Control unit for a motor vehicle wiper system, wiper system with such a control unit and a method for controlling a wiper system

Abstract

Control unit (35) for a wiper system (20) of a motor vehicle (10), comprising a control unit (95), a detection unit (95) and a memory (100), wherein the control unit (95) is connected to the memory (100) and the detection unit (90), wherein at least one first position characteristic curve (135) is stored in the memory (100), wherein the detection unit (90) is configured to detect a driving state of the motor vehicle and / or a system state of the wiper system (20) and to provide the control unit (95) with a status signal corresponding to the driving state, wherein the control unit (95) is configured to provide a control signal for controlling the wiper system (20) in a wiping movement across a window (15) of the motor vehicle (10), characterized in that a second position characteristic curve (140, 145) is stored in the memory (100), wherein the control unit (95) is trainedto detect the status signal of the detection device (90) and to select between the first and the second position characteristic curve (135, 140, 145) depending on the status signal and to provide a corresponding control signal according to the selection.

Description

The invention relates to a control unit according to claim 1, a wiping system according to claim 8 and a method for controlling a wiping system according to claim 10. State of the art Wiping systems for wiping a vehicle windshield are known in which a wiper blade is moved across the windshield by a wiper drive and a wiper arm coupled to the wiper drive, which holds the wiper blade, according to a predefined position characteristic curve. The position characteristic curve is fixed and predefined, so that it must be adapted to numerous driving conditions. Further prior art is known from DE 10 2011 089 904 A1, DE 10 2005 055 054 A1 and DE 10 2005 048 343 A1. The object of the invention is to provide an improved control unit for a wiper system of a motor vehicle, as well as an improved wiper system and an improved method for operating a wiper system. This task is solved by means of a control unit according to claim 1. Advantageous embodiments are specified in the dependent claims. According to the invention, it has been found that an improved control unit for a wiper system of a motor vehicle can be provided by the control unit comprising a control unit, a detection unit, and a memory. The control unit is connected to the memory and the detection unit.The detection device is configured to detect a driving state of the motor vehicle and / or a system state of the wiper system and to provide the control unit with a state signal corresponding to the driving state, the control unit being configured to provide a control signal for controlling the wiper system in a wiping movement across a window of the motor vehicle, at least one first position characteristic curve being stored in the memory, a second position characteristic curve being stored in the memory, the control unit being configured to detect the state signal of the detection device and to select between the first and the second position characteristic curve depending on the state signal and to provide a corresponding control signal according to the selection. This ensures that, depending on different system states or driving conditions, an optimal position characteristic is used for moving the wiper arm across the windshield. This guarantees a particularly quiet wiping process. In another embodiment, the first position characteristic curve is stored in memory using a formula, and the control unit is configured to determine a second position characteristic curve based on the formula stored in memory for the first position characteristic curve and the status signal. In this way, the memory requirement can be kept particularly low. In a further embodiment, the formula has at least one predefined coefficient, wherein the control device is configured to determine the coefficient depending on the status signal, and wherein the control device is configured to determine the second position characteristic curve based on the formula and the determined coefficient. In this way, the second position characteristic curve can be flexibly adapted. In a further embodiment, at least one predefined threshold value is stored in the memory, wherein the control unit is configured to compare the status signal with the threshold value, and wherein the control unit is configured to select the first or second position characteristic curve depending on the result of the comparison. This allows for particularly simple adaptation of the position characteristic curve to different driving states or system states. In a further embodiment, the first position characteristic curve has a first upper turning position and a first lower turning position, wherein the second position characteristic curve has a second upper turning position and a second lower turning position, the first upper and / or lower turning position being different from the second upper and / or lower turning position. This prevents the wiper blade from being over-wiped and simultaneously ensures that the wiper blade or wiper arm reliably returns to a rest position even at high driving speeds. In a further embodiment, the status signal contains information about the vehicle's speed, wherein the control device is configured to select the first position characteristic curve at a first speed and the second position characteristic curve at a second speed that is greater than the first speed, wherein the second upper turning position has a smaller distance to the first lower turning position than the first upper turning position, and / or wherein the second lower turning position has a greater distance to the first upper turning position than the first lower turning position. Furthermore, it is advantageous if the first position characteristic curve for wiping the wiper arm from the first lower turning position to the first upper turning position has a first duration, and the second position characteristic curve for moving from the second lower turning position to the second upper turning position has a second duration, the second duration being shorter than the first duration. Additionally or alternatively, it is conceivable that the first position characteristic curve for moving from the first upper turning position to the first lower turning position has a third duration, and the second position characteristic curve for moving from the second upper turning position to the second lower turning position has a fourth duration, the third duration being shorter than the fourth duration. This allows for a particularly favorable wiping behavior that is perceived as especially pleasant by the driver. The problem is also solved by a wiping system according to claim 8. Advantageous embodiments are specified in the dependent claim. According to the invention, an improved wiping system can be provided by comprising a wiper arm and a wiper drive, wherein the wiper drive is coupled to the wiper arm and configured to move the wiper arm to perform a wiping motion across a window of the motor vehicle, wherein a control unit is provided which is configured as described above, wherein the control unit is connected to the wiper arm and controls the wiping motion of the wiper drive by means of the control signal. This allows for particularly good wiping performance across the entire speed range of the vehicle, exhibiting, for example, particularly good wiping performance at high speeds and particularly quiet wiping performance at low speeds. In a further embodiment, the control unit is designed to move the wiper arm between a lower turning position and an upper turning position, wherein the first position characteristic curve has a different upper and / or lower turning position compared to the second position characteristic curve. However, the problem is also solved by a method for controlling a wiping system according to claim 10. According to the invention, it has been recognized that an improved method for controlling a wiper system, which is designed as described above, can be provided, wherein a driving state of the motor vehicle and / or a system state of the wiper system is detected, wherein a state signal corresponding to the driving state and / or the system state is provided, wherein the state signal is detected and a selection is made between the first and the second position characteristic curve depending on the state signal, and according to the selection, a corresponding control signal is provided to control the wiping movement of the wiper system. Disclosure of the invention The invention is explained in more detail below with reference to the figures. Figure 1 shows a schematic representation of a motor vehicle with a wiper system; Figure 2 shows a schematic representation of a control unit of the wiper system shown in Figure 1; Figure 3 shows a first diagram of a wiper angle of the wiper system plotted against time; Figure 4 shows a flowchart of a process carried out by the control unit; and Figure 5 shows a second diagram of the wiper angle plotted against time. Fig. 1 shows a perspective view of a motor vehicle 10. The motor vehicle 10 has a windshield 15 and a wiper system 20. The wiper system 20 comprises a wiper drive 25 and a wiper arm 30. Furthermore, the wiper system 20 includes a control unit 35. The control unit 35 is connected to the wiper drive 25 by means of a first connection 40. The wiper system 20 further comprises a wiper blade 45, which rests on the outer surface of the windscreen 15. The wiper blade 45 is coupled to the wiper arm 30 via a connecting element 50. A wiper shaft 51 of the wiper drive 25 is, in turn, attached to the wiper arm 30. The wiper drive 25 serves to guide the wiper blade 45 across the windscreen 15 in order to remove moisture and / or dirt from the windscreen 15. The wiper drive 25 moves the wiper blade 45 between a lower turning position 55 and an upper turning position. The upper turning position 60 is located near an A-pillar 65 of the vehicle 10. The lower turning position 55 is located near a hood 70 of the vehicle 10. A wiping area 75 is cleaned by the wiper blade 45 between the lower and upper turning positions 55, 60. The wiping area 75 is schematically marked with dashed lines in Fig. 1. The motor vehicle 10 also has a control element 80 located in the vehicle interior. Furthermore, a speed sensor 125 is provided. The speed sensor 125 is designed to detect the vehicle's speed as a driving condition of the motor vehicle 10. Of course, it is also conceivable that additional or alternative sensors are provided to detect the driving condition of the motor vehicle 10, either in addition to or as an alternative to the speed sensor 125. For example, it is conceivable that the detection device 90 is connected to a rain sensor, a light sensor, or other sensors. Fig. 2 shows a schematic representation of the control unit 35 shown in Fig. 1. Fig. 3 shows a first diagram of a wiping angle φ of the wiping system 20, plotted against a time t for a wiping interval. The wiping interval is defined by the time required to move the wiper blade once back between the lower turning position 55 and the upper turning position 150, 155, 160. The control unit 35 comprises a detection device 90, a control unit 95, and a memory 100. The control unit 95 is connected to the detection device 90 via a second connection 105. The control unit 95 is connected to the memory 100 via a third connection 110. The detection device 90 is connected to the operating element 80 via a fourth connection 115. The detection device 90 is further connected to the speed sensor 125 of the motor vehicle 10 via a fifth connection 120. The control unit 95 controls the wiper drive 25 by means of a control signal. This control signal can, for example, provide electrical energy to drive the wiper drive 25. Of course, it is also conceivable that the control signal could contain information about a travel speed and / or a voltage and / or a current to be supplied to the wiper drive 25. The driver can use the control element 80 to set a system state of the wiper system 20. This allows the wiper system 20 to be activated or deactivated, an automatic operating mode to be activated or deactivated, and / or a wiper interval to be set. The detection device 90 detects the system state of the wiper system 20 or the control element 80 via a fourth connection and provides the control unit 95 with a status signal corresponding to the detected system state of the wiper system 20. Additionally, the speed sensor 125 provides a speed signal corresponding to the vehicle speed via the fifth connection 120 to the detection device 90. The detection device 90 detects the speed signal and provides the control unit 95 with information about the vehicle's speed as part of the status signal. It should be noted that the detection device 90 can also be connected to other sensors and can detect their states. It is also conceivable that the detection device 90 is connected exclusively to the speed sensor 125 or the control element 80 and provides a status signal adapted accordingly to this configuration. The control unit 95 is designed to detect the status signal Z, which is provided via the second connection 105 by the detection unit 90. Memory 100 contains a first position characteristic curve 135, a second position characteristic curve 140, and a third position characteristic curve 145 (see Fig. 3). The first position characteristic curve 135, the second position characteristic curve 140, and the third position characteristic curve 145 are different from each other. The position characteristic curves 135, 140, and 145 have a common lower turning position 55. The common lower turning position 55 is reached after the same normalized time t. Relating the position of a wiper angle φ to a normalized time t for a wiper interval has the advantage that the position of the wiper blade 45 can be determined and displayed independently of the wiper interval. The first position characteristic curve 135 has a first upper turning position 150, and the second position characteristic curve 140 has a second upper turning position 155. The third position characteristic curve 145 has a third upper turning position 160. The upper turning positions 150, 155, 160 of the first position characteristic curve 135 correspond spatially to the upper turning position 55 shown in Fig. 1. The position characteristic curves 135, 140, and 145 differ in that they exhibit different temporal profiles. If the wiper blade 45 is guided over the disc 15 according to the first position characteristic curve 135, the corresponding positions are reached later than if the wiper blade 45 is guided over the disc 15 according to the third position characteristic curve 145. In this embodiment, the position characteristic curves 135, 140, and 145 are sinusoidal. Of course, it is also conceivable that the position characteristic curves 135, 140, and 145 could have a different profile. However, it is essential that the position characteristic curves 135, 140, and 145 are continuous. In this embodiment, the position characteristics 135, 140, and 145 are stored in memory 100 by means of tabularly assigned positions relative to time. The first position characteristic 135 requires a first time duration t1 to move from the first lower turning position 55 to the first upper turning position 150. The third position characteristic 140 / 145 has a second time duration t2 for moving between the lower turning position 55 and the third upper turning position 160. The second time duration t2 is shorter than the first time duration t1. The same applies to the second position characteristic 140. Since the time required to wipe across the disc 15 between the lower turning position 55, the upper turning position 150, 155, 160, and back to the lower turning position 55 is the same for all three position characteristic curves 135, 140, 145, a third time t3 for moving from the first upper turning position 150 down to the lower turning position 55 is shorter than a fourth time t4 of the first position characteristic curve 135, which is between the first upper turning position 160 and the lower turning position 55. It should be noted that other position characteristic curves are of course conceivable. It is also conceivable that the process sequence may include different or additional steps. The design described above has the advantage that the wiper blade 45's movement noise can be optimized even at low driving speeds, and the power required to move the wiper blade 45 across the disc 15 can be adjusted as the driving speed increases. Of course, it is also conceivable that the position characteristic curves 135, 140, 145 could be designed according to other optimization criteria. In particular, it would be conceivable, for example, to additionally or alternatively consider a subjective movement pattern of the wiper blade across the disc 15 when designing the position characteristic curves 135, 140, 145, in addition to or as an alternative to the operating noise. Furthermore, a first threshold value S1 and a second threshold value S2 are stored in the memory. In this embodiment, the first threshold value S1 corresponds to a first driving speed of the motor vehicle 10. The second threshold value S2 corresponds to a second driving speed of the motor vehicle 10, wherein the second threshold value S2 is selected such that a second driving speed corresponding to the threshold value is greater than the first driving speed corresponding to the first threshold value S1. Fig. 4 shows a flowchart of a procedure carried out by the control unit 35. In a first process step 200, the control unit 95 records the status signal Z. In a second process step 205, the control unit 95 checks whether the status signal Z indicates that the wiper system 20 is activated and that wiping of the wiper blade 45 across the disc 15 is desired. If this is not the case, the control unit 95 continues with the first process step 200. If the wiping system 20 is activated according to the status signal Z, the control unit 95 proceeds with the third process step 210. In the third process step 210, the control unit 95 checks whether the information about the detected driving speed provided by the status signal is less than the first threshold value S1. If this is the case, the control unit 95 proceeds to the fourth process step 215 and controls the wiper drive 25 according to the first position characteristic curve 135. This guides the wiper blade 45 across the disc 15 according to the first position characteristic curve 135. For example, it is conceivable that a driving speed of 50 km / h is chosen as the first threshold value S1. Of course, it is also conceivable that a different value is stored in memory 100 for the first threshold value S1. If the status signal Z is such that the information provided about the detected driving speed is greater than the first threshold value S1 stored in memory 100, the control unit 95 proceeds with a fifth process step 220. In the fifth process step 220, the control unit 95 compares information about the detected driving speed with the second threshold value S2 stored in memory 100. If the detected information about the second driving speed correlates with a value that is lower than the second threshold value S2, the control unit 95 proceeds to the sixth process step 225. If the value of the driving status signal F exceeds the second threshold value S2, the control unit 95 proceeds to the seventh process step 230. In the sixth process step 225, the control unit 95 controls the wiper drive 25 by means of a control signal such that the wiper blade 45 is guided along the second position characteristic curve 140 across the disc 15. For example, it is conceivable that a value corresponding to a driving speed of 160 km / h is stored in memory 100 as the second threshold value S2. If the control unit 95 continues with the seventh process step 230, the control unit 95 controls the wiper drive 25 according to the third position characteristic curve 145. Fig. 5 shows a second diagram of the wiper angle φ, plotted against time t. In the second diagram, as in the first diagram, the position characteristics 135, 140, 145 are shown, with the first position characteristic 145 corresponding to the first position characteristic 135 shown in Fig. 3. The second and third position characteristics 140, 145 are modified compared to Fig. 3. As an alternative to storing all position characteristic curves 135, 140, 145, it is conceivable that a formula for the first position characteristic curve 135 is stored in memory 100. The control unit 95 is configured to determine the second position characteristic curve 140 and, if necessary, further position characteristic curves based on the formula for the first position characteristic curve 135 stored in memory 100 and the detected status signal Z. The formula can, for example, be stored in memory 100 as an nth-order function, in particular as a third-order function. In this embodiment, the third-order function has four coefficients. These coefficients are stored in memory 100 for the function for the first position characteristic curve 135. Based on the status signal Z and the coefficients for the first position characteristic curve 135 stored in memory 100, the control unit 95 determines the new coefficients for the second position characteristic curve 140.After determining the new coefficients, the control unit 95 uses the new coefficients and the formula to determine the second position characteristic curve 140. Similarly, the control unit 95 can perform the same procedure for other position characteristic curves, in particular for the position characteristic curve 145. This has the advantage that, in the area of ​​the turning positions 55 and 60, the second position characteristic curve 140 can be precisely varied to provide improved wiper blade repositioning 45. This also has the advantage that, based on the driving speed or the operating state of the wiper system 20, the position characteristics 135, 140, 145 can be adapted, thus providing optimal noise behavior and, at the same time, optimal wiping performance with a maximum wiping area. In particular, at high driving speeds, as shown in Fig. 5, the upper turning position 150, 155, 160 can be varied such that a smaller wiping area 75 is predefined by the third position characteristic 145 in order to compensate for elastic deformation of the wiper arm 30 due to the wind load acting on the wiper arm 30 at high driving speeds and to prevent the wiper blade 45 from striking the A-pillar 65. Furthermore, the third position characteristic curve 145 in the lower turning position 55, as shown in Fig. 5, can also be modified using the above-described method of adapting the coefficients of the nth-order function to ensure that the wiper blade 45 is reliably brought to its rest position in the lower turning position 55 at high driving speeds. A lower turning position 170 of the third position characteristic curve 145 is selected such that it lies below the lower turning position 55 of the first and second position characteristic curves 135 and 140. In this way, the wind loads acting on the wiper blade 45 or on the wiper drive 25 can be reliably compensated. In the embodiment, for example, the second and / or third position characteristic curve 140, 145 has the upper turning position 155, 160 of the second or third position characteristic curve 150, 155 a smaller distance to the first lower turning position 55 of the first position characteristic curve 135 than the upper turning position 150 of the first position characteristic curve 135. Depending on the configuration of the second and / or the third position characteristic curve 140, 145, the second and / or third position characteristic curve 140, 145 has a second lower turning position 170, which has a greater distance to the first upper turning position 150 than the first lower turning position 55 of the first position characteristic curve 135. It should be noted that other position characteristics are of course conceivable. It is also conceivable that the procedure may include different or additional steps.

Claims

Control unit (35) for a wiper system (20) of a motor vehicle (10), comprising a control unit (95), a detection unit (95) and a memory (100), wherein the control unit (95) is connected to the memory (100) and the detection unit (90), wherein at least one first position characteristic curve (135) is stored in the memory (100), wherein the detection unit (90) is configured to detect a driving state of the motor vehicle and / or a system state of the wiper system (20) and to provide the control unit (95) with a status signal corresponding to the driving state, wherein the control unit (95) is configured to provide a control signal for controlling the wiper system (20) in a wiping movement across a window (15) of the motor vehicle (10), characterized in that a second position characteristic curve (140, 145) is stored in the memory (100), wherein the control unit (95) is trainedto detect the status signal of the detection device (90) and to select between the first and the second position characteristic curve (135, 140, 145) depending on the status signal and to provide a corresponding control signal according to the selection. Control unit (35) according to claim 1, characterized in that - the first position characteristic curve (135) is stored in the memory (100) using a formula, - wherein the control device (95) is configured to determine a second position characteristic curve on the basis of the formula for the first position characteristic curve stored in the memory (100) and the status signal. Control unit (35) according to claim 2, characterized in that - the formula has at least one predefined coefficient, - wherein the control device (95) is configured to determine the coefficient depending on the status signal, - wherein the control device (95) is configured to determine the second position characteristic curve on the basis of the formula and the determined coefficient. Control unit (35) according to one of claims 1 to 3, characterized in that - at least one predefined threshold value is stored in the memory (100), - wherein the control device is configured to compare the status signal with the threshold value (S1, S2), - wherein the control device (95) is configured to select the first or the second position characteristic curve depending on the result of the comparison. Control unit (35) according to one of claims 1 to 4, characterized in that - the first position characteristic curve (105) has a first upper turning position (60) and a first lower turning position (55), - wherein the second position characteristic curve (140, 145) has a second upper turning position (155, 160) and a second lower turning position (170), - wherein the first upper and / or lower turning position (155, 160, 170) is different from the second upper and / or lower turning position. Control unit (35) according to claim 5, characterized in that: - the status signal includes information about the vehicle's speed, - the control device (95) is configured to select the first position characteristic curve (135) at a first speed and the second position characteristic curve (140, 145) at a second speed that is greater than the first speed, - the second upper turning position (155, 160) has a smaller distance to the first lower turning position (55) than the first upper turning position (150), - and / or the second lower turning position has a larger distance to the first upper turning position than the first lower turning position (55, 35). Control unit (35) according to claim 5 or 6, characterized in that: - the first position characteristic curve for wiping the wiper arm (30) from the first lower turning position (55) and to the first upper turning position (150) has a first time duration; - the second position characteristic curve (140, 155) from the second lower turning position (55) and to the second upper turning position (155, 160) has a second time duration t2; - the second time duration t2 is shorter than the first time duration t1; and / or: - the first position characteristic curve (135) for moving from the first upper turning position (150) and to the first lower turning position (55) has a third time duration t3; - the second position characteristic curve for moving from the second upper turning position (55, 170) and to the second lower turning position has a fourth time duration t4; - the third time duration is shorter than the The fourth time period is Wiping system (20) with a wiper arm (45) and a wiper drive (25),- wherein the wiper drive (25) is coupled to the wiper arm (45) and is configured to move the wiper arm (45) to perform a wiping movement over a window (15) of the motor vehicle (10)- characterized in that- a control unit (35) according to one of claims 1 to 7 is provided,- wherein the control unit (35) is connected to the wiper drive (25),- wherein the control unit (35) controls the wiping movement of the wiper drive (25) by means of the control signal. Wiping system (20) according to claim 8, characterized in that the control unit (35) is configured to move the wiper arm (45) between a lower turning position (55, 170) and an upper turning position (150, 155, 160), wherein the first position characteristic curve (135) has a different upper and / or lower turning position (55, 150) compared to the second position characteristic curve (140, 145). Method for controlling a wiper system (20) according to claim 8 or 9, - wherein a driving state of the motor vehicle (10) is detected, - wherein a state signal corresponding to the driving state and / or the system state is provided, - wherein the state signal is detected and a selection is made between the first and the second position characteristic curve (135, 140, 145) depending on the state signal, and a corresponding control signal is provided according to the selection to control the wiping movement of the wiper system (20).

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