Early collision detection in dual-motor wiper systems

Abstract

Method for operating a device for wiping a disc (10), with at least two wipers (11, 12), each driven by an electric motor (14, 15), and each associated with a position sensor (16, 17) that generates position sensor signals depending on the position of the wipers (11, 12), and with a signal processing arrangement (20) that operates the electric motors (14, 15) depending on the position sensor signals and the predetermined target positions and has a storage medium (22) in which the target positions are stored, characterized in that the blocking position that a blocked wiper (12) assumes during a wiping cycle is stored in a further storage medium (23) of the signal processing arrangement (20) and is used in a subsequent wiping cycle to control an unblocked wiper (11).

Description

State of the art

[0001] The invention relates to a device for wiping a disc, comprising at least two wipers, each driven by an electric motor and each associated with a position sensor that generates position sensor signals depending on the wiper's position, and a signal processing arrangement that operates the electric motors depending on the position sensor signals and the predetermined target positions, and includes a storage medium in which the target positions are stored. The invention further relates to a method for operating such a device.

[0002] From EP 01 84 312, such a device for controlling a vehicle windshield wiper system is known, which has two independently operable windshield wipers, each driven by an electric motor that can change its direction of rotation. The positions of the windshield wipers are detected by a position sensor, which sends the output signals to a control circuit. The inner and outer limits of the wiping areas, as well as acceleration, speed, and deceleration values ​​that the windshield wipers must exhibit within the wiping area, are stored in a memory of the control arrangement. The known device enables the synchronous operation of the two independent windshield wipers. However, an overload, for example, by a windshield wiper becoming blocked, can lead to a desynchronization of the wipers. If there is a risk of collision because the wipers come too close to each other, an emergency operation is initiated, which stops the wipers.provides for a change in the wiping direction.

[0003] German patent DE 40 32 922 describes an improved control loop for a windshield wiper system in which the wipers maintain individual predefined positions and an arbitrary speed profile is possible for each wiper. In the case of overlapping multi-wiper systems, various methods for collision prevention and resynchronization of the wipers are possible if one wiper becomes blocked. These methods include reversing the wiping direction and limiting the wiping area of ​​the wipers. After detecting a blocked wiper blade, the unblocked wiper blade is stopped as quickly as possible.

[0004] A disadvantage of previous collision avoidance methods is that blockage detection sometimes occurs too close to the point of wiper collision, meaning a collision cannot always be prevented. This is especially true when wiper arms / blades are mechanically very flexible. A further disadvantage is that if a wiper remains blocked, collisions are still possible in subsequent wiper cycles. Disclosure of the invention

[0005] The present invention therefore aims to provide an improved device and an improved method that ensures that, in the event of continued blockage of a blocked wiper, the unblocked wiper can be controlled in subsequent wiping cycles in such a way that a collision of the two wipers is definitely excluded.

[0006] This problem is solved by a method for operating a device for wiping a disc according to claim 1 and by a device according to claim 9. Further advantageous embodiments of the invention are specified in the dependent claims.

[0007] A first aspect of the present invention comprises a method for operating a device for wiping a disc, with at least two wipers, each driven by an electric motor, and each associated with a position sensor that generates position sensor signals depending on the position of the wipers, and with a signal processing arrangement that operates the electric motors depending on the position sensor signals and the predetermined target positions and has a storage means in which the target positions are stored, wherein the storage of a blocking position, which a blocked wiper assumes during a wiping cycle, is stored in a further storage means of the signal processing arrangement and is used in a subsequent wiping cycle to control an unblocked wiper.This has the advantage that the unblocked wiper 'knows' the blocking position of the blocked wiper and can be controlled in such a way as to avoid a collision with the blocked wiper.

[0008] It is further preferred that the stopping process of the unblocked wiper is initiated before the blocked wiper reaches the blocking position. This has the advantage that the unblocked wiper can react in time to the blocking of the blocked wiper, thus reliably avoiding a collision.

[0009] According to a preferred method, the blocked wiper is designed to change its wiping direction when it reaches the blocked position. This ensures that the wiper does not stop at the blocked position but can continue wiping the remaining portion of the wiper area on the windshield.

[0010] According to a preferred embodiment of the method, synchronization of the blocked and unblocked wipers takes place at their rest positions or at the turning positions. This is particularly advantageous if the unblocked wiper continues the wiping process with a changed wiping direction before reaching the blocking position of the blocked wiper. This method ensures that both wipers are synchronized again at the end of each wiping cycle.

[0011] Furthermore, a method is advantageous in which the unblocked wiper continues the wiping process with a changed wiping direction in front of the blocked wiper, thereby achieving a resynchronization of the two wipers at the blockage position. This allows the wipers to be synchronized even during the wiping cycle.

[0012] A particularly advantageous method is one that updates the stored blocking position of the blocked wiper with each wiper cycle if it changes. This ensures that in the subsequent wiper cycle, the stop or reversing position of the unblocked wiper is also adjusted to the changed blocking position. When the blocked wiper is released, the normal system state—that is, the full wiping range for both wipers—is restored in the following wiper cycle.

[0013] According to a further aspect of the invention, the device for wiping a disc comprises at least two wipers, each driven by an electric motor and each associated with a position sensor that generates position sensor signals depending on the position of the wipers, and a signal processing arrangement that operates the electric motors depending on the position sensor signals and the predetermined target positions and includes a storage medium in which the target positions are stored. The device is designed such that the blocked position assumed by a blocked wiper during a wiping cycle can be stored in a further storage medium of the signal processing arrangement and can be used in a subsequent wiping cycle to control an unblocked wiper. This has the advantage that the position data of the blocked position is available over a longer period of time.For example, blocking positions can be saved and used to control the wiping process in subsequent wiping cycles. Because the unblocked wiper "knows" the blocking position of the blocked wiper, it can be controlled in such a way as to avoid a collision with the blocked wiper.

[0014] The exemplary embodiments are shown in the drawings and explained in more detail in the following figure description. Brief description of the drawings:

[0015] They show Fig. 1 a device according to the invention for wiping a disc; Fig. 2 a schematic representation of the blocking and stop position in case of overlapping wiping area with synchronized wipers; Fig. 3 a schematic representation of the blocking and stop position in the case of overlapping wiping area with opposing wipers; Fig. 4a a method for preventing collisions when the wiper is blocked; Fig. 4b a method for preventing collisions when the wiper blockage is lifted or changed. Embodiments of the invention

[0016] Fig. Figure 1 shows a device according to the invention for wiping a disc 10, the surface of which can be cleaned by a first and a second wiper 11, 12. The first wiper 11 wipes in an area designated by the letters ABC in Fig. The second wiper, 12, wipes in an area designated by the letters DEF. Fig. 1 is indicated. The wiper areas ABC and DEF indicate how Fig. Figure 1 shows an overlapping wiping area 13. The windshield wipers 11, 12 are each driven by a reversible electric motor 14, 15. The position of the two wipers 11, 12 is detected by a first and second position sensor 16, 17, each of which is connected by a Fig. The first and second mechanical connections 18, 19 shown are coupled to the associated wiper 11, 12 to determine the position of the wiper blades 11, 12. For example, the position sensors 16, 17 can be mounted on the respective drive shafts of the electric motors 14, 15. In addition to position sensors mechanically coupled to the wipers, other types of position sensors are also possible, such as optical position sensors.

[0017] The position sensors 16, 17 output the detected actual positions of the first and second wipers 11, 12 in the form of first and second position sensor signals 16', 17'. The position sensor signals 16', 17' are fed into a signal processing arrangement 20, which compares the actual position values ​​with the target position values ​​of the wipers 11, 12 in comparators 25, 26. The target position values ​​are specified by a setpoint 21. The control deviations determined by the comparison are converted into control signals 14', 15', which are output to the electric motors 14, 15, which in turn drive the first and second wipers 11, 12. A blockage of a wiper 11, 12 can be detected by evaluating the deviation of the actual position values ​​from the target position values ​​as well as the evaluation of the control signals 14', 15' and thus the supply voltage applied to the electric motors.The setpoint values ​​are stored in a memory 22 of the setpoint specification. Selective actual position values ​​of a wiper 11, 12 during a wiping cycle can be stored in a memory 23. This could, for example, be the blocking position of one of the two wipers 11, 12. The signal processing arrangement 20 can read the stored actual position values ​​of one of the two wipers 11, 12 during a subsequent wiping cycle and use them, for example, via the setpoint specification 21 to control the same or another wiper. The in . Fig. The device described above can also be extended to three or more wipers.

[0018] The position control of the wipers 11, 12 enables the synchronization of multi-wiper systems in which the wipers 11, 12 each have separate electric motors 14, 15 as drives. Synchronization is particularly essential when an overlapping wiping area 13 is present, within which there is a risk of collision. In normal, undisturbed operation of the two wipers 11, 12, synchronization is achieved by synchronously reading the memory 22, which contains the target position values, and synchronously setting the target position values. The specified target positions of the wipers 11, 12 are maintained by readjustment using the signal processing arrangement 20. Only under conditions deviating from normal operation, which can occur, for example, due to increased friction or blockage of at least one of the two wipers 11, 12, does a higher-level synchronization measure intervene.

[0019] The inventive method is described using the Fig. 2 to 4 explained in more detail. Fig. Figure 2 schematically represents the wiping areas ABC of the first wiper 11 and DEF of the second wiper 12 on the disc 10. Starting from a first and second rest position 26, 27, the two wipers 11, 12 sweep over the area during a wiping cycle. Fig. The two sketched circular segment-shaped areas are wiped in a first direction of movement up to the first and second turning positions 26', 27'. At the turning positions 26', 27', the wiping direction is reversed and the two wipers 11, 12 again cover the wiping areas up to the respective first and second rest positions (starting positions) 26, 27. This completes one wiping cycle and in continuous operation the next wiping cycle follows.

[0020] The two wipers 11, 12 can be positioned as in Fig. 2 shown moving in parallel in a wiping cycle, but a counter-rotating movement of the two wipers 11, 12 is also possible with a modified arrangement of the wiping areas, which is shown in Fig. Figure 3 shows the wiping areas ABC of the first wiper 11 and DEF of the second wiper 12 on the disc 10. Starting from a first and second rest position 26, 27, the two wipers 11, 12 sweep over the area shown in Figure 3 during a wiping cycle. Fig. The wiping direction is reversed at the turning positions 26' and 27'. The wipers 11 and 12 then sweep over the wiping areas again until they reach their respective first and second rest positions (starting positions) 26 and 27. This completes one wiping cycle, and in continuous operation, the next wiping cycle begins.

[0021] If one wiper 11, 12 is blocked in the overlapping wiping area 13, the other wiper must be stopped in time to prevent a collision. Blocked, as in Fig. 2 and Fig. As shown in Figure 3, in the first wiping cycle, the second wiper 12 is at the blocking position 44. Therefore, the first wiper 11 can only move up to the contact position 45, where it touches the second wiper 12. This restricts the wiping area of ​​the first wiper 11 by the hatched area. To avoid a collision, the movement of the first wiper 11 from its rest position 27 ( Fig. 2) or its turning position 27'( Fig. 3) are stopped before reaching contact position 45. When wiper 12 is detected as blocked in position 44, wiper 11 is in position 46. The known blockage detection and the stopping process of the first wiper 11 thus occur too close to reaching contact position 45, so that a collision or at least mutual contact between the two wipers cannot always be avoided. This is particularly the case if the wiper arms or wiper blades are mechanically very flexible. After the second wiper 12 reaches the blockage position 44, the first and second wipers 11, 12 change their wiping direction and thus again cover the respective remaining parts of the wiping areas ABC and DEF.

[0022] To prevent a collision between the two wipers 11 and 12 in subsequent wiper cycles if the second wiper 12 remains locked in position 44, the actual position values ​​of the second wiper 12's locking position 44 are stored in memory 23 of the signal processing arrangement 20 during the first wiper cycle. In subsequent wiper cycles, the actual position values ​​stored in memory 23 are read and used to control the first wiper 11. This makes it possible to send the signal to stop the first wiper 11 at position 47, i.e., before it reaches position 46 and thus before the second wiper 12 reaches the locking position 44. The remaining distance of the first wiper 11 to the contact position 45 is now long enough so that the first wiper 11 can be safely stopped in position 48 without touching the second wiper 12.

[0023] At position 47, instead of initiating the stopping process, the wiping speed of the first wiper (11) can also be reduced. The actual stopping process can then only be initiated when the second wiper (12) reaches the blocking position 44 with the known blocking detection. However, the already slower speed of the first wiper (11) ensures that a collision is reliably avoided in this case as well.

[0024] The position at which the stopping process is initiated for the first wiper (11) can be determined by the signal processing arrangement 20 by a fixed 'offset' relative to the wiper's blocking position 44. However, it is also possible for the 'offset' for the start of the stopping process to be variable and, for example, determined by the signal processing arrangement 20 depending on the wiping speed, the geometry, and the material properties of the two wipers 11, 12.

[0025] It is essential that even when the windshield wiper device is operated with the second wiper 12 blocked and the first wiper 11 stops prematurely at position 48, as in Fig. 2 and Fig. As shown in Figure 3, synchronization of the two wipers 11 and 12 can be achieved again. This is possible in two ways: firstly, if the first wiper 11, after being stopped at position 48, continues the wiping process with a reversed wiping direction in front of the second wiper 12, and synchronization of the two wipers 11 and 12 is achieved again at the blocking position 44; or secondly, if the first wiper 11, after reaching the stop position 48 or when the second wiper 12 reaches the blocking position 44, reverses its wiping direction and the wipers 11 and 12 "wait" for each other at their respective rest positions 26 and 27 (starting positions) or at their respective turning positions 26' and 27'.

[0026] The means Fig. 2 and Fig. The collision avoidance procedure described above can also be carried out conversely with the first wiper 11 as a blocked wiper and control of the second unblocked wiper 12 in subsequent wiping cycles by the stored blocking position of the blocked first wiper 11.

[0027] The stored blocking position of a wiper can also be used to control the blocked wiper in the subsequent wiping cycle. For example, the wiping speed of the blocked wiper can be reduced before it reaches the blocking position. This prevents the wiper from hitting the obstacle at full speed and potentially being damaged.

[0028] The inventive method for avoiding collisions between the two wipers 11, 12 of a windshield wiper device 10 when one wiper is blocked is shown in the flowcharts of the Fig. 4 shown. Fig. Figure 4a shows the procedure steps when a wiper 12 becomes blocked. First, it is checked whether the blockage position lies within the collision area 13 of the two wipers 11, 12. If this is not the case, the unblocked wiper 11 continues its wiping process until it reaches the turning position and takes the blocked wiper 12 with it on its reverse movement. This ensures the synchronization of the two wipers 11, 12 even with a limited wiping area of ​​the blocked wiper 12.

[0029] If the blocking position is in the collision area 13 and the two wipers 11, 12 move away from each other after one wiper has blocked, the unblocked wiper 11 continues its wiping action until it reaches the turning position and carries the blocked wiper 12 along with it on its backward movement. Thus, the synchronization of the two wipers 11, 12 is maintained even in this case, despite the limited wiping area of ​​the blocked wiper 12.

[0030] If the blocking position lies within the collision area 13 and the two wipers 11, 12 move towards each other after one wiper has become blocked, the actual position values ​​of the blocking position are stored in memory 23. At the blocking position of the blocked wiper 12, the known blocking detection triggers a stop, followed by a reversal of the wiping direction of both wipers 11, 12, and a resynchronization of the wipers 11, 12 at their respective rest positions (starting positions) 26, 27 or turning positions 26', 27'. In the subsequent wiping cycle, the stopping process of the unblocked wiper 11 is initiated by reading memory 23, i.e., using the stored actual position values ​​from the previous wiping cycle, before the blocked wiper 12 reaches the blocking position. This reliably prevents a collision between the two wipers 11, 12 (see Fig. 2 and Fig. 3) The unblocked wiper 11 then stops and reverses direction. Resynchronization occurs either at the stop position of the blocked wiper 12 or at the respective rest positions (starting positions) 26, 27 or at the respective turning positions 26', 27'. This ensures that the synchronization of both wipers 11, 12 is maintained even with a limited wiping range for both wipers.

[0031] Fig. Figure 4b shows the procedure steps for changing the blocking position or releasing the blockage of a wiper. When changing the blocking position of a wiper, it is first checked whether the new blocking position lies outside the overlap area 13 or, although within the overlap area, without any risk of collision, since the wipers 11 and 12 move away from each other (see Figure 4b). Fig. 4a). If this is the case, the current blocking position is deleted from memory 23 and the originally unblocked wiper 11 sweeps over the entire wiping area again in the following wiping cycle.

[0032] If the new blocking position is located in the overlap area 13 and there is a risk of collision because wipers 11 and 12 are moving towards each other, the actual position values ​​of the new blocking position of the blocked wiper 12 are stored in memory 23, and simultaneously the actual position values ​​of the previous blocking position are deleted. In this wiper cycle, the control of the unblocked wiper 11 is carried out, depending on the location of the new blocking position, either using the previous blocking position or by the known blocking detection. In the subsequent wiper cycle, the stopping process of the unblocked wiper 11 is initiated by reading memory 23, i.e., using the actual position values ​​newly stored in memory 23 from the previous wiper cycle, before the blocked wiper 12 reaches the new blocking position. This reliably prevents a collision between the two wipers 11 and 12 (see Fig. 2 and Fig.3) The unblocked wiper 11 then stops and reverses direction. Resynchronization occurs either at the stop position of the blocked wiper 12, or at the respective rest positions (starting positions) 26, 27, or at the respective turning positions 26', 27'. This ensures that the synchronization of both wipers 11, 12 is maintained even with a limited wiping range for both wipers.

[0033] When a wiper is released from its blockage, the actual position values ​​of the current blockage position are deleted from memory 23. In the subsequent wiper cycle, both wipers 11 and 12 can then again cover the entire wiper area.

Claims

[1] Method for operating a device for wiping a windscreen (10), comprising at least two wipers (11, 12), each driven by an electric motor (14, 15), each having an associated position sensor (16, 17) which generates position sensor signals as a function of the position of the wipers (11, 12), and comprising a signal processing arrangement (20) which operates the electric motors (14, 15) as a function of the position sensor signals and the predetermined target positions and has a storage means (22) in which the target positions are stored, characterized by that the blocking position assumed by a blocked wiper (12) during a wiping cycle is stored in a further storage means (23) of the signal processing arrangement (20) and is used in a subsequent wiping cycle to control a non-blocked wiper (11). [2] Method according to claim 1, characterized bythat the stopping process for the unblocked wiper (11) is initiated before the blocked wiper (12) reaches the blocking position (44). [3] Method according to claim 2, characterized by that the wiping direction of the blocked wiper (12) is changed when the blocking position (44) is reached. [4] Method according to claim 3, characterized by that the unblocked wiper (11) also continues the wiping process with a changed wiping direction when the blocked wiper (12) reaches the blocking position (44). [5] Method according to claim 4, characterized by that the synchronization of the blocked and the unblocked wiper (11, 12) takes place at the rest positions (26, 27) or the turning positions (26', 27'). [6] Method according to claim 3, characterized bythat the unblocked wiper (11) in front of the blocked wiper (12) continues the wiping process with a changed wiping direction and thereby a renewed synchronization of the two wipers (11, 12) at the blocking position (44) is achieved. [7] Method according to one of the preceding claims, characterized by that the blocking position stored in the storage means (23) is used in a subsequent wiping cycle to control the blocked wiper (12). [8] Method according to one of the preceding claims, characterized by that during each wiping cycle the blocking position of the blocked wiper (12) stored in the storage means (23) is updated if it changes. [9] Device for wiping a windscreen (10), with at least two wipers (11, 12), each driven by an electric motor (14, 15), and each associated with a position sensor (16, 17) which generates position sensor signals as a function of the position of the wipers, and with a signal processing arrangement (20) which operates the electric motors (14, 15) as a function of the position sensor signals and the predetermined target positions and has a storage means (22) in which the target positions are stored, characterized by that the blocking position assumed by a blocked wiper (12) during a wiping cycle can be stored in a further storage means (23) of the signal processing arrangement (20) and can be used in a subsequent wiping cycle to control a non-blocked wiper (11).

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