CN109058323B

CN109058323B - Method for calculating a setpoint position of a clutch actuator

Info

Publication number: CN109058323B
Application number: CN201810413982.5A
Authority: CN
Inventors: 亨里克·贝尔; 马提亚·克鲁格
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2017-05-31
Filing date: 2018-05-03
Publication date: 2022-01-07
Anticipated expiration: 2038-05-03
Also published as: CN109058323A; DE102017111966A1

Abstract

The invention relates to a method for calculating a setpoint position of a clutch actuator in a clutch control, wherein a setpoint torque (TrqReq)₁) By means of a clutch characteristic curve (A) and an operating stroke (L) of a clutch actuator for operating the clutch_Tgt) Corresponding to the rated torque (TrqReq)₁) Corresponding operating stroke (L)_Tgt) Corrected by a correction factor (KF) related to the stroke lag of the clutch. In a method for improving the dynamic performance of the regulation, the target torque (TrqReq) is determined₁) Corresponding nominal position (L) of the clutch actuator_Tgt) The travel lag of the clutch torque is taken into account.

Description

Method for calculating a setpoint position of a clutch actuator

Technical Field

The invention relates to a method for calculating a setpoint position of a clutch actuator in a clutch control, wherein a setpoint torque corresponds to an operating travel of the clutch actuator for actuating a clutch via a clutch characteristic curve, wherein the operating travel corresponding to the setpoint torque is corrected by a correction factor that is dependent on a travel delay of the clutch.

Background

DE 102011011152 a1 discloses a method for controlling a friction clutch, wherein the friction clutch is arranged between a heat engine and a transmission, and a clutch actuator operated in the axial direction is driven by an actuating element of the friction clutch along an operating path, which corresponds to a setpoint torque that can be transmitted by the friction clutch via a clutch characteristic curve. The hysteresis occurring along the operating path between the setpoint torque and the actual torque actually transmitted by the friction clutch needs to be compensated for by correcting the actual value determined for controlling the clutch actuator by means of a correction quantity.

FIG. 3 shows a sudden decrease to the clutch torque rating TrqReq₁The setpoint position of the clutch actuator then changes, wherein a curve of the clutch setpoint torque is shown as a function of the travel L of the clutch actuator. Based on the current clutch characteristic curve A, the target torque TrqReq₁ComputingNominal position L_TGT-1. In this calculation, the lagging branch of the engaged state is disengaged from the clutch characteristic a, which moves further to the left due to the lag (curve a 1). When the clutch characteristic curve a is moved further, the setpoint position LAct is also determined again, so that the setpoint position L is obtained_TGT-2And L_TGT-3. In this case, the movement between the hysteresis branches of the disconnection and engagement conditions is adjusted in the internal hysteresis range by a correction factor KF. The actual position derived from the current characteristic curve therefore approaches the target position with hysteresis.

Since the hysteresis distance of the clutch is not constant over the entire torque range, a decreasing hysteresis distance corresponding to a lower setpoint torque can lead to an overshoot of the setpoint torque of the clutch actuator corresponding to the setpoint position. This can result in a torque in a superposition shift of the dual clutch transmission that is less accurate when one clutch is disengaged and the second clutch is engaged.

Disclosure of Invention

The object of the present invention is to provide a method for calculating a setpoint position of a clutch actuator in a clutch control system, in which the dynamic behavior of the control process is improved and overshooting of the control characteristic is avoided.

According to the invention, this object is achieved in that the travel delay of the clutch torque is taken into account when determining the setpoint position of the clutch actuator corresponding to the setpoint torque. This has the advantage that an overshooting adjustment behavior is avoided when calculating the setpoint position in the control software. Since, in addition to the hysteresis of the current position, the hysteresis of the setpoint position is also modeled, the iterative method for determining the setpoint position is dispensed with, so that an increase in the dynamic performance is achieved. This is particularly important for clutch systems with large hysteresis distances. Furthermore, the internal consistency of the clutch torque model is enhanced, since the setpoint position for the setpoint torque does not change during the adjustment process. This is particularly advantageous for torque accuracy in overlap shifts.

Advantageously, the target position of the clutch actuator corresponding to the target torque is determined on the basis of a hysteresis model, wherein the hysteresis characteristic is supplemented by two outer hysteresis branches, wherein the first outer hysteresis branch corresponds to an exact calculation of the clutch characteristic without taking account of the hysteresis compensation and the second outer hysteresis branch corresponds to an exact calculation of the clutch characteristic including a complete hysteresis distance (volle Hystereseweite).

In one embodiment, the target position of the clutch actuator in the internal hysteresis range is calculated by scaling (Skaleirus) the difference between the target position and the actual position of the clutch actuator by means of a correction factor, wherein the scaled difference is added to the actual position. By means of this scaled difference, the setpoint position of the clutch actuator can be derived immediately, so that computation time is saved.

In one variant, the ratio of the setpoint position scaled by the correction factor to the hysteresis-free setpoint position of the clutch actuator is defined. In this case, setting such a correction factor not only solves the problem relating to hysteresis. Deviations that are not due to hysteresis are excluded by the definition of the ratio.

In one specific embodiment, the torque gradient in the internal hysteresis range of the hysteresis model is used as a correction factor, which is limited to half the torque gradient of the nominal clutch characteristic curve. Therefore, the same torque change requires double the stroke of execution. In this case, these are empirical values, but they can be arbitrarily modified in a separate clutch system with a large hysteresis range. With such a relatively flat moment slope, the actual target position can be determined computationally simply.

In one variant, the setpoint position corresponding to the setpoint torque is calculated on the basis of the existing clutch characteristic as long as the movement of the actuator continues on the same hysteresis branch.

In one embodiment, the difference between the setpoint position and the actual position falls on the outer hysteresis branch, and the setpoint position is determined directly from the clutch characteristic without hysteresis compensation or the clutch characteristic with the complete hysteresis distance. In this case, since the hysteresis model can be directly mapped to the nominal position, the calculation time is saved.

Advantageously, the nominal position is limited by the position covered by the external hysteresis branch. Therefore, it is possible to reliably switch between the inner hysteresis branch and the outer hysteresis branch based on the current clutch characteristic.

Drawings

The invention has a large number of embodiments. One of which is set forth in detail in connection with the illustrations shown in the accompanying drawings.

The attached drawings are as follows:

figure 1 is an embodiment of the method according to the invention,

figure 2 is a comparison of the method according to the invention and the prior art regulation process,

fig. 3 is an embodiment of a method according to the prior art.

Detailed Description

Fig. 1 shows an embodiment of the method according to the invention, which is explained in conjunction with a clutch characteristic curve, in which a clutch torque Trq is plotted against the position Lact of a clutch actuator controlling the clutch. In this case, the setpoint position of the clutch actuator corresponding to the setpoint torque TrqReq1 is calculated directly while taking into account the clutch hysteresis. For this purpose, a three-part moment model with three branches a, B, C is used. Characteristic a constitutes an internal hysteresis range associated with the current clutch position. It is supplemented by a left lagging branch B and a right lagging branch C. The left hysteresis branch B is the branch of the open condition, which is determined by explicit calculations of the clutch characteristic including complete hysteresis compensation. The right lagging branch C shows the branch of the engaged condition, which is determined without regard to the lagging distance. In this embodiment, the current clutch position is on the lagging branch of the engaged condition.

In the initial state with time 0, the current actuator travel L_Current-0And clutch moment TrqReq₀And correspondingly. If now the clutch torque is determined from the value TrqReq₀Abrupt transition to valueTrqReq₁If the temporary target position L is constant, then the correction factor KF is used to determine the temporary target position L at point P2_Tgt-KFWherein the correction factor KF is set to the moment slope and has its initial point P1 at the intersection of the initial state, the moment slope and the sought constant nominal moment TrqReq at the point P2₁Crossing, rated torque TrqReq₁Determining a temporary target position L_Tgt-KF. To this end, the actual position L_Current-0And a nominal position L_Tgt-CurrentThe difference between is scaled by a correction factor KF. The scaled difference is then added to the current position L_Current-0The above. Thus, since the difference in scaling is negative, the nominal position L is obtained_Tgt-KF。

In this case, the above calculation is based on the current hysteresis characteristic curve a and is valid over the internal hysteresis range H. The scaled difference is located at a point P2 outside the two outer hysteresis branches B, C. Thus, the desired setpoint torque TrqReq for the clutch is assigned₁Nominal position L of_TgtDirectly from the respective additional curve B or C. Here determined from curve B at point P3. The switching between the internal hysteresis H and the external hysteresis branch B, C can be effected as a function of a desired position L predetermined by the external hysteresis branch B, C_TGTThe limit of (2).

Fig. 2 shows a comparison of the method according to the invention and the regulation process according to the prior art. Fig. 2a shows the prior art here, while fig. 2b shows an exemplary embodiment of the method according to the present invention. The sudden change in the setpoint torque Trq shown in the characteristic curve 2a is reproduced by the setpoint position LAct, which approaches the setpoint torque TrqReq in steps₁. In contrast, as shown in fig. 2b, when the setpoint torque Trq changes suddenly, a sudden change in the setpoint position LAct is simultaneously effected, which can be achieved by a direct hysteresis calculation.

The solution according to the invention shortens the control process and makes the actuator speed higher by directly taking hysteresis into account. In the method according to the invention, the setpoint torque Trq is predefined in correspondence with a setpoint position of the clutch actuator that does not change during the control process.

Claims

1. Method for calculating a setpoint position of a clutch actuator in a clutch control unit, wherein a setpoint torque (TrqReq)₁) By means of a clutch characteristic curve (A) and an operating stroke (L) of a clutch actuator for operating the clutch_Tgt) Correspondingly, the nominal torque (TrqReq) is corrected by a correction factor (KF) related to the travel delay of the clutch₁) Corresponding operating stroke (L)_Tgt)，

Characterized in that the determination of the target torque (TrqReq) is carried out₁) Corresponding nominal position (L) of the clutch actuator_Tgt) Taking into account the clutch torque (TrqReq)₁) Is delayed.

2. Method according to claim 1, characterized in that the determination of the nominal torque (TrqReq) is based on a hysteresis model₁) Corresponding nominal position (L) of the clutch actuator_Tgt) Wherein the hysteresis characteristic (A) is supplemented by two outer hysteresis branches (B, C), wherein the first outer hysteresis branch (B) corresponds to an exact calculation of the clutch characteristic without taking account of the hysteresis compensation and the second outer hysteresis branch (C) corresponds to an exact calculation of the clutch characteristic including the complete hysteresis distance.

3. Method according to claim 1 or 2, characterized in that the nominal position (L) of the clutch actuator is scaled by means of the correction factor (KF)_Tgt) And actual position (L)_Current-0) The difference between them is used to calculate the nominal position (L) of the clutch actuator_Tgt) Wherein the scaled difference is added to the actual position (L)_Current-0) The above.

4. Method according to claim 1 or 2, characterized in that a nominal position taking into account the correction factor (KF) is defined in relation to a nominal position of the clutch actuator without hysteresis limitation.

5. Method according to claim 2, characterized in that the torque slope in the internal hysteresis range (H) of the hysteresis model is used as a correction factor, which is limited to half the torque slope of the nominal clutch characteristic curve.

6. Method according to claim 2 or 5, characterized in that the nominal position of the clutch actuator corresponding to the nominal torque is calculated on the basis of the existing clutch characteristic if the movement of the actuator continues on the same hysteresis branch.

7. Method according to claim 2 or 5, characterized in that in the nominal position (L)_Tgt) And actual position (L)_Current-0) Falls outside the outer hysteresis branch (B, C), the nominal position (L) is determined directly from a clutch characteristic without hysteresis compensation or a clutch characteristic with a complete hysteresis distance_Tgt)。

8. Method according to claim 2 or 5, characterized in that the nominal position (L)_Tgt) Limited by the position covered by the outer hysteresis branch (B, C).