed, extended by an additional distance control function, so that the use of such a distance-related speed control is possible even in dense highway and highway traffic.

Furthermore, it is already known that motor vehicles consume very little fuel when sailing, d. H. when they use their kinetic energy to roll as far as possible without the drag torque of the engine slowing them down. In an automatic vehicle, for example, this state can be established by engaging the selector lever in the "N" position, by a manual switch by pressing the clutch or by inserting the empty gear. Sailing is used relatively seldom in automatic vehicles, and practically never in manual controls. The cause is the complicated operation to achieve the sailing mode.

From the DE 10 2011 050 739 A1 A method for operating a vehicle in ACC operation is already known, wherein upon detection or approach to a preceding vehicle depending on the speed of the vehicle and the vehicle ahead, the current driving resistance of the vehicle, the distance between the two vehicles, and if necessary the acceleration of the vehicle and of the vehicle in front is determined and implemented for a consumption-optimal operating strategy (eg sailing operation, overrun operation or braking operation) for adjusting the setpoint distance. So z. B. then activates a sailing operation, if by the sailing operation, an approach of the vehicle to a desired distance without falling below a permissible minimum distance is possible.

It is an object of the present invention to provide a speed control system improved in terms of comfort and fuel economy, taking into account the possibility of initiating a sailing operation.

This object is achieved by a speed control system according to claim 1. Advantageous developments emerge from the dependent claims.

The invention is based on a basically known speed control system for regulating the speed of a vehicle to a predetermined setpoint speed, wherein the control unit transmits corresponding drive signals to a drive unit or brake unit for achieving and maintaining the setpoint speed. The cruise control system further comprises a control element, by means of which the setpoint speed can be increased or reduced manually by the driver when the cruise control is activated. Today controls are often designed so that in a short operation, an increase or reduction of the target speed in small steps, ie z. B. by 1 km / h is possible, and with a longer operation or greater pressure on the control element, an increase or reduction in larger speed interval steps (eg 10 km / h) takes place. The desired speed newly requested by the manual operation of the operating element is transmitted to the control unit and then the speed control is adjusted to the new target speed by inducing a delay.

The invention is based on the recognition that, with a manual reduction of the setpoint speed during a cruise control by a small amount of the driver, usually only a slight deceleration or deceleration of the vehicle is desired or expected. If, on the contrary, he asks for a greater reduction of the setpoint speed, he usually wishes or expects a faster or clearly perceptible reduction of the current speed to the new, lower setpoint speed.

Based on the above considerations, a cruise control system is proposed which is configured such that when the cruise control is activated and the speed is manually reduced, the control unit generates a signal or signal change depending on the difference between the actual speed and the desired speed of the vehicle which leads to the initiation of a sailing operation or a pushing operation of the drive unit, and / or to initiate a braking operation of the brake unit. Sailing operation of the drive unit can be triggered, for example, by sending a signal to initiate a sailing operation to the drive unit. or by a signal preventing the sailing operation withdrawn signal, that is no longer sent out. Thus, since coasting and coasting are mutually exclusive, coasting can be initiated by the control unit sending out a signal to prevent sailing, or by taking back a signal to start sailing. In other words, the control unit decides, as a function of the difference between the current actual speed and manually reduced setpoint speed, by which measures this reduction of the speed is to be converted to the setpoint speed and causes it by sending corresponding signals to the drive unit or brake unit ,

Advantageously, at a difference between the actual speed and the manually reduced setpoint speed, which is less than a predetermined first differential limit, the control unit sends to the drive unit a signal for initiating a sail operation or resumes a signal preventing the sail operation, whereupon the drive unit switches to a sailing mode in which the kinetic energy of the motor vehicle is used to roll as far as possible without the drag torque of the motor braking the motor vehicle. If, therefore, the setpoint speed is only reduced by a small amount (eg up to 10 km / h), the required speed reduction is carried out by targeted activation or activation of the sail operation.

A "sailing" of the vehicle can be achieved by releasing the operative connection between the drive machine and drive wheels, for example by an automatic actuation of the clutch or by an automatic insertion of the backlash. Likewise, the motor of the motor vehicle in the "sailing mode" can also be completely turned off.

Further advantageously, the control unit may initiate a coasting or braking operation at a difference between the actual speed and the manually reduced target speed that is not less than a predetermined first differential limit. In particular, the control unit may at a difference between the actual speed and the manually reduced target speed, which is not smaller than a predetermined first difference limit, but smaller than a predetermined second difference limit (at least not less than the predetermined first difference limit) to the drive unit transmits a signal to initiate or sustain a coasting operation, whereupon the drive unit shifts to (or maintains) the coasting mode. Pushing operation basically refers to the driving condition in which, when the force is not separated (eg when the clutch is not engaged), the engine is dragged through the vehicle, ie kept in rotary motion. So if the target speed is reduced by an amount greater than z. B. 10 km / h and less than z. B. 20 km / h, the required speed reduction is performed by a targeted activation or activation of the overrun operation.

Finally, the cruise control can also be developed such that the control unit at a difference between the actual speed and the manually reduced target speed, which is not less than a predetermined second difference limit, to the brake unit, a signal for initiating or maintaining a braking operation emits, whereby the brake unit causes a braking torque for deceleration of the vehicle or converts a received from the control unit delay or a received braking torque. If, therefore, the setpoint speed is reduced by a large amount (eg, more than 20 km / h), the required speed reduction is carried out by a targeted activation or activation of the braking operation, since such a large reduction of the setpoint speed is assumed is that the driver wants to reach this speed difference in an adequate amount of time.

Since current disturbances, the z. B. due to weather conditions or the road profile can affect each of the above-mentioned driving operations (sailing operation, overrun, braking operation) different degrees and thus the period of time within which the speed reduction can be achieved, is greatly influenced by the interference is in According to a further advantageous embodiment of the invention, the first and / or second difference limit can be variably predefined as a function of predetermined parameters, in particular as a function of detected disturbing influences which may have a current or immediate effect on the longitudinal acceleration. If z. B. detected that the vehicle is on a road with a slope or strong back prevails, the first and / or the second difference limit can be set lower than when the vehicle is on a road with a steep slope or strong headwind prevails. Likewise, the first and / or second difference limit can be correspondingly set differently depending on an operating mode of the vehicle selected by the driver (eg, sport, comfort, ECO mode).

The invention will now be explained in more detail with reference to the following embodiment. It shows

1 a structure of a speed control system, and

2 a simplified flowchart illustrating a control of the speed control implemented in the control unit with a manual reduction of the target speed during the active cruise control.

The 1 shows as a central element of a cruise control system in a vehicle for controlling the speed of a vehicle to a predetermined target speed, a control unit SE, which for reaching and holding a predetermined target speed vsoll corresponding drive signals "sail" or "thrust" to a drive unit AE or sends a drive signal "brake" to a brake unit. The speed control system further comprises an operating element B, by means of which, when the cruise control is activated, the setpoint speed vsoll can be at least manually reduced by the driver. The newly requested by the manual operation of the control element B reduced target speed vsoll is transmitted to the control unit SE and then the speed control by inducing a suitable deceleration event (sailing operation, coasting or braking operation) adapted to the new target speed vsoll.

To initiate a suitable deceleration event, the control unit SE receives further relevant data, which may affect the actual deceleration of the vehicle. The relevant data se may be so-called disturbance data or operating mode data.

A concrete procedure for initiating a suitable deceleration event with manual reduction of the target speed will now be explained with reference to the following explanations 2 shown.

The procedure begins in step 10 as soon as it is detected that the automatic cruise control GR of the vehicle is active. If this is the case, the next step is 20 depending on the control unit supplied to the disturbance data se a first difference limit D1 and a second difference limit D2 set.

Subsequently, in step 30 checks whether the driver has requested a reduction of the target speed vsoll. If, on actuation of the corresponding control element, it is detected that the new setpoint speed vsoll is less than the current speed vist (which should at least be almost identical to the original setpoint speed), the next step is 40 checks whether the difference Δv between the actual speed vist and the manually reduced target speed vsoll is less than the predetermined first differential limit D1. If the difference Δv is smaller than the predetermined first difference limit D1, it goes to step 45 passed over and sent to the drive unit AE a signal "sailing" to initiate a sailing operation. The drive unit AE then switches by releasing the operative connection between the drive machine and the drive wheels, for example by an automatic actuation of the clutch or by an automatic insertion of the empty passage in the sailing operation. The brake unit is not activated.

If the difference .DELTA.v is not less than the predetermined first difference limit D1, it is determined from step 40 after step 50 passed and checked there, whether the difference .DELTA.v between the actual speed vist and the manually reduced target speed vsoll is not less than the predetermined first difference limit D1, but less than the predetermined second difference limit D2. If so, move to 55 passed over and sent to the drive unit AE a signal "push" to initiate a push operation. The drive unit AE then switches to overrun mode, in which the motor is carried along by the vehicle if the force is not separated. The brake unit is not activated.

Is the condition in step 50 not met, will by step 50 after step 60 transited and sent to the brake unit BE a signal "brake" to initiate a braking operation. The signal "brake" can be configured such that a required to achieve the new target speed braking torque request is transmitted to the brake unit BE, which then controls the brakes according to the requested braking torque. The drive unit is not actively activated in this case, ie no drive signal is sent to the drive unit.

For the sake of completeness, it should be noted that the sailing mode can also be part of an efficiency program that can be activated by the driver if he wants to save fuel. However, if a driver wants to be sporty and has the shortest possible delay times, he can deactivate the efficiency program. Activation of the sail mode or the push mode with manual reduction of the setpoint speed would then only take place when the efficiency program is active (eg Eco mode).

In all solution variants, the engine can also be turned off in sailing mode and thus similar to today already available start / stop automatics additionally fuel can be saved. However, it is a prerequisite that it is not necessary by appropriate technical design that the engine is running permanently (eg by electrically servo-assisted brake and steering).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011050739 A1 [0004]

Claims (6)

Speed control system for controlling the speed of a vehicle to a predetermined target speed, wherein the control unit for reaching and holding the target speed sends corresponding drive signals to a drive unit or brake unit, characterized in that when activated cruise control (GR) and a manual reduction of the target Speed (vsoll) the control unit (SE) as a function of the difference (Δv) between the actual speed (vist) and the target speed (vsoll) of the vehicle a signal ("sailing", "thrust", "brake" ) or a signal change is generated, which leads either to initiate a sailing operation of the drive unit (AE) or to initiate a pushing operation of the drive unit (AE) and / or to initiate a braking operation of the brake unit (BE). Speed control system according to claim 1, characterized in that the control unit (SE) at a difference (Δv) between the actual speed (vist) and the manually reduced target speed (vsoll), which is smaller than a predetermined first difference limit (D1) in that the drive unit (AE) emits a signal ("sailing") to initiate a sail operation or retracts a previously transmitted signal for preventing a sail operation, and switches the drive unit (AE) in a sailing operation in which the kinetic energy of the motor vehicle is utilized to roll as far as possible without the drag torque of the engine braking the motor vehicle. Speed control system according to one of the preceding claims, characterized in that the drive unit (AE) in the sailing operation, the active connection between the drive machine and drive wheels dissolves and / or automatically shuts off the drive machine. Speed control system according to one of the preceding claims, characterized in that the control unit (SE) at a difference (Δv) between the actual speed (vist) and the manually reduced target speed (vsoll), which is not less than a predetermined first difference limit ( D1) and smaller than a predetermined second difference limit (D2), to the drive unit (AE) sends a signal ("thrust") for initiating or maintaining a push operation and the drive unit (AE) switches to overrun mode. Cruise control system according to one of the preceding claims, characterized in that the control unit (SE) at a difference (Δv) between the actual speed (vist) and the manually reduced target speed (vsoll) which is not smaller than a predetermined second difference limit ( D2) is to the brake unit (BE) a signal ("brake") for initiating a braking operation, in particular a brake torque ("brake") vorgebendendes signal for initiating a braking operation emits and the brake unit (BE) a braking torque, in particular that of the control unit (SE) causes predetermined braking torque ("brake"). Velocity control system according to one of the preceding claims, characterized in that the first and / or second difference limit (D1, D2) in dependence of predetermined parameters (se), in particular as a function of detected disturbing influences that can affect the current or timely on the longitudinal acceleration, are variably predetermined ,

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