DE102004005728B4 - Method and device for controlling an output unit of a vehicle - Google Patents

Abstract

Method for controlling a drive unit of a vehicle comprising an engine (10), a transmission (30) and a torque converter (20) arranged between the engine (10) and the transmission (30), such that at least one operating parameter of the engine (10) occurs a load change is set so that a quantity which characterizes the torque output by the motor (10) to the torque converter (20) initially corresponds to a variable characterizing the loss torque of the motor (10) within predeterminable limits and then to a prescribable time profile is increased, characterized in that the occurrence of a load change is assumed when the difference of the torque converter input speed (n12) and the torque converter output speed (n22) corresponds to a predetermined value.

Description

State of the art

The invention relates to a method and a device for controlling a drive unit of a vehicle according to the preamble of the independent claims 1 and 7.

In vehicles with a gearbox, which is connected to a motor via a torque converter, for example via a hydrodynamic torque converter, load changes may occur during the transition from push to train operation and vice versa during the transition from train operation to overrun operation. At a load change can be achieved by the relaxation of strained components, eg. As the drive shafts, and caused by the tension relaxed components or any existing loose in the drive train rotational shocks between the components of the drive train. This single or multiple shocks perceives the driver of the vehicle both haptically and acoustically true. In addition, jerky vibrations of the drive train are excited, which lead to a further impairment of ride comfort.

From the DE 100 18 551 A1 a method for controlling a drive unit of a vehicle with an actuating element for influencing the power is known, wherein starting from the position of an operating element, a power-determining signal can be predetermined, and the control of the actuating element is dependent on a filtered power-determining signal. The signal is thereby filtered with a filter having at least one high pass and one low pass, which are connected in parallel. Through this filter state changes between thrust and train can be carried out very quickly. Due to the rapid change of state, a spontaneous vehicle reaction to the driver's specification can be realized. The damping of the shock when hitting the new plant position causes a significant reduction in noise during the load change process, a reduction in the load impact during load changes due to small changes in driver specification and a reduced excitation of the drive train to bucking. Regulations that are used at the point of load change are difficult to apply and there is also a risk of instability.

The DE 199 48 153 A1 describes a method for reducing load changes in the transition of a motor vehicle from the train to the overrun operation. In this case, a torque command of the internal combustion engine influencing actuator issued control command is transmitted delayed. In a transition from the train to the overrun operation, a PT member of the first order is initialized with a torque that becomes based on the driver's requested torque. This is done so that the drive train of the motor vehicle switches without load and retarded is retarded to a torque of zero.

From the DE 195 38 369 A1 is known a method for reducing the load change beats. The torque correction takes place via the ignition angle. In this method, the induced base torque is used. This base torque is converted into an indicated target torque, which has a lower rise compared to the induced base torque.

The object of the present invention is to develop a method and a device for controlling a drive unit of a vehicle in such a way that easy application is possible and that instabilities are practically ruled out. Filtering should be avoided as far as possible, a delayed response to driver specifications should be avoided.

Advantages of the invention

This object is achieved in a method and in a device for controlling a drive unit of a vehicle with the features of the independent claims 1 and 6.

The basic idea of the invention is to set the engine torque at a detected load change to the lost torque and to change in conjunction with a progressive increase of the torque in the direction of the driver default. Under loss torque is understood to be the sum of the moments caused by engine friction, the drive of ancillaries, etc., in short the moments that are not available for the propulsion of the vehicle available. A load change therefore always occurs when the difference between the engine torque and the torque loss changes the sign. The occurrence of a load change change is assumed when the difference between the torque converter input speed and the torque converter output speed is equal to zero. In other words, a load change is detected by a slip on the torque converter, where slip here means the difference between the torque converter input speed and the torque converter output speed.

In another advantageous embodiment, the load change detection is performed by at least one torque sensor.

In yet another embodiment, the load change detection is performed by at least one flow or pressure sensor in the torque converter.

Preferably, the torque-time characteristic of the output torque from the engine to the torque converter after adjustment to the loss torque is set so that a predetermined maximum temporal gradient is not exceeded.

An advantageous embodiment of the method proposes a tangential waveform, the maximum temporal gradient corresponds in this case a parabola.

Alternatively, other characteristics of the gradient, e.g. B. ramped Gradientenverläufe possible.

In principle, instead of a slope limitation, the signal curve can also be represented by a filter of a higher order, in particular an order greater than or equal to 2.

drawing

Further advantages and features are the subject of the following description and the drawings of embodiments of the invention.

In the figure show:

1 a block diagram of a known from the prior art drive unit of a vehicle;

2 schematically a flow chart of a method making use of the invention;

3 the speed and the torque at a load change transition from overrun to traction and

4 the speed and the torque at a load change transition from the train operation to the overrun operation.

Description of the embodiments

A drive unit of a vehicle, shown in FIG 1 , has a motor 10 , z. As an internal combustion engine, on, via a crankshaft 12 with a torque converter 20 connected is. The torque converter 20 is via a transmission input shaft 22 with a gear 30 connected. The gear 30 is about an axis 32 with a wheel 40 connected. It is understood that this must be considered as a schematic representation only. In practice, the transmission output shaft 32 for example, connected via one or more differential gear with the wheel axles. At the crankshaft 12 , which may also be referred to as a torque converter input shaft, is a speed sensor 14 provided, the speed of the crankshaft 12 detected. At the transmission input shaft 22 , which may also be referred to as a torque converter output shaft, is also a speed sensor 24 arranged, the speed of the transmission input shaft 22 detected. The signals of the speed sensors 14 and 24 become a control device 50 supplied and processed in a manner described in more detail below. The control device 50 allows via a schematically illustrated control line 54 the control of actuators for influencing the of the engine 10 to the torque converter 20 delivered torque.

A method of controlling the in 1 shown drive unit of a vehicle is described below in connection with 2 and 3 described. First, in a step S210, it is determined whether there is a load change. This is done, for example, by checking whether the crankshaft speed or torque converter input speed n ₁₂ and the torque converter output speed or transmission input speed n _{22 are the} same (step S210). Another way (not shown) to detect a load change, is to close due to the measured or otherwise determined flow and / or pressure conditions in the torque converter to a load change. When there is a load change, there is no slip on the torque converter 20 in front. In a viscous torque transmission, as in a hydrodynamic torque converter 20 is present, no moment is transmitted in this state. In a load change detected in this way, the torque M _mot output by the engine is now adjusted by driving an actuating element to influence the torque output by the engine so that it _loses a loss torque M within predeterminable limits S M S _≦ M _{mot ≦} M _loss + S (step S220). As loss torque M _loss to be the sum of the moments is referred to that are not related by engine friction, the drive of auxiliary units and the like for propelling the vehicle. Then, the engine torque in a manner to be described in more detail below a torque-time curve M = f (t) is increased (step S230), so that it is a predetermined by the driver of the vehicle engine torque M _FV (see 3 . 4 ) approaches.

The above in connection with 2 described method will be described below with reference to 3 explained in more detail.

In the upper graph of the 3 For example, torque converter input speed n ₁₂ and torque converter output speed n _{22 are} plotted against time. In a coasting mode of the vehicle designated I, the torque converter output speed n _{22 is} greater than the torque converter input speed n ₁₂ . The torque converter input speed n ₁₂ , the crankshaft speed of the engine 10 is followed, in terms of its timing substantially the torque converter output speed n ₂₂ , but with a smaller value.

At a time t ₁ , the driver now gives a torque value M _FV (see the lower diagram of FIG 3 ) in front. The crank mechanism of the engine 10 is now accelerated with an increasing moment so that the crankshaft or torque converter input speed n ₁₂ increases. This results in a spontaneous response, as in 3 , upper and lower diagram. Have as soon as the torque converter input rotational speed n ₁₂ and the torque converter output speed n ₂₂ assumed the same value n ₁₂ = n _22, which is detected in step S210, the actuating elements for influencing be from the motor 10 output torque is controlled so that that of the engine 10 output torque of the torque loss _loss corresponds to M within predeterminable limits ± S: M _loss - S ≤ M ≤ M _{mot loss} + S, as in the lower half 3 is shown; the barriers ± S are shown here schematically and not to scale. In this state, no torque is transmitted by the hydraulic torque converter. This time t ₂ is assumed to be the time of the load change and the resulting load impact. Starting from the loss _torque M set in this _way , the output _{torque of} the motor M _mot is then subsequently increased taking into account a predefinable, maximum permissible gradient. The increase in the output torque is limited, for example parabolic, so that a in 3 shown tangent torque-time curve results, with which the engine torque M _{mot is} increased so that it approaches the driver predetermined torque value M _MV . As a result, a "gentle" flipping of the engine and drive train is effected in a designated with II train operation of the vehicle, thus reducing the occurrence of a load shock.

In 4 is a load change transition from train operation in the overrun mode of the vehicle shown.

In the lower diagram of the 4 the torque is plotted against time, in the upper graph, the torque converter input speed n ₁₂ and the torque converter output speed n ₂₂ are shown.

The train operation of the vehicle is shown in these graphs in the area labeled III, whereas the coasting operation is illustrated in the area of the graphs labeled IV.

In the towing mode of the vehicle, the torque converter output speed n _{22 is} below the torque converter input speed n ₁₂ . At a time t ₃ , the predetermined by the driver torque M _{FV changes} . The driver of the vehicle, for example, the gas back with the intention of operating the vehicle from this point in overrun operation. Accordingly occurs in the in the lower graph in 4 represented a jump of the driver predetermined torque M _FV to the value 0 on. From the time t ₃ is now the crank mechanism of the engine 10 delayed with a decreasing moment so that the crankshaft speed or torque converter input speed n ₁₂ decreases. The value of the torque converter input rotational speed n ₁₂ reaches the value of the torque converter output rotational speed n ₂₂ at time t ₄ , which is determined as a load change change (step S210). At time t ₄ is therefore - as described above - the actuator for influencing the of the engine 10 output torque is controlled so that that of the engine 10 output torque M _mot corresponds within the limits ± S the loss torque _loss M: M _loss - S ≤ M ≤ M _{mot loss} + S. In this state, by the hydraulic torque converter 20 no torque transmitted. Starting from the loss torque M _loss thus set, the output torque M _{mot of} the motor is then subsequently 10 taking into account a - given above - predetermined, maximum allowable gradient reduced. The reduction of the output torque M _mot , for example, parabolic, so that the in 4 shown tangent-shaped torque-time curve results, with which the engine torque M _{mot is} reduced, so that it is z. B. approaches a value predetermined by the driver. As a result, in turn, a "gentle" Umlegen the engine and the drive train from the designated III train operation in the designated IV thrust operation is possible.

The advantage of the above-described method lies in the fact that it is easy to apply. In the load change point, the powertrain has a highly nonlinear behavior. Regulations that are used at the load change point are therefore difficult to apply and there is a risk of instability. The method described above represents a pure control, so that instabilities are structurally excluded.

Claims (5)

Method for controlling a motor ( 10 ), a transmission ( 30 ) and one between the engine ( 10 ) and the transmission ( 30 ) arranged torque converter ( 20 ) having a drive unit of a vehicle that at least one operating parameter of the engine ( 10 ) is set at the occurrence of a load change so that a size that of the engine ( 10 ) to the torque converter ( 20 ) Torque characterized, first one of the loss torque of the engine ( 10 ) characterizing magnitude within predeterminable limits and is subsequently increased according to a predeterminable time profile, characterized in that the occurrence of a load change is assumed when the difference between the torque converter input speed (n ₁₂ ) and the torque converter output speed (n ₂₂ ) corresponds to a predefinable value. A method according to claim 1, characterized in that the occurrence of a load change change is assumed when the difference between the torque converter input speed (n ₁₂ ) and the torque converter output speed (n ₂₂ ) is equal to zero. Method according to one of the preceding claims, characterized in that the variable which characterizes the torque delivered by the engine to the torque converter is changed so that a predeterminable maximum amount of time of the gradient is not exceeded. A method according to claim 3, characterized in that the torque-time curve is tangent. Device for controlling a drive unit of a vehicle with an engine, a transmission and between the engine ( 10 ) and the transmission ( 30 ) arranged torque converter ( 20 ) and at least one control device ( 50 ) for influencing that of the engine ( 10 ) and at least one means ( 14 . 24 ) for detecting a load change, wherein the control device ( 50 ) if the at least one means ( 14 . 24 ) detects a load change for detecting a load change, at least one operating parameter of the engine ( 10 ) is set so that a size similar to that of the engine ( 10 ) to the torque converter ( 20 ) torque output, within predeterminable limits of a size corresponding to the loss torque of the engine ( 10 ), and subsequently increased according to a predeterminable time profile, characterized in that means are provided which assume the occurrence of a load change when the difference of the torque converter input speed (n ₁₂ ) and the torque converter output speed (n ₂₂ ) a predetermined Value corresponds.

Images