DE2938268A1 - Control for automatic transmission - uses torque-time curve with sections of different slope, to avoid jerking - Google Patents

Abstract

The control defines a torque curve for the gear's output, the curve having two or more sections of different slope. Control starts at a time defined by the point in time when the coupling laminae are applied when the gear is engaged. When the gear is disengaged, control starts at a time defined by the turbine's speed differing from the gear's output speed multiplied by the gear ratio before the beginning of the gear change. Each section of the curve has the rate of change of gear output torque constant so that a linear relationship exists between torque and time. The measured values for the throttle position and gearing output torque can be transmitted to a digital micro-computer via an a-d converter and multiplexer.

Description

Device for controlling the switching sequence of an automatic

rule step transmission prior art The invention relates to a Device according to the preamble of the main claim. One such device is from DE-OS 27 08 621 known. In the known device, when upshifting the control pressure of a closing one contained in the transmission during the shifting process Clutch controlled from a certain point in time so that the transmission output torque ideally follows a linearly rising curve until the switching process is complete is finished. Then occurs in the known device at the end of the ramp-like If the torque increases, a sharp drop in torque results, which is more uncomfortable Jerk can be felt, albeit the known device opposite to a transmission without control of the shifting process brings improvements.

Advantages of the invention In contrast, the invention has the characterizing Merkamlen of claim 1 has the advantage that the jerk is reduced during the switching process can be. This is made possible by the fact that the nominal curve has at least one has rising and at least one falling part, and is thereby it allows the amount by which the output torque at the end of the shift drops suddenly in the case of a toggle circuit, compared to the state of the art greatly decrease. The rate of change is preferably in each of the sections of the transmission output torque constant, so that in a graphic representation results in a linear relationship between moment and time; because this rate of change in addition to the absolute value of the change in torque within a certain period of time a measure for the shifting jerk can be found in the linear course described Avoid shifting jerks particularly easily. In addition, the calculation is such The process is particularly easy. The calculation can be done in such a way that for each individual switching case a sample of a torque curve in a memory of the device is included, for example the same for all traction upshifts Pattern may or may not be used and depending on the engine condition at which the switching process should take place, so depending on the absolute speed and the absolute The engine torque, which depends on the accelerator pedal position, will be the values of the Nuster expiry changed. This change takes place in the case of the linear ones described Sections by changing the slope and length of the individual curve sections.

It can prove to be advantageous if certain limit values which are not exceeded even in extreme switching cases can. These are primarily the absolute duration of the switching process; these Switching duration must not be too long to avoid excessive wear during the switching process to prevent actuated clutches. If there is a risk that this permissible period of time would be exceeded during a switching process, the switching process is therefore ended, whereby it is accepted that this creates an unpleasant shift jolt. Such a limit value, which is normally not exceeded, is only of secondary importance becomes (with the exception of the case just described) the sudden change in moment at the end of the shifting process when shifting traction up and shifting thrust down. the other sections of the torque curve are taken into account just now determined boundary conditions.

The subclaims contain advantageous developments of the invention outlined, which is partially independent of the invention described in claim 1 are usable. So the torque curve can have two parts with different slopes have, for example for a thrust upshift, or three parts of different Incline, for example for a tractive power upshift.

Parts of the torque curve should be below these parts with different slopes be understood, which correspond to a change in the moment over time, in a graphic representation do not run horizontally.

In addition, there may also be sections in which the output torque does not change over time and which therefore have a slope of 0. It is advantageous, according to the feature of claim 4, the regulation to one possible to start early and preferably during the entire switching process to regulate. Depending on whether it is the clutch that is used during the entire Switching sequence can be controlled mouse, mc one to be closed or one to be opened Coupling is, it may be advantageous according to the feature of claim 5 or of claim 6 to determine the point in time t1. In the present application The expression Eupplung used is also intended to include a brake, which is used to to set a rotatable part of the gearbox relative to the gearbox housing, because too Couplings can also be used for this purpose.

In the case of a tractive power upshift, it is important that shortly after the start the output torque is briefly reduced during the switching process. Lower this ab lasts up to a point in time t2, which is determined according to the features of claim 7 is, then the output torque increases again at the output of the transmission. This determination of the point in time t2 by a speed comparison is very exact. It can be particularly advantageous when shifting traction upshifts and downshifting thrust be to proceed according to the feature of claim 8 and hierc'jrch the switching jerk to diminish. The embodiment according to claim 9 is advantageous because it allows the switching process to be kept as short as possible can without the shifting jolt being perceived as too strong. In some switching cases it is necessary to open another clutch at the same time coupling close. It has been shown that in this case it is beneficial to reduce the pressure to steer exactly in opposite directions in the two clutches. This can happen in individual cases however, it may be useful to check the pressure changes per unit of time in the two clutches not to make the same size, but to make the pressure changes proportional to each other do. This embodiment can be realized particularly easily by that to a control device regulating the pressure of one clutch, a reversing amplifier is coupled, which is used to influence the pressure of the other clutch will. The embodiment according to claim 11 makes it possible in an advantageous manner determine whether the accelerator pedal position was changed during the shift. If, for example, the gas pressure gauge is depressed much more strongly during the switching process, so there is the possibility that a rotating part of the transmission, which is through a engaging clutch is to be slowed down slowly, in turn accelerated will. Under these circumstances, the switching process could not be as short as desired Duration to be carried out to the end. By the monitoring device this is State recognized and appropriate measures can correct the termination of the switching process can still be effected, for example by the fact that the pressure in said clutch is enlarged accordingly.

Drawing An embodiment of the invention is shown in the drawing and explained in more detail in the following description. It shows Fig. 1 is a schematic representation an automatic planetary gear with flow converter to which the invention is applied, Fig. 2 is a schematic Representation of the drive motor with gearbox and one of the gearshift operations of the gearbox controlling control unit, FIG. 3 is a schematic representation of the control unit from FIG Fig. 2, Fig. 4 the chronological sequence of a shift process in a tractive force upshift, FIG. 5 shows a representation of the torque curve corresponding to FIG. 4 in a Thrust downshift and FIG. 6 shows the torque curve during a tractive force downshift in a representation corresponding to FIG. 5.

Description of the Embodiment In that shown in FIG Gearbox diagram of the automatic 3 HP 22 gearbox from Zahnradfabrik Friedrichshafen drives the input shaft 1 of a flow converter to be coupled to the drive motor 2 the pump 3 of the converter, via which the turbine 4 is set in motion, which is connected to the transmission input 5 of the planetary gear 6. The planetary gear has two sun gears 7 and 8, two outer gears 9 and 10, and two webs 11 and 12 with associated planetary gears 13 and 14, respectively. The planetary gear 6 has also freewheels 15 and 16. These gear parts are in the connected in the manner shown in Fig. 1 and also parts of the transmission are through hydraulically actuated clutches A, B, C, CF and D, which are also shown in FIG. 1 are rotatably connectable to each other or to parts of the housing. The transmission output 20 is with the driven wheels of a not shown Motor vehicle, in which the transmission is installed, coupled. Clutch A is in first gear closed, so transmits power, and when the gearbox selector lever is in position 1 is, upshifting to second and third gear is prevented In addition, clutch D is closed. The clutches A, C are in second gear and CF closed. In third gear, clutches A, B and CF are closed and in reverse the clutches B and D are closed.

As shown in FIG. 2, an internal combustion engine 22 drives via the converter 2 and the transmission 6 to the drive wheels 23 of a motor vehicle. A transmission control unit 25 signals about the position via input lines in the manner shown of the selector lever 26 and other signals supplied, also via transducers 27 to 31 measured values about the throttle valve position of the motor 22, the pump speed, the Turbine speed, the output speed of the transmission 6 or the output torque on Transmission output. The transmitter 27 is designed as a resistance transmitter, the rest Encoders deliver a speed-dependent, pulse-shaped signal, with the phase shift two speed sensors contained in the encoder 31 is the measure for the output torque. Since the motor is directly coupled to the pump, the pump speed is the same as that Engine speed. Electrical control lines 33 lead from the control unit to electromagnetic ones Pressure regulators, which are arranged within the housing of the transmission 6 and the Regulate the pressure applied to the various clutches. aside from that lead control lines 34 to solenoid valves in the housing of the transmission 6, which the Connect the pressure regulator to the clutches to be actuated; instead can a separate pressure regulator can be provided for each coupling Fig. 3 shows the control device 25 in a simplified block diagram. The input signals, among other things for the selector lever position and the different speeds fed to an input of a computing device 41 via a signal processor 40, which is designed as a small digital computer. The measured values for the throttle valve position and the transmission output torque Mab are via an analog-digital converter and Multiplexer 42 is fed to another input of the computing device.

In the computing device 41 are the various in FIGS. 4 to 6 shown curve profiles of the transmission output torque Mab are stored, and The computing device 41 determines when as a function of the input signals a switching process must be triggered, and it then controls the switching process, in particular the pressures in the various clutches to be actuated. An output of the computing device 41 leads via a digital-to-analog converter 45 to the input of a PID controller 46, the output of which on the one hand with an input of a Auxiliary amplifier 47 and on the other hand via a feedback inverting amplifier 48 is connected to one input of a power amplifier 49, the other Input via a digital-to-analog converter 50, an amplifier 51 and a switch 52 an output signal of the computing device 41 is fed. A capacitor 53 When the switch 52 is closed, the output voltage of the amplifier is constantly adjusted 51 is charged and holds this voltage value when the switch 52 is opened will. The output of amplifier 49 is fed back to the input of amplifier 51. The wiring of the inverting amplifier 48 in the manner shown with resistors R1 and R2 cause the inverting amplifier 48 to have a gain of value -R2 / R1 has.

With the outputs of amplifier 47 and 49, the inputs are one Switching device 55 and 56 connected. which can be controlled by the computing device 41 are and the switching of the output signal of the amplifier 47 to one of the Clutches A to D have an effect, and with certain gear changes also the output signal of the amplifier 49 switch through to one of the clutches A to D, but to one other clutch than the switching device 55. The PID controller 46 is through a Switch 57, which, like switch 52, is actuated by computing device 41 is, between two operating states with different steepness of the proportional range switchable.

4 shows the course over time for a tractive force upshift of the transmission output torque Mab, which is required to reduce the shift jerk as much as possible to keep it small. In addition, in Fig. 4, the pressure curves within a Switching process within a relatively short time to be disengaged clutch and one during of the shifting process to be closed, which is only at the end of the shifting process is completely closed, shown. With tO to t5 there are different for the switching sequence indicates important points in time, the meaning of which is explained below.

t0 is the point in time at which it is recognized that a shift is necessary will. Depending on the current switching case, the computing device 41 the switching device 55 and / or 56 switched so that the output signals of the Amplifier 47 and 49 reach the clutches to be switched.

In the period between t0 and t1, the electrical control current is of the pressure regulator of the clutch to be closed is set to the pilot control value, which corresponds to 100 to 110% of the filling pressure. This causes the slats the coupling can easily come into contact with one another without, however, noticeably Transfer moment. The control current of the pressure regulator of the clutch to be disengaged is lowered from a relatively high safety pressure to the value of about 110% of the pressure required for the moment to be transmitted.

The current transmission output torque Mab is also determined and depending on the driving condition (engine speed and throttle position) and Depending on the switching case, this is at the end of the switching according to the point in time t5 torque to be expected nab is determined.

It becomes Mab for the time t4 according to the formula Mab (t4) = Mab (t5) + M; DM 5 f (gear, n) determined. The difference between Mab (t5) and Mab (t4) becomes dimensioned in such a way that this sudden momentum jump occurring within a short period of time is not perceived as an annoying jolt.

Using the value Mab (t4) and the preset as a template Curve for Mab, as shown in Fig. 4, Mab between tl and t2 a descending area, then an ascending area and between t3 and t4 has a falling area again, the torque slopes in these three areas depending on the type of shift and driving condition calculated. The probable values for the times t1 to t5 are also calculated. The control current of the pressure regulator of the clutch to be disengaged is preset to be smaller Incline further lowered. In addition, the Turbine speed nT, which is the same as the transmission input speed, with the value iv x nab compared.

tl is in the case where the clutch to be closed is mainly is responsible for the course of the moment Mab, determined by the fact that in this Coupling 1OC to 110% of the filling pressure can be achieved.

In a circuit case in which an openable clutch for the The torque curve is decisive, so it is only complete at the end of the shifting process is open, the time tl is determined by the fact that there is a discrepancy between the turbine speed nT and the value iv x nab is determined.

At time tl, the control of the transmission output torque Mab switched on in order to achieve that the actually existing output torque the corresponds as precisely as possible to the output torque specified by the curve according to FIG. It is regulated according to the moment-time Eurve; because this scheme with high Speed, the precalculated Zeitp-mckte t1 to give way t5 at most of the times t1 to t5 that can actually be determined by measurement slightly from; these deviations therefore make it not mandatory, to correct the gradients calculated for the individual parts of the torque curve. On the other hand, depending on the switching case, it is necessary to have one or more of the times t1 to t5 to be measured exactly, so that the necessary switching operations in Gearbox and / or switching the control of the torque curve to a range another slope takes place at the right time; for example it is necessary the switching of the control for the torque curve Mab according to FIG. 4 from the falling one Range between times t1 and t2 to the increasing range after Point in time t2 exactly at the measured point in time t2, the definition of which will be explained below will make.

In the period t1 to t2, the speed nT is constantly with the value iv x nab compared. The point in time t2 is thereby in the case of a tractive force upshift determines that the speed nT deviates from the value iv x nab; this time becomes t2 only required if a clutch to be closed is decisive for the shift sequence is.

In the period between t2 and t3, the speed of change is the turbine speed nT is determined and monitored. The time t3 is defined by that a speed comparison shows that the ratio nT / nab one by the computing device 41 has reached the previously determined value.

This value is taking into account the driving speed and thus the speeds of the individual transmission parts at the beginning of the shift and taking into account the switching case selected so that the clutch to be closed, their printing, as shown in FIG. 4, at this point in time is over 100%, already a large part of the switching process due to changes in the speed of parts The kinetic energy released by the gearbox and the gearbox input is reduced Has. As soon as time t3 is determined by measurement, the computer switches the control so that the output torque Mab now drops as shown in FIG.

In the period between t3 and t4 it will now decrease with time Output torque is constantly monitored to see whether it is even greater than that for the Output torque calculated at time t4.

The time t4 is determined by the fact that the output torque Mab has reached the value Mab (t4).

In the time period t4 to t5, the output torque becomes the described Switching case normally held at the value Nab (t4). It also becomes a control of the switching process a value A n = nT - was calculated (nT and nab are the rates of change the speed nU or nab).

If ß n exceeds an upper limit value, this leads to an excessively large torque jump or a lower limit value, which would result in too long a grinding time would intervene in the torque control loop and the pressure in the relevant Coupling corrected so that the relevant limit values are no longer exceeded will.

The value t n can, for example, deviate from its nominal value if the Shifting takes place on a steep incline or on a steep incline.

During the period t4 to t5, the speed nT is also with compared to the value in x nab.

The time t5 is determined by nT = in x nab.

At this point the control is switched off and the The pressure of the clutch to be closed is brought to the safe working pressure by the control.

So far it was assumed that the accelerator pedal position during of the switching process remains unchanged. To record changes of this kind, is checked during the entire period between tl and t5 during the control process, whether the moment M acting on the turbine is? changes. MIT is a function of Throttle position, engine speed and turbine speed. This moment can go through Measurement or can be determined by calculation. If fiT changes, the setpoint of Mab at time t4 and at time t5 as well as during the whole The rule sequence that occurs after the change in NT has occurred. The amount by which the nominal value of the torque Mab is changed is in x fiT, is therefore proportional to the change a MT of the turbine torque; who so changed The torque curve results from the torque curve shown in FIG. 4 a parallel shift in the vertical direction. The place of transition from the torque curve in FIG. 4 corresponds to the torque curve shifted in parallel depending on the rate of change of the accelerator pedal position more or less strongly noticeable acceleration jolt or deceleration jolt, which can also be felt, if there is no switching process.

If, due to measurement problems, it is not possible to set the point in time t2 at To determine an upshift exactly, a comparison is made between the drive torque and the control current of the pressure regulator for the clutch to be closed. If both values correspond to a threshold value to be specified, then the control process is interrupted and the pressure of the clutch to be closed for as long raised with a constant slope until there is a speed difference between the speed nT and the value iv x nab can be measured.

In the description just given, the following indices are used: Turbine, corresponds to gear input from: gear output in: gear ratio after the shift iv: transmission ratio before the shift.

Fig. 5 shows the torque curve for a thrust backshift. As shown, it is not necessary here to determine time t2. The moment Mab rises from the point in time t1 to the point in time t3 and falls again from there at time t4 and then remains constant until time t5, at which it suddenly occurs drops to a lower value, as also in FIG. 4, FIG. 6 shows the torque curve for a pull-back switch with pulling force reduction. This is where the moment takes Mab decreases sharply from time t1 to time t2 and remains then constant up to point in time t3 or increases or decreases up to this point in time up to this point in time, as shown by three different curves is. From time t3 to time t5, the torque continues to rise and remains then constant.

The time t4 is therefore not required here. With this moment curve, in which the output torque Mab is relatively low at time t2, for example 30% of the value before the start of the switching process, the drive motor has the option of because of the extensive decoupling of the masses to be accelerated, the speed quickly increases which is required after the end of the switching process.

The arrangement according to FIG. 3 can also be modified in such a way that that through the switch 57 the output of the PID controller 46 before the start of the switching process and at the end of the switching process at the level corresponding to the safety pressure is being held. During the switching process, the switch 57 is opened. the different gradients of the torque curve are realized that the PID controller 46 from the computer 41 via the digital-to-analog converter 45 different Input voltages are supplied.

Claims (12)

Claims 1. Device for controlling the switching sequence of an automatic Multi-step transmission with a device for generating a predetermined torque curve, whose slope is selected depending on the respective switching state, and with a device for comparing this course with the actual moment at Transmission output which, depending on the comparison result, actuated a hydraulically The clutch of the transmission controls so that the actual torque is the given Moment approximates, characterized in that the predetermined omenten curve in several Sections that connect to one another and whose steepness is different is selectable, and that the times (t2, t3, t4) for the transition between two Sections of the torque curve depending on measured torque values and / or Speed readings are determined. 2. Apparatus according to claim 1, characterized in that the torque curve two parts different Has slope. 3. Apparatus according to claim 1, characterized in that the torque curve has three parts of different slope. 4. Device according to one of the preceding claims, characterized in that that the control of the output torque begins at a point in time t1, in which a closing clutch, which is decisive for the shifting process, begins to engage or in the case of a clutch to be disengaged which is decisive for the shifting process, the clutch starts to open. 5. Apparatus according to claim 4, characterized in that at one to be closed clutch the time tl is determined by the fact that the pressure in the hydraulically operated clutch, the filling pressure level slightly, preferably by 10%. 6. Apparatus according to claim 4, characterized in that at one to be disengaged clutch the time tl is determined by the fact that the turbine speed nT of the output speed multiplied by the gear ratio before the start of the shift of the transmission deviates. 7. Device according to one of the preceding claims, characterized in that that a point in time t2, towards which the torque curve drops from the point in time tl, in the case of an upshift, for the shifting sequence of which a clutch to be closed is decisive is determined by the fact that the turbine speed nT is determined by that with the transmission ratio output speed multiplied before the start of the switching process deviates. 8. Vo-direction according to one of the preceding claims, characterized in that that a point in time t3, from which on the starting moment in a traction upshift and a thrust downshift drops, is determined by the fact that the speed ratio nT / nab reaches a predetermined value. 9. Device according to one of the preceding claims, characterized in that that from a point in time t4 to the output torque until the end of the switching process is kept constant. 10. Apparatus according to claim 9, characterized in that from the time t4 to the difference An = nT - nab is determined and the output torque is controlled in this way is that the value ß n remains within two predetermined limit values. 11. Device according to one of the preceding claims, characterized in that that a controller is provided for opposing control of two clutches, whose Output with one coupling and through a reversing amplifier (48) with the other Coupling is coupled. 12. Device according to one of the preceding claims, characterized in that that the transmission input torque is continuously determined during a shift and when the transmission input torque changes, the specified course of the transmission output torque is adjusted accordingly.