Patent Publication Number: US-2023142181-A1

Title: Snow melting apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is based on Japanese Patent Application No. 2021-181868 filed on Nov. 8, 2021. The entire disclosures of all of the above applications are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a snow melting apparatus. 
     BACKGROUND 
     Conventionally, a heating apparatus has been used to heat a window glass of a vehicle. 
     SUMMARY 
     According to an aspect of the present disclosure, a wiper system includes a wiper blade to wipe a windshield, an angle sensor, and a motor. The motor is configured to drive the wiper blade to reverse a wipe operation of the wiper blade at a reversal position based on the angle sensor, such that rotation of the motor when the wiper blade moves to a released position is reversed to rotation of the motor when the wiper blade moves to a standby position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: 
         FIG.  1    is a block diagram illustrating a configuration of a snow melting system; 
         FIG.  2 A  is an explanatory diagram illustrating a windshield where snow accumulates; 
         FIG.  2 B  is an explanatory diagram illustrating a wiper blade moved to a standby position; 
         FIG.  2 C  is an explanatory diagram illustrating a wiper blade moved to a released position; 
         FIG.  2 D  is an explanatory diagram illustrating a first heating element provided for the windshield; 
         FIG.  3    is a block diagram illustrating a configuration of a wiper system; 
         FIG.  4    is an explanatory diagram illustrating a snow chunk detection range according to a first embodiment; 
         FIG.  5    is a flowchart illustrating a motor control process; 
         FIG.  6    is a flowchart illustrating a retraction process; 
         FIG.  7    is a flowchart illustrating a first snow chunk detection process according to the first embodiment; 
         FIG.  8    is a flowchart illustrating a second snow chunk detection process according to the first embodiment; 
         FIG.  9    is a flowchart illustrating the first snow chunk detection process according to a modification of the first embodiment; 
         FIG.  10    is a flowchart illustrating the second snow chunk detection process according to a modification of the first embodiment; 
         FIG.  11    is a flowchart illustrating the first snow chunk detection process according to a second embodiment; 
         FIG.  12    is an explanatory diagram illustrating a snow chunk detection range according to the second embodiment; 
         FIG.  13    is a flowchart illustrating the first snow chunk detection process according to a modification of the second embodiment; 
         FIG.  14 A  illustrates a configuration where a device included in the snow melting system supplies power to the first heating element and the second heating element; and 
         FIG.  14 B  illustrates a configuration where an external battery supplies power to the first heating element and the second heating element. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, examples of the present disclosure will be described. 
     According to an example of the present disclosure, a window glass heating apparatus includes an inner heater and an outer heater. The inner heater is provided to the inner glass of a windshield and heats the entire surface of the windshield. The outer heater is provided to the outer glass of the windshield and heats part of the windshield near a wiper standby position and the front pillar. When a defogger switch is turned on, the window glass heating apparatus energizes the inner heater. When a de-icer switch is turned on, the window glass heating apparatus energizes the outer heater. According to an example of the present disclosure, a window glass heating apparatus energizes the inner and outer heaters when a wiper switch is turned on and when the outside air temperature is below 2° C. This configuration aims to melt the snow on the windshield to ensure good visibility. 
     An assumable configuration is to determine whether to energize the inner or outer heater based on conditions of the defogger switch and the outside temperature. The inventor has conducted a detailed examination and found the following issue in this assumable configuration. Specifically, the inner or outer heater may be energized even when the windshield is not covered with snow. Therefore, an inconvenience may arise due to unnecessarily energizing of the inner or outer heater. 
     According to an example of the present disclosure, a snow melting apparatus comprises a wiper system. The wiper system includes a wiper blade to wipe a windshield, an angle sensor, and a motor. The motor is configured to drive the wiper blade to reverse a wipe operation of the wiper blade at a reversal position based on the angle sensor, such that rotation of the motor when the wiper blade moves to a released position is reversed to rotation of the motor when the wiper blade moves to a standby position. The snow melting apparatus further comprises a first heating element installed near a front pillar and configured to generate heat when energized. The snow melting apparatus further comprises a determiner configured to determine whether snow accumulates on a surface of the windshield based on an operation of the wiper system. The snow melting apparatus further comprises a controller configured to control energization of the first heating element. The controller is configured to energize the first heating element on determination of the determiner that snow accumulates on the surface of the windshield. 
     This configuration may enable to efficiently melt snow on a windshield. 
     The description below explains embodiments of the present disclosure by reference to the accompanying drawings. 
     1. First Embodiment 
     1-1. Configuration 
     A snow melting system  1  illustrated in  FIG.  1    is installed in vehicles. The snow melting system  1  includes a wiper system  2 , a first heating element  3 , a second heating element  4 , a body ECU  5 , and a rain sensor  6 . The wiper system  2  and the body ECU  5  communicate with other ECUs and onboard devices via an onboard network configured as CAN or LIN. CAN stands for Controller Area Network. LIN stands for Local Interconnect Network. CAN is a registered trademark. 
     The wiper system  2  includes a wiper blade  21  illustrated in  FIGS.  2 A through  2 D , and a wiper motor  22 , an angle sensor  23 , and a wiper control portion (wiper controller)  24  illustrated in  FIG.  3   . 
     The wiper blade  21  wipes off raindrops adhering to the windshield  10 . 
     The wiper motor  22  drives the wiper blade  21 . The wiper motor  22  can switch between normal rotation (forward) and reverse rotation (backward).  FIG.  4    illustrates a standby position  11  and a released position  12 . The direction in which the wiper blade  21  moves from the standby position  11  to the released position  12  is defined as the normal rotation of the wiper motor  22 . The reverse of the same is defined as the reverse rotation. The released position  12  corresponds to a reversal position near the front pillar. The standby position  11  corresponds to a reversal position near the retracted position  13  of the wiper blade  21 . The wiper blade  21  is retracted to the retracted position  13  when the wiper system  2  does not perform a wipe operation. 
     Returning to  FIG.  3   , the angle sensor  23  detects a rotational position of an output shaft of the wiper motor  22  that rotates a wiper rod (not shown). The angle sensor  23  outputs a rotation signal corresponding to the rotation angle of the output shaft against a reference position of the output shaft. 
     The wiper control portion  24  is mainly composed of a well-known microcomputer  40  including a CPU  41 , ROM  42 , RAM  43 , and flash memory  44 , for example. The CPU  41  executes a program stored in the ROM  42  as a non-transitory tangible storage medium. Execution of the program implements the method corresponding to the program. Based on the program, the wiper control portion  24  performs a motor control process illustrated in  FIG.  5    and a retraction process illustrated in  FIG.  6   , to be described later. The wiper control portion  24  may include one or more microcomputers. 
     A technique to embody functions of the elements included in the wiper control portion  24  is not limited to the software. One or more hardware components may be used to embody all or part of the functions. When an electronic circuit as hardware implements the above-described functions, for example, the electronic circuit may be provided as a digital circuit, an analog circuit, or a combination of these. 
     When a rotation signal of the angle sensor  23  indicates the released position  12 , the wiper control portion  24  controls the wiper motor  22  to rotate reversely. When a rotation signal of the angle sensor  23  indicates the standby position  11 , the wiper control portion  24  controls the wiper motor  22  to rotate normally. By repeating this operation, the wiper blade  21  wipes the windshield  10  while reciprocating in a wiping range between the standby position  11  and the released position  12 . The wiper system  2  reverses the rotation of the connected wiper motor  22  when the wiper blade  21  moves to the released position  12  and then to the standby position  11 . The wipe operation of the wiper blade  21  reverses at the reversal position. 
     The voltage applied to the wiper motor  22  is generated based on PWM. The wiper control portion  24  includes an H-bridge circuit  25  using FETs as switching elements. The voltage at a predetermined duty ratio is output under the control of the wiper control portion  24 . 
     The wiper control portion  24  includes a current detection circuit  26 . The current detection circuit  26  detects current values output from the wiper motor  22 . 
     The wiper control portion  24  includes a LIN communication circuit  27 . The LIN communication circuit  27  transmits and receives frames compliant with the LIN communication protocol. 
     The wiper control portion  24  outputs a snow chunk detection signal. The snow chunk detection signal indicates that snow accumulates on the windshield  10 . The method of determining whether snow accumulates on the windshield  10  will be described in detail later. 
     The first heating element  3  illustrated in  FIGS.  1  and  2 B  is provided inside the front pillar and generates heat when energized. For example, a relay  31  turns on and energizes the first heating element  3  when the body ECU  5  outputs a signal to turn on the first heating element  3 . The first heating element  3  is powered by a battery. 
     The second heating element  4  is provided near the standby position of the wiper blade  21  and generates heat when energized. For example, a relay  32  turns on and energizes the second heating element  4  when the body ECU  5  outputs a signal to turn on the second heating element  4 . The second heating element  4  is powered by a battery. 
     The body ECU  5  is mainly composed of a well-known microcomputer including a CPU  51 , ROM  52 , RAM  53 , and flash memory  55 , for example. The CPU  51  executes a program stored in the ROM  52  as a non-transitory tangible storage medium. Execution of the program implements the method corresponding to the program. Based on the program, the body ECU  5  performs a first snow chunk detection process illustrated in  FIG.  7    and a second snow chunk detection process illustrated in  FIG.  8   , to be described later. The body ECU  5  may include one or more microcomputers. 
     A technique to embody functions of the elements included in the body ECU  5  is not limited to the software. One or more hardware components may be used to embody all or part of the functions. When an electronic circuit as hardware implements the above-described functions, for example, the electronic circuit may be provided as a digital circuit, an analog circuit, or a combination of these. 
     The body ECU  5  may determine that the amount of raindrop exceeds a predetermined raindrop threshold, based on a raindrop signal (to be described) output from the rain sensor  6 . Then, the body ECU  5  outputs a signal to the wiper system  2  to start the wipe operation. The body ECU  5  also outputs a signal to the wiper system  2  to start the wipe operation when a driver turns on a wiper switch (not shown). 
     The rain sensor  6  detects the amount of raindrop adhering to the windshield  10 . The rain sensor  6  is provided for the wiping range of the windshield  10 . The amount of light received by a light receiving element is assumed to be 100% under the condition of the windshield  10  with no raindrops. The rain sensor  6  detects a change in the amount of received light as the amount of raindrop. Namely, the rain sensor  6  detects a decrease in the amount of received light as the amount of raindrop. The rain sensor  6  outputs a raindrop signal, indicating the amount of raindrop, to the body ECU  5 . 
     1-2. Processes 
     1-2-1. Motor Control Process 
     By reference to a flowchart illustrated in  FIG.  5   , the description below explains a motor control process performed by the CPU  41  of the wiper control portion  24  when the wiper system  2  is performing the wipe operation. 
     In S 101 , the CPU  41  controls the wiper motor  22  so that the wiper blade  21  operates according to the normal rotation or the reverse rotation. 
     In S 102 , the CPU  41  determines whether snow accumulates in the snow chunk detection range on the surface of the windshield  10 . The snow chunk detection range includes an open-side detection range  14  and a close-side detection range  15  illustrated in  FIG.  4   . The open-side detection range  14  corresponds to a predetermined area from the released position  12  toward the standby position  11 . The close-side detection range  15  is a combination of a standby-side detection range and a retraction-side detection range. The standby-side detection range corresponds to a predetermined area from the standby position  11  toward the released position  12 . The retraction-side detection range corresponds to an area from the retracted position  13  to the standby position  11 . 
     Whether snow accumulates in the snow chunk detection range is determined based on the value of the angle sensor  23  and the output current value of the wiper motor  22 . Specifically, it is determined that snow accumulates in the snow chunk detection range when all of the following four conditions are satisfied. The CPU  41  identifies the conditions that the angle sensor  23  indicates an angle corresponding to the open-side detection range  14 ; the rotation speed of the wiper motor  22  is slower than a predetermined speed threshold; the output current value of the wiper motor  22  is larger than a predetermined current threshold; a predetermined time has elapsed. In this case, it is determined that snow accumulates in the open-side detection range  14 . It may be determined that a snow chunk is detected in the open-side detection range  14  in three successive cycles, for example. Then, the CPU  41  may confirm that the snow chunk is detected toward the released position  12 . The determination that a snow chunk is detected is synonymous with the determination that snow accumulates. There may be conditions that the angle sensor  23  indicates an angle corresponding to the close-side detection range  15 ; the rotation speed of the wiper motor  22  is slower than a predetermined speed threshold; the output current value of the wiper motor  22  is larger than a predetermined current threshold; a predetermined time has elapsed. When these conditions are all satisfied, the CPU  41  determines that snow accumulates in the close-side detection range  15 . It may be determined that snow accumulates in the open-side detection range  14  or the close-side detection range  15 . Then, the CPU  41  determines that snow accumulates in the snow chunk detection range. The CPU  41  outputs a snow chunk detection signal representing the information about snow accumulation in the open-side detection range  14  as well as the information about snow accumulation in the close-side detection range  15 . The CPU  41  operates the wiper blade  21  with a predetermined torque and continues the wipe operation while it is determined that no snow accumulates in the snow chunk detection range. At this time, the CPU  41  provides control so that the output current value of the wiper motor  22  conforms to a predetermined output value. The continued wipe operation can push the snow, adhering to the surface of the windshield  10 , toward the front pillar and the standby position. 
     In S 102 , it may be determined that no snow accumulates in the snow chunk detection range. Then, the CPU  41  proceeds to S 103 . 
     In S 103 , the CPU  41  controls the wiper motor  22  so that the wiper blade  21  moves to the reversal position and then reverses. Then, the CPU  41  returns to S 101 . 
     In S 102 , it may be determined that snow accumulates in the snow chunk detection range. Then, the CPU  41  controls the wiper motor  22  so that the wiper blade  21  reverses immediately. Then, the CPU  41  returns to S 101 . 
     1-2-2. Retraction Process 
     By reference to a flowchart illustrated in  FIG.  6   , the description below explains a retraction process performed by the CPU  41  of the wiper control portion  24  when the wiper blade  21  is directed to be retracted. 
     In S 201 , the CPU  41  controls the wiper motor  22  so that the wiper blade  21  operates according to the normal rotation or the reverse rotation. 
     In S 202 , the CPU  41  determines whether the wiper motor  22  is requested to stop. Whether the wiper motor  22  is requested to stop is determined based on a signal output from the body ECU  5  when the wiper switch is turned off, or a signal output from the body ECU  5  when the amount of raindrop is determined to be smaller than a predetermined raindrop threshold. 
     In S 201 , it may be determined that the wiper motor  22  is not requested to stop. Then, the CPU  41  returns to S 201 . 
     It may be determined that the wiper motor  22  is requested to stop. Then, the CPU  41  proceeds to S 203 . 
     In S 203 , the CPU  41  determines whether snow accumulates in the close-side detection range  15 . 
     In S 203 , it may be determined that no snow accumulates in the close-side detection range  15 . Then, the CPU  41  proceeds to S 204  and controls the wiper motor  22  so that the wiper blade  21  moves to the retracted position  13 . 
     In S 203 , it may be determined that snow accumulates in the close-side detection range  15 . Then, the CPU  41  proceeds to S 205  and controls the wiper motor  22  so that the wiper blade  21  stops immediately. 
     1-2-3. First Snow Chunk Detection Process 
     By reference to a flowchart illustrated in  FIG.  7   , the description below explains a first snow chunk detection process performed by the CPU  51  of the body ECU  5 . This process is repeatedly performed while the ignition switch is turned on. 
     In S 301 , the CPU  51  performs an initialization process. Specifically, the CPU  51  assigns initial values to parameters. 
     In S 302 , the CPU  51  determines whether there is a wiper operation request. The wiper operation request signifies a request to turn on the wiper switch. The request to turn on the wiper switch includes a request for wiping speed. The CPU  51  determines whether there is a wiper operation request based on the raindrop signal output from the rain sensor  6  or the information that the driver turns on the wiper switch. 
     In S 302 , it may be determined that there is a wiper operation request. Then, the CPU  51  proceeds to S 303 . 
     In S 303 , the CPU  51  determines whether snow accumulates in the open-side detection range  14 . The CPU  51  determines whether snow accumulates in the open-side detection range  14 , based on the snow chunk detection signal received from the wiper control portion  24 . S 303  is comparable to a process as a determination portion (determiner). 
     In S 303 , it may be determined that snow accumulates in the open-side detection range  14 . Then, the CPU  51  proceeds to S 304  and turns on the first heating element  3 . S 304  is comparable to a process as a control portion. 
     In S 303 , it may be determined that no snow accumulates in the open-side detection range  14 . Then, the CPU  51  proceeds to S 305  and turns off the first heating element  3 . 
     In S 306 , the CPU  51  determines whether snow accumulates in the close-side detection range  15 . The CPU  51  determines whether snow accumulates in the close-side detection range  15 , based on the snow chunk detection signal received from the wiper control portion  24 . 
     In S 306 , it may be determined that snow accumulates in the close-side detection range  15 . Then, the CPU  51  proceeds to S 307  and turns on the second heating element  4 . Then, the CPU  51  returns to S 302 . 
     In S 306 , it may be determined that no snow accumulate in the close-side detection range  15 . Then, the CPU  51  proceeds to S 308  and turns off the second heating element  4 . Then, the CPU  51  returns to S 302 . 
     In S 302 , it may be determined that there is no wiper operation request. Then, the CPU  51  proceeds to S 309  and turns off the first heating element  3 . Then, the CPU  51  proceeds to S 310 . 
     In S 310 , the CPU  51  determines whether a rotation signal of the angle sensor  23  for the wiper motor  22  indicates the retracted position  13 . The rotation signal is input from the wiper control portion  24 . 
     In S 310 , it may be determined that the rotation signal of the angle sensor  23  for the wiper motor  22  does not indicate retracted position  13 . Then, the CPU  51  proceeds to S 311  and outputs a signal to the wiper control portion  24  so that the wiper blade  21  is retracted to the retracted position  13 . 
     In S 310 , it may be determined that the rotation signal of the angle sensor  23  for the wiper motor  22  indicates the retracted position  13 . Then, the CPU  51  proceeds to S 312  and turns off the second heating element  4 . Then, the CPU  51  returns to S 302 . 
     In S 313 , the CPU  51  determines whether snow accumulates in the close-side detection range  15 . 
     In S 313 , it may be determined that snow accumulates in the close-side detection range  15 . Then, the CPU  51  proceeds to S 314  and turns on the second heating element  4 . 
     In S 313 , it may be determined that no snow accumulates in the close-side detection range  15 . Then, the CPU  51  proceeds to S 315  and turns off the second heating element  4 . Then, the CPU  51  returns to S 302 . 
     In S 316 , the CPU  51  determines whether there is a wiper operation request. 
     In S 316 , it may be determined that there is no wiper activation request. Then, the CPU  51  proceeds to S 317 . 
     In S 316 , it may be determined that there is a wiper activation request. Then, the CPU  51  returns to S 303 . 
     In S 317 , the CPU  51  determines whether a predetermined time has elapsed. 
     In S 317 , it may be determined that the predetermined time has elapsed. Then, the CPU  51  proceeds to S 318  and outputs a signal to the wiper control portion  24  so that the wiper blade  21  is retracted to the retracted position  13 . 
     In S 317 , it may be determined that the predetermined time does not elapse. Then, the CPU  51  returns to S 316 . 
     In S 319 , the CPU  51  determines whether snow accumulates in the close-side detection range  15 . 
     In S 319 , it may be determined that snow accumulates in the close-side detection range  15 . Then, the CPU  51  returns to S 316 . 
     In S 319 , it may be determined that no snow accumulates in the close-side detection range  15 . Then, the CPU  51  proceeds to S 320  and turns off the second heating element  4 . Then, the CPU  51  returns to S 302 . 
     1-2-4. Second Snow Chunk Detection Process 
     By reference to a flowchart illustrated in  FIG.  8   , the description below explains a second snow chunk detection process performed by the CPU  51  of the body ECU  5  and the CPU  41  of the wiper control portion  24 . This process is repeatedly performed while the ignition switch is turned off. 
     In S 401 , the CPU  51  determines whether there is a request to stop the wiper motor  22 . 
     In S 401 , it may be determined that there is a request to stop the wiper motor  22 . Then, the CPU  51  proceeds to S 402  and turns off the first heating element  3  and the second heating element  4 . 
     In S 401 , it may be determined that there is no request to stop the wiper motor  22 . Then, the CPU  51  returns to S 401 . 
     In S 403 , the CPU  51  notifies the CPU  41  of the request to stop the wiper motor  22 . 
     In S 404 , the CPU  41  determines whether snow accumulates in the close-side detection range  15 . 
     In S 404 , it may be determined that snow accumulates in the close-side detection range  15 . Then, the CPU  41  proceeds to S 405  and controls the wiper motor  22  to immediately stop the wiper blade  21 . 
     In S 404 , it may be determined that no snow accumulates in the close-side detection range  15 . Then, the CPU  41  proceeds to S 406  and controls the wiper motor  22  so that the wiper blade  21  moves to the retracted position  13 . 
     1-3. Modification of the First Embodiment 
     The first embodiment provides the first heating element  3  and the second heating element  4 . However, the second heating element  4  may not be provided. 
     1-3-1. First Snow Chunk Detection Process 
     By reference to a flowchart illustrated in  FIG.  9   , the description below explains the first snow chunk detection process in a configuration where only the first heating element  3  is provided. 
     In S 501 , the CPU  51  performs an initialization process. Specifically, the CPU  51  assigns initial values to parameters. 
     In S 502 , the CPU  51  determines whether the wiper switch is turned on. 
     In S 502 , it may be determined that the wiper switch is turned on. Then, the CPU  51  proceeds to S 503 . 
     In S 503 , the CPU  51  determines whether snow accumulates in the open-side detection range  14 . S 503  is equal to S 303 . S 503  is comparable to a process as the determination portion. 
     In S 503 , it may be determined that snow accumulates in the open-side detection range  14 . Then, the CPU  51  proceeds to S 504  and turns on the first heating element  3 . S 504  is comparable to a process as the control portion. 
     In S 503 , it may be determined that no snow accumulates in the open-side detection range  14 . Then, CPU  51  proceeds to S 505  and turns off the first heating element  3 . 
     In S 502 , it may be determined that the wiper switch is turned off. Then, the CPU  51  proceeds to S 506  and turns off the first heating element  3 . 
     1-3-2. Second Snow Chunk Detection Process 
     By reference to a flowchart illustrated in  FIG.  10   , the description below explains the second snow chunk detection process in a configuration where only the first heating element  3  is provided. 
     In S 601 , the CPU  51  determines whether there is a request to stop the wiper motor  22 . 
     In S 601 , it may be determined that there is a request to stop the wiper motor  22 . Then, the CPU  51  proceeds to S 602  and turns off the first heating element  3 . 
     In S 601 , it may be determined that there is no request to stop the wiper motor  22 . Then, the CPU  51  returns to S 601 . 
     In S 603 , the CPU  51  notifies the CPU  41  of the request to stop the wiper motor  22 . 
     In S 604 , the CPU  41  determines whether snow accumulates in the close-side detection range  15 . 
     In S 604 , it may be determined that snow accumulates in the close-side detection range  15 . Then, the CPU  41  proceeds to S 605  and controls the wiper motor  22  to immediately stop the wiper blade  21 . 
     In S 604 , it may be determined that no snow accumulates in the close-side detection range  15 . Then, the CPU  41  proceeds to S 606  and controls the wiper motor  22  so that the wiper blade  21  moves to the retracted position  13 . 
     1-4. Effects 
     As described in detail above, the first embodiment provides the following effects. 
     ( 1   a ) The CPU  51  turns on the first heating element  3  when it is determined that snow accumulates in the open-side detection range  14 . The CPU  51  turns on the second heating element  4  when it is determined that snow accumulates in the close-side detection range  15 . This configuration turns on only the heating element closer to a snow chunk. Therefore, this configuration enables to melt snow chunks and to prevent the heating elements from being unnecessarily energized. This configuration enables to efficiently melt the snow accumulated on the windshield  10 . 
     ( 1   b ) The first heating element  3  is provided inside the front pillar. This configuration enables to melt the snow accumulated near the released position  12  from the front pillar. The first heating element  3  is hidden from the driver&#39;s field of view. Therefore, this configuration enables to prevent the driver&#39;s view from being obstructed. 
     ( 1   c ) When the wiper blade  21  is retracted, the CPU  51  turns on the second heating element  4  after determining that snow accumulates in the close-side detection range  15 . This configuration enables to melt a snow chunk around the retracted position  13  and then retract the wiper blade  21 . This configuration enables to prevent the wiper blade  21  from being damaged by forcibly wiping snow chunks. 
     1-5. Correspondence Relationship 
     In terms of the first embodiment, the wiper system  2  corresponds to the wiper system of the snow melting apparatus. The first heating element  3  corresponds to the first heating element of the snow melting apparatus. The second heating element  4  corresponds to the second heating element of the snow melting apparatus. The body ECU  5  corresponds to the determination portion (determiner) and the control portion (controller) of the snow melting apparatus. In terms of the modification of the first embodiment, the wiper system  2  corresponds to the wiper system of the snow melting apparatus. The first heating element  3  corresponds to the first heating element of the snow melting apparatus. The body ECU  5  corresponds to the determination portion (determiner) and the control portion (controller) of the snow melting apparatus. 
     2. Second Embodiment 
     The basic configuration of the second embodiment is equal to that of the first embodiment. Differences are described below. The same reference numerals as used for the first embodiment depict the same configuration. The preceding explanation is referenced. 
     The second embodiment differs from the first embodiment in the range to determine whether snow accumulates, corresponding to S 303  and S 306  in  FIG.  7   . The second embodiment differs from the first embodiment in the range to determine whether snow accumulates, corresponding to S 503  in  FIG.  9   . 
     2-1. First Snow Chunk Detection Process 
     By reference to a flowchart illustrated in  FIG.  11   , the description below explains the first snow chunk detection process performed by the CPU  51  of the body ECU  5 . This process is repeatedly performed while the ignition switch is turned on. 
     S 701  and S 702  are equal to S 301  and S 302 . 
     In S 703 , the CPU  51  determines whether snow accumulates in a released-side determination area  61 . As illustrated in  FIG.  12   , the released-side determination area  61  ranges from a first reference position  64   a  to a second reference position  64   b . The first reference position  64   a  is distanced from the released position  12  of the wiper blade  21  toward the standby position  11  of the wiper blade  21 . The second reference position  64   b  is distanced from the first reference position  64   a  toward the standby position  11  of the wiper blade  21 . The CPU  51  does not determine whether snow accumulates, in an area  65  from the released position  12  to the first reference position  64   a  of the wiper blade  21 . Specifically, the CPU  41  determines that snow accumulates in the snow chunk detection range when all of the following four conditions are satisfied. The conditions are as follows: the angle sensor  23  indicates an angle corresponding to the released-side determination area  61 ; the rotation speed of the wiper motor  22  is slower than a predetermined speed threshold; the output current value of the wiper motor  22  is larger than a predetermined current threshold; a predetermined time has elapsed. Under these conditions, it is determined that snow accumulates in the released-side determination area  61 . It may be favorable to conclude the detection of a snow chunk at the released position  12  when it is determined that a snow chunk is detected in the released-side determination area  61  in three successive cycles, for example. It may be favorable to provide hysteresis for angles detected by the angle sensor  23 . Specifically, suppose it is once determined that snow accumulates in the released-side determination area  61 . Then, the first heating element  3  turns on and then off at a reference position that may be shifted toward the released position  12 . It is possible to prevent the first heating element  3  from repeatedly turning on and off in a short time. S 703  is comparable to a process as the determination portion. 
     In S 703 , it may be determined that snow accumulates in the released-side determination area  61 . Then, the CPU  51  proceeds to S 704  and turns on the first heating element  3 . S 704  is comparable to a process as the control portion. 
     In S 703 , it may be determined that no snow accumulates in the released-side determination area  61 . Then, the CPU  51  proceeds to S 705  and turns off the first heating element  3 . 
     In S 706 , the CPU  51  determines whether snow accumulates in a standby-side determination area  62 . The standby-side determination area  62  ranges from a first reference position  67   a  to a second reference position  67   b . The first reference position  67   a  is distanced from the standby position  11  of the wiper blade  21  toward the released position  12  of the wiper blade  21 . The second reference position  67   b  is distanced from the first reference position  67   a  toward the released position  12  of the wiper blade  21 . The CPU  51  does not determine whether snow accumulates, in an area  68  from the retracted position  13  to the first reference position  67   a  of the wiper blade  21 . 
     In S 706 , it may be determined that snow accumulates in the standby-side determination area  62 . Then, the CPU  51  proceeds to S 707  and turns on the second heating element  4 . 
     In S 706 , it may be determined that no snow accumulates in the standby-side determination area  62 . Then, the CPU  51  proceeds to S 708  and turns off the second heating element  4 . 
     S 709  through S 720  are equal to S 309  through S 320 . 
     2-2. Modification of the Second Embodiment 
     The second embodiment provides the first heating element  3  and the second heating element  4 . However, the second heating element  4  may not be provided. 
     2-2-1. First Snow Chunk Detection Process 
     By reference to a flowchart illustrated in  FIG.  13   , the description below explains the first snow chunk detection process in a configuration where only the first heating element  3  is provided. 
     S 801 , S 802 , and S 806  are equal to S 501 , S 502 , and S 506 . 
     In S 803 , the CPU  51  determines whether snow accumulates in the released-side determination area  61 . S 803  is equal to S 703 . S 803  is comparable to a process as the determination portion. 
     In S 803 , it may be determined that snow accumulates in the released-side determination area  61 . Then, the CPU  51  proceeds to S 804  and turns on the first heating element  3 . S 804  is comparable to a process as the control portion. 
     In S 803 , it may be determined that no snow accumulates in the released-side determination area  61 . Then, the CPU  51  proceeds to S 805  and turns off the first heating element  3 . 
     2-3. Effects 
     As described in detail above, the second embodiment provides the following effects in addition to the effects of the first embodiment. 
     ( 2   a ) The CPU  51  determines whether snow accumulates in the released-side determination area  61 . The released-side determination area  61  ranges from the first reference position  64   a  to the second reference position  64   b . The first reference position  64   a  is distanced from the released position  12  of the wiper blade  21  toward the standby position  11  of the wiper blade  21 . The second reference position  64   b  is distanced from the first reference position  64   a  toward the standby position  11  of the wiper blade  21 . The CPU  51  does not determine whether snow accumulates, in the area  65  from the released position  12  to the first reference position  64   a  of the wiper blade  21 . This configuration enables to prevent the first heating element  3  from turning on when the snowfall is not enough to turn on the first heating element  3 . The first heating element  3  can be used more efficiently. 
     ( 2   b ) The CPU  51  determines whether snow accumulates in the standby-side determination area  62 . The standby-side determination area  62  ranges from the first reference position  67   a  to the second reference position  67   b . The first reference position  67   a  is distanced from the standby position  11  of the wiper blade  21  toward the released position  12  of the wiper blade  21 . The second reference position  64   b  is distanced from the first reference position  67   a  toward the released position  12  of the wiper blade  21 . The CPU  51  does not determine whether snow accumulates, in the area  68  from the retracted position  13  to the first reference position  67   a  of the wiper blade  21 . This configuration enables to prevent the second heating element  4  from turning on when the snowfall is not enough to turn on the second heating element  4 . The second heating element  4  can be used more efficiently. 
     3. Other Embodiments 
     While there have been described the specific preferred embodiments of the present disclosure, it is to be distinctly understood that the disclosure is not limited thereto but may be otherwise variously embodied. 
     ( 3   a ) According to the above-described embodiments, the first heating element  3  is provided inside the front pillar. However, the position to provide the first heating element  3  is not limited thereto. For example, the first heating element  3  may be provided for the windshield  10  near the front pillar as illustrated in  FIG.  2 D . The first heating element  3  may be provided as a film heater. The first heating element  3  may be attached to the windshield  10  on the side of the vehicle compartment or may be provided between the outer glass and the inner glass constituting the windshield  10 . 
     ( 3   b ) According to the above-described embodiments, the body ECU  5  turns on the wiper switch when it is determined that the amount of raindrop detected by the rain sensor  6  exceeds the predetermined raindrop threshold. However, the timing to turn on the wiper switch is not limited thereto. For example, the driver may manually turn on the wiper switch. 
     ( 3   c ) The first embodiment determines whether snow accumulates in the open-side detection range  14  and the close-side detection range  15 . The second embodiment determines whether snow accumulates in the released-side determination area  61  and the standby-side determination area  62 . However, the ranges to detect the snowfall accumulation are not limited thereto. For example, it may be favorable to detect whether snow accumulates on the whole surface of the windshield  10 . 
     ( 3   d ) The above-described embodiments determine the snowfall accumulation in the snow chunk detection range when all of the four conditions are satisfied, namely, the detection range, the rotation speed of the wiper motor  22 , the output current value of the wiper motor  22 , and the elapsed time. However, other methods may be used to determine the snowfall accumulation in the snow chunk detection range. For example, only part of the four conditions may be used to determine the snowfall accumulation in the snow chunk detection range. A combination with other conditions may be used to determine the snowfall accumulation in the snow chunk detection range. For example, it may be favorable to determine the snowfall accumulation in the snow chunk detection range based on images of a camera installed to capture the surface of the windshield  10 . Moreover, the outside temperature may be taken into consideration to determine the snowfall accumulation. Specifically, the above-described determinations may be supplemented with a determination as to whether the value of the outside air temperature sensor is smaller than or equal to a predetermined temperature threshold. 
     ( 3   e ) According to the above-described embodiments, the first heating element  3  and second heating element  4  are powered by the battery, as illustrated in  FIGS.  1  and  14 B . However, as illustrated in  FIG.  14 A , the first heating element  3  and the second heating element  4  may be powered by a device included in the snow melting system  1 . 
     ( 3   f ) A function of one element in the embodiments may be distributed into several elements. Functions of several elements may be integrated into one element. The configurations of the embodiments may be partially omitted. The configuration of one of the embodiments may be at least partially added to or replace the configurations of the other embodiments.