EP2122098B1 - Method for controlling an actuator - Google Patents

Description

The invention relates to a method for controlling an actuating element of a motor vehicle. The invention further relates to an adjustment system for controlling an actuating element.

In an adjustment system for an actuating element of a motor vehicle, for example in a window lifting system, it is usually necessary to move the associated control element in a defined position in which the actuator is under predetermined mechanical loads in a stable position. This can be, for example, a closed position or end position of the actuating element. For example, the window pane of a vehicle door in the closed state must be moved to an end position, wherein the holding force of the window pane relative to the adjacent seal must be large enough to balance the weight of the window pane and the associated supporting parts and keep the window stable and tightly closed , In particular, this wind noise during driving to be avoided. Even with a sunroof stability and tightness are crucial criteria that determine the necessary holding power. However, since the weight is essentially intercepted by the sunroof itself, the necessary holding force is relatively less. The actually applied stationary holding forces in adjustment systems of this type, however, are usually greater than the forces that would be required for optimal performance of the holding function, since the actuator to reach the end position usually has to overcome opposing forces by a closure element or by a seal.

In such an adjustment system, the adjustment element designed for adjusting is usually moved with a maximum torque of the associated drive in the mechanical end position. The maximum torque of the drive must be sufficiently large so that the actuator during the movement of opposing forces, for example, by rubber seals exerted resistors on a window pane against the adjustment overcome.

To form a anti-pinch adjustment systems are known in which a drive parameter, in particular a torque is detected in dependence on the position of the actuating element, and is closed at an irregular deviation from the normal behavior to a pinching. In this case, an association between the size of the drive parameter and the position of the control element must be specified, as due to mechanical inadequacies along the displacement variations of the drive parameter can be expected during normal operation. Thus, for example, when adjusting a side window along a predetermined path, the resistances exerted by the mechanism can be different depending on the position, depending on the position. In this respect, it is important for the functionality of the anti-trap protection that the real position of the control element is known. This is usually from the revolutions of the drive closed to the real position, which requires a calibration over a reference position.

For calibration, the drive is switched off after reaching the end position after a predetermined period of time and assigned the end position as the reference position of the adjustment. To fulfill the holding function, the actuator is usually moved with the maximum torque of the drive in the final position and the drive off. In particular, in the case of a self-locking gear or due to the necessary restoring forces against a shutdown drive the actuator remains up to an independent, partial relaxation of the system, for example by restoring forces during shutdown or by a derivation of surges by the system components or their absorption within the system tolerances stand substantially with the last-applied torque of the drive as a holding torque in the final position.

A strong holding torque in the stationary state disadvantageously exerts a load on the components of the system, since counterforce forces are built up by the holding torque, which, if they are not or only insufficiently degraded, act as deformation forces on the components. Currently used components made of cost-effective materials, such as plastics, are sensitive to long-term stationary mechanical effects and can be plastic despite toughness and breaking strength be deformed. In an adjustment system, this can lead to faster wear and disadvantageous noise during operation. In particular, in adjustment systems with a pinch protection of the operation described above can be affected by claimed components necessary for the identification of a Einklemmfalles position assignment of the control element despite regular calibration. In an irregular or suddenly increased resistance, which is registered for example by a reduced speed of the drive or by an increased torque via a control module, the drive can be misreversed or stopped without the presence of an actual Einklemmfalles. Thus, a window pane, which has to overcome the opposing forces of a surface engaging rubber seal outside the range of a possible Einklemmfalls shortly before reaching the end position and this requires a high torque to be stopped in case of incorrect position assignment by activating the anti-trap, so that the final position is no longer reached becomes.

The EP 091018 B discloses the features of the preamble of claim 1. The invention has for its object to provide a method for controlling an actuating element, which overcomes the disadvantages of the prior art. A second object of the invention is to provide an adjustment system for a control element of a vehicle, which is durable and which works precisely.

The first object is solved by the features of claim 1.

In this case, a force variable is to be interpreted as a physical variable which underlies a force as a variable, in particular a force or force component itself or a variable composed of a force and another variable, for example a torque or a pressure.

The invention is based on the consideration that the holding torque of the end position in a control of the conventional type is usually greater than the holding torque required for the optimal situation-dependent holding function. In this respect, the holding torque can be reduced by a controlled relaxation of the system components in the end position, without the predetermined for the given position system properties, such as tightness or holding force are affected.

For an adjustment of the aforementioned type, a presetting and / or limiting the drive torque to the target value of the holding torque for the steady state of the control element in the end position usually no solution, since in the region of the end position before reaching this high torque of the Drive may be required, for example, to overcome there local counter forces. Thus, the end position would not be reached in the regular case.

The central advantage of the invention is that for an actuating element, which is movable in a defined end position, the holding forces determining variables are adapted to a variable setpoint at a given time, so that a relaxation of the system while maintaining the holding function of the control element achieved at any time. The setpoint can be specified for a defined end position by a function of external state variables. The set of these external state variables may include, for example, characteristics of the materials of the system components and their thermal reaction behavior. For example, thermoplastic materials are less resilient at higher temperatures than at low temperatures. Further, the set of external state variables may include mechanical coupling constants of the system components describing how an external mechanical disturbance propagates between the system components and how the system as a whole reacts to such when, for example, the system is subjected to vibratory forces. These and other influences can be decisive for the desired value. By a targeted control of the drive via minimal corrections of the positioning of the actuating element, the relevant force variable in adaptation to the target value is specifically adjustable. A fixed pre-adjustment of this size, for example, the torque as a holding torque, is eliminated.

According to the invention, the method is developed in such a way that the force magnitude acting on the adjusting element after adjustment in the defined position is determined after a prescribable period of time. During this so-called relaxation time, the corresponding force magnitude can be partially reduced by autonomous relaxation over the system components. This ensures that the corrections to be triggered are at least smaller and at most the same size as without a relaxation time.

A force acting on the actuator force magnitude, such as a resistance force is equal in magnitude equal to the force exerted by the actuator force that is transmitted from the drive to the actuator. This follows from the third Newton's law and makes it possible to equalize the force acting on the actuator force magnitude of the corresponding force size of the drive. In the following, therefore, an acting on the actuator force magnitude with the corresponding force exerted by the actuator force magnitude are discussed synonymous with each other.

In a preferred embodiment of the invention, when the setpoint is exceeded, the drive is driven by the determined force magnitude by a tolerance amount to the system voltage. This makes it possible to take into account mechanical variations of the adjustment system, which are manufacturing, material or installation-related.

If the actuating element can be moved by means of a drive unit which has rotatable parts, a torque is advantageously determined as a force variable, since the drive of such a drive unit is characterized by a known torque or can be detected in a known manner. The torque is derived for this purpose with known motor characteristic and constant drive voltage in particular from the speed. If, however, the adjusting element can be moved, for example, on magnetic rails by a linear motor, it is preferable to consider linear force components as force variables.

The force variables associated with the adjusting element in the defined end position can be determined by measuring, for example, with the aid of a number of essentially uniformly distributed sensors. For reasons of cost, however, it is advantageous to determine the force variables from drive parameters. This eliminates the need to capture the force variables by well-positioned measurement arrangements, such as about substantially gleichvärteilt arranged sensors. For such an advantageous embodiment thus eliminates the need for additional components, the system and the method is simplified.

For a drive unit which has rotatable parts, a characteristic of the drive force, in particular the torque, from the rotational speed of the drive can be determined. Advantageously, the force magnitude is detected via a characteristic of the drive from the known instantaneous speed. The characteristic in turn depends on further parameters, for example on an applied electrical drive voltage. Usually force magnitude and speed are dependent on each other via a power law, in particular they are inversely proportional to each other. In logarithmic representation, this results in a parameter-dependent linear function for the characteristic curve.

In a preferred embodiment of the method, a desired value for the force magnitude in the defined end position is predetermined, which depends on the temperature of the environment and the state of motion of the entire system. For the specification of the desired value, it is advantageous to reduce the number of all possible determining parameters to such an extent that the ratio of the variation of the nominal value to the variation of one of the remaining parameters is sufficiently large in order to be resolvable as a measured variable with respect to the fluctuations of the system tolerances. All other parameters are negligible in practice. In this respect, it is advantageous to consider the global ambient temperature instead of the thermal reaction behavior of the individual components, since the relevant components and their materials are known in practice. For example, a gear made of thermoplastic material, which is arranged in the transmission of the drive system, easily deformed at elevated temperature, the target value of the force size, which characterizes the contact between the actuator and the seal in the end position, must be lowered. On the other hand, by thermal expansion plastics can also offer increased resistance, which may also have to be considered.

Furthermore, it is advantageous for the method to take into account a movement quantity of the rest system of the adjustment system relative to the environment as a globally relevant parameter for the desired value. For example, the target value for a moving vehicle is adapted to the speed. At higher speeds, a higher setpoint is required due to the higher back pressure than at low speeds or at standstill to avoid wind noise. Will the Set value adapted to the driving speed, a dynamic adjustment of the setpoint is possible taking into account the necessary holding forces, resulting in a minimum load on the system components.

By an independent relaxation, the position of the control element, which has been moved to the defined position, be slightly modified. Such a change in position may affect a corresponding change in the position of the drive, if this is sufficiently large so as not to be absorbed in the movement tolerances of the system. Preferably, the force acting on the actuator residual force magnitude is determined after a relaxation by such a change in position.

In order to determine the position of the actuating element from drive parameters, it is also necessary to define a reference position to which the drive movement is related. The drive revolutions are preferably counted and from this the change in position relative to the reference position is detected. As a reference position, the initially defined position, in particular the end position of the actuating element, is preferably selected.

In a further preferred development of the method, the actuating element is moved along a guide means, in particular along a guide rail. Thus, simplifying the positioning of the control element by a parameter can be detected, since a one-dimensional movement takes place.

The second object is achieved by an adjustment system for an actuator of a vehicle, is provided with a drive for moving the control elements and with a control module, which is set up for driving the drive according to a method of the type mentioned.

Fig. 1

schematisch ein Verstellsystem, und

Fig. 2

ein Fenster-Hebesystem für ein Kraftfahrzeug.

In the following an exemplary embodiment of such an adjustment system will be explained with reference to a drawing. In each case show in a schematic representation

Fig. 1

schematically an adjustment system, and

Fig. 2

a window lift system for a motor vehicle.

In Fig. 1 schematically an adjustment system 8 is shown, which comprises an actuating element 1, which along a guide rail 2 along an adjustment direction 3 to a defined end position 4 is movable. The actuator 1 is assigned a drive 5, here in the form of an electric motor, which is controlled by a control module 6. The drive 5 has a voltage-dependent characteristic which assigns a torque of the drive 5 to a certain speed of the drive 5. When driving the drive 5 via the control module 6, the actuating element 1 is moved in the direction of displacement 3. The resistance to movement is in equilibrium with the driving force of the actuating element 1, so that the drive 5 exerts a defined torque during the process, to which a specific rotational speed of the drive 5 is assigned. The position of the control element 1 is detected by the change in position relative to a reference position over the number of drive revolutions.

Now approaching the actuator 1 of the final position 4, it enters a zone 7 increased resistance to movement. The balance is disturbed, the movement slows down initially and thus the speed of the drive 5. On the characteristic curve, an increased torque is set with which the actuator 1 is now moved to the final position 4. After the procedure in the end position 4, the increased torque of the drive 5 initially acts as a holding torque, since complete relaxation is prevented by a reverse-locking gear of the drive 5. For the final position 4, depending on external state variables such as the temperature or the state of motion of the overall system, a setpoint value for the holding torque is predetermined, which is lower than the currently applied holding torque after traveling to the end position 4. An excessive holding torque in the stationary state can be a burden for the system components represent a premature wear of material result.

The drive 5 comprises components made of a thermoplastic, so that at elevated temperature, the target value for the holding torque must be specified lower to avoid plastic deformation. On the other hand, an increased setpoint value is predetermined if the overall system is in motion and therefore due to increased dynamic pressure, a higher tightness of the actuating element 1 relative to a seal has to be achieved. Also, due to increased vibrations than in the state of rest, a higher setpoint must be specified so that the actuator 1 can be kept stable in the final position 4.

If the control element 1 is stopped in the end position, the holding torque corresponding to the drive torque according to the method in the end position is partially reduced by system relaxation. After a relaxation time of predetermined duration, after which the self-relaxation is completed, which is read by means of a slight movement of the control element and / or the drive. Since the restoring forces of the system can be described by spring constants, from the path difference of the control element 1, the decrease in the holding torque can be calculated. For the usual conditions, the relationship between the path difference and the holding torque or the holding force is considered to be substantially linear. The proportionality constant is 40N / mm, for example. It is also possible to determine the characteristic curve between the path difference and the holding force loss experimentally and to specify the control module. The residual actual holding torque determined in this way is then compared in the control module 6 with the predetermined desired value. If both values deviate by more than a defined tolerance, the drive 5 is actuated correctively by the control module 6, so that a system voltage is possible in such a way that, after a new comparison, both values deviate from one another by at most the tolerance amount.

In Fig. 2 a window lifting system 9 is shown for a vehicle door, in which along a guide rail 2A as an actuator, a driver 10 is movable, which can move a window 11. The drive 5 thereby moves the driver 10 by means of a cable drum 12, along which a cable 13 extends, which is fastened to the driver 10. Further, a control module 5 is provided, which drives the drive 5 according to the aforementioned method.

LIST OF REFERENCE NUMBERS

1

actuator

2.2A

guide rail

3

adjustment

4

end position

5

drive

6

control module

7

Zone of increased resistance

8th

adjustment

9

Window lifting system

10

takeaway

11

windowpane

12

cable drum

13

rope

Claims (11)

1. Method for controlling an actuator (1) in a motion system (8) of a motor vehicle, for example in a window regulator system (9), wherein

   - the actuator (1) is moved to a defined endposition (4) by means of a drive (5),

   - a force level acting on the actuator (1) in the defined endposition (4) is detected,

   - the detected force level is compared to a target value,
   characterized in that in the event that the detected force level exceeds the target value, the drive is correctively actuated for system relief, and wherein the detection of the force level takes place after a relaxation period.
2. Method according to claim 1,
   wherein the drive (5) is actuated for system relief in the event that the detected force level exceeds the target value by a tolerance amount.
3. Method according to claim 1 or 2,
   wherein a torque is determined as the force level.
4. Method according to one of claims 1 to 3,
   wherein the force level is determined from drive parameters.
5. Method according to claim 4,
   wherein the force level is determined from the speed of the drive (5), in particular by means of a characteristic curve.
6. Method according to one of claims 1 to 5,
   wherein the target value is predetermined as a function of the ambient temperature, the spatial position of the actuator (1) and/or the state of motion of the system.
7. Method according to one of claims 1 to 6,
   wherein the force level after the relaxation period is derived from a changed position of the drive (5) and/or of the actuator (1).
8. Method according to one of claims 5 to 7,
   wherein the spatial position of the actuator (1) is accomplished by detecting drive rotations with a reference position defined by calibration.
9. Method according to claim 8,
   wherein the reference position is predetermined by the defined position (e.g. 4).
10. Method according to one of the preceding claims,
    wherein the actuator (1) is moved along a guide means, in particular a guide rail (2).
11. Motion system (8) of a motor vehicle, for example window regulator system (9), for moving an actuator (1), having a drive (5) for moving the actuator (1) and having a control module (6) that is designed to carry out a method, wherein

    - the actuator (1) is moved to a defined endpostion (4) by means of the drive (5),

    - a force level acting on the actuator (1) in the defined endposition (4) is determined,

    - the determined force level is compared to a target value,

    characterized in that in the event that the determined force level exceeds the target value, the drive is correctively actuated for system relief, and wherein the detection of the force level takes place after a relaxation period.

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