DE10119724B4 - Device for preventing load impacts in the drive train of motor vehicles - Google Patents

Abstract

contraption for the prevention of load impacts in the powertrain of motor vehicles, with one from a definable sudden increase driver's torque (mv) or from a definable gradient the same activated function control device (10) for a modified Default torque (mv (L)), which is the modified default torque (mv (L)) at first only on one opposite setting driver initial torque (mv) smaller initial value (ml) Torque input device and the driver's default torque (mv) after a definable delay time (t1 + t2; t3) as modified default moment (mv (L)) taking over Time control device has, characterized in that a Blocking device (13 to 16) is provided, which designed so is that it activates the function control device (10) only within a predefinable speed range (nmin to nmax) and / or with respect to one lower limit torque (mg) smaller torque actual value (mist) allowed.

Description

The The invention relates to a device for preventing load impacts in the drive train of Motor vehicles resulting from a jerky excitation and for example, by a meshing game in the drive train come to fruition, which when changing from push to the Druckbetriebsbereich occurs and leads to a striking. The load impact manifests itself in high-frequency vibrations.

A other unwanted Vibration type in addition to the load impact is the jerking, the moment jumps in a row the mechanical and elastic properties in particular of the drive train is generated and low-frequency vibrations leads. A known solution to avoid jerking is an active ignition intervention, the jerking can be compensated by oscillating engine torque generation, in particular with a phase shift to the jerky vibration. Avoiding However, juddering is not the subject of the present invention, however can the known measures to avoid jerking with the measures according to the invention combined to avoid load impacts become.

The the invention underlying technical problem of load shocks exists in that, in particular for vehicles with manual and comfort gearboxes, stronger still in all-wheel drive vehicles due to the two drive shafts, heavy load impacts in the drive train at transitions from the thrust occur in the train operation. For example, such load impacts occur abrupt release of the accelerator pedal (thrust range) and subsequently fast Giving up gas (pulling area). This unwanted effect can be determined by a Gearing in the drive train explained become. At the transition from Push operation into the train operation moves the driving gear in the field of play between one tooth flank to the other tooth flank. The fast moving tooth meets on the opposite Tooth flank, it comes to a load impact. To the load blow too avoid, a strong damping of the accelerator pedal is made in a known manner. Such damping However, there is always a trade-off between the agility of the vehicle and the avoidance of the load impact. Especially in four-wheel drive vehicles is a particularly strong damping required so that the driver due to the strong damping a Dead time in the response of the vehicle and registered a bad agility.

The DE 199 05 604 A1 describes a method for damping load changes in a motor vehicle. If the gradient of a driver's request in the form of an accelerator pedal position exceeds a threshold, the driver's desired signal is fed to a filter or a delay element.

The DE 197 33 472 C2 describes a method for preventing jerky vibrations during acceleration of a motor vehicle, in which starting from a predetermined jump-shaped increase of the driver default torque or from a predetermined gradient of the driver input torque initially a modified default torque is set with a smaller initial value and after a delay time, the driver torque itself is taken.

The DE 198 38 454 C1 describes a method for reducing load changes in motor vehicles. When the throttle valve is opened, the course of the throttle position adjacent to the initial closing position has a local maximum and a local minimum between the local maximum and the target opening position.

The DE 198 19 050 C1 describes a method for avoiding jerky vibrations when accelerating motor vehicles. When the accelerator pedal is actuated, the engine torque has a local maximum between a lower torque value and an upper torque value adjacent to the lower torque value and a local minimum between the local maximum and the upper torque value.

The DE 37 38 719 C2 describes a method for preventing load changes in a motor vehicle. Positioning commands of the driver for a power actuator of the engine are transmitted delayed in the range of the zero crossing of the engine torque curve.

The DE 197 53 996 A1 describes a method for damping jerking or load shocks in an internal combustion engine. A setpoint of a load variable, which is given with an accelerator pedal, is filtered with a filter that has integral behavior, which is first order and whose filtered setpoint is fed back.

The DE 197 12 843 A1 describes a method for controlling an internal combustion engine. The change over time of the setpoint values of a desired torque is limited within a value range around the zero value of the setpoint value to a predetermined change value.

The DE 43 21 333 A1 describes a method for controlling a drive unit of a drive zeugs. In the transition from a push to a pulling phase, the execution of the driver's request for setting the engine power is delayed.

The DE 38 19 616 A1 describes an arrangement for preventing load changes in a vehicle internal combustion engine. Triggered by the beginning of the movement of an accelerator pedal actuation of a fuel injection pump associated throttle or bypass valve is briefly made in the sense of reducing the amount of fuel reaching the injection to the zero-load fuel demand of the internal combustion engine.

A The object of the present invention is a device to avoid load impacts in the powertrain of motor vehicles to create, in the agility of the vehicle as good as not affected becomes.

These The object is achieved by the Characteristics of claim 1 solved.

In accordance with the invention one advantageously the actual jump of the desired torque smaller desired jump ahead, so that the free flight phase, for example a tooth flank of a gear in the drive train, with a smaller Pulse or lower speed begins. Only at the time, in which the game is overcome is, so after the settable delay time, the full Value of the setpoint torque given, so that the load impact without loss the agility is avoided. An agility loss is thus only during the very short delay time and thus is so small that it is essentially from the driver not noticed. Since the device according to the invention on a pilot control is based, a very simple implementation without regulation is possible would hardly be feasible because the disturbance is one Pulse and no continuously introduced disturbance is.

The inventive device has one Blocking device that activates the function control unit permitted only under certain conditions, preferably only within a predetermined speed range and / or with respect to a lower limit torque smaller torque actual value. At very small or very high speed Activation of the device is not required because of the load impact There is very low. Of the Minimum value and / or the maximum value of the speed range will be appropriately determined depending on the gear, again with small courses the load impact is more pronounced and serious.

By in the subclaims listed activities are advantageous developments and improvements in the claim 1 specified device possible.

In front All-wheel drive vehicles have proven to be advantageous when the function control means for decreasing the initial value after a predefinable function or after a predetermined holding time has. In this case, the torque setting device is expediently also designed to specify the lowered initial value. In a simpler version, for example, sufficient for vehicles with manual and comfort gearboxes is, the small initial value can also until the expiry of the definable Delay Time to be kept.

to Optimization of the device is the torque setting device for parameter-dependent Torque specification and / or the time control device designed for parameter-dependent timing, in particular for gear-dependent and / or to the speed-dependent and / or height-dependent specification. In particular, the gear-dependent Attitude is of particular importance as the selected gear ratio has a significant impact on the impact load. The lower the selected gear is, the stronger is the load impact and the smaller the flight time of the drive element, For example, gear, about the area of the game. At low gear is the device of the invention really important. The parameter dependence can be empirical or be determined mathematically.

Farther a locking device has proved to be advantageous by the a re-triggering of the function control unit during the definable delay time is prevented. Overlapping Effects with multiple triggering could otherwise have negative effects have and at a loss of comfort to lead.

Conveniently, is also an on actuation a clutch pedal or at standstill of the motor vehicle or at the driver's request, the function control device shutdown shutdown provided for that ensures that in such cases no unwanted Torque default occurs.

The Function control device and / or the blocking device and / or the locking device and / or the shutdown device are preferably as Processor unit formed, with the individual functions through Program steps are realized.

One embodiment The invention is illustrated in the drawing and in the following description explained in more detail. It demonstrate:

1 a circuit implementation of a device for the prevention of load impacts in the drive train of motor vehicles as an embodiment of the invention,

2 an example of a functional sequence for 4WD vehicles and

3 an example of a functional sequence for vehicles with manual and comfort gearboxes.

At the in 1 illustrated embodiment, an electronic function control device 10 by a triggering device 11 over an and-member 12 triggered or activated if the trigger condition is fulfilled. For this purpose, the trigger device 11 supplied to the driver input torque m _v for the prime mover of the motor vehicle, in which a load shock to be prevented by impulsive excitation of the drive train. The driver default torque m _v can be specified directly by an accelerator pedal or in some other way, for example via a vehicle speed controller. In the triggering device 11 the driver command torque is then monitored to see if there is a sudden increase greater than a set value or if a certain gradient of the driver command torque is above a certain value. For this purpose, in the exemplary embodiment, the driver default torque m _{v is} compared with a value m _v occurred shortly before. If the difference is greater than the settable value c, then a trigger signal for activating the function controller 10 generated.

The function control device serves to generate a default torque function deviating from the driver default torque, by means of which a load impact is to be prevented. For this purpose, parameter-dependent by a in the function control device 10 contained timing means two times t1 and t2 and formed by a torque setting means two default moments ml and m2. The formation of these times and moments is carried out in dependence on the respective speed stage G of a vehicle transmission, the actual speed value _n, a frequency dependent on the geodetic height height function f (h) of the driver's preset moment m _v and the torque actual value _m. From these sizes, the in 2 generated by a solid line torque setpoint m _v (L) generated by a load impact or the resulting high-frequency vibrations should be prevented.

Above all, such load impacts occur with abrupt release of the accelerator pedal (thrust area) and subsequent rapid acceleration (traction area). During the transition from the thrust area to the traction area, there is a play-related movement of a drive element, for example a gear in the drive train, whereby this gear moves very quickly from one tooth flank to the other tooth flank. Then the flying tooth hits on the opposite tooth flank and it would come to the load impact, if no countermeasures are taken. These consist according to the invention in that prior to the actual desired jump of the driver's default torque m _v , which is represented by a dashed line, a small momentum pulse is sent ahead, which has only one compared to the driver's default torque smaller size ml. The free-flying phase of the tooth then starts at a lower speed. After the small momentum pulse of height ml and length t1, the moment is again reduced to the original value or the value zero for a period of time t2. After the time t1 + t2, the game or the free flight phase is overcome and it is now the torque setpoint the driver's default torque m _v adjusted or adopted this value. The times t1 + t2 must therefore be selected accordingly.

The Flight time, ie the time until the usually occurring load impact is gear-dependent, dependent on the moment, speed related, dependent from the inert masses to be moved or the period of oscillation of the dynamic systems of the powertrain, from the subsurface of the vehicle, from the geodetic altitude and other parameters, so that the respective values for ml, m2, t1 and t2 determined empirically or via computer models be and the respective sizes in maps be filed. Depending on the effort, the addressed parameters or other parameters for the determination of the torque curve are taken into account. In particular, must however the chosen one Gear ratio to be considered. The lower this is, the higher is the blow and the smaller the flight time. The times t1, t2 and the length of the pre-impulse therefore be given accordingly. Furthermore, the Vorimpulshöhe and the Time interval depend on the speed, above all, average speeds are critical for the load impact, so that here the device according to the invention is of particular importance. about the sizes indicated intake air pressure may also affect fuel quality, ambient and / or operating temperature of the internal combustion engine and the density of combustion media consideration Find. In the simplest case, you can the default values are also specified only gear-dependent.

For motor vehicles with four-wheel drive ver sharpening the problem of the load impact, since different vibration modes can be set for different driven axles. Even at small transitions from overrun to train operation, load impacts can occur. This in 2 shown example of the predetermined by the function control device history of the corrected or modified torque setpoint can be further refined, for example by specifying multiple moment pre-pulses or by specifying a continuous function instead of a jump function.

In 3 is a simpler course of the through the function control device 10 predetermined modified torque setpoint m _v (L) shown, which is sufficient for example in vehicles with manual and comfort gearboxes that have no four-wheel drive. For this purpose, a torque pre-pulse of length t 1 is generated only a desired jump on a opposite the driver's preset moment m _v lower value ml in place, wherein after a delay time t3 which corresponds substantially to the sum of the times t1 and t2, the driver Preset torque m _{v is} switched. The dash-dotted line in the 2 and 3 in each case gives the course of the torque actual value m _ist . In the simpler version according to 3 must be the function control device 10 only the sizes ml and t3 form and the corresponding functional sequence according to 3 produce.

When applying the parameters t1, t2, t3, m1 and m2 according to the 2 and 3 Certain relationships have to be considered. For example, according to 2 to see the pulse height ml in connection with the pulse time t1. The smaller the speed _is m, the longer the time t1 and the smaller the pulse height ml. The integral of pulse height over pulse time is approximately constant, that is, to avoid an abrupt load, must be of the plant change of low speeds carried out cautiously. This feedforward control ensures that the engine load decreases slightly to decelerate the two independent shafts in the four-wheel drive in the system change. The speed dependency acts such that the times shorten with increasing speed due to the faster torque reduction. The context corresponds approximately to a 1 / x function. The waiting or delay time t2 or t1 + t2 is only gear-dependent and corresponds to the different natural frequencies of the drive train. The altitude and temperature compensation acts in such a way that with increasing altitude and temperature the maximum engine torque and thus also the pulse height decreases. This prolongs the pulse time t1. In the simpler version according to 3 For example, for vehicles with manual and comfort gearboxes, the conditions are very similar. The torque limitation acts as a time-limited suction tube constriction and ensures that the engine load is kept constant during system change. The smaller the rotational speed n _is , the longer the limiting time t3 and the smaller the limiting torque ml. The integral limiting torque ml over the limiting time t3 is approximately constant, ie here too the change of drive must be carried out more cautiously at lower rotational speeds in order to avoid the impact of the load. The remaining comments too 2 apply here as well.

If a sensor signal for torque detection of the drive shaft of the drive motor, so this can be used to determine the time for the torque jump of the modified torque setpoint m _v (L) on the driver's default torque m _v who, so this the application of the tooth flanks are detected can. This can in principle also be realized in the context of a control instead of a feedforward control.

The response and activation of the function control device 10 occurs only under certain trigger conditions. On the one hand, the torque actual value m _is in a comparison stage 13 compared with a lower limit m _g . Only when the torque actual value is smaller, an input signal to a first input of an AND gate 14 placed. The load impact only works from the thrust area to the small positive traction area, which corresponds to this lower limit momentum ml. If, at the moment of activation, the torque actual value is greater than m _g , then the load impact damping does not become active and the rate of change of the default torque is converted unfiltered. The lower limit torque ml is just above the effective zero moment. This ensures that only from the thrust up to this lower limit torque ml, the load impact damping is active and thus no agility loss is caused above this value.

In a second comparison stage 15 the actual speed value n _{ist is} compared with a minimum speed value n _min , which is a function of the respective gear ratio g. Only when the actual speed value n _is above this minimum speed value n _min , then a signal to a second input of the AND gate 14 placed. Finally, the actual speed value n _is still in a third comparison stage 16 compared with a maximum speed value n _max , which also represents a function of the respective gear ratio g. Only if the actual speed value n _{ist is} smaller than this maximum speed value n _max is then a signal to a third input of the AND gate 14 placed. The load impact damping is thus activated only in a range between the minimum speed value n _min and the maximum speed value n _max . At very low and very high speed namely the load impact damping is not required, so that the Activation of the function control unit 10 only an unnecessary loss of agility would bring with it.

If all three conditions are fulfilled, then the output of the AND element becomes 14 generates a signal via an OR gate 17 a second entrance of the and-member 12 is supplied with the result that a signal of the trigger device 11 under this condition, the function control unit 10 can activate.

To prevent retriggering of the function control unit 10 during the course of the Lastschlagfunktion according to 2 or 3 During this time, a corresponding signal of the function control device 10 to a second input of the OR gate 17 through which a lock is achieved. This could be the OR member 17 also between the exit of the and-member 12 and the trigger input of the function control device 10 be switched.

A trained as an OR limiter 18 for the function control device 10 serves to abort an already initiated load impact function under specifiable conditions. These conditions are in the embodiment, the standstill of the vehicle (speed v = 0) and the operation of the clutch pedal K. Further, a forced by the driver or other components of the vehicle deactivation via a switch 19 possible. The shutdown device 18 acts on a reset input of the function control input 10 one.

In a practical embodiment, the function control unit 10 and the other components described are at least partially realized as a processor unit, wherein the respective functions are realized by program steps. This processor unit can also be part of a central control computer for the vehicle.

Claims (8)

Device for preventing load impacts in the drive train of motor vehicles, with a function control device which can be activated starting from a definable jump-like increase of the driver torque (mv) or from a definable gradient of the same ( 10 ) for a modified default torque (mv (L)), the torque setting device adjusting the modified default torque (mv (L)) initially only to an initial value (ml) which is smaller than the driver default torque (mv) and the driver default torque (mv) having a determinable delay time (t1 + t2; t3) as a modified default torque (mv (L)), characterized in that a blocking device ( 13 to 16 ) which is designed to enable the activation of the function control device ( 10 ) only within a predefinable speed range (nmin to nmax) and / or with respect to a lower limit torque (mg) smaller torque actual value (mist) allowed. Device according to claim 1, characterized in that that the minimum value (nmin) and / or the maximum value (nmax) of the Speed range gear-dependent is determinable. Device according to Claim 1 or 2, characterized that the torque setting device for parameter-dependent torque specification and / or the time control device is designed for parameter-dependent timing is. Device according to claim 3, characterized in that that the torque specification and / or the time specification is gear-dependent and / or speed-dependent and / or formed height-dependent is. Device according to one of the preceding claims, characterized in that a re-triggering of the function control device ( 10 ) during the definable delay time preventing locking device ( 17 ) is provided. Device according to one of the preceding claims, characterized in that upon actuation of a clutch pedal (K) or at standstill of the motor vehicle (v = 0) or at the driver's request, the function control device ( 10 ) shutdown shutdown device ( 18 ) is provided. Device according to one of the preceding claims, characterized characterized in that the settable delay time (t1 + t2; t3) in Essentially the for corresponds to the change in the drive train required time. Device according to one of the preceding claims, characterized in that the function control device ( 10 ) And at least a part of the remaining components is designed as a processor unit.