Patent Publication Number: US-2022221050-A1

Title: Shift range control device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of International Patent Application No. PCT/JP2020/035189 filed on Sep. 17, 2020, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2019-181710 filed on Oct. 1, 2019. The entire disclosures of all of the above applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a shift range control device. 
     BACKGROUND 
     A shift range control device for switching a shift range by controlling driving of a motor has been known. For example, when an angle deviation becomes smaller than an angle determination threshold value, a control is switched to a sudden braking control. For example, when reversal of the motor is detected, the control is switched to a stationary phase energization control. 
     SUMMARY 
     The present disclosure provides a shift range control device. The shift range control device switches a shift range by controlling driving of a motor. The shift range control device calculate an actual rotation position of the motor. The shift range control device sets a target range according to a required range and a target rotation position according to the target range. The shift range control device controls the driving of the motor such that the actual rotation position reaches the target rotation position. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The 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 perspective view showing a shift-by-wire system according to a first embodiment; 
         FIG. 2  is a diagram showing a schematic configuration of the shift-by-wire system according to the first embodiment; 
         FIG. 3  is a flowchart showing a drive mode selection process according to the first embodiment; 
         FIG. 4  is a flowchart showing a reversal detection process according to the first embodiment; 
         FIG. 5  is a flowchart showing a control selection process according to the first embodiment; 
         FIG. 6  is a time chart showing a motor control process and a schematic diagram showing a state in which a detent roller moves; 
         FIG. 7  is a flowchart showing the motor control process according to the first embodiment; 
         FIG. 8  is a time chart showing the motor control process according to the first embodiment; 
         FIG. 9  is a time chart showing the motor control process according to the first embodiment; 
         FIG. 10  is a time chart showing the motor control process according to the first embodiment; and 
         FIG. 11  is a flowchart showing a drive mode selection process according to a second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In a shift range control device as an example, a stationary phase energization control is continued for a stationary phase energization time, and then the energization is turned off. Here, by making a range confirmation determination when the stationary phase energization is completed, it is possible to make a determination in a state where the motor is reliably stopped. However, for example, when a hydraulic control of a transmission is started after the range confirmation determination, it is preferable that the range confirmation determination is quick in terms of feeling. On the other hand, when the range confirmation is determined and the hydraulic control of the transmission is started while the motor is being driven, the transmission may fail in a case where the motor overshoots due to, for example, a momentary power interruption. 
     The present disclosure provides a shift range control device capable of appropriately determining a range confirmation. 
     An exemplary embodiment of the present disclosure provides a shift range control device. The shift range control device switches a shift range by controlling driving of a motor. The shift range control device includes a motor position calculation unit, a target setting unit, a drive control unit, a reversal determination unit, and a range confirmation determination unit. The motor position calculation unit is configured to calculate an actual rotation position based on a detection value of a rotation position detection unit that detects a rotation of the motor. The target setting unit is configured to set a target range according to a required range and a target rotation position according to the target range. The drive control unit is configured to control the driving of the motor such that the actual rotation position reaches the target rotation position, and perform a stop control that causes the motor to stop in response to the actual rotation position being within a control range including the target rotation position. The reversal determination unit configured to detect a reversal of the motor. The range confirmation determination unit is configured to determine that the shift range is confirmed according to the required range when the reversal of the motor is detected during the stop control. 
     In the exemplary embodiment of the present disclosure, the reversal determination unit detects the reversal of the motor. The range confirmation determination determines that the shift range is confirmed according to the required range when the reversal of the motor is detected during the stop control. As a result, it is possible to appropriately determine the confirmation of the shift range. 
     First Embodiment 
     Hereinafter, a shift range control device according to the present disclosure will be described with reference to the drawings. In a plurality of embodiments, the same reference marks are used for substantially the same elements, and description thereof will be omitted. 
     A shift range control device according to one embodiment is shown in  FIGS. 1 to 10 . As shown in  FIGS. 1 and 2 , a shift-by-wire system  1  includes a motor  10 , a shift range switching mechanism  20 , a parking lock mechanism  30 , a shift range control device  40 , and the like. 
     The motor  10  rotates while receiving an electric power from a battery mounted on a vehicle (not shown), and functions as a driving source of the shift range switching mechanism  20 . The motor  10  of the present embodiment is a switched reluctance motor having three phases and has U-phase, V-phase, and W-phase motor windings wound around a stator (not shown). 
     As shown in  FIG. 2 , an encoder  13 , which is a rotational position detection unit, detects a rotational position of a rotor (not shown) of the motor  10 . The encoder  13  is, for example, a magnetic rotary encoder, and includes a magnet that rotates integrally with the rotor, a Hall IC for magnetic detection, and the like. The encoder  13  outputs an encoder signal, which is a pulse signal, at predetermined angles in synchronization with the rotation of the rotor. 
     A speed reducer  14  is provided between a motor shaft  105  (see  FIG. 6 ) of the motor  10  and an output shaft  15 , decelerates the rotation of the motor  10 , and outputs the rotation to the output shaft  15 . As a result, the rotation of the motor  10  is transmitted to the shift range switching mechanism  20 . The output shaft  15  is provided with an output shaft sensor  16  for detecting an angle of the output shaft  15 . The output shaft sensor  16  is, for example, a potentiometer. 
     As shown in  FIG. 1 , the shift range switching mechanism  20  has a detent plate  21 , a detent spring  25 , a detent roller  26 , and the like, and transmits a rotational driving force output from the speed reducer  14  to a manual valve  28  and a parking lock mechanism  30 . 
     The detent plate  21  is fixed to the output shaft  15  and driven by the motor  10 . The detent plate  21  has a pin  24  protruding in parallel with the output shaft  15 . The pin  24  is connected to the manual valve  28 . When the detent plate  21  is driven by the motor  10 , the manual valve  28  reciprocates in an axial direction. In other words, the shift range switching mechanism  20  converts a rotational motion of the motor  10  into a linear motion and transmits the linear motion to the manual valve  28 . The manual valve  28  is provided in a valve body  29 . When the manual valve  28  reciprocates in the axial direction, a hydraulic supply path to a hydraulic clutch (not shown) is switched, and an engagement state of the hydraulic clutch is switched. In this way, the shift range is switched. 
     On a detent spring  25  side of the detent plate  21 , four valley portions  22  corresponding to the P (parking), R (reverse), N (neutral), and D (drive) ranges are formed. The detent roller  26  moves in the valley portion  22  as the motor  10  is driven. 
     A play is formed between the motor shaft  105  and the output shaft  15 . In  FIG. 6 , the speed reducer  14  and the output shaft  15  are integrated, and a play is formed between the motor shaft  105  and the speed reducer  14 , but the motor shaft  105  and the speed reducer  14  may be integrated and a play may be formed between the speed reducer  14  and the output shaft  15 . The “play” can be regarded as the total amount of plays provided between the motor shaft  105  and the output shaft  15 . 
     The detent spring  25  is an elastically deformable plate-like urging member, and is provided with the detent roller  26  at a tip of the detent spring  25 . The detent roller  26  is fitted into any one of the valley portions  22 . The detent spring  25  urges the detent roller  26  toward the center of rotation of the detent plate  21 . When a rotational force equal to or greater than a predetermined force is applied to the detent plate  21 , the detent spring  25  is elastically deformed, and the detent roller  26  moves among the valley portions  22 . When the detent roller  26  is fitted into any one of the valley portions  22 , the swinging motion of the detent plate  21  is regulated, the axial position of the manual valve  28  and the state of the parking lock mechanism  30  are determined, and the shift range of an automatic transmission  5  is fixed. 
     The parking lock mechanism  30  includes a parking rod  31 , a conical member  32 , a parking lock pawl  33 , a shaft part  34  and a parking gear  35 . The parking rod  31  is formed in a substantially L-shape, and one end  311  is fixed to the detent plate  21 . The other end  312  of the parking rod  31  is provided with the conical member  32 . The conical member  32  is formed to reduce in diameter toward the other end  312 . When the detent plate  21  rotates in the direction in which the detent roller  26  fits into the valley portion corresponding to the P range, the conical member  32  moves in the direction of the arrow P. 
     The parking lock pawl  33  comes into contact with a conical surface of the conical member  32  and is provided so as to be swingable around the shaft part  34 . On the parking gear  35  side of the parking lock pawl  33 , a protrusion  331  that can mesh with the parking gear  35  is provided. When the conical member  32  moves in the direction of the arrow P due to the rotation of the detent plate  21 , the parking lock pawl  33  is pushed up and the protrusion  331  and the parking gear  35  mesh with each other. On the other hand, when the conical member  32  moves in the direction of the arrow NotP, the meshing between the protrusion  331  and the parking gear  35  is released. 
     The parking gear  35  is provided on an axle (not shown) and is enabled to mesh with the protrusion  331  of the parking lock pawl  33 . When the parking gear  35  meshes with the protrusion  331 , rotation of the axle is restricted. When the shift range is one of the ranges (Not P range) other than the P range, the parking gear  35  is not locked by the parking lock pawl  33 . Therefore, the rotation of the axle  95  is not restricted by the parking lock mechanism  30 . When the shift range is the P range, the parking gear  35  is locked by the parking lock pawl  33  and the rotation of the axle is restricted. 
     As shown in  FIG. 2 , the shift range control device  40  includes a drive circuit  41 , an ECU  50 , and the like. The drive circuit  41  is a three-phase inverter that switches the energization of the motor windings, has a switching element (not shown), and switches the energization of each phase of the motor  10 . A motor relay  46  is provided between the drive circuit  41  and a battery. The motor relay  46  is turned on while a start switch of the vehicle, such as an ignition switch, is turned on, so that power is supplied to the motor  10  side. Further, by turning off the motor relay  46 , the supply of electric power to the motor  10  side is cut off. 
     The ECU  50  is mainly composed of a microcomputer and the like, and internally includes a CPU, a ROM, a RAM, an I/O, a bus line for connecting these components, and the like, which are not shown. Each processing in the ECU  50  may be software processing by executing a program stored in advance in a tangible memory device (that is, a readable non-transitory tangible recording medium) such as the ROM by the CPU, or may be hardware processing by a dedicated electronic circuit. The same applies to a host ECU  60  described later. 
     The ECU  50  controls the switching of the shift range by controlling the drive of the motor  10  based on a driver required shift range, a signal from a brake switch, a vehicle speed, and the like. In the present embodiment, the ECU  50  acquires information such as a brake signal, a vehicle speed, and a required range from the host ECU  60 . The ECU  50  includes a motor position calculation unit  51 , a target setting unit  52 , a mode selection unit  53 , a drive control unit  54 , a reversal determination unit  55 , a range confirmation determination unit  56 , and the like. 
     The motor position calculation unit  51  counts pulse edges of each phase of an encoder signal output from the encoder  13 , and calculates an encoder count value θen. The encoder count value θen is a value corresponding to the rotation position of the motor  10  and corresponds to an “actual rotation position”. In the present embodiment, the rotation direction of the motor  10  when switching from the P range to the D range is defined as a forward rotation, and the rotation direction of the motor  10  when switching from the D range to the P range is defined as a reverse rotation. The encoder count value θen is counted up when the motor  10  rotates in the forward rotation and is counted down when the motor  10  rotates in the reverse rotation. 
     The target setting unit  52  sets a target range according to the required range acquired from the host ECU  60 . Further, a target count value θcmd, which is a position where the motor  10  is to be stopped, is set according to the target range. The mode selection unit  53  selects the drive mode. 
     The drive control unit  54  controls the drive of the motor  10  so that the detent roller  26  fits into the valley portion  22  according to the target range according to the selected drive mode. When the target range is changed, the drive control unit  54  drives the motor  10  by feedback control. In the drawing, the feedback is referred to as “F/B”. Specifically, the motor  10  is rotated by energizing the energizing phase according to the encoder count value θen and switching the energizing phase according to the encoder count value θen. 
     When the encoder count value θen is within the control range including the target count value θcmd, the drive mode is switched from the feedback control to the stop control, and the motor  10  is stopped. The stop control of the present embodiment is a stationary phase energization control that continues energization to the same phase. In the present embodiment, after the stop control is performed over a stop control continuation time TH 1 , the drive mode is set to the standby mode, and the drive control of the motor  10  is terminated. The stop control continuation time TH 1  is set in accordance with a time required to stop the motor  10 . Hereinafter, when the encoder count value θen is within the control range including the target count value θcmd (for example, θcmd±2 counts), it is defined as “reaching the target”. 
     The reversal determination unit  55  determines the reversal of the rotor of the motor  10  based on the encoder count value θen. Hereinafter, the reversal of the rotor of the motor  10  is simply referred to as “motor reversal”. In the present embodiment, the rotation direction of the motor  10  is opposite to that at the time of feedback control, which is referred to as “motor reversal”. The range confirmation determination unit  56  determines the range confirmation in the shift-by-wire system  1 . When the range confirmation is determined, the range confirmation determination unit  56  transmits a range confirmation flag FlgC, which is information indicating that the range has been confirmed, to the host ECU  60 . 
     The host ECU  60  controls the drive of a shift hydraulic control solenoid  6  based on the vehicle speed, an accelerator opening degree, the driver required shift range, and the like. In the present embodiment, when the driver required shift range changes and the range confirmation flag FlgC from the ECU  50  is turned on, the drive of the shift hydraulic control solenoid  6  is started. By controlling the shift hydraulic control solenoid  6 , the shift stage is controlled. The number of the shift hydraulic control solenoids  6  is determined according to the number of shift stages or the like. Further, when the range confirmation flag FlgC is turned on, the host ECU  60  notifies the user of the confirmed range by, for example, changing the display of the instrument panel. 
     By the way, it is preferable in terms of feeling that the time from the change of the required shift range to the start of the hydraulic control of the automatic transmission  5  is short. On the other hand, if the hydraulic control is started while the motor  10  is being driven, an abnormality may occur in the automatic transmission  5  in a case where the motor  10  overshoots or undershoots due to, for example, a momentary power interruption. 
     Here, when the reversal of the motor  10  is detected while the detent roller  26  is located at the valley portion  22  according to the required range, overshoot does not occur and the detent roller  26  can be located at the valley portion  22  according to the required range. Therefore, in the present embodiment, the range is confirmed based on the reversal determination of the motor  10  during the stop control, so that the timing of start of the hydraulic control of the automatic transmission  5  is made as early as possible. 
     This drive mode selection process in the present embodiment will be described with reference to a flowchart of  FIG. 3 . This process is executed in a predetermined cycle (for example, 1 [ms]) by, for example, the mode selection unit  53  of the ECU  50 . A part of the process may be executed by another calculation unit of the ECU  50 . The same applies to other control processes. Further, the calculation cycle may be the same or different for each process. Hereinafter, “step” in step S 101  is omitted, and is simply referred to as a symbol “S.” The other steps are the same. 
     In S 101 , the mode selection unit  53  determines the current drive mode. When the drive mode is the standby mode, the process proceeds to S 102 , when the drive mode is the feedback mode, the process proceeds to S 104 , and when the drive mode is the stop mode, the process proceeds to S 106 . 
     In S 102 , the mode selection unit  53  determines whether the target range has been switched. When it is determined that the target range has not been switched (S 102 : NO), the standby mode is continued. When it is determined that the target range has been changed (S 102 : YES), the process proceeds to S 103  and the drive mode is switched to the feedback mode. 
     In S 104 , to which the process proceeds when the drive mode is the feedback mode, the mode selection unit  53  determines whether the encoder count value θen has reached the target based on the encoder count value θen and the target count value θcmd. When the mode selection unit  53  determines that the target has not been reached (S 104 : NO), the feedback mode is continued. When the mode selection unit  53  determines that the target has been reached (S 104 : YES), the process proceeds to S 105  and the drive mode is switched to the stop mode. 
     In S 106 , to which the process proceeds when the drive mode is the feedback mode, the mode selection unit  53  determines whether the stop control continuation time TH 1  has elapsed after switching to the stop mode. When the mode selection unit  53  determines that the stop control continuation time TH 1  has not elapsed (S 106 : NO), the stop mode is continued. When the mode selection unit  53  determines that the stop control continuation time TH 1  has elapsed (S 106 : YES), the process proceeds to S 107 . 
     In S 107 , the mode selection unit  53  determines whether a re-feedback flag FlgA or a target reset flag FlgB, which will be described later, is on. When the mode selection unit  53  determines that the re-feedback flag FlgA or the target reset flag FlgB is on (S 107 : YES), the process returns to S 102  and the drive mode is switched to the feedback mode. When the target reset flag FlgB is on, the target range and the target count value θcmd according to the required range are reset. When the mode selection unit  53  determines that both the re-feedback flag FlgA and the target reset flag FlgB are off (S 107 : NO), the process proceeds to S 108  and the drive mode is set to the standby mode. 
     A reversal detection process will be described with reference to the flowchart of  FIG. 4 . This process is executed in a predetermined cycle (for example, 1 [ms]) by, for example, the reversal determination unit  55  of the ECU  50 . In S 201 , the reversal determination unit  55  determines whether the drive mode is the stop mode. When the reversal determination unit  55  determines that the drive mode is not the stop mode (S 201 : NO), the process proceeds to S 202  and the reversal flag FlgR is turned off. When the reversal determination unit  55  determines that the drive mode is the stop mode (S 201 : YES), the process proceeds to S 203 . 
     In S 203 , the reversal determination unit  55  determines whether the value obtained by subtracting the previous value from the current value of the encoder count value θen is 0. Here, when the current value of the encoder count value ben is equal to the previous value, a positive determination is made. In the figure, the subscript (n) means the current value, and (n−1) means the previous value. When the reversal determination unit  55  determines that the value obtained by subtracting the previous value from the current value of the encoder count value θen is 0 (S 203 : YES), the process proceeds to S 204 , and a stationary timer that measures an encoder stationary time T 2  is counted up. When the reversal determination unit  55  determines that the value obtained by subtracting the previous value from the current value of the encoder count value θen is not 0 (S 203 : NO), the process proceeds to S 205 . 
     In S 205 , the reversal determination unit  55  determines whether the rotation direction of the motor  10  in the feedback mode before entering the stop mode is the forward rotation direction. When the reversal determination unit  55  determines that the rotation direction of the motor  10  is the forward rotation direction (S 205 : YES), the process proceeds to S 206 , and when the reversal determination unit  55  determines that the rotation direction of the motor  10  is the reverse rotation direction (S 205 : NO), the process proceeds to S 207 . 
     In S 206 , the reversal determination unit  55  determines whether the value obtained by subtracting the previous value from the current value of the encoder count value θen is a negative value. Here, when the current value of the encoder count value θen is smaller than the previous value, a positive determination is made. When the reversal determination unit  55  determines that the value obtained by subtracting the previous value from the current value of the encoder count value θen is greater than 0 (S 206 : NO), the motor  10  is not reversed. Thus, S 208  is not performed and the routine is terminated. When the reversal determination unit  55  determines that the value obtained by subtracting the previous value from the current value of the encoder count value θen is a negative value (S 206 : YES), the process proceeds to S 208  and the reversal flag FlgR is turned on. 
     In S 207 , the reversal determination unit  55  determines whether the value obtained by subtracting the previous value from the current value of the encoder count value θen is a positive value. Here, when the current value of the encoder count value θen is greater than the previous value, a positive determination is made. When the reversal determination unit  55  determines that the value obtained by subtracting the previous value from the current value of the encoder count value θen is smaller than 0 (S 207 : NO), the motor  10  is not reversed. Thus, S 208  is not performed and the routine is terminated. When the reversal determination unit  55  determines that the value obtained by subtracting the previous value from the current value of the encoder count value θen is a positive value (S 207 : NO), the process proceeds to S 208  and the reversal flag FlgR is turned on. 
     A control selection process will be described with reference to the flowchart of  FIG. 5 . This process is executed in a predetermined cycle (for example, 1 [ms]) by, for example, the range confirmation determination unit  56  of the ECU  50 . In S 301 , the range confirmation determination unit  56  determines whether the drive mode is the stop mode. When the range confirmation determination unit  56  determines that the drive mode is not the stop mode (S 301 : NO), the process proceeds to S 302 , and the re-feedback flag FlgA, the target reset flag FlgB, and the range confirmation flag FlgC are turned off. When the reversal determination unit  55  determines that the drive mode is the stop mode (S 301 : YES), the process proceeds to S 303 . 
     In S 303 , the range confirmation determination unit  56  determines whether the target range matches with the required range. When the range confirmation determination unit  56  determines that the target range does not match with the required range (S 303 : NO), the process proceeds to S 304 , the target range is reset to match with the required range, and the target reset flag FlgB is turned on in S 305 . When the range confirmation determination unit  56  determines that the target range matches with the required range (S 303 : YES), the process proceeds to S 306 . 
     In S 306 , the range confirmation determination unit  56  determines whether the count deviation ΔCP, which is the absolute value of the difference between the target count value θcmd and the encoder count value θen, is equal to or less than a re-drive determination value CPerr. The re-drive determination value CPerr is set again according to the position where the motor  10  needs to be driven. When the range confirmation determination unit  56  determines that the count deviation ΔCP is greater than the re-drive determination value CPerr (S 306 : NO), the process proceeds to S 308  and the re-feedback flag FlgA is turned on. When the range confirmation determination unit  56  determines that the count deviation ΔCP is equal to or less than the re-drive determination value CPerr (S 306 : YES), the process proceeds to S 307 . 
     In S 307 , the range confirmation determination unit  56  determines whether the target range matches with the current range. When the range confirmation determination unit  56  determines that the target range does not match with the current range (S 307 : NO), the process proceeds to S 308  and the re-feedback flag FlgA is turned on. When the range confirmation determination unit  56  determines that the target range matches with the current range (S 307 : YES), the process proceeds to S 309 . 
     In S 309 , the range confirmation determination unit  56  determines whether the reversal flag FlgR is on. When the range confirmation determination unit  56  determines that the reversal flag is on (S 309 : YES), the process proceeds to S 311 . When the range confirmation determination unit  56  determines that the reversal flag is off (S 308 : NO), the process proceeds to S 310 . 
     In S 310 , the range confirmation determination unit  56  determines whether the stationary determination time TH 2  has elapsed since the encoder count value θen has unchanged. The stationary determination time TH 2  is set shorter than the stop control continuation time TH 1 . When the range confirmation determination unit  56  determines that the stationary determination time TH 2  has not elapsed since the encoder count value θen has unchanged (S 310 : NO), the process of S 311  is not performed and this routine is terminated. When the range confirmation determination unit  56  determines that the stationary determination time TH 2  has elapsed since the encoder count value θen has unchanged (S 310 : YES), the process proceeds to S 311  and the range determination flag FlgC is turned on. Further, the range confirmation determination unit  56  transmits the range confirmation flag FlgC to the host ECU  60 . 
     The motor control process will be described based on time charts shown in  FIGS. 6 to 10 . The time chart of  FIG. 6  shows the drive mode, the range required from the host ECU  60 , the current range and the target range, the motor position, the reversal flag FlgR, and the range confirmation flag FlgC from the top, with the common time axis as the horizontal axis. In  FIG. 6 , the target range and the target count value θcmd are shown by a dash-dot line, and the current range and the encoder count value θen are shown by a solid line. The same applies to  FIG. 7  and later. Further, on the lower side of the time chart of  FIG. 6 , the rotation direction of the motor  10  is set to the left-right direction on the paper surface, and the state in which the detent roller  26  moves the detent plate  21  is schematically shown. 
     When the driver&#39;s required shift range is switched from the P range to the D range by the driver&#39;s shift operation at time x 10 , information that the required range is set to the D range is transmitted from the host ECU  60  to the ECU  50 . The ECU  50  sets the target range to the D range and sets the target count value θcmd according to the target range. Further, the ECU  50  switches the drive mode from the standby mode to the feedback mode, and drives the motor  10  so that the encoder count value θen reaches the target count value θcmd. As a result, the detent roller  26  moves from the valley portion corresponding to the P range to the valley portion corresponding to the D range. 
     When the encoder count value θen reaches the target at time x 11 , the drive mode is switched from the feedback mode to the stop mode. Further, when the reversal of the motor  10  is detected at time x 12  in the stop mode, the reversal flag FlgR is turned on. When the motor  10  is reversed while the stop control is being performed, the motor  10  does not overshoot, so that the detent roller  26  can be reliably held in the valley corresponding to the D range. Therefore, in the present embodiment, the range confirmation flag FlgC is turned on at time x 12  and transmitted to the host ECU  60 . In the host ECU  60 , when the range confirmation flag FlgC is turned on, the hydraulic control of the automatic transmission  5  is started. In addition, the range display of the instrument panel or the like is switched to the D range. 
     At time x 13  when the stop control continuation time TH 1  elapses from time x 11  when the stop control is started, the stop control is terminated and the standby mode is entered. Also, the reversal flag FlgR and the range confirmation flag FlgC are turned off. As a result, the range is fixed at time x 13  when the stop control is completed, and the start of the hydraulic pressure control can be accelerated as compared with the case where the hydraulic pressure control of the automatic transmission  5  is started, which contributes to the improvement of the feeling. 
     Each of the time charts of  FIGS. 7 to 10  shows the drive mode, the range required from the host ECU  60 , the current range and the target range, the motor position, the reversal flag FlgR, the range confirmation flag FlgC, the re-feedback flag FlgA, and the target reset flag FlgB from the top, with the common time axis as the horizontal axis. 
       FIG. 7  shows a case where the required range is changed during range switching. The process at time x 20  is the same as the process at time x 10  in  FIG. 6 . In  FIG. 7 , the required range is changed from the D range to the N range at time x 21  during the range switching. 
     When the encoder count value θen reaches the target at time x 22 , the drive mode is switched from the feedback mode to the stop mode. At this time, since the required range and the target range do not match, the target reset flag FlgB is turned on. Further, the motor  10  is reversed at time x 23  during the stop control, and the reversal flag FlgR is turned on. However, since the target reset flag FlgB is on, the range confirmation flag FlgC is not turned on at this time, and the range is not confirmed. 
     Since the target reset flag FlgB is on at time x 24  when the stop control continuation time TH 1  has elapsed from the time when the stop control is started x 22 , the target range and the target count value θcmd are reset and the drive mode is changed to the feedback mode, and then the motor  10  drives. Also, the reversal flag FlgR and the target reset flag FlgB are turned off. 
     When the encoder count value θen reaches the control range including the newly set target count value θcmd at time x 25 , the drive mode is switched from the feedback mode to the stop mode. Further, when the reversal of the motor  10  is detected at time x 26  in the stop mode, the reversal flag FlgR is turned on. At this time, since the re-feedback flag FlgA and the target reset flag FlgB are off, the range determination flag FlgC is turned on and transmitted to the host ECU  60 . The processes of time x 26  and time x 27  are respectively the same as the processes of time x 12  and time x 13  in  FIG. 6 . 
       FIG. 8  is an example of switching the shift range from the P range to the N range, and shows a case where an overshoot of the motor  10  occurs. The process from time x 30  to time x 31  is the same as the process from time x 10  to time x 11  in  FIG. 6 , except that each of the required range and the target range is the N range. 
     When the count deviation ΔCP becomes greater than the re-drive determination value CPerr due to the overshoot of the motor  10  at time x 32  during the stop control, the re-feedback flag FlgA is turned on. Further, the motor  10  is reversed at time x 33  during the stop control, and the reversal flag FlgR is turned on. However, since the re-feedback flag FlgA is on, the range confirmation flag FlgC is not turned on at this time, and the range is not confirmed. 
     Since the re-feedback flag FlgA is on at time x 34  when the stop control continuation time T 1  has elapsed from time x 31  at which the stop control is started, the drive mode is switched to the feedback mode and the motor  10  is driven. Since the required range has not been changed, the target range and the target count value θcmd are not changed. 
     When the encoder count value θen reaches the control range including the target count value θcmd again at time x 35 , the drive mode is switched from the feedback mode to the stop mode. Further, when the reversal of the motor  10  is detected at time x 36  in the stop mode, the reversal flag FlgR is turned on. At this time, since the re-feedback flag FlgA and the target reset flag FlgB are off, the range determination flag FlgC is turned on and transmitted to the host ECU  60 . The processes of time x 36  and time x 37  are respectively the same as the processes of time x 12  and time x 13  in  FIG. 6 . 
       FIG. 9  is an example of switching the shift range from the P range to the N range, and shows a case where an overshoot of the motor  10  occurs. The process from time x 40  to time x 41  is the same as the process from time x 10  to time x 11  in  FIG. 6 , except that each of the required range and the target range is the N range. 
     At time x 42 , the detent roller  26  moves to the valley portion  22  corresponding to the D range due to the overshoot of the motor  10 . When the current range becomes the D range, the target range and the current range do not match, and thus the re-feedback flag FlgA is turned on. Further, the motor  10  is reversed at time x 43  during the stop control, and the reversal flag FlgR is turned on. However, since the re-feedback flag FlgA is on, the range confirmation flag FlgC is not turned on at this time, and the range is not confirmed. The process of time x 44  to time x 47  is the same as the process of x 34  to time x 37  in  FIG. 8 . 
       FIG. 10  shows a case where the motor  10  is stopped without reversing. The processes of time x 50  and time x 51  are respectively the same as the processes of time x 10  and time x 11  in  FIG. 6 . When the encoder count value θen unchanges without the reversal of the motor  10  at time x 52 , the time counting of the encoder stationary time T 2  is started. When the unchange of the encoder count value θen continues over the stationary determination time TH 2 , the range confirmation flag FlgC is turned on at time x 53 , at which the stationary determination time TH 2  has elapsed from time x 52 , and then is transmitted to the host ECU  60 . 
     At time x 54  when the stop control continuation time TH 1  elapses from time x 51  at which the stop control is started, the stop control is terminated and the standby mode is entered. Also, the range confirmation flag FlgC is turned off. In the present embodiment, the stationary determination time TH 2  is set shorter than the stop control continuation time TH 1 . Thus, even when the motor  10  stops within the control range without reversing, the start of the hydraulic control of the automatic transmission  5  can be accelerated, which contributes to the improvement of the feeling, as compared with the case where the range is confirmed at time x 54  when the stop control is completed. 
     As described above, the shift range control device  40  according to the present embodiment switches the shift range by controlling driving of the motor  10 , and includes the motor position calculation unit  51 , the target setting unit  52 , the mode selection unit  53 , the drive control unit  54 , the reversal determination unit  55 , the range confirmation determination unit  56 . The motor position calculation unit  51  calculates the encoder count value θen based on the detection value from the encoder  13  that detects the rotation of the motor  10 . The target setting unit  52  sets the target range according to the required range and the target count value θcmd according to the target range. The drive control unit  54  controls the drive of the motor  10  so that the encoder count value θen becomes the target count value θcmd. When the encoder count value θen reaches the control range including the target count value θcmd, the drive control unit  54  causes the motor  10  to stop. 
     The reversal determination unit  55  detects the reversal of the motor  10 . The range confirmation determination unit  56  determines that the shift range is confirmed according to the required range when the reversal of the motor  10  is detected during the stop control. In the present embodiment, attention is paid to the fact that overshoot does not occur if the motor reversal during stop control is detected. Thus, when the reversal is detected, it is determined that the shift range is confirmed. As a result, it is possible to appropriately determine the confirmation of the shift range. Further, for example, the range can be confirmed in a shorter time than when the range is confirmed after the stop control is completed. Further, by promptly confirming the range, the start of hydraulic control of the automatic transmission  5  can be accelerated, so that the driver&#39;s feeling can be improved. 
     When, in the stop control, the state that the encoder count value θen unchanges for the stationary determination time TH 2 , which is shorter than the stop control continuation time TH 1  for continuing the stop control, the range confirmation determination unit  56  determines that the shift range according to the required range is confirmed. As a result, even when the rotor does not reverse, it is possible to appropriately determine the range confirmation. 
     When the required range does not match with the target range during the stop control, the ECU  50  resets the target range, re-drives the motor  10 , and determines the range confirmation in a state where the required range matches with the target range. In other words, when the required range does not match with the target range, for example, when the required range is changed during range switching, the shift range is not confirmed and the motor  10  is re-driven even when the reversal of the motor  10  is detected during stop control. This configuration can prevent erroneous determination of the range confirmation. 
     When the required range does not match with the current range during the stop control, the ECU  50  re-drives the motor  10  and determines the range confirmation in the state where the required range matches with the current range. In other words, for example, when the target range does not match with the current target due to overshoot, the shift range is not confirmed and the motor  10  is re-driven even if the reversal of the motor  10  is detected during the stop control. This configuration can prevent erroneous determination of the range confirmation. 
     When the count deviation ΔCP, which is the deviation between the target count value θcmd and the encoder count value θen, is larger than the re-drive determination value CPerr during the stop control, the ECU  50  drives the motor  10  again and then determines the range confirmation in the state where the count deviation ΔCP is equal to or smaller than the re-drive determination value CPerr. In other words, for example, when the count deviation ΔCP becomes larger than the re-drive determination value CPerr due to overshoot, the shift range is not confirmed and the motor  10  is re-driven even if the reversal of the motor  10  is detected during the stop control. This configuration can prevent erroneous determination of the range confirmation. 
     When it is determined that the shift range corresponding to the required range is confirmed, the ECU  50  notifies the host ECU  60 , which is another control unit, of information that the shift range has been confirmed. As a result, various processes executed by the range confirmation such as the hydraulic control of the automatic transmission  5  and notification to the user can be promptly started. 
     Second Embodiment 
     A second embodiment is shown in  FIG. 11 . Since a drive mode selection process is different in this embodiment, this point will be mainly described. The drive mode selection process in the present embodiment will be described with reference to a flowchart of  FIG. 11 . 
     In the present embodiment, when it is determined in S 106  that the stop control continuation time TH 1  has not elapsed (S 106 : NO), the process proceeds to S 107 , and then it is determined whether the re-feedback flag FlgA or the target reset flag FlgB is turned on. When it is determined that the re-feedback flag FlgA or the target reset flag FlgB is on (S 107 : YES), the process proceeds to S 103  and the drive mode is switched to the feedback mode. When it is determined that both the re-feedback flag FlgA and the target reset flag FlgB are off (S 107 : NO), the stop control is continued. 
     That is, in the present embodiment, when the required range is changed during the range switching or when the motor  10  overshoots, the feedback mode is switched without waiting for the stop control continuation time TH 1  to elapse. The same effects as those of the above embodiments can be obtained even in the configuration described above. 
     In the embodiment, the encoder  13  corresponds to a “rotation position detection unit”, the host ECU  60  corresponds to “another control unit”, the encoder count value θen corresponds to an “actual rotation position”, the target count value θcmd corresponds to a “target rotation position”, the count deviation ΔCP corresponds to a “deviation between the target rotation position and the actual rotation position”, and the range confirmation flag FlgC corresponds to “information that the shift range has been confirmed”. 
     OTHER EMBODIMENTS 
     In the above embodiment, the rotation position detection unit is an encoder. In another embodiment, the rotation position detection unit may be a linear sensor such as a resolver as long as it can detect the rotation position of the rotor. In the above embodiments, the potentiometer is exemplified as the output shaft sensor. In other embodiments, the output shaft sensor may be something other than a potentiometer, or the output shaft sensor may be omitted. 
     In the above embodiments, the motor is a switched reluctance motor. In other embodiments, the motor may be something other than a switched reluctance motor, for example, a DC brushless motor or the like. According to the embodiments described above, the four valley portions are formed in the detent plate. As another embodiment, the number of the valley portions is not limited to four but may be any number. For example, the detent plate may have two valley portions and the P range and the NotP range may be switched. The shift range switching mechanism, the parking lock mechanism, and the like may be different from those of the above embodiment. 
     In the embodiment described above, the speed reducer is provided between the motor shaft and the output shaft. Although the detail of the speed reducer is not mentioned in the above-described embodiments, the speed reducer may have any configuration, such as one using a cycloid gear, a planetary gear, or a spur gear that transmits a torque from a speed reduction mechanism substantially coaxial with the motor shaft to the drive shaft, and one using these gears in combination. In another embodiment, the speed reducer between the motor shaft and the output shaft may be omitted, or a mechanism except for the speed reducer may be provided. 
     The control unit and the technique according to the present disclosure may be achieved by a dedicated computer provided by constituting a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control circuit and the method described in the present disclosure may be realized by a dedicated computer configured as a processor with one or more dedicated hardware logic circuits. Alternatively, the control circuit and method described in the present disclosure may be realized by one or more dedicated computer, which is configured as a combination of a processor and a memory, which are programmed to perform one or more functions, and a processor which is configured with one or more hardware logic circuits. The computer programs may be stored, as instructions to be executed by a computer, in a tangible non-transitory computer-readable medium. As described above, the present disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit of the present disclosure. 
     The present disclosure has been described in accordance with the embodiments. However, the present disclosure is not limited to such embodiments and structures. The present disclosure also encompasses various modifications and variations within the scope of equivalents. Furthermore, various combination and formation, and other combination and formation including one, more than one or less than one element may be made in the present disclosure.