DE19838454C1 - Process for reducing load change shock in motor vehicles - Google Patents

Abstract

The invention relates to a method for reducing power-off reaction in automobiles by modifying the curve of engine torque. In order to convert the curve of engine torque between a lower initial torque value and an upper target torque value, the curve of throttle valve position is modified between an initial closing position corresponding to an initial torque value and a target opening position corresponding to the targeted torque value. In order to effectively reduce power-off reaction without impairing driveability of the vehicle, the curve of the throttle valve position has, in the vicinity of the initial closing position, a local maximum opening the throttle valve and, in-between the local maximum and the target opening position, a local minimum closing the throttle valve, wherein the local maximum of the throttle valve position corresponds to a local torque maximum which is high enough to suppress or substantially reduce the play in the transmission system of the vehicle.

Description

The invention relates to a method for reducing load Exchange stroke in motor vehicles according to the preamble of the An saying 1.

A load change occurs particularly in the transition between Overrun and train operation of a motor-operated force vehicle and manifests itself in the form of an undesirable driving pressure and an annoying load impact noise. The Load change is caused by rapid changes in torque testifies, for example, by accelerating from the pusher can arise out by on the output side of the Motors a strong angular momentum is generated, which over a Einma flywheel or a dual mass flywheel on the drive strand is transmitted. In the phase of the moment build up The change between push and pull operations must first Play in the drive train can be overcome. After the game has been passed through, the angular momentum of the heavy secondary mass of the two-mass flywheel suddenly on the drive train transfer. This load change impact affects the subject tive driver's sense of comfort and has an undesirable Energy input into the engine driveline vibration system Body. Bearings in the vehicle are thereby additionally burdened.

Following the game run is a quick moments structure generated, for example when accelerating. Due to the  kinetic energy stored in the flywheel occurs Overswing the flywheel, the flywheel Vibrations are transmitted to the drive train. This Vibrations are known as jerky vibrations, which like that Load change impact to the category of longitudinal vehicle vibrations counting.

It is known from DE 40 13 943 C2, jerky vibrations prevent by regulating the engine torque by a Fuel injection depending on the period of oscillation Jerky vibration is affected. Through a targeted withdrawal or increase the engine torque in the corresponding phases of Jerking vibration is attempted, which is caused by the jerking to avoid gentle longitudinal movements.

The method known from DE 40 13 943 C2 requires that first the period of vibration of the jerky vibration is detected becomes. Then the engine torque curve over the Fuel injection in opposite phase to the bucking vibration influences. This procedure has the disadvantage that for capturing the first jerking vibration supply that has the highest amplitude can be waited for must be taken before the anti-jerking measures can be taken NEN, so that the driving comfort does not ver is improved. Another disadvantage is that the Momen The course of the bucking movement is counteracted, which is a rapid successive swelling and falling of the engine moments. This multiple withdrawal of moments affects the basic acceleration of the vehicle and ver deteriorates the exhaust gas behavior of the internal combustion engine.

A method for suppressing vibrations of a vehicle body Series is also known from the document DE 38 31 575 A1. According to this method, the engine output torque becomes ei  direction varies, the phase of which is opposite to that against the vehicle body vibration. To vibration comm The current body vibrations must be determined and the engine output torque synchronized with the vibrations be settled. In addition to a considerable effort in measurement and re Gel technology also leads to vibration suppression damped oscillating torque curve or acceleration behave, as in the method according to DE 40 13 943 C2 Acceleration and exhaust behavior are impaired.

Neither DE 40 13 943 C2 nor DE 38 31 575 A1 disclose a method of avoiding load change or the impact to reduce the impact of load changes.

DE 34 04 154 A1 describes a control device for a Motor vehicle known with a load change in the drive train occurring vibrations can be damped. Angular velocities in the drive train are via sensors detected and fed to the control device, the accelerator pedal position serves as the reference variable for the control. About the rule signal, the fuel injection is influenced, given if can also be the case with spark-ignited internal combustion engines Throttle valve position can be set.

The invention is based on the problem of load change impact oh ne impairment of the agility of the vehicle effectively to reduce.

This problem is solved according to the invention with the features of the Proverb 1 solved.

The new method assumes that the Position of the throttle valve between an initial closing point and a target opening position according to one  engine torque is changed. To avoid or re Reduction of the load change shock is now provided, the Dros First flap up to a first, a local maximum open the corresponding opening position and then the first opening position on a second, a local Mini mum lower corresponding opening position before the target opening position is reached, the local maximum of Throttle valve position causes a local torque maximum that especially big enough to play in the powertrain of the power vehicle in the transition between overrun and train operation overcome. The local maximum of the throttle position is therefore sufficient to play drivetrain, in particular gear game to balance. The associated maximum torque can be kept small enough to make the game soft run so that speed differences of interacting transm power links of the drive train with only low speed rose to be balanced and the interacting over load-bearing elements come to the plant without bumps.

After equalizing the game, following the second, the motorized opening position corresponding to the local minimum ment can be set up quickly without changing the load, which means that Responsiveness and agility of the vehicle, in particular when accelerating, is improved. A load change Triggering angular impulses are avoided. Another before part lies in the even, strong vibrations free course of the engine torque after reaching the torque target what by reducing the vehicle longitudinal vibrations is achieved. In addition, the load on the bearings of the Engine and drive train as well as the load on the body lowered.

Another advantage is that the short-term Opening of the throttle valve in the area of the local maximum  Throttle valve course a fast, delay-free filling development of the intake manifold of the internal combustion engine with intake air enabled before the torque increases to the torque target value light becomes. In addition, the direct control the throttle valve delays in the area of the local maximum as a result of damped conversion of the accelerator pedal movement and as a result Avoid inertia of engine and control components.

The throttle valve is expediently set using a electrically actuated actuator with a current supply function is acted upon by the desired course the throttle valve position is effected. The current supply function on is advantageous as an approximately rectangular function trained with time-discrete current intervals, which in simp can be generated in a safe manner.

The energization function preferably has a jump point, with which the local maximum in the course of the throttle valve position is simulated and which is advantageous approximately as short rectangular pulse is formed. The jump point causes a very brief, partial opening of the throttle where by a significant increase in the intake manifold pressure and the Mo tormoments is to be achieved. In addition to the game compensation thereby the maximum vehicle load in the shortest possible time acceleration reached. Already energizing the throttle valve pe of 80% of the possible maximum value over a period of 20 ms is usually sufficient to turn the throttle valve one open small angle and increase the intake manifold pressure to achieve, the maximum vehicle acceleration avoiding a load change after about 180 ms poses.

In a preferred development, the reduction or elimi nation of the load change impact with the reduction or Elimi  Combination of bucking vibrations combined. The jerking vibration can function in a similar way to the load alternating shock can be damped by the throttle valve position initially to an opening corresponding to a local maximum position raised, then to a local minimum corresponding opening position lowered and finally to the Target opening position according to the desired maximum torque is provided. The load change shock and the jerking swing damping are carried out sequentially in time. In The first step is the function for the load shock absorption applied and then on a Mi nimum returned before in a second, subsequent Step the vibration damping with a new lift Exercise to a second local maximum and decrease to one second local minimum is carried out. This makes him Most step play in the drive train balanced and an over Carrying a pulse of angular momentum from the engine to the drive train prevented. In the second step, the drive train is created by the Applying a momentum biased, vibrates during the local minimum to the point of reversal of the vibration deflection kung continues and becomes at the reversal point with full preload the target torque value. By combining both Steps is a load-free and smooth acceleration realizable with almost maximum possible agility.

The amplitudes of the local maxima of load change shock absorption and bucking vibration damping are expediently mutually dependent Right. The amplitude of the first local maximum is in the Usually less than the amplitude of the second local maximum, because the balance of play in the drive train with a small one  ren torque can be done as the preload of the transmission strangs.

The course of the throttle valve position is both for the load shock absorption as well as for the damping of the bucking vibrations regardless of the course of the accelerator pedal position. It will only the start position and the end position of the accelerator pedal and against also the accelerator change speed for the Vibration reduction is taken into account, but not the second between the accelerator pedal start position and the accelerator pedal end position en course. This decouples the course of Accelerator pedal position and throttle valve position reached, the Throttle valve position in the manner described above With regard to the reduction in load impact and jerking vibration optimized function follows.

Further advantages and practical embodiments are the further claims, the description of the figures and the drawing conditions. Show it:

Fig. 1 to Fig. 5 shows the course of the accelerator pedal position, the Bestrom ungsfunktion of the actuator of the throttle valve, the throttle position, the intake pipe pressure and the engine torque for a reduction of the load change shock,

Fig. 6 to Fig. 10 a Fig. 1 to 5 corresponding function ver run for a combined reduction of load change and bucking vibrations.

Figs. 1 to 5 show the function curves for the transition from overrun operation to traction operation of a motor vehicle with internal combustion engine with reduction of the load change shock occurring in the transition.

In Fig. 1 the course of the accelerator pedal position St _{G is} shown. At time t ₀ , the accelerator pedal position St _G ramps up from the initial value zero to an end value that is at most 100%. The course of the accelerator pedal position St _G is converted into an energization function I shown in FIG. 2, which represents the current course of an electrical actuator via which the position of the throttle valve of the internal combustion engine can be adjusted. With a value I = 0 of the energization function, the throttle valve is closed, with a value I <0, the throttle valve is opened to a greater or lesser extent depending on the amplitude of the energization function.

With a short time delay compared to the increase in the accelerator pedal position, a rectangular current pulse is applied at time t ₁ , the amplitude of which is below the maximum value of 100% of the energization function and which is maintained until time t ₂ . The rectangular current pulse represents a local current maximum I ^L _max . Between the times t ₂ and t ₃ , the energization function I falls to a local minimum I ^L _min , which is zero in the exemplary embodiment shown. At time t ₃ , the energization function I ramps up to the final value corresponding to the maximum accelerator pedal position St _G , where it may be expedient to provide an approximately rectangular function instead of a ramp-shaped increase for the energization function.

The local energization _maximum I ^L _max can increase to a maximum value of 100%, the local energization _minimum I ^L _min can assume a value greater than zero. If necessary, current maximum I ^L _max and current minimum I ^L _{min are} at the same value.

The local current _maximum I ^L _max is given up with a short time delay at time t ₁ compared to the beginning of the increase in the accelerator pedal position at time t ₀ . In this period of time, the parameters determining the course of the energization function and therefore the course of the throttle valve position can be determined by measuring and evaluation devices. A change in the throttle valve position is expediently triggered by applying the energization function I to the actuator in the event that the change in the accelerator pedal position - and hence the speed of the accelerator pedal - is above a given threshold value, which results from the starting position of the accelerator pedal, the accelerator pedal travel difference, the engine speed and / or gear position. The initial course of the energization function, in particular the course of the local maximum I ^L _max and the local minimum I ^L _min , can first be determined from these parameters. From further, cyclically recorded measurements at a later time after t ₂ , the end level of the energization function I or the throttle valve position DK can be determined.

The throttle valve position DK shown in FIG. 3 arises in response to the energization function I according to FIG. 2. At time t ₁ , the throttle valve opens parabolically increasing from the initial closed position to the local maximum DK ^L _max and then drops parabolically to the local minimum DK ^L _min , which in the exemplary embodiment shown is zero. From time t ₃ , the throttle valve position begins to increase parabolically to the target opening position DK _o .

Instead of parabolic throttle movements, the Dros Selklappe also follow other functional courses.

In response to the change in the throttle valve position, the course of the intake manifold pressure p _2S shown in FIG. 4 and the course of the engine torque M shown in FIG. 5 are established. Both functions rise like the energization function I and the throttle valve position DK from an initial value to a local maximum p ^L _2Smax or M ^L _max , then fall to a local minimum p ^L _2Smin or M ^L _min and finally rise to a respective one End value or target value. Depending on the driver's specification, local maxima and minima of different heights are set with correspondingly different gradients, the qualitative course remaining essentially the same. The functions of intake manifold pressure p _2S and engine torque M, like the throttle valve function, are continuous up to the second derivative.

As can be seen FIG. 5, the engine torque M increases up to the time point t _{1 is} a lower torque initial value M _and a is less than zero. During this period, the vehicle is in overrun mode. In response to the current function I rising at the time t ₁ to the local maximum I ^L _max , the motor torque M rises steeply, intersects approximately the zero line at the time t ₂ and reaches the local maximum M ^L _max in the period between t ₂ and t ₃ . In the further course, the engine torque drops to the local minimum M ^L _min , which is reached approximately at time t ₃ and can again be below zero. Finally, the engine torque increases to the target torque value M _o .

Cutting through the zero line also marks an over corridor between pushing and pulling the vehicle. Below the moment zero line, the vehicle is in the thrust driven, above the zero line in train operation.

If necessary, the engine torque can also take the course shown in dashed lines, in which, from time t _2, the engine torque increases with a weak gradient and approximately intersects the zero line between t ₂ and t ₃ . This course of the function shows no pronounced local moment maxima and minima.

The local maximum M ^L _{max of} the engine torque is appropriately large enough to overcome the game in the drive train of the motor vehicle in whole or in part. The local maximum DK ^L _{max of} the throttle valve position required for this is specified via the amplitude and the duration of the local maximum I ^L _{max of} the energization function.

The reduction of the load cycle impact continues until time t ₃ , which marks the end of the local minimum I ^L _{min of} the energization function I and from which the energization function rises to the target value.

The reactions of the throttle valve, the boost pressure and the engine moments occur with a time delay compared to the Be flow function I.

The load change shock can also be dampened in the transition from train operation to push operation, which is characterized by a change from positive engine output torque to negative engine end torque. In principle, the functions of FIGS. 1 to 5 are run in the opposite direction, from right to left, taking into account that the energization function and the throttle valve position respond to a change in the accelerator pedal position with a time lag.

A further reduction of the load impact can be achieved by a soft The driveline is tuned by the driveline is provided with a low torsional stiffness, which at can be realized for example by thin sideshafts.

The function curves shown by 10 in Figs. 6 show a combination of reduction of load change shock and bucking oscillations. The graphs each show three function curves, namely a curve for fast acceleration (solid line), a curve for slower acceleration to the same target level (dash-dotted line) and a curve for acceleration to a lower target level (dashed line) ).

According to FIG. 6, the accelerator pedal position St _G ramps up to the end position at time t ₀ . This increase is converted into the energization function I shown in FIG. 7 for the electric actuator of the throttle valve. The energization function I has two successive local maxima, a first maximum I ^L _max , which begins at time t ₁ and is designed as a rectangle, and a second maximum I ^R _max , which begins at a later time t ₃ and is also formed in a rectangular shape is. In the further course, the current supply function I suddenly increases to the final value at time t ₅ .

The first local maximum I ^L _max begins with a time delay compared to the start t _{0 of} the accelerator pedal movement St _G. Between the first maximum I ^L _max and the second maximum I ^R _{max there} is a first local minimum I ^L _min between the times t ₂ and t ₃ . The second local maximum I ^R _{max is} followed by a second local minimum I ^R _min between the end of the second local maximum I ^R _max at time t ₄ and the start of the increase to the final value at time t ₅ .

The first local maximum I ^L _max and the first local minimum I ^L _min up to the time t ₃ are associated with the reduction in the load cycle impact. The second local maximum I ^R _max and the second local minimum I ^R _min between the times t ₃ and t ₅ are assigned to the reduction of the jerky vibrations.

Depending on the course of the accelerator pedal position St _G , the energization function I takes a different course. The minima and maxima can vary with regard to amplitude, time start, duration and function type. So it may be useful to specify ramp-shaped or trapezoidal functions with a high gradient instead of rectangular functions or to implement functions that are continuous up to the first or the second derivative. As entered for the second local maximum I ^R _max , the local maxima can have several levels. If necessary, each maximum is divided into several individual rectangular functions with intermediate minima. The amplitudes can rise up to the maximum value of 100%, the amplitude of the first local maximum I ^L _max assigned to the load shock damping preferably being significantly less pronounced than the amplitude of the second local maximum I ^R _max assigned to the bucking vibration damping. The time interval between the first and the second local maximum, which is characterized by the duration of the first local minimum, is expediently small compared to the duration of the second local minimum.

The course of the throttle valve position DK shown in FIG. 8 arises in response to the energization function I. The throttle valve position rises to a first local maximum DK ^L _max at time t ₁ , then drops to a first local minimum DK ^L _min , rises to a second local maximum DK ^R _max at time t ₃ and then falls to a second local Minimum DK ^R _min before the increase to the target opening position Dk _o takes place at time t ₅ . The local minima DK ^L _min and DK ^R _min are zero or close to zero.

The local minima and maxima can also be seen in the curves of the boost pressure p _2S and the engine torque M according to FIGS . 9 and 10. According to FIG. 9, the boost pressure initially rises to the first local maximum p ^L _2smax , depending on the intake manifold _volume the first local minimum p ^L _2smin decreases, rises to the second, _higher local maximum p ^R _2smax and falls to the second local minimum p ^L _2smin before the increase to the final boost pressure value occurs. The drop to the minimum depends on the intake manifold volume, with a large intake manifold volume having more air intake capacity than a smaller intake manifold volume and therefore producing a lower boost pressure drop.

Similarly, the engine torque increases at time t ₁ starting from the negative torque start value M _u to the first local maximum M ^L _max , which is approximately shortly after time t ₂ - the time of the start of the first local minimum I ^L _{min of} the loading flow function - is achieved. At time t ₃ - the time of the beginning of the second local maximum I ^L _{max of} the energization function - the first local minimum M ^L _min , which is just below the zero line, is reached. Then the jerky vibration damping takes place, in which the engine torque rises to the second local maximum M ^R _max , falls to the second local minimum M ^R _min and finally increases after the time t ₅ to the upper torque target value M _o .

The functions for throttle valve position, boost pressure and the engine torque are continuous until the second derivative. These functions react to the Course of the energization function I.

The functions are run from left to right for acceleration; In accordance with the negative torque start value M _u and the positive torque target value M _o , the acceleration process also includes a transition from overrun to train operation, in which the load change shock to be damped occurs. In the event of a vehicle deceleration, the functions are run in the opposite direction from right to left, taking into account the time delay in the course of the current supply and the change in the throttle valve position compared to the change in the accelerator pedal position. In the event of a change of sign in the course of the moment from a positive initial value to a negative final value (transition from train operation to overrun operation), load changes in the vehicle as well as jerky vibrations are effectively reduced or eliminated.

It may be indicated, only load change to dampen beatings or only jerky vibrations.

Both in terms of shock absorption and jerking Vibration damping is the course of the energization function or the throttle valve position decoupled from the course of the gas pedal position. Only key data from the course of the Accelerator pedal position such as start value, end value, change speed dity etc. are taken into account and from this key data functional curves formed for the throttle valve position, with Use of an electric actuator for the throttle valve a manipulation of the energizing function of the actuator is taken.

Claims (14)

1.Procedure for reducing load cycle shock in motor vehicles by changing the engine torque curve, with the implementation of an engine torque curve (M) between a lower initial torque value (M _u ) and an upper torque target value (M _o ) the course of the throttle valve position (DK ) between a moment of the initial value (M _u) corresponding initial closed position _(u DK) and the torque target value (M _o) ent speaking target opening position (DK _o) is varied, characterized in that
that the course of the throttle valve position (DK) is changed between an initial closed position (DK _u ) and a target opening position (DK _o ),

• 1. that the throttle valve is first opened up to a first opening position (DK ^L _max ),
• 2. that the throttle valve is then closed up to a second opening position (DK ^L _min ),
• 3. that the throttle valve is set to the target opening position (DK _o ) below,

the first opening position (DK ^L _max )

• 1. is greater than the initial closed position (DK _u ) and greater than the second open position (DK ^L _min ),
• 2. is smaller than the target opening position (DK _o )
• 3. and corresponds to a moment that overcomes the play in the drive train.

2. The method according to claim 1, characterized, that the throttle valve via an electrically actuated position member is set and the course of the throttle valve lung (DK) by a current acting on the actuator tion function (I) is controlled. 3. The method according to claim 2, characterized in that for setting the first opening position (DK ^L _max ) in the United course of the throttle valve position (DK), the energization function (I) has at least one jump. 4. The method according to claim 2 or 3, characterized, that the lighting function (I) is approximately a rectangle function is. 5. The method according to any one of claims 2 to 4, characterized in that the energization in the region of the first opening position (DK ^L _max ) in the course of the throttle valve position (DK) lasts about 20 ms. 6. The method according to any one of claims 2 to 4, characterized in that the energization in the region of the first opening position (DK ^L _max ) in the course of the throttle valve position (DK) has about 80% of the maximum energization. 7. The method according to any one of claims 1 to 4, characterized in that the second open position (DK ^L _min ) is zero. 8. The method according to any one of claims 1 to 7, characterized, that the change in throttle valve position (DK) is triggered when the accelerator pedal speed of the motor vehicle is above a given threshold. 9. The method according to claim 8, characterized, that the threshold is determined by at least one of the following para meter is determined: the starting position of the accelerator pedal, the Accelerator pedal travel difference, engine speed, gear position. 10. The method according to any one of claims 1 to 9, characterized, that adjusting the throttle to reduce the load alternating shocks at the transition between overrun and Zugbe drive took place. 11. The method according to any one of claims 1 to 10, characterized in that the setting of the throttle valve to reduce the load alternating shock is combined with a method for avoiding jerky vibrations, following the first opening position (DK ^L _max ) and the second Opening position (DK ^L _min ), which are assigned to the load impact reduction, a further opening position, which is assigned to a second local maximum (DK ^R _max ) and a subsequent opening position, which is assigned to a second local minimum (DK ^R _min ), which is assigned to the jerking vibration reduction are provided in the course of the throttle valve position (DK) before reaching the target opening position (DK _o ). 12. The method according to claim 11, characterized in that the amplitude of the first maximum assigned first opening position (DK ^L _max ) for damping the load is less than the amplitude of the opening assigned to the second maximum opening (DK ^R _max ) for damping the jerky vibration . 13. The method according to claim 12, characterized in that the amplitude of the first opening position associated with the first maximum (DK ^L _max ) is approximately 50% of the amplitude of the opening position associated with the second maximum (DK ^R _max ). 14. The method according to any one of claims 11 to 13, characterized in that the duration of the first opening position (DK ^L _max ) assigned to the first maximum is not greater than the duration of the opening position (DK ^R _max ) assigned to the second maximum.