Method for controlling the shifting of an automated dual clutch transmission

The invention relates to a method for the shift control of an automated double clutch transmission, comprising a first partial transmission with a first transmission input shaft, a first motor clutch, and a first group of gears and a second partial transmission with a second transmission input shaft, a second motor clutch, and a second group of gears, With which a shifting operation between a load gear and a target gear assigned to the same sub-transmission is effected as a multiple gear with the shifting steps, the clutch change from the motor clutch of the load gear to the motor clutch of the intermediate gear, the load gear setting, Clutch changeover from the motor clutch of the intermediate gear to the motor clutch of the target gear, and with which the motor speed of the assigned drive motor is guided to the synchronous speed of the target gear at the end of the shifting operation.

US Pat. No. 5,915,512 discloses a transmission having the features of the preamble of claim 1

The design of the double clutch transmission has long been known, for example from DE 35 46 454 A1, in which a gear shift transmission for a motor vehicle with double clutch is proposed. The dual clutch transmission has a first motor clutch, a first transmission input shaft, and a first group of gears forming a first sub-transmission and a second motor clutch, a second transmission input shaft, and a second group of gears that form a second sub-transmission. By placing one of the gears, the respective transmission input shaft can be connected to a common transmission output shaft. In the case of the usual reciprocal assignment of the gears, in which the straight gear ratios are assigned to the one partial transmission and the uneven gears are assigned to the other partial transmission, a simple sequential shifting operation from an inserted load gear into a next higher or next lower speed gear train assigned to the other sub- In the case of a clutch which can be passively closed, in an opening of the motor clutch assigned to the partial transmission of the target gear, in an engagement of the target gear, and in a subsequent overlapping opening of the motor clutch assigned to the partial transmission of the load gear, and closing of the motor clutch assigned to the partial transmission of the target gear. Thus, the force transmission takes place alternately via the first partial transmission with the first motor coupling and the first transmission input shaft, and via the second partial transmission with the second motor coupling and the second transmission input shaft, wherein no pull or thrust force interruption takes place as a particular advantage during the change of the gear Type of the power-shift gearbox. Since manual mechanical actuation of two motor clutches and the shifting of the gears with temporarily two simultaneously inserted gears would require a considerable mechanical outlay, double clutch transmissions, if known, are designed to be automated, ie both the actuation of the motor clutches and the shifting of the gears via assigned actuating drives Which can be electromagnetically, electromotorically, pressure-medium-like, for example, hydraulically, or in a different manner.

In certain operating situations which are essentially caused by a sudden change in the road inclination, for example a transition from a horizontally extending road into a steeply rising road, and / or the driver's power requirement, for example a rapid passage of the accelerator pedal to achieve a rapid acceleration (kick-down ), A simple sequential shift may not be sufficient to meet the requirements of the engine and transmission control and / or the driver. In this case, a shifting process is required in which at least one gear is skipped, ie, the load gear and the target gear are assigned to the same sub-transmission. To avoid a pull or thrust force interruption in this case as well, such a shifting operation is preferably performed as a so-called multiple circuit, using an intermediate gear assigned to the other partial transmission.

In order to carry out such a multiple circuit as quickly as possible, the required speed adaptation, ie the adaptation of the motor speed to the synchronous speed of the target gear effective in the associated motor coupling, is already carried out during the shifting process. In this case, a desired speed gradient is specified, according to which the motor speed is guided to the synchronous speed of the target gear by means of the motor control and / or the overlap control of the motor clutches at the end of the shifting operation. If the actual switching progress, ie the timing of the individual switching steps, and the resulting total switching time correspond to the estimated total switching time, the motor speed reaches the synchronous speed of the target gear exactly at the desired time. The partial switching times of the individual switching steps and thus also the total switching time of the multiple circuit can not be predicted precisely, because of changing operating conditions, in particular different operating temperatures, and by wear on the motor clutches and the shifting and synchronization elements of the transmission. The engine speed therefore generally does not change the synchronous speed To the desired time. If the shifting process, ie, the execution of the individual shifting steps, takes place faster than expected, the shifting sequence is preceded by the speed adaptation, ie, at the end of the shifting process, a waiting time must be accepted in which the engine speed still passes through the remaining speed difference to reach the synchronous speed . If, on the other hand, the shifting process is slower than expected, the speed adjustment is in advance of the gear sequence, ie, at the end of the shifting operation, the engine speed must remain at the synchronous speed of the target gear reached too early until the shifting process is completed. In the first case, a real deceleration of the entire circuit sequence occurs; in the second case, only one apparent deceleration of the circuit sequence, which may be perceived as an unpleasant phenomenon due to the temporarily constant engine speed.

It is therefore the problem of the present invention to provide a method for controlling such a circuit process, which is defined at the outset, with which the speed adaptation can be improved and the known deficiencies can be avoided.

The problem is solved according to the invention in conjunction with the preamble of claim 1 in that, at the beginning of the switching process (t = t₀) An initial target speed gradient (dn_M/ Dt)₀ With which the motor speed n_M At an estimated total switching time Δt_SΣ'The synchronous speed n_MS To the end of the shifting operation, the engine speed n is reached_M Of the drive motor at the beginning of the shifting operation is initially started according to the predetermined initial setpoint speed gradient (dn_M/ Dt)₀ During the switching process, the actual switching progress is determined and compared with the estimated switching progress, and that the desired rotational speed gradient dn_M/ Dt is adapted to the actual switching progress with a detected deviation of the switching progress.

Advantageous refinements of the method according to the invention are listed in the subclaims 2 to 12.

The engine speed n_M Is thus first determined according to the predefined initial target rotational speed gradient (dn_M/ Dt)₀ Controlled or regulated to the synchronous speed n_MS Of the target gear, and reaches this at the desired point in time at the end of the shifting operation, as long as the actual shift progress, ie the timing of the shifting operation or the individual shifting steps S1-S5, corresponds to the estimated shift progress. However, if there are delays or accelerations in the circuit sequence, eg due to changed operating conditions, such as extreme operating temperatures or wear on shifting and synchronization elements, these deviations are detected by the method according to the invention and by the adaptation of the desired rotational speed gradient dn_M/ Dt. When the shift progress is determined in comparison with the estimated shift progress, the desired speed gradient dn_M/ Dt is accordingly increased in magnitude and reduced in magnitude with a determined slower switching progress. This causes the engine speed n_M The synchronous speed n_MS At the right time at the end of the switching process. A waiting period usual in the prior art with a faster shifting progress until the engine speed n_M The synchronous speed n_MS Is thus avoided. In the reverse case, a phase which is customary according to the prior art in the case of a slower shift progress, in which the engine speed n_M On the synchronous speed n_MS Must be kept largely constant. The method according to the invention ensures that the circuit sequence of the multi-circuit explained at the outset is executed as quickly as possible and as conveniently as possible. The method according to the invention is preferably used for carrying out a pullback, but is also applicable in the case of a drawbar shifting, a thrust reversing, and a thrust boosting.

The adaptation of the desired rotational speed gradient dn_M/ Dt is expediently performed by the fact that the previously valid desired rotational speed gradient dn_M/ Dt by a corrected target rotational speed gradient (dn_M/ Dt)_cor With which the engine speed n_M At an estimated residual switching time Δt_SR'The synchronous speed n_MS To the end of the switching process.

Since a continuous check of the switching progress and a quasi-continuous adaptation of the desired rotational speed gradient dn_M/ Dt would be too expensive, the determination of the switching progress and the need for adaptation of the desired rotational speed gradient dn_M/ Dt is advantageously performed after the end of each switching step S1-S4. Since, however, a correction of the desired rotational speed gradient dn_M/ Dt no longer makes sense after the last switching step S5, the adaptation takes place only up to the penultimate switching step S4. Minor deviations of the engine speed n_M Of the synchronous speed n_MS At the end of the switching process, which may be due to deviations of the switching progress in the last switching step S5 must be tolerated.

The initial target speed gradient (dn_M/ Dt)₀ Can be carried out in a simple manner at the beginning of the shifting process by detecting the instantaneous engine speed n_M0 And the synchronous speed of the target gear n_MS And by a quotient formation of the difference between the synchronous rotational speed n_MS And the initial engine speed n_M0 And a previously known estimated total switching time Δt_SΣ'((Dn_M/ Dt)₀ = (N_MS - n_M0) / Δt_SΣ' ) be determined. For this purpose, the estimated total switching time Δt_SΣ'As the sum of the estimated partial switching times Δt_Si'Of the individual switching steps S1-S5 (Δt_SΣ'= Σ Δt_Si', I = 1-5). The estimated total switching time Δt_SΣ'And / or the estimated partial switching times Δt_SiAre determined beforehand, ie, during the development of the relevant double clutch transmission or of the motor vehicle, in test bench and / or driving tests, and are stored in a transmission data store from which they can be read out as required.

Similarly, the corrected target speed gradient (dn_M/ Dt)_cor In a simple manner by detecting the instantaneous engine speed n_M And by a quotient formation of the difference between the synchronous rotational speed n_MS And the current engine speed n_M And a previously known estimated residual switching time ΔT_SR'((Dn_M/ Dt)₀ = (N_MS - n_M) / Δt_SR') be determined. For this purpose, in a discontinuous procedure, ie an adaptation of the desired rotational speed gradient dn_M/ Dt at the end of each switching step S1-S4, the estimated residual switching time Δt_SR'As the sum of the estimated partial switching times Δt_Si'Of the individual, still outstanding switching steps SI + 1 - S5 (Δt_SR'= Σ Δt_Si', I = I + 1 - 5).

Through running-in processes and wear on switching and synchronization elements in the double-clutch transmission, it can lead to permanent shifts of the partial switching times Δt in the course of the operating time or life_Si And thus the residual switching times Δt_SR And the total switching time Δt_SΣ come. In order to avoid larger corrections of the desired rotational speed gradient,_nM/ Dt, in particular during the first switching steps, it is therefore sensible to store the stored values ​​of the estimated total switching time Δt_SΣ'And / or the estimated residual switching times Δt_SR'And / or the estimated partial switching times Δt_Si'For deviations of the switching progress by means of the values ​​of the actual switching times Δt_SΣ or Δt_SR or Δt_Si to correct. Such an adaptive correction can be achieved in the simplest case in that the stored values ​​of the estimated switching times Δt_SΣ'Or Δt_SR'Or Δt_Si'By the values ​​of the actual switching times Δt_SΣ or Δt_SR or Δt_Si be replaced. For the purpose of eliminating statistical outliers, however, it is better if the stored values ​​of the estimated switching times Δt_SΣ'Or Δt_SR'Or Δt_Si'By means of a correction function with the values ​​of the actual switching times Δt_SΣ or Δt_SR or Δt_Si Getting corrected.

Since the clutch change from the motor coupling of the intermediate gear to the motor clutch of the target gear at a constant engine speed n_M Can be controlled more easily and more quickly, the initial nominal speed gradient (dn_M/ Dt)₀ And the corrected target rotational speed gradients (dn_M/ Dt)_cor Expediently determined such that the engine speed n_M The synchronous speed n_MS To the end of the penultimate switching step S4. In the sense of the previous description of the method according to the invention, the penultimate switching step S4 is then regarded as the last switching step and the end of the penultimate switching step S4 is regarded as the end of the switching process.

Further details of the invention will become apparent from the following detailed description and the appended drawings which are given by way of example to explain the control method according to the invention.

For this purpose, <dl id="dl0001"><dt>FIG</dt><dd>The motor speed sequence in the case of a circuit process according to the invention, in the form of a time diagram, FIG</dd><dt>FIG</dt><dd>The motor speed sequence in a circuit diagram according to the prior art, in the form of a time diagram.</dd></dl>

FIG. 2 shows the chronological sequence of a pull-back shifting of a double-clutch transmission, which is implemented as a multiple circuit of the initially defined type and proceeds according to the state of the art. For this purpose, FIG. 2 shows the course of the motor speed n_M Of an assigned drive motor over the time t during the switching process, which comprises a total of five switching steps. In the first switching step S1, the transition is engaged, in the second switching step S2, the clutch change takes place from the motor clutch of the load gear to the motor clutch of the intermediate gear, the load gear is designed in the third shifting step S3, and the fifth gear step S5 is engaged in the fourth shifting step S4 The clutch is changed from the motor coupling of the intermediate gear to the motor coupling of the target gear. Since the last clutch change can be controlled more easily and more quickly with a constant engine speed, it is provided that the engine speed n_M The synchronous speed n_MS Of the target gear reaches already at the end of the penultimate shifting step S4. The last clutch change can then take place at a virtually constant engine speed, namely the synchronous speed n_MS, Respectively.

The switching process begins at time t₀ And will end at the time t₅. A prerequisite for this is, however, that the individual switching steps S1-S5 are executed as scheduled, ie S1 between t₀ and t₁ With the estimated time duration Δt_S1', S2 between t₁ and t₂ With the estimated time duration Δt_S2', Etc., and thus the entire switching process in the provided time interval .DELTA.t_SΣ'. The total switching time Δt_SΣ', Which results from the sum of the provided partial switching times Δt_Si', I = 1-5, is, in addition to the rotational speed difference between the synchronous rotational speed n_MS And the engine speed at the beginning of the shifting operation n_M0 The basis for the determination of a desired rotational speed gradient dn_M/ Dt, according to which the motor speed n_M During the switching process to the synchronous speed n_MS to be led. On account of the above, the speed adjustment takes place during the switching steps S1 to S4, ie, the penultimate switching step S4 is viewed as the last switching step (Δt_SΣ'= ΣΔt_Si', I = 1 - 4).

If the switching progress, ie the actual time duration Δt, corresponds_Si Of the individual switching steps S1 to S4 or the actual total switching time Δt_SΣ, The anticipated shift progress, ie Δt_Si = Δt_Si'Or Δt_SΣ = Δt_SΣ', The motor speed n reaches_M With the desired rotational speed gradient dn_M/ Dt at exactly the desired time, namely the end of switching step S4, the synchronous rotational speed n_MS Of the finish (t_S = t₄). The corresponding speed profile is represented by curve 1 (solid line). However, this ideal case rarely corresponds to reality. Due to changed operating conditions, such as different operating temperatures and wear on circuit and synchronization elements of the respective transmission, there is in practice deviations of the timing of the shifting process.

In the following, two such cases are exemplified. In case A, the entire switching process runs faster than expected because the actual time duration Δt_S2 Of the second switching step S2 is shorter than expected (Δt_S2 &lt;Δt_S2'). Accordingly, the fourth switching step S4 is already at time t_4A Whereas the motor speed n_M Corresponding to curve 2 (= curve 1), the synchronous rotational speed n_MS Only at time t₄ reached. Thus, there is a waiting time Δt_WA, In which the further circuit sequence is based on the reaching of the synchronous rotational speed n_MS Must wait. The ideal rotational speed profile (desire) would in this case be represented by curve 2 '(dashed line). In case B, the entire switching process runs slower than expected because the actual time duration Δt_S2 Of the second switching step S2 is longer than expected (Δt_S2 &gt; Δt_S2'). As a result, the fourth switching step S4 is not performed until the time t_4B Whereas the motor speed n_M Corresponding to curve 3, the synchronous rotational speed n_MS Already at time t₄ reached. The engine speed n_M Must in this case be approximately constant at the synchronous speed n_MS Until the fourth switching step S4 is completed. This does not result in a real deceleration of the circuit, but an apparent waiting time Δt felt by the driver as a result of the time-constant constant engine speed_WB. The ideal rotational speed profile (desire) would in this case be represented by curve 3 '(dash-dotted line).

On the other hand, the same switching process takes place according to the method according to the invention as shown in FIG. First, an initial target rotational speed gradient (dn_M/ Dt)₀ , With which the engine speed n_M While maintaining the estimated total switching time Δt_SΣ'The synchronous speed n_MS To the end of the switching process, ie, at the end of the fourth switching step S4 (see curve 1, 1a / solid line). After this initial target speed gradient (dn_M/ Dt)₀, Which, as indicated, is the quotient of the difference between the synchronous speed n_MS And the initial engine speed n_M0 And a previously known estimated total switching time Δt_SΣ'Can be calculated ((dn_M/ Dt)₀ = (N_MS - n_M0) / Δt_SΣ'), The motor speed n_M Of the drive motor at the beginning of the shifting process. After the end of each switching step S1-S3, the actual switching progress is determined and compared with the estimated switching progress. In the case of a detected deviation of the switching progress from the estimated switching progress, ie a substantial deviation of the actual partial switching time Δt_Si From the estimated partial switching time Δt_Si'Of the just completed switching step, the desired rotational speed gradient dn_M/ Dt which is initially identical to the initial target speed gradient (dn_M/ Dt)₀ Is adapted to the actual switching progress. This is expediently achieved by the fact that the previously valid desired rotational speed gradient dn_M/ Dt by a corrected target rotational speed gradient (dn_M/ Dt)_cor With which the engine speed n_M When an estimated residual switching time Δt is maintained_SR'The synchronous speed n_MS To the end of the switching process.

For the purpose of illustrating the method according to the invention in FIG. 1, two cases are shown by way of example, as previously described in FIG. 2 for the prior art. In case A, the entire switching process runs faster than expected because the actual time duration Δt_S2 Of the second switching step S2 is shorter than expected (Δt_S2 &lt;Δt_S2'). This deviation, however, is now determined after the completion of the second switching step S2 at time t_2A detected. Thereupon the previously valid desired rotational speed gradient, after which the engine speed has been changed so far, is corrected by a corrected setpoint rotational speed gradient (dn_M/ Dt)_cor With which the engine speed n_M Corresponding to curve 2a (dotted line), the synchronous rotational speed n_MS Exactly at the desired time t_4A To which the switching operation (without the fifth switching step S5) is prematurely terminated. The corrected target speed gradient (dn_M/ Dt)_cor Is larger in magnitude and, as indicated, can be expressed as the quotient of the difference between the synchronous speed n_MS And the current engine speed n_M2A And a previously known estimated residual switching time ΔT_SR'Can be calculated ((dn_M/ Dt)_cor = (N_MS - n_M2A) / Δt_SR'), The estimated residual switching time Δt_SR'In the present case is the sum of the estimated partial switching times of the switching steps S3 and S4 (ΔT_SR'= Δt_S3'+ Δt_S4').

A waiting time Δt which is customary according to the prior art_WA (See FIG. 2), in which further circuit sequence for reaching the synchronous rotational speed n_MS Must now be avoided. The actual rotational speed profile for case A results from the juxtaposition of the partial curves 1a, 2a, and 2.

In case B, the entire switching process runs slower than expected because the actual time duration Δt_S2 Of the second switching step S2 is longer than expected (Δt_S2 &gt; Δt_S2'). The occurring deviation is determined again after the conclusion of the second switching step S2 at time t_{2 B} detected. The previously valid target speed gradient is then corrected by a corrected target speed gradient (dn_M/ Dt)_cor With which the engine speed n_M Corresponding to curve 3a (dot-dashed line), the synchronous rotational speed n_MS Exactly at the desired time t_4B To which the switching operation (without the fifth switching step S5) is terminated late. The corrected target speed gradient (dn_M/ Dt)_cor Is reduced in magnitude and can be stored as before as a quotient of the difference between the synchronous speed n_MS And the current engine speed n_MB And the previously known estimated residual time Δt_SR'Can be calculated ((dn_M/ Dt)_cor = (N_MS - n_M2B) / Δt_SR'). An apparent waiting time Δt according to the prior art_WA (See FIG. 2), in which the engine speed n_MS Must be kept largely constant in order to wait for the end of the switching process or the conclusion of the fourth switching step S4 is now also avoided. The actual rotational speed profile now results from the juxtaposition of the partial curves 1 a, 3 a, 3.

Through the application of the control method according to the invention, which makes it possible to check the switching progress and a required adaptation or correction of the desired rotational speed gradient dn_M/ Dt at least after each switching step, it can thus be achieved that, in the case of a double clutch transmission in the case of a multiple shifting of the initially defined type, the shifting process itself, ie the engaging and disengaging of the engaged gears and the first clutch change, and the parallel speed adjustment largely terminate at the same time will.

REFERENCE LIST

<dl id="dl0002" compact="compact"><dt>n_M</dt><dd>Motor speed</dd><dt>n_M0</dt><dd>n_M At the beginning of the switching process</dd><dt>n_M2A</dt><dd>n_M To the end of switching step S2 in case A</dd><dt>n_M2B</dt><dd>n_M To the end of switching step S2 in case B.</dd><dt>n_MS</dt><dd>Synchronous speed</dd><dt>S1</dt><dd>first switching step</dd><dt>S2</dt><dd>second switching step</dd><dt>S3</dt><dd>third switching step</dd><dt>S4</dt><dd>fourth switching step</dd><dt>S5</dt><dd>fifth switching step</dd><dt>SI</dt><dd>I-th switching step, current switching step</dd><dt>SI + 1</dt><dd>(I + 1) -th switching step, next switching step</dd><dt>t</dt><dd>time</dd><dt>t₀</dt><dd>T at the beginning of the switching process</dd><dt>t₁</dt><dd>T to the end of S1 (estimated)</dd><dt>t₂</dt><dd>T to the end of S2 (estimated)</dd><dt>t_2A</dt><dd>T to the end of S2 (is case A)</dd><dt>t_{2 B}</dt><dd>T to the end of S2 (is case B)</dd><dt>t₃</dt><dd>T to the end of S3 (estimated)</dd><dt>t_3A</dt><dd>T to the end of S3 (is case A)</dd><dt>t_3B</dt><dd>T to the end of S3 (is case B)</dd><dt>t₄</dt><dd>T to the end of S4 (estimated)</dd><dt>t_4A</dt><dd>T to the end of S4 (is case A)</dd><dt>t_4B</dt><dd>T to the end of S4 (is case B)</dd><dt>t₅</dt><dd>T to the end of S5 (estimated)</dd><dt>t_S</dt><dd>T, to which n_MS is reached</dd><dt>Δt_S1</dt><dd>Time duration of S1 (is)</dd><dt>Δt_S1'</dt><dd>Time duration of S1 (estimated)</dd><dt>Δt_S2</dt><dd>Time duration of S2 (is)</dd><dt>Δt_S2'</dt><dd>Time duration of S2 (estimated)</dd><dt>Δt_S3</dt><dd>Time duration of S3 (is) </dd><dt>Δt_S3'</dt><dd>Time duration of S3 (estimated)</dd><dt>Δt_S4</dt><dd>Duration of S4 (is)</dd><dt>Δt_S4'</dt><dd>Duration of S4 (estimated)</dd><dt>Δt_S5'</dt><dd>Time duration of S5 (estimated)</dd><dt>Δt_Si</dt><dd>Time duration of the i-th switching step (is)</dd><dt>Δt_Si'</dt><dd>Time duration of the i-th switching step (estimated)</dd><dt>Δt_SR</dt><dd>Duration of the remaining switching steps, residual switching time (is)</dd><dt>Δt_SR'</dt><dd>Duration of the remaining switching steps, residual switching time (estimated)</dd><dt>Δt_SΣ</dt><dd>Time duration of all switching steps, total switching time (is)</dd><dt>Δt_SΣ'</dt><dd>Time duration of all switching steps, total switching time (estimated)</dd><dt>Δt_WA</dt><dd>Waiting time in Case A</dd><dt>ΔT_WB</dt><dd>(Apparent) waiting time in Case B</dd><dt>dn_M/ dt</dt><dd>Target speed gradient</dd><dt>(dn_M/ Dt)₀</dt><dd>Initial target speed gradient</dd><dt>(dn_M/ Dt)_cor</dt><dd>Corrected target speed gradient</dd></dl>