Control device

Abstract

This control device comprises: a drive unit that swings a wiper arm by rotating a rotary shaft by supplying electric power to a motor; and a control unit that controls the drive unit to switch from a first mode, in which the angular velocity of the rotary shaft is set to a first speed, to a second mode, in which the angular velocity of the rotary shaft is set to a second speed, at a first time point that is a first period earlier than an inversion time point when the wiper arm reaches an inversion position, and to switch from the second mode to the first mode at a second time point that is a second period earlier than the inversion time point, the second period being shorter than the first period.

Description

Control device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from patent application serial number 2024-068924, filed April 22, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a control device.

[0003] Patent document 1 states, "According to the wiper device of the present invention, the control means controls the drive means so that the angular velocity and angular acceleration of the wiper arm, which swings around the wiper rotation axis, at the reversal position are approximately zero. Therefore, the wiper blade can be reliably reversed at the reversal position without overrunning."

[0004] JP 2007-237921 A

[0005] It is known that wiper systems can overrun, where the wiper blades exceed the reverse position. When this overrun occurs, the wiping range deviates from the intended range. Therefore, it is necessary to effectively control the overrun in order to keep the wiping range within the intended range.

[0006] In Patent Document 1, a technique for suppressing overrun is disclosed in which preset target value data is prepared and a drive means is controlled in accordance with the target value data to set the angular velocity and angular acceleration at the wiper arm reversal position to approximately zero. However, this conventional technique has the problem of requiring the creation of a target map and adjusting the control gain each time, which is time-consuming and complicated to adjust.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a control device in a wiper system that can control overrun with relatively simple control and keep the wiping range within the intended range.

[0008] In order to achieve the above object, the control device of the present disclosure includes a drive unit that supplies power to a motor to rotate the rotating shaft and oscillate the wiper arm, and a control unit that controls the drive unit to switch from a first mode in which the angular velocity of the rotating shaft is set to a first speed to a second mode in which the angular velocity is set to a second speed at a first time point that is a first period before the reversal time point when the wiper arm reaches the reversal position, and to switch from the second mode to the first mode at a second time point that is a second period before the reversal time point that is shorter than the first period.

[0009] According to the present disclosure, the overrun can be controlled by a relatively simple control, and the wiping range can be kept within the intended range.

[0010] 1 is a diagram illustrating a first example of the wiper system 1. FIG. 2 is a simulation result showing overrun when operated in Hi mode according to a comparative example. FIG. 3 is a simulation result showing overrun when operated in Lo mode according to a comparative example. FIG. 4 is a diagram illustrating an example of a control system 10 that may include the control device 100 according to the present embodiment. FIG. 5 is a diagram illustrating an example of the functional configuration of a control unit 120 provided in the control device 100 according to the present embodiment. FIG. 6 is a diagram illustrating control by the control device 100 according to the first embodiment. FIG. 7 is a simulation result showing overrun by the control device 100 according to the first embodiment. FIG. 8 is a diagram illustrating control by the control device 100 according to the second embodiment. FIG. 9 is a simulation result showing overrun by the control device 100 according to the second embodiment. FIG. 10 is a diagram for explaining a first period and a second period in the control by the control device 100 according to the second embodiment. FIG. 11 is a diagram illustrating control by the control device 100 according to the third embodiment. FIG. 12 is a diagram illustrating a second example of the wiper system 1.

[0011] Hereinafter, one embodiment of the present disclosure will be described.

[0012] Fig. 1 is a diagram showing a first example of a wiper system 1. Fig. 1 shows an example of a wiper system 1 mounted on a vehicle. The wiper system 1 includes a wiper blade 2, a wiper arm 3, a rotating shaft 4, and a motor 5.

[0013] The wiper blade 2 is used to wipe away raindrops and other debris from the surface of the windshield. The tip of the wiper arm 3 is connected to the wiper blade 2, and the base of the wiper arm 3 is connected to a rotating shaft 4. The rotating shaft 4 is a wiper pivot shaft. The motor 5 is a wiper motor that rotates the rotating shaft 4 to swing the wiper arm 3.

[0014] In the wiper system 1, power is supplied to the motor 5, and the rotary shaft 4 is rotated to swing the wiper arm 3 between a first reversal position P1, which is the upper reversal position, and a second reversal position P2, which is the lower reversal position, so that the wiper blade 2 reciprocates to wipe away raindrops and the like adhering to the wiping area.

[0015] During this reciprocating wiping motion, it is known that the wiper blade 2 may overrun the first reversal position P1 or the second reversal position P2, resulting in a wiping range that deviates from the intended range. Therefore, it is necessary to effectively control the overrun in order to keep the wiping range within the intended range.

[0016] The control device 100 according to this embodiment controls such overrun with a relatively simple control, thereby keeping the wiping range within the intended range.

[0017] Figure 2 shows the results of a simulation of overrun when the engine is operated in Hi mode in a comparative example. In Figure 2, the horizontal axis represents time in seconds [s]. The right vertical axis represents angular acceleration [rad / s]. ２ 2, the left vertical axis indicates the angle in [deg]. The length from the rotary shaft 4 to the tip of the wiper arm 3 is set to 700 mm.

[0018] In FIG. 2 , waveform w1 represents the angular acceleration at the tip of the wiper arm 3. Therefore, values ​​on the right vertical axis are applied to waveform w1. Waveform w2 represents the rotation angle of the rotary shaft 4. Waveform w3 represents the swing angle at the tip of the wiper arm 3. Therefore, values ​​on the left vertical axis are applied to waveforms w2 and w3. Here, values ​​on the right vertical axis are expressed as + (plus) and - (minus) with zero in between. This indicates that + (plus) indicates the side of the angular acceleration that acts to increase the speed of the rotary shaft 4 in the rotation direction toward the first reversal position P1, and - (minus) indicates the side that acts to decrease the speed. Therefore, the plus and minus signs of the angular acceleration are reversed in the rotation direction of the rotary shaft 4 toward the second reversal position P2.

[0019] FIG. 2 shows the results of a simulation of overrun when the wiper arm 3 is operated in Hi mode with an angular velocity of 64 cycles per minute, i.e., 64 cycles per minute, where one reciprocation of the rotary shaft 4 is one cycle. Even if the angular velocity of the rotary shaft 4 is controlled as designed, the tip of the wiper arm 3 experiences a negative angular acceleration (-53 rad / s in FIG. 2) when the angle of the rotary shaft 4 reaches the designed value for the reversal position. ２ ) In other words, the largest deceleration occurs when the angle of the rotary shaft 4 reaches a value designated as the reversal position, and therefore the reversal position at the tip of the wiper arm 3 exceeds the design value due to inertial force. As a result, the wiper blade 2 overruns the reversal position, causing the wiping range to deviate from the intended range.

[0020] The right side of Figure 2 shows an enlarged view of the vicinity of the first reversal position P1 shown on the left side of Figure 2. As shown on the right side of Figure 2, when operated in Hi mode, an overrun of 2.23 degrees occurs due to the angular difference between the reversal position at the tip of the wiper arm 3 and the design value of the rotary shaft 4. In this simulation, the length to the tip of the wiper arm 3 is set to 700 mm, so the amount of overrun at the tip of this wiper arm 3 can be expressed as a distance of 2.23 degrees × (π / 180) × 700 mm = 27.3 mm.

[0021] 3 shows the results of a simulation of overrun when the wiper arm 3 is operated in Lo mode in a comparative example. The definitions of the axis, waveform, and length from the rotary shaft 4 to the tip of the wiper arm 3 in FIG. 3 are the same as those in FIG. 2, and therefore will not be described here.

[0022] 3 shows the results of simulating overrun when the wiper arm 3 is operated in Lo mode, where the angular velocity of the rotary shaft 4 is 42 cycles per minute, i.e., when one reciprocation of the wiper arm 3 is one cycle, the cycle is 42 cycles per minute. When the wiper arm 3 is operated in Lo mode, the magnitude is smaller than when the wiper arm 3 is operated in Hi mode, but when the angle of the rotary shaft 4 reaches the value designed as the reversal position, the tip of the wiper arm 3 experiences a negative angular acceleration (-22 rad / s in FIG. 3). ２ ) In other words, even when the wiper is operated in the Lo mode, as in the Hi mode, the largest deceleration occurs when the angle of the rotary shaft 4 reaches a value designed as the reversal position, so the reversal position of the tip of the wiper arm 3 also exceeds the designed value due to inertial force, resulting in an overrun in which the wiper blade 2 exceeds the reversal position. Therefore, even when the wiper is operated in the Lo mode, the wiping range deviates from the intended range.

[0023] As shown on the right side of Figure 3, when operated in Lo mode, an overrun of 1.04 degrees occurs due to the angular difference between the reversal position at the tip of the wiper arm 3 and the design value of the rotary shaft 4. When the amount of overrun at the tip of the wiper arm 3 is expressed as a distance, as in Figure 2, it becomes 12.7 mm.

[0024] The control device 100 according to this embodiment effectively controls such overrun with relatively simple control, thereby keeping the wiping range within the intended range. In the first and second embodiments, the control device 100 actively oscillates the operation of the wiper arm 3 for a predetermined period before the wiper arm 3 reaches the reversing position, thereby offsetting the angular acceleration of the reversing operation of the wiper arm 3 with an angular acceleration of the opposite sign, thereby reducing the inertial force. In this way, the control device 100 suppresses the occurrence of overrun, thereby keeping the wiping range within the intended range.

[0025] On the other hand, in the third embodiment, the control device 100 actively vibrates the operation of the wiper arm 3 for a predetermined period before the wiper arm 3 reaches the reversing position, thereby amplifying the angular acceleration of the reversing operation of the wiper arm 3 by an angular acceleration of the same sign, thereby increasing the inertial force. In this way, the control device 100 actively utilizes overrun to prevent a short circuit (a situation where the intended wiping range is not reached), thereby keeping the wiping range within the intended range.

[0026] 4 is a diagram showing an example of a control system 10 that may include the control device 100 according to this embodiment. The control system 10 is a system for controlling the motor 5. The control system 10 includes a battery 11, an operation switch 12, a position detector 13, and the control device 100.

[0027] The battery 11 is a source of power supply, and may be, for example, an on-board battery installed in a vehicle.

[0028] The operation switch 12 is a switch that allows a user (e.g., a driver) to operate the operation mode of the wiper system 1. Hereinafter, a case where there are three operation modes, namely, an OFF mode, a Lo mode, and a Hi mode, will be described as an example. In the OFF mode, the wiper system 1 may operate to stop rotation of the rotary shaft 4, i.e., to rotate the rotary shaft 4 at 0 cycles per minute. In the Lo mode, the wiper system 1 may operate to rotate the rotary shaft 4 at, for example, 42 cycles per minute. In the Hi mode, the wiper system 1 may operate to rotate the rotary shaft 4 at, for example, 64 cycles per minute.

[0029] When there are three operating modes, in the first embodiment, the speed in Lo mode or Hi mode is defined as the first speed, and the speed in OFF mode (i.e., the rotating shaft 4 is at 0 cycles / min) is defined as the second speed.

[0030] In the second embodiment, the speed in the Hi mode is defined as the first speed, and the speed in the Lo mode is defined as the second speed. In this way, in the first and second embodiments, the second speed may be slower than the first speed.

[0031] On the other hand, in the third embodiment, the speed in the Lo mode is defined as the first speed, and the speed in the Hi mode is defined as the second speed. Thus, in the third embodiment, the second speed may be faster than the first speed.

[0032] In the above description, the operation modes are described as three modes, namely, OFF mode, Lo mode, and Hi mode, but the present invention is not limited to this. For example, the operation modes may be five modes, including a Mid mode and an ExHi mode. In the Mid mode, the wiper system 1 may operate to rotate the rotary shaft 4 at a speed (e.g., 53 cycles / min) faster than the speed in the Lo mode and slower than the speed in the Hi mode. In the ExHi mode, the wiper system 1 may operate to rotate the rotary shaft 4 at a speed (e.g., 75 cycles / min) faster than the speed in the Hi mode.

[0033] In the first embodiment, when there are five operating modes, the speed of any one of the Lo mode, Mid mode, Hi mode, and ExHi mode can be defined as the first speed, and the speed of the OFF mode can be defined as the second speed.

[0034] Furthermore, in the second embodiment, when there are five operating modes, the speed of any one of Mid mode, Hi mode, and ExHi mode can be defined as the first speed, and the speed of Lo mode can be defined as the second speed; the speed of Hi mode or ExHi mode can be defined as the first speed and the speed of Mid mode can be defined as the second speed; or the speed of ExHi mode can be defined as the first speed and the speed of Hi mode can be defined as the second speed.

[0035] On the other hand, in the third embodiment, when there are five operating modes, the speed of the Lo mode can be defined as the first speed, and any one of the speeds of the Mid mode, Hi mode, and ExHi mode can be defined as the second speed, the speed of the Mid mode can be defined as the first speed, and the speed of the Hi mode or ExHi mode can be defined as the second speed, or the speed of the Hi mode can be defined as the first speed, and the speed of the ExHi mode can be defined as the second speed.

[0036] The position detector 13 detects the rotation of the rotating shaft 4. The position detector 13 may be, for example, a rotation detection unit disposed in the motor 5 (disposed around the rotation axis of the armature of the motor 5 or around the output shaft of the motor 5, or both), and outputs a pulse signal to the control device 100 in accordance with the rotation of the rotating shaft 4. The control device 100 can recognize the angle of the rotating shaft 4 by counting the pulse signals output from the position detector 13.

[0037] The control device 100 controls the power supplied to the motor 5 to swing the wiper arm 3. The control device 100 includes a drive unit 110 and a control unit 120.

[0038] The drive unit 110 supplies power to the motor 5 to rotate the rotary shaft 4 at a speed corresponding to the operation mode, thereby swinging the wiper arm 3 back and forth. At this time, the drive unit 110 may adjust the angular velocity of the rotary shaft 4 by shorting both terminals of the motor 5, or may adjust the angular velocity of the rotary shaft 4 by changing the duty ratio of a PWM signal, which is a control signal for supplying power to the motor 5.

[0039] The control unit 120 controls the drive unit 110. When the wiper system 1 is not near the reversing position, the control unit 120 controls the drive unit 110 to operate the wiper system 1 in the operation mode operated by the operation switch 12. On the other hand, when the wiper system 1 is near the reversing position, the control unit 120 controls the drive unit 110 to switch the angular velocity of the rotary shaft 4 from a first mode, in which the angular velocity is a first speed, to a second mode, in which the angular velocity is a second speed, at a first time point that is a first period before the reversing point when the wiper arm 3 reaches the reversing position, and from the second mode to the first mode at a second time point that is a second period before the reversing point that is shorter than the first period. This will be described in detail.

[0040] 5 is a diagram showing an example of the functional configuration of the control unit 120 included in the control device 100 according to this embodiment. The control unit 120 includes a storage unit 121, a comparison unit 122, and a switching unit 123.

[0041] The storage unit 121 stores the relationship between the angle or time of the rotary shaft 4 and the operation mode. That is, the storage unit 121 may store a switching table that defines at what angle of the rotary shaft 4 or at what time the operation mode of the wiper system 1 is switched.

[0042] The comparison unit 122 compares the detection result with the switching table stored in the storage unit 121. When determining the switching timing based on the angle, the comparison unit 122 may compare the angle of the rotating shaft 4 recognized by counting pulse signals output from the position detector 13 with the switching table. Then, the comparison unit 122 may instruct the switching unit 123 to switch the operation mode when it determines that the predetermined switching timing has occurred based on the angle of the rotating shaft 4. On the other hand, when determining the switching timing based on the time, the comparison unit 122 may compare the time output from a timer (not shown) with the switching table. Then, the comparison unit 122 may instruct the switching unit 123 to switch the operation mode when it determines that the predetermined switching timing has occurred based on the time.

[0043] The switching unit 123 switches the operation mode based on an instruction from the comparison unit 122. In response to this, the control unit 120 supplies the drive unit 110 with a drive voltage according to the operation mode.

[0044] The control device 100 according to this embodiment may be configured as follows, for example. The control performed by the control device 100 according to this embodiment will be described in detail using three embodiments: a first embodiment, a second embodiment, and a third embodiment.

[0045] 6 is a diagram schematically illustrating the control by the control device 100 according to the first embodiment. In FIG. 6, only the control near the first reversal position P1 when the wiper arm 3 pivots from the second reversal position P2 to the first reversal position P1 is illustrated as an example. However, the control can also be applied to the control near the second reversal position P2 when the wiper arm 3 pivots from the first reversal position P1 to the second reversal position P2.

[0046] As described above, in the first embodiment, the speed in the Lo mode or Hi mode is defined as the first speed, and the speed in the OFF mode is defined as the second speed. Note that, as shown in the simulation results above, the overrun is larger in the Hi mode than in the Lo mode, so in the description of FIG. 6, the speed in the Hi mode, which is the stricter condition, is defined as the first speed.

[0047] Therefore, when the wiper system 1 is operated in the Hi mode, the control unit 120 controls the drive unit 110 to rotate the rotary shaft 4 at the Hi mode speed except near the reversal position. On the other hand, the control unit 120 executes a unique control near the reversal position. More specifically, the control unit 120 switches from the Hi mode to the OFF mode at a first time point that is a first period before the reversal point when the wiper arm 3 reaches the reversal position (first reversal position P1 in FIG. 6 ), i.e., controls the drive unit 110 to stop the rotation of the rotary shaft 4. At this time, the control unit 120 may switch from the Hi mode to the OFF mode by controlling the drive unit 110 to stop the supply of power to the motor 5.

[0048] Next, the control unit 120 controls the driving unit 110 to maintain the OFF mode for a certain period from the first time point, and then controls the driving unit 110 to switch from the OFF mode to the Hi mode at a second time point when the certain period has elapsed since the first time point.

[0049] In the first embodiment, the control unit 120 controls the drive unit 110 in this manner, for example, to switch from a first mode (Hi mode) in which the angular velocity of the rotating shaft 4 is set to a first speed (64 cycles / min) to a second mode (OFF mode) in which the angular velocity is set to a second speed (0 cycles / min) at a first time point that is a first period before the reversal time point when the wiper arm 3 reaches the reversal position, and then switches from the second mode (OFF mode) to the first mode (Hi mode) at a second time point that is a second period before the reversal time point that is shorter than the first period.

[0050] The lengths of the first period and the second period may be set appropriately depending on the wiping speed of the wiper system 1, the condition of the wiping surface (e.g., water repellent), the shape of the wiping surface (e.g., undulating shape), the shape of the wiping pattern (e.g., wiping angle, wiping range), etc., and may be recognizable from a switching table stored in the memory unit 121. As an example, the first period may be approximately 0.095 seconds, and the second period may be approximately 0.066 seconds. The second period may be set to any length that provides sufficient acceleration to offset the vibration generated during the first period and does not cause the user to feel uncomfortable with the behavior of the wiper system 1 when the operation mode of the wiper system 1 is turned off for a certain period.

[0051] 7 shows the results of a simulation showing overrun caused by the control device 100 according to the first embodiment. In FIG. 7, the definitions of the axes and waveforms are the same as those in FIG. 2, and therefore will not be described here.

[0052] As shown in the waveform w1, when the angle of the rotary shaft 4 reaches a value designed as the reversal position, the angular acceleration at the tip of the wiper arm 3 is approximately 0 rad / s. ２ The magnitude (absolute value) of such acceleration is -53 rad / s shown in Figure 2. ２ 3. ２ smaller than the size of

[0053] This means that positive angular acceleration is generated by actively vibrating the wiper system 1 by switching its operating mode to OFF mode for a certain period of time just before the reversal position, and this positive angular acceleration offsets the negative angular acceleration that occurs during normal reversal operation.

[0054] In this case, the positive angular acceleration completely cancels out the negative angular acceleration, making the angular acceleration 0 rad / s ２ However, it is not realistic to completely cancel the angular acceleration by simply switching the operation mode. Therefore, it is preferable that the magnitude of the angular acceleration after cancellation is -22 rad / s in this case. ２ If the magnitude is less than this, it can be said that the overrun suppression is functioning satisfactorily.

[0055] Therefore, the control unit 120 controls the power supplied from the drive unit 110 to the motor 5 so that the angular acceleration at the tip of the wiper arm 3 at the time of reversal is smaller than that in the case where the wiper arm 3 is reversed without switching to the low-speed mode (Lo mode in this case), which is the slowest of the multiple wiping operation modes. Note that the term "lowest low-speed mode" here means the operation mode with the lowest speed among the finite speed modes, and may be interpreted as not including the OFF mode in which the speed is zero.

[0056] As shown on the right side of FIG. 7 , when the wiper system 1 is controlled by the control device 100 according to the first embodiment, an overrun of 0.38° occurs due to the angular difference between the reversal position at the tip of the wiper arm 3 and the design value of the rotary shaft 4. Here, the length from the rotary shaft 4 to the tip of the wiper arm 3 is set to 700 mm, and the overrun amount at the tip of the wiper arm 3 is expressed as 4.6 mm. This is significantly smaller than the 12.7 mm overrun amount achieved when the wiper arm is operated in the Lo mode, demonstrating that overrun is sufficiently suppressed. At this time, the rotary shaft 4 rotates at 62.2 cycles per minute, maintaining the wiping speed in the Hi mode. The control device 100 according to the first embodiment actively generates vibration during a predetermined period immediately prior to the reversal position, thereby offsetting the angular acceleration of the reversal motion with an angular acceleration of the opposite sign, thereby reducing inertial force and suppressing overrun, thereby preventing the wiping range from deviating from the intended range.

[0057] 8 is a diagram schematically illustrating the control by the control device 100 according to the second embodiment. In FIG. 8, only the control near the first reversal position P1 when the wiper arm 3 pivots from the second reversal position P2 to the first reversal position P1 is illustrated as an example. However, the control can also be applied to the control near the second reversal position P2 when the wiper arm 3 pivots from the first reversal position P1 to the second reversal position P2.

[0058] As described above, in the second embodiment, the speed in the Hi mode is defined as the first speed, and the speed in the Lo mode is defined as the second speed.

[0059] Therefore, when the wiper system 1 is operated in the Hi mode, the control unit 120 controls the drive unit 110 to rotate the rotary shaft 4 at the Hi mode speed except near the reversal position. On the other hand, the control unit 120 executes a unique control near the reversal position. More specifically, the control unit 120 switches from the Hi mode to the Lo mode at a first time point that is a first period before the reversal point when the wiper arm 3 reaches the reversal position (first reversal position P1 in FIG. 8 ). In other words, the control unit 120 controls the drive unit 110 to decelerate the rotation of the rotary shaft 4.

[0060] Next, the control unit 120 controls the driving unit 110 to maintain the Lo mode for a certain period of time from the first time point, and then controls the driving unit 110 to switch from the Lo mode to the Hi mode at a second time point when the certain period of time has elapsed since the first time point.

[0061] In the second embodiment, the control unit 120 controls the drive unit 110 in this manner, for example, to switch from a first mode (Hi mode) in which the angular velocity of the rotating shaft 4 is set to a first speed (64 cycles / minute) to a second mode (Lo mode) in which the angular velocity is set to a second speed (42 cycles / minute) at a first time point that is a first period before the reversal time point when the wiper arm 3 reaches the reversal position, and then switches from the second mode (Lo mode) to the first mode (Hi mode) at a second time point that is a second period before the reversal time point that is shorter than the first period.

[0062] 9 shows the results of a simulation showing overrun caused by the control device 100 according to the second embodiment. In FIG. 9, the definitions of the axes and waveforms are the same as those in FIG. 2, and therefore will not be described here.

[0063] As shown in the waveform w1, when the angle of the rotary shaft 4 reaches a value designed as the reversal position, the angular acceleration at the tip of the wiper arm 3 is approximately 0 rad / s. ２ The magnitude (absolute value) of such acceleration is -53 rad / s shown in Figure 2. ２3. ２ smaller than the size of

[0064] This means that, as in the first embodiment, positive angular acceleration is generated by switching the operation mode of the wiper system 1 to Lo mode for a certain period of time just before the reversal position, thereby actively generating vibration, and this positive angular acceleration offsets the negative angular acceleration during normal reversal operation.

[0065] In the second embodiment, as in the first embodiment, the control unit 120 controls the power supplied from the drive unit 110 to the motor 5 so that the angular acceleration at the tip of the wiper arm 3 at the time of reversal is smaller than that when the wiper arm 3 is reversed without switching to the low-speed mode (here, Lo mode), which is the slowest of the multiple wiping operation modes.

[0066] As shown on the right side of Figure 9, when the wiper system 1 is controlled by the control device 100 according to the second embodiment, an overrun of 0.47 degrees occurs due to the angular difference between the reversal position at the tip of the wiper arm 3 and the design value of the rotary shaft 4. This amount of overrun at the tip of the wiper arm 3 is expressed as a distance of 5.8 mm. This is significantly smaller than the 12.7 mm overrun achieved when the wiper system is operated in Lo mode, demonstrating that overrun is sufficiently suppressed. At this time, the rotary shaft 4 rotates at 61.7 cycles per minute, maintaining the wiping speed in Hi mode.

[0067] It should be noted that when control is performed by the control device 100 according to the second embodiment, the effect of suppressing overrun is lower than when control is performed by the control device 100 according to the first embodiment. This is thought to be because when the operation mode is set to the Lo mode for a certain period of time, the magnitude of the positive angular acceleration generated by vibration is smaller than when the operation mode is set to the OFF mode for a certain period of time, and this positive angular acceleration is not able to completely cancel out the negative angular acceleration during normal reversal operation.

[0068] Here, it can be said that there is a trade-off between the overrun suppression effect and the unnatural behavior of the wiper system 1. That is, when the operation mode is controlled to the OFF mode for a certain period as in the first embodiment, the magnitude of the positive angular acceleration can be increased, thereby enhancing the overrun suppression effect; however, the speed difference before and after switching is large, thereby increasing the unnatural behavior of the wiper system 1. On the other hand, when the operation mode is controlled to the Lo mode for a certain period as in the second embodiment, the speed difference before and after switching can be reduced, thereby reducing the unnatural behavior of the wiper system 1; however, the magnitude of the positive angular acceleration is small, thereby reducing the overrun suppression effect. Therefore, whether to adopt the first embodiment or the second embodiment should be determined by comprehensively taking into account the overrun suppression effect, the unnatural behavior of the wiper system 1, and other factors.

[0069] In the first and second embodiments, the length of the first period and the length of the second period may be set based on the natural vibration of the wiper system 1. Here, the case of the second embodiment will be described.

[0070] 10 is a diagram illustrating the first and second periods in the control by the control device 100 according to the second embodiment. For ease of explanation, FIG. 10 illustrates the results of a simulation performed under the condition that the wiper arm 3 is a rigid body, unlike the simulation described above. The definitions of the axes and waveforms in FIG. 10 are the same as those in FIG. 2, and therefore will not be described here.

[0071] The center of Fig. 10 shows the operating modes of the wiper system 1. As shown in the center of Fig. 10, the wiper system 1 operates in the Hi mode until a first time point that is a first period before the reversal time when the wiper arm 3 reaches the reversal position, switches from the Hi mode to the Lo mode at the first time point, operates in the Lo mode for a certain period from the first time point, switches from the Lo mode to the Hi mode at a second time point that is a second period before the reversal time that is shorter than the first period, and operates in the Hi mode from the second time point.

[0072] 10 shows the waveform of the natural vibration of the wiper system 1 including the wiper arm 3. Here, since the wiper system 1 is a direct-coupled system without a link mechanism (the output shaft of the motor 5 is the rotary shaft 4), the case where the natural vibration of the wiper arm 3 is used as the natural vibration of the wiper system 1 will be described as an example.

[0073] The natural frequency f of the wiper arm 3 can be calculated from the stiffness value of the wiper arm 3. In this case, the stiffness of the wiper arm 3 can be calculated using FEM (Finite Element Method), regression, or the like. Here, it is assumed that the natural frequency f of the wiper arm 3 is calculated as 5.45 Hz. In this case, the period T of the natural vibration of the wiper arm 3 can be calculated as 0.183 s using the reciprocal of the natural frequency f.

[0074] The first period may be set to approximately 3 / 4 times the period T of the natural vibration calculated in this manner, based on the peak (inflection point) of the angular acceleration. Here, the first period is set to 0.138 s. The reason for using "approximately" is that the optimal value may deviate due to stiffness errors, inertia, etc.

[0075] If the second period is too short, the rotation speed will decrease significantly, and if it is too long, the angular acceleration to compensate for this will decrease. Taking these factors into consideration, the second period was set to 0.028 seconds.

[0076] In this way, the first period may be set in accordance with the natural vibration of the wiper system 1 including the wiper arm 3. More specifically, the first period may be set within a predetermined range based on 3 / 4 times the period T of the natural vibration.

[0077] By setting the first period in consideration of the natural vibration of the wiper system 1, it is possible to maximize the vibration that occurs when the operation mode of the wiper system 1 is set to the Lo mode for a certain period immediately before the reversal position, thereby increasing the magnitude of the positive angular acceleration. In this way, by matching the acceleration peak of the angular velocity at the tip of the wiper arm 3 with the natural vibration of the wiper arm 3, it is possible to maximize the cancellation effect. Furthermore, if the rigidity of the wiper system 1 is predicted in advance by analysis or the like, it is possible to calculate the first period from the natural vibration frequency, thereby eliminating the need for calibration on an actual device.

[0078] The control device 100 according to the second embodiment, for example, controls the vibration to be generated actively during a predetermined period immediately before the reversal position, and offsets the angular acceleration of the reversal motion with an angular acceleration of the opposite sign, thereby reducing the inertial force and suppressing overrun, thereby preventing the wiping range from deviating from the intended range.

[0079] In this way, in the first and second embodiments, the second speed may be slower than the first speed. Furthermore, in the first and second embodiments, the inertial force is reduced by canceling out the angular acceleration of the reversal movement of the wiper arm 3 with an angular acceleration of the opposite sign. This allows the control device 100 to prevent overrun, thereby preventing the wiping range from deviating from the intended range.

[0080] On the other hand, in the third embodiment, the second speed may be faster than the first speed. In the third embodiment, the inertial force is increased by amplifying the angular acceleration of the reversing movement of the wiper arm 3 by an angular acceleration of the same sign. In this way, the control device 100 actively utilizes overrun to prevent short circuits that occur mainly in operation in the low-speed mode, thereby preventing deviation of the wiping range from the intended range.

[0081] Fig. 11 is a diagram schematically illustrating control by the control device 100 according to the third embodiment. Fig. 11 is the same as Fig. 8 except that the Lo mode and Hi mode are reversed, and therefore detailed description thereof will be omitted here.

[0082] As described above, in the third embodiment, the speed in the Lo mode is defined as the first speed, and the speed in the Hi mode is defined as the second speed.

[0083] Therefore, when the wiper system 1 is operated in the Lo mode, the control unit 120 controls the drive unit 110 to rotate the rotary shaft 4 at the Lo mode speed except near the reversal position. On the other hand, the control unit 120 executes a unique control near the reversal position. More specifically, the control unit 120 controls the drive unit 110 to switch from the Lo mode to the Hi mode, i.e., to accelerate the rotation of the rotary shaft 4, at a first time point that is a first period before the reversal point when the wiper arm 3 reaches the reversal position (first reversal position P1 in FIG. 11 ).

[0084] Next, the control unit 120 controls the driving unit 110 to maintain the Hi mode for a certain period of time from the first time point, and then controls the driving unit 110 to switch from the Hi mode to the Lo mode at a second time point when the certain period of time has elapsed since the first time point.

[0085] In the third embodiment, the control unit 120 controls the drive unit 110 in this manner, for example, to switch from a first mode (Lo mode) in which the angular velocity of the rotating shaft 4 is set to a first speed (42 cycles / minute) to a second mode (Hi mode) in which the angular velocity is set to a second speed (64 cycles / minute) at a first time point that is a first period before the reversal time when the wiper arm 3 reaches the reversal position, and then switches from the second mode (Hi mode) to the first mode (Lo mode) at a second time point that is a second period before the reversal time that is shorter than the first period.

[0086] As a result, in the third embodiment, the inertial force is increased, resulting in a larger overrun. A simulation using the control device 100 according to the third embodiment resulted in an overrun of 27.6 mm. This is even larger than the 12.7 mm overrun in the Lo mode obtained from FIG. 3 and is equivalent to the 27.3 mm overrun in the Hi mode obtained from FIG. 2.

[0087] Therefore, the control by the control device 100 according to the third embodiment can generate an overrun of the same magnitude as that generated when the control device 100 is operated in the Hi mode. In this way, the control device 100 according to the third embodiment intentionally generates a large overrun.

[0088] Instead, the wiping range is designed with this kind of overrun in mind. Here, the reversal position is designed to be approximately 27 mm before the target, anticipating the 27.6 mm overrun and the 27.3 mm in FIG. 2 . This allows the control device 100 according to the third embodiment to actively utilize the intentionally large overrun to operate within the intended wiping range, or to actively utilize the intentionally large overrun to prevent a short circuit in situations where a short circuit would occur, such as when in low-speed mode and friction with the windshield surface (wiping surface) is high, thereby preventing the wiping range from deviating from the intended range.

[0089] Although the present embodiment has been described using three possible embodiments, the present embodiment may be modified or applied in various ways. For example, in FIG. 4 , the position detector 13 recognizes the angle of the rotary shaft 4 by counting pulse signals. However, the present invention is not limited to this. The pre-reverse position may be detected by a mechanical position detector composed of a movable contact that rotates integrally with the rotary shaft and a fixed contact that slides against the movable contact. This simplifies control. Furthermore, in the above description, a wiper system 1 without a link mechanism has been shown as an example. However, the present embodiment is equally applicable to a wiper system 1 with a link mechanism.

[0090] Fig. 12 is a diagram showing a second example of the wiper system 1. Fig. 12 may be the same as Fig. 1 except for the inclusion of the link mechanism 6, and therefore detailed description thereof will be omitted here. Note that, when the wiper system 1 includes the link mechanism 6 as shown in Fig. 12, the natural vibration of the wiper system 1 may be calculated by taking into account the natural vibration of the entire system including the wiper arm 3 and the link mechanism 6.

[0091] In addition, although the above description has been given as an example of a case where the transition from the first period to the second period is continuous and uninterrupted, the present invention is not limited to this. A very short stop period may be inserted during the transition from the first period to the second period.

[0092] In this way, the control device 100 according to this embodiment switches from a first mode in which the angular velocity of the rotating shaft 4 is set to a first speed to a second mode in which the angular velocity is set to a second speed at a first time point that is one period before the reversal point when the wiper arm 3 reaches the reversal position, and switches from the second mode to the first mode at a second time point that is a second period before the reversal point that is shorter than the first period.

[0093] As a result, according to the control device 100 of this embodiment, overrun can be controlled simply by switching the operation mode of the wiper system 1 (e.g., OFF / Hi / Lo) at a predefined angle or time, thereby simplifying control compared to conventional technology.

[0094] The controller and methods described herein may be implemented by a special-purpose computer having a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the apparatus and methods described herein may be implemented by a special-purpose computer having a processor configured with dedicated hardware logic circuitry. Alternatively, the apparatus and methods described herein may be implemented by one or more special-purpose computers configured by a combination of a processor executing a computer program and one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0095] The present disclosure also includes the following: (Supplementary Note 1) A control device comprising: a drive unit that supplies power to a motor to rotate a rotary shaft and swing a wiper arm; and a control unit that controls the drive unit to switch from a first mode in which the angular velocity of the rotary shaft is set to a first speed to a second mode in which the angular velocity is set to a second speed at a first time point that is a first period before a reversal time point when the wiper arm reaches a reversal position, and to switch from the second mode to the first mode at a second time point that is a second period before the reversal time point that is shorter than the first period. (Supplementary Note 2) The control device according to Supplementary Note 1, wherein the second speed is slower than the first speed. (Supplementary Note 3) The control device according to Supplementary Note 2, wherein the control unit switches from the first mode to the second mode by controlling the drive unit to stop supplying power to the motor. (Supplementary Note 4) The control device according to Supplementary Note 2 or 3, wherein the control unit controls the power supplied from the drive unit to the motor so that the angular acceleration at the tip of the wiper arm at the time of reversal is smaller than that in a case where the wiper arm is reversed without switching to a low-speed mode, which is the lowest of a plurality of wiping operation modes. (Supplementary Note 5) The control device according to any one of Supplementary Notes 1 to 4, wherein the first period is a period set in accordance with a natural vibration of a wiper system including the wiper arm. (Supplementary Note 6) The control device according to Supplementary Note 5, wherein the first period is a period set within a predetermined range based on 3 / 4 times the period of the natural vibration. (Supplementary Note 7) The control device according to Supplementary Note 1, wherein the second speed is faster than the first speed.

[0096] The above describes one embodiment of the present invention, but the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modified forms within the scope of the gist of the present invention.

Claims

1. A control device comprising: a drive unit that supplies power to a motor to rotate a rotary shaft and swing a wiper arm; and a control unit that controls the drive unit to switch from a first mode, in which the angular velocity of the rotary shaft is set to a first speed, to a second mode, in which the angular velocity is set to a second speed, at a first time point that is a first period before the reversal point when the wiper arm reaches the reversal position, and to switch from the second mode to the first mode at a second time point that is a second period before the reversal point that is shorter than the first period.

2. The control device according to claim 1, wherein the second speed is slower than the first speed.

3. The control device according to claim 2, wherein the control unit switches from the first mode to the second mode by controlling the drive unit to stop supplying power to the motor.

4. The control device according to claim 2, wherein the control unit controls the power supplied to the motor from the drive unit so that the angular acceleration at the tip of the wiper arm at the time of reversal is smaller than that in the case where the wiper arm is reversed without switching to the low-speed mode, which is the slowest of multiple wiping operation modes.

5. The control device according to claim 2, wherein the first period is a period set in accordance with a natural vibration of a wiper system including the wiper arm.

6. The control device according to claim 5, wherein the first period is a period set within a predetermined range based on 3 / 4 times the period of the natural vibration.

7. The control device according to claim 1, wherein the second speed is faster than the first speed.

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