Wiping device

Abstract

Provided is a wiper device capable of reducing the risk of interference between a wiper blade and other members. A wiper device in which a wiper blade is reciprocated by driving a power source using a predetermined drive signal, and in which the reverse position of the wiper blade is corrected by changing the drive signal in accordance with the wind pressure acting on the wiper blade, the wiper device is provided with a drive control unit for controlling the rotation of the wiper blade by controlling the rotation of the wiper blade in accordance with the wind pressure acting on the wiper blade. The drive control unit acquires a first wind pressure estimation value based on the vehicle speed and a second wind pressure estimation value based on the drive signal, corrects the reverse position based on the first wind pressure estimation value when the first wind pressure estimation value is greater than the second wind pressure estimation value, and corrects the reverse position based on the second wind pressure estimation value when the first wind pressure estimation value is equal to or less than the second wind pressure estimation value. The reversal position is corrected on the basis of the second wind pressure estimation value.

Description

Technical Field

[0001] The present invention relates to a wiping device. Background Art

[0002] As is well known, wiping devices are mounted on various vehicles, and the wiping devices wipe rainwater on the surface (wiped surface) of the front glass or the rear glass. The wiping device wipes the rainwater on the wiped surface by reciprocating a wiper blade by using a motor (power source). As an example of such a wiping device, a window wiping device is disclosed in Patent Document 1 below, which uniformly wipes the wiped surface by changing a control signal of the motor according to a wind load obtained from a vehicle speed and / or a wiping speed.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-512919 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] Incidentally, in the technique of changing the control signal of the motor according to the vehicle speed, it is impossible to cope with the influence of a crosswind (a headwind or a tailwind with respect to the wiper blade). That is, in the technique of changing the control signal according to the vehicle speed, for example, when the wiper blade is affected by a tailwind, the overrun of the wiper blade becomes large, and as a result, interference between the wiper blade and other members such as a pillar of the vehicle may occur.

[0008] In view of the above circumstances, an object of the present invention is to provide a wiping device capable of reducing the risk of interference between a wiper blade and other members.

[0009] Technical Means for Solving the Problems

[0010] In order to achieve the above object, in the present invention, as a first solution means of the wiping device, the following means is adopted: A wiping device that reciprocates a wiper blade by driving a power source by using a predetermined drive signal, and corrects a reverse position of the wiper blade by changing the drive signal according to a wind pressure acting on the wiper blade. The wiping device includes a drive control unit that acquires a first wind pressure estimated value based on a vehicle speed and a second wind pressure estimated value based on the drive signal. When the first wind pressure estimated value is greater than the second wind pressure estimated value, the reverse position is corrected based on the first wind pressure estimated value. When the first wind pressure estimated value is less than or equal to the second wind pressure estimated value, the reverse position is corrected based on the second wind pressure estimated value.

[0011] In the present invention, as a second solution means of the wiping device, the following means is adopted: in the first solution means, the drive signal is a Pulse Width Modulation (PWM) signal, and the drive control unit obtains the second wind pressure estimation value based on the duty ratio of the PWM signal.

[0012] In the present invention, as a third solution means of the wiping device, the following means is adopted: in the second solution means, the duty ratio is an average value within a specified time during the forward or return stroke of the wiper blade.

[0013] In the present invention, as a fourth solution means of the wiping device, the following means is adopted: in any one of the first solution means to the third solution means, one or two power sources are provided. One power source is used to make one or two wiper blades reciprocate, and two power sources are used to make two wiper blades reciprocate independently.

[0014] Effect of the Invention

[0015] Through the present invention, it is possible to provide a wiping device that can reduce the risk of interference between the wiper blade and other components. Description of the Drawings

[0016] Figure 1 is a block diagram showing the functional structure of the wiping device A according to the first embodiment of the present invention.

[0017] Figure 2 is a flowchart showing the operation of the wiping device A according to the first embodiment of the present invention.

[0018] Figure 3 is a characteristic diagram showing the correction reference change of the reverse position according to the first embodiment of the present invention.

[0019] Figure 4 is a block diagram showing the functional structure of the wiping device B according to the second embodiment of the present invention. Detailed Description of the Invention

[0020] 〔First Embodiment〕

[0021] Refer to Figures 1 to 3 The first embodiment of the present invention will be described. The wiping device A of the first embodiment is a device that is mounted on various vehicles such as gasoline vehicles, hybrid vehicles, or electric vehicles to wipe the rainwater adhering to the surface (wiped surface) of a wiped member such as a front glass or a rear glass.

[0022] As​​​​Figure 1 As shown, the wiping device A adopts a dual-motor drive method in which a pair of wiper blades 1a and 1b are independently driven by a pair of motors 7a and 7b as power sources. That is, the wiping device A of the first embodiment is provided with two power sources, and a pair of wiper blades 1a and 1b are reciprocated independently by the two power sources.

[0023] As shown in the figure, the wiping device A includes a pair of wiper blades 1a and 1b, a pair of wiper arms 2a and 2b, and a pair of motors 7a and 7b. In addition, in Figure 1 each symbol of, "a" represents a component or part existing on the driver's side of the vehicle or related to the driver's side. In addition, in Figure 1 each symbol of, "b" represents a component or part existing on the passenger's side of the vehicle or related to the passenger's side.

[0024] As shown in the figure, a pair of wiper blades 1a and 1b are rod-shaped members placed on the front glass W (the object to be wiped). A pair of wiper blades 1a and 1b are in contact with the surface (the wiped surface) of the front glass W and reciprocate (oscillate) on the wiped surface, thereby wiping the rainwater adhering to the wiped surface. In the Figure 1 , the symbol Ra is the wiping range of the wiper blade 1a on the driver's side, and the symbol Rb is the wiping range of the wiper blade 1b on the passenger's side.

[0025] The wiping range Ra on the driver's side is the moving range of the wiper blade 1a from the lower reverse position to the upper reverse position and with the wiper shaft 3a on the driver's side as the fulcrum. In contrast, the wiping range Rb on the passenger's side is the moving range of the wiper blade 1b from the lower reverse position to the upper reverse position and with the wiper shaft 3b on the passenger's side as the fulcrum.

[0026] During the reciprocating movement of a pair of wiper blades 1a and 1b within the wiping range Ra and the wiping range Rb, they stop within a specified period at the lower reverse position and the upper reverse position. Specifically, if a pair of wiper blades 1a and 1b move from the lower reverse position towards the upper reverse position, they temporarily stop at the upper reverse position within the specified stop period T, and after passing through the stop period T, they move from the upper reverse position towards the lower reverse position.

[0027] A pair of wiper blades 1a and 1b are reciprocated within the wiping range Ra and the wiping range Rb by being driven by a pair of motors 7a and 7b. Therefore, the lower reverse position and the upper reverse position are set by a pair of motors 7a and 7b. The details will be described later. The lower reverse position and the upper reverse position are corrected according to the speed of the vehicle (vehicle speed) or the drive signals of a pair of motors for driving a pair of wiper blades 1a and 1b respectively.

[0028] A pair of wiper blades 1a and 1b are mechanically connected to a pair of motors 7a and 7b via a pair of wiper arms 2a and 2b. That is, the driver's side wiper blade 1a is connected to the motor 7a via the wiper arm 2a provided on the driver's side. The passenger's side wiper blade 1b is connected to the motor 7b via the wiper arm 2b provided on the passenger's side.

[0029] As shown in the figure, the pair of wiper arms 2a and 2b are rod-shaped members, and one end is connected to the middle part of the pair of wiper blades 1a and 1b, and the other end is connected to the pair of wiper shafts 3a and 3b. That is, one end of the driver's side wiper arm 2a is connected to the middle part of the driver's side wiper blade 1a, and the other end is connected to the driver's side wiper shaft 3a.

[0030] On the other hand, one end of the passenger's side wiper arm 2b is connected to the middle part of the passenger's side wiper blade 1b, and the other end is connected to the passenger's side wiper shaft 3b. In addition, such a pair of wiper arms 2a and 2b are members included in the components of the pair of wiper blades 1a and 1b.

[0031] The pair of wiper arms 2a and 2b function as power transmission parts that mechanically transmit the rotational force of the pair of motors 7a and 7b to the pair of wiper blades 1a and 1b. In addition, the pair of wiper arms 2a and 2b function as force-applying members that press the pair of wiper blades 1a and 1b against the surface (the surface to be wiped) of the front glass W with a specified pressing force.

[0032] The pair of motors 7a and 7b are power generating devices that cause the pair of wiper blades 1a and 1b to reciprocate via the pair of wiper arms 2a and 2b. By rotating the pair of wiper shafts 3a and 3b respectively provided on the pair of motors 7a and 7b within a specified angle range, the pair of wiper blades 1a and 1b placed on the surface (the surface to be wiped) of the front glass W are caused to reciprocate.

[0033] The pair of motors 7a and 7b are set as power sources corresponding to the pair of wiper shafts (output shafts) 3a and 3b. The pair of motors 7a and 7b each include a motor main body 8 and a speed reduction mechanism 9. In addition, the pair of motors 7a and 7b (power sources) include a wiper control unit 10a and a wiper control unit 10b built in each speed reduction mechanism 9.

[0034] A pair of wiper control units 10a and 10b are drive control units that control a pair of motors 7a and 7b (power sources). The driver's side wiper control unit 10a controls the driver's side motor 7a to cause the driver's side wiper blade 1a to reciprocate on the surface to be wiped. The passenger's side wiper control unit 10b controls the passenger's side motor 7b to cause the passenger's side wiper blade 1b to reciprocate on the surface to be wiped.

[0035] The driver's side wiper control unit 10a includes a Central Processing Unit (CPU) 21a, a communication circuit 22a, a Read Only Memory (ROM) 23a, a Random Access Memory (RAM) 24a, an angle detection circuit 31a, a drive circuit 32a, and a lock detection timer 33a. In addition, the passenger's side wiper control unit 10b includes a CPU 21b, a communication circuit 22b, a ROM 23b, a RAM 24b, an angle detection circuit 31b, a drive circuit 32b, and a lock detection timer 33b.

[0036] The driver's side wiper control unit 10a and the passenger's side wiper control unit 10b are communicatively connected via a pair of communication circuits 22a and 22b. In addition, one of the wiper control units 10a is connected to an electronic control unit (ECU) of the vehicle, which is an upper control device, via a communication line. Switch signals such as the ON / OFF (low speed (Lo) operation, high speed (Hi) operation, intermittent (INT) operation) of the wiper switch and the ON / OFF of the mist switch for spraying washer fluid are input from the ECU to the wiper control unit 10a. In addition to this, a vehicle speed signal indicating the vehicle speed V is also input.

[0037] By performing feedback control on a pair of motors 7a and 7b based on the elapsed time of movement from the absolute position that is the control reference, the moving positions of a pair of wiper blades 1a and 1b are set. In this position control, for example, the lower reverse position is used as the absolute position. For a pair of motors 7a and 7b, the target rotational speeds TR of the pair of motors 7a and 7b at each time point are preset in advance as a working map corresponding to the elapsed time t of movement from the lower reverse position (reference position).

[0038] A pair of wiper control units 10a and 10b measure the elapsed time t from the lower reverse position (reference position) in a pair of CPUs 21a and 21b and determine the current rotational speeds of a pair of motors 7a and 7b, and compare the current rotational speeds at the elapsed time t with the target rotational speed TR on the operating map. A pair of CPUs 21a and 21b perform feedback control on a pair of drive circuits 32a and 32b based on the difference between the current rotational speed and the target rotational speed TR, thereby generating a pair of pulse width modulation (PWM) drive signals for driving and controlling the pair of motors 7a and 7b.

[0039] That is, the upper reverse positions of a pair of wiper blades 1a and 1b are set according to a pair of control command values respectively output from a pair of CPUs 21a and 21b based on the difference between the current rotational speed and the target rotational speed TR. A pair of drive circuits 32a and 32b generate a pair of PWM drive signals for driving the pair of motors 7a and 7b based on the pair of control command values, thereby setting the upper reverse positions at specified positions.

[0040] In addition, as shown in the figure, between the pair of motors 7a and 7b and the pair of CPUs 21a and 21b, a pair of angle detection circuits 31a and 31b for detecting the positions of the pair of wiper blades 1a and 1b are provided. The pair of angle detection circuits 31a and 31b output relative position signals proportional to the rotational angles of the pair of motors 7a and 7b and indicating the movement amounts of the pair of wiper blades 1a and 1b to the pair of CPUs 21a and 21b.

[0041] That is, the angle detection circuit 31a on the driver's side is provided between the motor 7a on the driver's side and the CPU 21a on the driver's side. The angle detection circuit 31a outputs a relative position signal proportional to the rotational angle of the motor 7a on the driver's side and indicating the movement amount of the wiper blade 1a on the driver's side to the CPU 21a. In addition, the angle detection circuit 31a outputs an absolute position signal indicating the position of the wiper blade 1a on the driver's side to the CPU 21a.

[0042] On the other hand, the angle detection circuit 31b on the passenger side is provided between the motor 7b on the passenger side and the CPU 21b on the passenger side. The angle detection circuit 31b outputs a relative position signal proportional to the rotational angle of the motor 7b on the passenger side and indicating the movement amount of the wiper blade 1b on the passenger side to the CPU 21b. In addition, the angle detection circuit 31b outputs an absolute position signal indicating the position of the wiper blade on the passenger side to the CPU 21b.

[0043] The relative position signal is a pulse signal (motor pulse) respectively output from a pair of motors 7a and 7b along with the rotation of the pair of motors 7a and 7b. The relative position signal is a pulse signal proportional to the rotation angle of the pair of motors 7a and 7b. The absolute position signal is a single pulse signal output from the pair of motors 7a and 7b when a pair of wiper blades 1a and 1b reach the lower reverse position (reference position).

[0044] The rotational speeds of a pair of motors 7a and 7b and the rotational speeds of a pair of wiper shafts 3a and 3b have a certain relationship based on the reduction ratio of the reduction mechanism 9. The rotation angles of the pair of wiper shafts 3a and 3b are obtained through the calculation of a pair of CPUs 21a and 21b based on the number of pulses of the relative position signal. In addition, the rotation angles of the pair of wiper shafts 3a and 3b and the movement angles of the pair of wiper blades 1a and 1b have a certain relationship based on the reduction ratio.

[0045] That is, a pair of CPUs 21a and 21b detect the movement angles of a pair of wiper blades 1a and 1b by accumulating the number of pulses of the relative position signal. A pair of CPUs 21a and 21b obtain the current positions of the pair of wiper blades 1a and 1b based on the accumulation result of the number of pulses of the relative position signal and the absolute position signal. In addition, a pair of CPUs 21a and 21b detect the current rotational speeds of the pair of motors 7a and 7b by counting the relative position signal (motor pulse).

[0046] In addition, a pair of CPUs 21a and 21b use the built-in timer to measure the elapsed time t from the acquisition moment of the absolute position signal. In addition, a pair of CPUs 21a and 21b obtain the target positions of the pair of wiper blades 1a and 1b and the target rotational speed TR of the pair of motors 7a and 7b at the current elapsed time from the ROMs 23a and 23b.

[0047] A pair of CPUs 21a and 21b compare the current positions of the pair of wiper blades 1a and 1b with the target positions to grasp the current conditions of the pair of wiper blades 1a and 1b (the situation of lagging behind or leading ahead relative to the target positions). In addition, a pair of CPUs 21a and 21b calculate the rotational speeds of the pair of motors 7a and 7b based on the conditions of the rotational speeds of the pair of motors 7a and 7b (higher or lower than the target rotational speed TR), and control the rotation of the pair of motors 7a and 7b based on the rotational speeds.

[0048] That is, in a pair of ROMs 23a and 23b, taking the elapsed time t from the acquisition moment of the absolute position signal as a parameter, the positions of a pair of wiper blades 1a and 1b and the target values of the rotational speeds of a pair of motors 7a and 7b are pre-stored in the form of a working map. A pair of CPUs 21a and 21b perform feedback control on a pair of motors 7a and 7b by comparing the target values and the current values of the rotational speeds in such a working map.

[0049] In addition, in each working map, the precedence relationship of a pair of wiper blades 1a and 1b is preset in advance. Further, in each working map, based on the elapsed time t from the acquisition moment of the absolute position signal and the current positions of a pair of wiper blades 1a and 1b, and according to the position of the other party, the target rotational speed TR is determined. For example, even if the elapsed time t and the current positions of a pair of wiper blades 1a and 1b are the same, when the current position of the other party is close to itself, it is set in such a way that the target rotational speed TR becomes larger, and when the current position of the other party is far from itself, it is set in such a way that the target rotational speed TR becomes smaller.

[0050] The current positions of a pair of wiper blades 1a and 1b exchange information between a pair of CPUs 21a and 21b via a pair of communication circuits 22a and 22b, and are respectively written into a pair of RAMs 24a and 24b. A pair of CPUs 21a and 21b perform synchronous control on a pair of drive circuits 32a and 32b based on the positional relationship of a pair of wiper blades 1a and 1b written into a pair of RAMs 24a and 24b, thereby generating a pair of PWM drive signals for driving a pair of motors 7a and 7b.

[0051] Here, among the external forces acting on a pair of wiper blades 1a and 1b, there is the wind pressure acting on a pair of wiper blades 1a and 1b. The wind pressure is an external disturbance when a pair of motors 7a and 7b perform position control on a pair of wiper blades 1a and 1b.

[0052] The wind pressure is a physical quantity having a certain correlation with the speed of the vehicle (vehicle speed), and can be speculated (predicted) based on the vehicle speed. In addition, the wind pressure can be speculated (predicted) based on the drive current of a pair of motors 7a and 7b as the power sources of a pair of wiper blades 1a and 1b.

[0053] In addition, the drive current of a pair of motors 7a and 7b is obtained based on the duty ratio of the PWM drive signals supplied to a pair of motors 7a and 7b. Therefore, the wind pressure can be speculated (predicted) based on the duty ratio of the PWM drive signals.

[0054] Details will be described later. To suppress the variation in the up-reverse position caused by the wind pressure, a pair of CPUs 21a and 21b obtain a wind pressure estimated value E1 (first wind pressure estimated value) based on the vehicle speed and obtain a wind pressure estimated value E2 (second wind pressure estimated value) based on the duty ratio of the PWM drive signal. In addition, a pair of CPUs 21a and 21b correct the target rotation speed TR based on the wind pressure estimated value E1 or the wind pressure estimated value E2, thereby stabilizing the variation in the up-reverse position.

[0055] Next, along Figure 2 The flowchart shown illustrates the characteristic operation of the wiping device A of the first embodiment, that is, the correction process of the target rotation speed TR based on the vehicle speed and the duty ratio of the PWM drive signal.

[0056] In the wiping device A, a pair of CPUs 21a and 21b obtain a switch signal and a vehicle speed signal at a predetermined timing by communicating with an upper control device (ECU), thereby obtaining the vehicle speed (step S1). Then, a pair of CPUs 21a and 21b perform a predetermined arithmetic process on the vehicle speed to obtain an estimated value of the wind pressure acting on the pair of wiper blades 1a and 1b due to the vehicle speed as the wind pressure estimated value E1 (step S2).

[0057] Next, a pair of CPUs 21a and 21b perform a predetermined arithmetic process on the duty ratio of the PWM drive signal generated by the pair of drive circuits 32a and 32b to obtain an estimated value of the wind pressure acting on the pair of wiper blades 1a and 1b due to the duty ratio as the wind pressure estimated value E2 (step S3).

[0058] Here, the duty ratio of the PWM drive signal is set by a control command output from a pair of CPUs 21a and 21b to the pair of drive circuits 32a and 32b. That is, the control command specifies the duty ratio of the PWM drive signal for the pair of drive circuits 32a and 32b. Therefore, a pair of CPUs 21a and 21b obtain the wind pressure estimated value E2 based on the control command they have obtained, that is, the duty ratio of the PWM drive signal.

[0059] In addition, such a wind pressure estimated value E2 is calculated, for example, based on the average value of the duty ratios during a predetermined period of the forward or return stroke of the pair of wiper blades 1a and 1b. That is, a pair of CPUs 21a and 21b perform an averaging process on a plurality of sequential duty ratios (control commands) generated at a predetermined time interval, calculate the average value of the duty ratios during a predetermined period, and use the average value to calculate the wind pressure estimated value E2.

[0060] After a pair of CPUs 21a and 21b obtain the wind pressure estimated value E1 and the wind pressure estimated value E2, they evaluate the magnitude relationship between the wind pressure estimated value E1 and the wind pressure estimated value E2. That is, the pair of CPUs 21a and 21b determine whether the wind pressure estimated value E1 is greater than the wind pressure estimated value E2 in step S4.

[0061] When the determination in step S4 by the pair of CPUs 21a and 21b is "No", the wind pressure estimated value E2 is set as the correction coefficient H (step S5). On the other hand, when the determination in step S4 by the pair of CPUs 21a and 21b is "Yes", the wind pressure estimated value E1 is set as the correction coefficient H (step S6). That is, the pair of CPUs 21a and 21b set the correction coefficient H based on the magnitude relationship between the wind pressure estimated value E1 and the wind pressure estimated value E2.

[0062] Then, the pair of CPUs 21a and 21b correct the target rotation speed TR of the operation map obtained from the pair of ROMs 23a and 23b by using the correction coefficient H set by the above processing. That is, the target rotation speed TR of the pair of wiper blades 1a and 1b is corrected based on the larger wind pressure estimated value among the wind pressure estimated value E1 and the wind pressure estimated value E2 (step S7).

[0063] As described above, the wiping device A of the first embodiment drives a pair of motors 7a and 7b (power sources) by using a PWM drive signal (prescribed drive signal) to make the pair of wiper blades 1a and 1b perform reciprocating motions, and corrects the up-and-down reversal positions of the pair of wiper blades 1a and 1b by changing the PWM drive signal according to the external force acting on the pair of wiper blades 1a and 1b.

[0064] In addition, the wiping device A includes a pair of wiper control units 10a and 10b (drive control units). The pair of wiper control units 10a and 10b (drive control units) obtain the wind pressure estimated value E1 (first wind pressure estimated value) based on the vehicle speed and the wind pressure estimated value E2 (second wind pressure estimated value) based on the PWM drive signal. When the wind pressure estimated value E1 is greater than the wind pressure estimated value E2, the up-and-down reversal positions of the pair of wiper blades 1a and 1b are corrected based on the wind pressure estimated value E1. When the wind pressure estimated value E1 is less than or equal to the wind pressure estimated value E2, the up-and-down reversal positions of the pair of wiper blades 1a and 1b are corrected based on the wind pressure estimated value E2.

[0065] In such a wiping device A, the larger one of the wind pressure estimated value E1 and the wind pressure estimated value E2 is set as the correction coefficient H to correct the upward reversal positions of the pair of wiper blades 1a and 1b. Therefore, according to the first embodiment, the variation of the reversal position can be stabilized, and thus a wiping device A that can reduce the risk of interference between the pair of wiper blades 1a and 1b and other components (such as the pillar of a vehicle) can be provided.

[0066] Figure 3 (a) shows the initial settings of the wind pressure estimated value E1 and the wind pressure estimated position value E2' that depend on the vehicle speed. In the Figure 3 (a), the dashed line is the wind pressure estimated value E1 based on the vehicle speed signal, and the solid line is the initial wind pressure estimated value E2' based on the duty ratio of the PWM drive signal. As shown in the Figure 3 (a), the wind pressure estimated value E1 (dashed line) is set to a value larger than the initial wind pressure estimated value E2' (solid line).

[0067] Relative to Figure 3 the initial setting as in Figure 3 (a),

[0068] (b) shows the wind pressure estimated values E1 and E2 when external disturbances caused by a tailwind act on the pair of wiper blades 1a and 1b. In this case, since the tailwind acts on the pair of wiper blades 1a and 1b, the wind pressure estimated value E2 based on the duty ratio is greater than the wind pressure estimated value E1 based on the vehicle speed signal. Then, in this case, the wind pressure estimated value E2 based on the duty ratio is set as the correction coefficient H to correct the upward reversal positions of the pair of wiper blades 1a and 1b. Figure 3 the initial setting as in Figure 3 (a),

[0069] [Second Embodiment]

[0070] Next, a second embodiment of the present invention will be described with reference to Figure 4 . In addition, in the second embodiment, the same reference numerals are given to the same components as in the first embodiment.

[0071] As Figure 4As shown, the wiping device B of the second embodiment includes a pair of wiper blades 1a, 1b, a pair of wiper arms 2a, 2b, a link mechanism 4, a motor 7, an angle detection circuit 31, a drive circuit 32, and a wiper control unit 10A. In addition, the wiper control unit 10A includes a CPU 50, a ROM 51, and a RAM 52.

[0072] The wiping device B adopts a single-motor drive method. The single-motor drive method mechanically connects a pair of wiper arms 2a, 2b by using the link mechanism 4, and thus drives a pair of wiper blades 1a, 1b by using a single motor 7 (power source). That is, the wiping device B is provided with one power source, and uses one power source to reciprocate a pair of wiper blades 1a, 1b. Similar to the wiping device A of the first embodiment, such a wiping device B wipes rainwater on the surface (wiped surface) of the front glass or the rear glass of the vehicle.

[0073] The link mechanism 4 is a mechanical part that is mechanically connected to the other ends of a pair of wiper arms 2a, 2b and is also connected to the output shaft of the motor 7. In addition, the link mechanism 4 includes a support shaft fixed to the vehicle and is rotatable about the support shaft. The output shaft of the motor 7 is connected to the link mechanism 4, and by operating the rotation angle of the link mechanism 4, a pair of wiper blades 1a, 1b perform reciprocating motion on the wiped surface.

[0074] The angle detection circuit 31 has the same functions as the pair of angle detection circuits 31a, 31b in the first embodiment, and outputs a relative position signal that is proportional to the motor rotation angle of the motor 7 and represents the movement amount of the wiper blade 1a on the driver's seat side or the wiper blade 1b on the passenger seat side. In addition, the angle detection circuit 31 outputs an absolute position signal representing the position of a specific wiper blade among the pair of wiper blades 1a, 1b.

[0075] The drive circuit 32 has the same functions as the drive circuit 32a and the drive circuit 32b in the first embodiment, and drives the motor 7 based on a control instruction input from the CUP 50. That is, the drive circuit 32 drives the motor 7 according to the difference between the current rotation speed of the motor 7 and the target rotation speed TR.

[0076] The wiper control unit 10A has the same functions as the wiper control unit 10a in the first embodiment. In addition, the wiper control unit 10A directly controls the drive circuit 32 by referring to a switch signal and a vehicle speed signal input from an upper control device, thereby indirectly performing feedback control on the motor 7. In the wiper control unit 10A, the CPU 50 has the same functions as the CPU 21a in the first embodiment. In the second embodiment, the wiper control unit 10A, the angle detection circuit 31, and the drive circuit 32 may also be built into the motor 7.

[0077] The CPU 50 controls the drive circuit 32 based on the operation map stored in the ROM 23a, the relative position signal and the absolute position signal input from the angle detection circuit 31, and the switch signal and the vehicle speed signal input from the upper control system. In addition, the ROM 51 has the same function as the ROM 23a in the first embodiment and stores the operation map and the like. The RAM 52 temporarily holds the intermediate generated data of the CPU 50.

[0078] In such a wiping device B, the CPU 50 obtains the switch signal and the vehicle speed signal at a predetermined timing by communicating with the upper control device (ECU), thereby obtaining the vehicle speed. Then, the CPU 50 performs a predetermined arithmetic process on the vehicle speed to obtain an estimated value of the wind pressure acting on the pair of wiper blades 1a and 1b due to the vehicle speed as the wind pressure estimated value E1.

[0079] Then, the CPU 50 performs a predetermined arithmetic process on the duty ratio (Duty ratio) of the PWM drive signal generated by the drive circuit 32 to obtain an estimated value of the wind pressure acting on the pair of wiper blades 1a and 1b due to the Duty ratio as the wind pressure estimated value E2.

[0080] After the CPU 50 obtains the wind pressure estimated value E1 and the wind pressure estimated value E2 in the above-described manner, it evaluates the magnitude relationship between the wind pressure estimated value E1 and the wind pressure estimated value E2. That is, the CPU 50 determines whether the wind pressure estimated value E1 is greater than the wind pressure estimated value E2. In the case where the determination is "No", the wind pressure estimated value E2 is set as the correction coefficient H.

[0081] On the other hand, in the case where the determination is "Yes", the CPU 50 sets the wind pressure estimated value E1 as the correction coefficient H. That is, the CPU 50 sets the correction coefficient H based on the magnitude relationship between the wind pressure estimated value E1 and the wind pressure estimated value E2. Then, the CPU 50 corrects the target rotation speed TR of the operation map obtained from the ROM 51 by using the correction coefficient H set by the above processing. That is, the target rotation speed TR of the pair of wiper blades 1a and 1b is corrected based on the larger wind pressure estimated value among the wind pressure estimated value E1 and the wind pressure estimated value E2.

[0082] In this way, the wiping device B of the second embodiment drives the motor 7 (power source) by using the PWM drive signal (predetermined drive signal) to reciprocate the pair of wiper blades 1a and 1b, and corrects the upper and reverse positions of the pair of wiper blades 1a and 1b by changing the PWM drive signal according to the external force acting on the pair of wiper blades 1a and 1b.

[0083] In addition, the wiping device B includes a wiper control unit 10A (drive control unit). The wiper control unit 10A (drive control unit) obtains a wind pressure estimated value E1 (first wind pressure estimated value) based on the vehicle speed and a wind pressure estimated value E2 (second wind pressure estimated value) based on a PWM drive signal. When the wind pressure estimated value E1 is greater than the wind pressure estimated value E2, the upward reverse positions of the pair of wiper blades 1a and 1b are corrected based on the wind pressure estimated value E1. When the wind pressure estimated value E1 is less than or equal to the wind pressure estimated value E2, the upward reverse positions of the pair of wiper blades 1a and 1b are corrected based on the wind pressure estimated value E2.

[0084] In such a wiping device B, the larger one of the wind pressure estimated value E1 and the wind pressure estimated value E2 is set as a correction coefficient H to correct the upward reverse positions of the pair of wiper blades 1a and 1b. Therefore, according to the second embodiment, the variation in the upward reverse position can be stabilized, and thus a wiping device B that can reduce the risk of interference between the pair of wiper blades 1a and 1b and other components (such as vehicle pillars) can be provided.

[0085] Furthermore, the present invention is not limited to the above-described embodiments and can be variously modified. For example, Figure 1 and Figure 4 the block diagrams are merely examples of control structures and can be variously modified without departing from the gist of the present invention.

[0086] In addition, in the above-described embodiment, the risk of interference with other components (such as vehicle pillars) is reduced by stabilizing the upward reverse position, but the present invention is not limited thereto. For example, when the reference positions of the pair of wiper blades 1a and 1b are located at the upward reverse positions, by setting the correction coefficient H based on the wind pressure estimated value E1 and the wind pressure estimated value E2, the variation in the downward reverse position can be stabilized.

[0087] In addition, in the above-described embodiment, a drive control unit that adjusts the drive current according to the duty ratio of the PWM drive signal to drive the power source has been described, but the present invention is not limited thereto. For example, a drive control unit that generates a drive signal of a type that adjusts the drive current according to the amplitude to drive the power source may also be used. In addition, in this case, the wind pressure estimated value E2 is estimated based on the amplitude of the drive signal.

[0088] Explanation of reference numerals

[0089] 1a, 1b: Wiper blades

[0090] 2a, 2b: Wiper arms

[0091] 3a, 3b: Wiper shafts

[0092] 7a, 7b: Motor (power source)

[0093] 10a, 10b, 10A: Wiper control unit (drive control unit)

[0094] 21a, 21b, 50: CPU

[0095] 22a, 22b: Communication circuit

[0096] 23a, 23b: ROM

[0097] 24a, 24b: RAM

[0098] 31a, 31b: Angle detection circuit

[0099] 32a, 32b: Drive circuit

Claims

1. A wiper device, which drives a power source by using a predetermined drive signal to make a wiper blade reciprocate, and corrects the reverse position of the wiper blade by changing the drive signal according to the wind pressure acting on the wiper blade, the wiper device comprising a drive control unit, The drive control unit obtains a first wind pressure estimation value based on the vehicle speed and a second wind pressure estimation value based on the drive signal, and when the first wind pressure estimation value is greater than the second wind pressure estimation value, the reversal position is corrected based on the first wind pressure estimation value, and when the first wind pressure estimation value is less than the second wind pressure estimation value, the reversal position is corrected based on the second wind pressure estimation value.

2. The wiper device according to claim 1, characterized in that: The driving signal is a pulse width modulation (PWM) signal, The drive control unit acquires the second wind pressure estimated value based on a duty ratio of the pulse width modulation signal.

3. The wiper device according to claim 2, characterized in that: The duty cycle is an average value of the outward stroke or the return stroke of the wiper blade within a specified time.

4. The wiper device according to any one of claims 1 to 3, characterized in that One or two power sources are provided. One power source is used to make one or two wiper blades reciprocate. Two power sources are used to make two wiper blades reciprocate independently.

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