JP7067382B2 - Shift range controller - Google Patents

Description

The present invention relates to a shift range control device.

Conventionally, a shift range control device for switching a shift range by controlling a motor in response to a shift range switching request from a driver has been known. For example, in Patent Document 1, the motor is driven with the maximum duty until the motor speed becomes equal to or higher than the target motor speed.

Japanese Unexamined Patent Publication No. 2018-40464

For example, if the duty at low speed rotation is large, the current becomes large and there is a risk that the drive circuit or the like will break down. The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a shift range control device capable of suppressing an overcurrent.

The shift range control device of the present invention controls the switching of the shift range by controlling the drive of the motor (10) having the motor windings (11, 12), and controls the switching of the shift range with the drive circuit (41, 42). , A control unit (50). The drive circuit includes switching elements (411 to 416, 421 to 426) for switching the energization of the motor winding.

The control unit includes a motor angle calculation unit (51), a drive control unit (53), and a duty limiting unit (55). The motor angle calculation unit calculates the motor angle based on the signal acquired from the rotation angle sensor (13) that detects the rotation position of the motor. The drive control unit controls the drive of the motor so that the motor angle becomes the target rotation angle according to the target shift range. The duty limiting unit determines a duty limiting value that limits the duty, which is the ratio of the on-time of the switching element in a predetermined period, according to the motor angle. As a result, overcurrent can be suppressed.

It is a perspective view which shows the shift-by-wire system by 1st Embodiment. It is a schematic block diagram which shows the shift-by-wire system by 1st Embodiment. It is a circuit diagram which shows the motor and the motor driver by 1st Embodiment. It is explanatory drawing which shows the relationship between the torque, the rotation speed and the motor current by 1st Embodiment. It is a flowchart explaining the duty limit value calculation process by 1st Embodiment. It is a time chart explaining the drive control processing by 1st Embodiment. It is a time chart explaining the drive control processing by a reference example. It is a flowchart explaining the duty limit value calculation process by 2nd Embodiment. It is a time chart explaining the drive control processing by 2nd Embodiment. It is a time chart explaining the drive control processing by a reference example.

Hereinafter, the shift range control device according to the present invention will be described with reference to the drawings. Hereinafter, in a plurality of embodiments, substantially the same configurations are designated by the same reference numerals and description thereof will be omitted.

(First Embodiment)
The first embodiment is shown in FIGS. 1 to 6. As shown in FIGS. 1 and 2, the shift-by-wire system 1 as a shift range switching system 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 by being supplied with electric power from a battery 45 mounted on a vehicle (not shown), and functions as a drive source for the shift range switching mechanism 20. The motor 10 of this embodiment is a permanent magnet type DC brushless motor.

As shown in FIG. 3, the motor 10 has two sets of motor windings 11 and 12 wound around a stator (not shown). The first motor winding 11 has a U1 coil 111, a V1 coil 112, and a W1 coil 113. The second motor winding 12 has a U2 coil 121, a V2 coil 122, and a W2 coil 123.

As shown in FIG. 2, the encoder 13 as a motor rotation angle sensor detects the rotation position of the rotor 105. The encoder 13 is, for example, a magnetic rotary encoder, and is composed of a magnet that rotates integrally with the rotor, a Hall IC for magnetic detection, and the like. The encoder 13 is a three-phase encoder that outputs an encoder signal, which is an A-phase, B-phase, and C-phase pulse signal, at predetermined angles in synchronization with the rotation of the rotor.

The speed reducer 14 is provided between the motor shaft of the motor 10 and the output shaft 15, and decelerates the rotation of the motor 10 to output 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 that detects the angle of the output shaft 15. The output shaft sensor 16 of this embodiment 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, and the like, and the rotational driving force output from the speed reducer 14 is applied to the manual valve 28 and the parking lock mechanism 30. Communicate to.

The detent plate 21 is fixed to the output shaft 15 and driven by the motor 10. In the present embodiment, the direction in which the detent plate 21 separates from the base of the detent spring 25 is the forward rotation direction, and the direction in which the detent plate 21 approaches the base is the reverse rotation direction.

The detent plate 21 is provided with a pin 24 that protrudes 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 the axial direction. That is, the shift range switching mechanism 20 converts the rotational motion of the motor 10 into a linear motion and transmits it to the manual valve 28. The manual valve 28 is provided on the valve body 29. When the manual valve 28 reciprocates in the axial direction, the hydraulic pressure supply path to the hydraulic clutch (not shown) is switched, and the engagement state of the hydraulic clutch is switched to change the shift range.

Two recesses 22 and 23 are provided on the detent spring 25 side of the detent plate 21. In the present embodiment, the side near the base of the detent spring 25 is the recess 22, and the side far from the base is the recess 23. In the present embodiment, the recess 22 corresponds to the NotP range other than the P range, and the recess 23 corresponds to the P range.

The detent spring 25 is a plate-shaped member that can be elastically deformed, and a detent roller 26 is provided at the tip thereof. The detent spring 25 urges the detent roller 26 toward the center of rotation of the detent plate 21. When a predetermined or greater rotational force is applied to the detent plate 21, the detent spring 25 is elastically deformed, and the detent roller 26 moves between the recesses 22 and 23. By fitting the detent roller 26 into any of the recesses 22 and 23, the swing of the detent plate 21 is restricted, the axial position of the manual valve 28 and the state of the parking lock mechanism 30 are determined, and automatic transmission is performed. The shift range of the machine 5 is fixed. The detent roller 26 fits into the recess 22 when the shift range is the NotP range, and fits into the recess 23 when the shift range is the P range.

The parking lock mechanism 30 includes a parking rod 31, a cone 32, a parking lock pole 33, a shaft portion 34, and a parking gear 35. The parking rod 31 is formed in a substantially L shape, and one end 311 side is fixed to the detent plate 21. A cone 32 is provided on the other end 312 side of the parking rod 31. The conical body 32 is formed so that the diameter is reduced toward the other end 312 side. When the detent plate 21 swings in the reverse rotation direction, the cone 32 moves in the P direction.

The parking lock pole 33 is in contact with the conical surface of the conical body 32 and is provided so as to be swingable around the shaft portion 34. On the parking gear 35 side of the parking lock pole 33, a convex portion capable of engaging with the parking gear 35 is provided. 331 is provided. When the detent plate 21 rotates in the reverse rotation direction and the conical body 32 moves in the P direction, the parking lock pole 33 is pushed up and the convex portion 331 and the parking gear 35 mesh with each other. On the other hand, when the detent plate 21 rotates in the forward rotation direction and the conical body 32 moves in the NotP direction, the meshing between the convex portion 331 and the parking gear 35 is released.

The parking gear 35 is provided on an axle (not shown) so as to be able to mesh with the convex portion 331 of the parking lock pole 33. When the parking gear 35 and the convex portion 331 mesh with each other, the rotation of the axle is restricted. When the shift range is the NotP range, the parking gear 35 is not locked by the parking lock pole 33, and the rotation of the axle is not hindered by the parking lock mechanism 30. Further, when the shift range is the P range, the parking gear 35 is locked by the parking lock pole 33, and the rotation of the axle is restricted.

As shown in FIGS. 2 and 3, the shift range control device 40 includes motor drivers 41 and 42 as drive circuits, an ECU 50, and the like. As shown in FIG. 3, the first motor driver 41 is a three-phase inverter that switches the energization of the first motor winding 11, and the switching elements 411 to 416 are bridge-connected. One end of the U1 coil 111 is connected to the connection point of the paired U-phase switching elements 411 and 414. One end of the V1 coil 112 is connected to the connection point of the paired V-phase switching elements 412 and 415. One end of the W1 coil 113 is connected to the connection point of the paired W-phase switching elements 413 and 416. The other ends of the coils 111 to 113 are connected by the connection portion 115.

The second motor driver 42 is a three-phase inverter that switches the energization of the second motor winding 12, and the switching elements 421 to 426 are bridge-connected. One end of the U2 coil 121 is connected to the connection point of the paired U-phase switching elements 421 and 424. One end of the V2 coil 122 is connected to the connection point of the paired V-phase switching elements 422 and 425. One end of the W2 coil 123 is connected to the connection point of the paired W-phase switching elements 423 and 426. The other ends of the coils 121 to 123 are connected by the connection portion 125. The switching elements 411 to 416 and 421 to 426 of the present embodiment are MOSFETs, but other elements such as IGBTs may be used.

As shown in FIGS. 2 and 3, a motor relay 46 is provided between the motor driver 41 and the battery 45. A motor relay 47 is provided between the motor driver 42 and the battery 45. The motor relays 46 and 47 are turned on when a start switch such as an ignition switch is turned on, and electric power is supplied to the motor 10 side. Further, when the motor relays 46 and 47 are turned on, electric power is supplied from the battery 45 to the motor 10 side, and when the motor relays 46 and 47 are turned off, the electric power from the battery 45 to the motor 10 side is cut off. A voltage sensor 48 for detecting the battery voltage is provided on the high potential side of the battery 45.

As shown in FIG. 2, the ECU 50 is mainly composed of a microcomputer or the like, and internally includes a CPU, ROM, RAM, I / O, and a bus line connecting these configurations, which are not shown. .. Each process in the ECU 50 may be a software process by executing a program stored in advance in a substantive memory device such as a ROM (that is, a readable non-temporary tangible recording medium) on the CPU, or a dedicated process. It may be hardware processing by an electronic circuit.

The ECU 50 controls the on / off operation of the switching elements 411 to 416, and causes the motor 10 to match the driver-required shift range input by operating a shift lever or the like (not shown) with the shift range in the shift range switching mechanism 20. Control the drive. Further, the ECU 50 controls the drive of the hydraulic pressure control solenoid 6 for shifting based on the vehicle speed, the accelerator opening degree, the driver required shift range, and the like. The shift stage is controlled by controlling the shift hydraulic control solenoid 6. The number of shifting hydraulic control solenoids 6 is provided according to the number of shifting stages and the like. In the present embodiment, one ECU 50 controls the drive of the motor 10 and the solenoid 6, but the motor ECU for controlling the motor 10 and the AT-ECU for solenoid control may be separated. Hereinafter, the drive control of the motor 10 will be mainly described.

The ECU 50 has an angle calculation unit 51, a drive control unit 53, a duty limiting unit 55, and the like. The angle calculation unit 51 counts the pulse edges of each phase of the encoder signal output from the encoder 13, and calculates the encoder count value θen. The encoder count value θen is a value corresponding to the rotation position of the motor 10 and corresponds to the “motor angle”.

The drive control unit 53 controls the drive of the motor 10 so that the encoder count value θen becomes the target count value θcmd set according to the target shift range. In the present embodiment, the motor 10 is rotated by switching the energized phase based on the encoder count value θen. For example, if the energized phase is the UV phase, the switching elements 411 and 421, which are the upper arm elements of the U phase, are turned on, and the switching elements 415 and 425, which are the lower arm elements of the V phase, are turned on and off at the set duty D. Duty D is the ratio of the on-time in one cycle, and in the present embodiment, the acceleration time is defined as positive and the deceleration time is defined as negative. The duty limiting unit 55 sets a duty limit value Dlim that limits the duty D.

Here, the relationship between the motor rotation speed, the torque, and the motor current is shown in FIG. In FIG. 4, the horizontal axis represents torque, and the vertical axis represents motor rotation speed and motor current. As shown in FIG. 4, when a large torque is output in a state where the motor rotation speed is small, the motor current becomes large. Further, if the motor current Im exceeds the upper limit value Ilim, the motor drivers 41 and 42 may fail.

As a reference example, if the duty in the acceleration range at the initial stage of motor drive is set to 100% in order to improve the responsiveness so that the range switching time is shortened, the motor current Im exceeds the upper limit value Illim at low speed of the motor, and the motor driver 41. There is a risk of destroying 42. As a measure to avoid this, a current limiting circuit can be provided, but a separate component for realizing the function is required, which increases the number of components and the mounting area on the board. Further, when the current limiting function is added by software, high-spec calculation performance such as AD conversion at a predetermined timing of the on-time of the switching element is required. In addition, if the current limiting circuit or software limits the current, the maximum torque decreases and the responsiveness decreases.

Therefore, in the present embodiment, by varying the duty limit value Dlim according to the encoder count value θen, overcurrent can be prevented without changing the circuit, without sacrificing responsiveness, and the motor drivers 41 and 42. To protect.

The duty limit value calculation process of this embodiment will be described with reference to the flowchart of FIG. This process is executed by the duty limiting unit 55 at a predetermined cycle during range switching. Hereinafter, the “step” in step S101 is omitted and simply referred to as the symbol “S”. The same is true for the other steps.

Prior to the description of the duty limit value calculation process, the drive count θA and the remaining count θB will be described. When the target shift range is switched, the encoder count value θen_init at the start of driving, which is the encoder count value before starting driving of the motor 10, is held in a storage unit (not shown). Let the absolute value of the difference between the current encoder count value θen and the encoder count value θen_init at the start of driving be the drive count θA (see equation (1)).

θA = | θen-θen_init | ... (1)

Further, when the target shift range is switched, the target count value θcmd corresponding to the target shift range is set. The absolute value of the difference between the target count value θcmd and the current encoder count value θen is defined as the remaining count θB (see equation (2)).

θB = | θcmd-θen | ... (2)

In S101 in FIG. 5, the duty limiting unit 55 determines whether or not the drive count θA is smaller than 1. When it is determined that the drive count θA is smaller than 1, the process proceeds to S102, and the duty limit value Dlim is set to 50%. When it is determined that the drive count θA is 1 or more (S101: NO), the process proceeds to S103.

In S103, the duty limiting unit 55 determines whether or not the drive count θA is smaller than 2. When it is determined that the drive count θA is smaller than 2, the process proceeds to S104, and the duty limit value Dlim is set to 60%. When it is determined that the drive count θA is 2 or more (S103: NO), the process proceeds to S105.

In S105, the duty limiting unit 55 determines whether or not the drive count θA is smaller than 3. When it is determined that the drive count θA is smaller than 3, the process proceeds to S106, and the duty limit value Dlim is set to 70%. When it is determined that the drive count θA is 3 or more (S105: NO), the process proceeds to S107.

In S107, the duty limiting unit 55 determines whether or not the drive count θA is smaller than 4. When it is determined that the drive count θA is smaller than 4, the process proceeds to S108, and the duty limit value Dlim is set to 80%. When it is determined that the drive count θA is 4 or more (S107: NO), the process proceeds to S109.

In S109, the duty limiting unit 55 determines whether or not the drive count θA is smaller than 5. When it is determined that the drive count θA is smaller than 5, the process proceeds to S110 and the duty limit value Dlim is set to 90%. When it is determined that the drive count θA is 5 or more (S109: NO), the process proceeds to S111.

In S111, the duty limiting unit 55 determines whether or not the remaining count θB is smaller than 2. When it is determined that the remaining count θB is smaller than 2, the process proceeds to S112, and the duty limit value Dlim is set to 50%. When it is determined that the remaining count θB is 2 or more (S111: NO), the process proceeds to S113.

In S113, the duty limiting unit 55 determines whether or not the remaining count θB is smaller than 3. When it is determined that the remaining count θB is smaller than 3, the process proceeds to S114, and the duty limit value Dlim is set to 60%. When it is determined that the remaining count θB is 3 or more (S113: NO), the process proceeds to S115.

In S115, the duty limiting unit 55 determines whether or not the remaining count θB is smaller than 4. When it is determined that the remaining count θB is smaller than 4, the process proceeds to S116, and the duty limit value Dlim is set to 70%. When it is determined that the remaining count θB is 4 or more (S115: NO), the process proceeds to S117.

In S117, the duty limiting unit 55 determines whether or not the remaining count θB is smaller than 5. When it is determined that the remaining count θB is smaller than 5, the process proceeds to S118, and the duty limit value Dlim is set to 80%. When it is determined that the remaining count θB is 4 or more (S117: NO), that is, when the drive count θA is 5 or more and the remaining count θB is 5 or more, the duty is not limited and this processing is performed. finish.

In FIG. 5, the duty limit value Dlim at the initial stage of driving is set to 50%, and the duty limit value Dlim is increased by 10% each time the encoder count value θen changes by 1 count. The restriction has been lifted. Further, the duty limit value Dlim is set to 80% when the remaining 4 counts are reached up to the target count value θcmd, and the duty limit value Dlim is reduced by 10% each time the encoder count value θen changes by 1 count to reach the target count value θcmd. The duty limit value Dlim in the remaining 1 count is set to 50%. The duty limit value Dlim and the count width for switching the duty limit value Dlim shown in FIG. 5 are examples and can be set arbitrarily.

The drive control process of this embodiment is shown in the time chart of FIG. In FIG. 6, the horizontal axis is a common time axis, and the shift range switching request, the angle, the duty, the rotation speed, and the motor current are shown from the upper stage. As for the angles, the encoder count value θen is shown by a solid line, and the target count value θcmd is shown by a alternate long and short dash line. Further, the encoder count value corresponding to the P range is described as (P), and the angle corresponding to the notP range is described as (notP). Further, in the present embodiment, the actual duty D is indicated by a solid line, the duty limit value Dlim is indicated by a two-dot chain line, and acceleration is defined as positive and deceleration is defined as negative. That is, even if the positive and negative values are different, if the absolute values are the same, the ratio of the on-time in a predetermined period is the same, and the duty limit value Dlim is set to both positive and negative values having the same absolute value. Here, a case of switching from the P range to the notP range will be described as an example. The same applies to FIGS. 7, 9 and 10.

As shown in FIG. 6, when the required shift range is switched from the P range to the notP range at time t10, the switching request is turned on. Further, the control mode is switched from the standby mode to the feedback mode, and the target count value θcmd is set. In the present embodiment, the acceleration region is from time t10 to time t12, the constant speed region is from time t12 to time t13, and the deceleration region is from time t13 to time t15. Further, at time t15, when the encoder count value θen falls within a predetermined range including the target count value θcmd (for example, ± 2 counts), the feedback mode is switched to the stop mode. In the stop control, the fixed phase energization is performed with a predetermined duty, and the motor 10 is surely stopped. The stop control is not limited to the fixed phase energization, and may be any control. After performing stop control for a predetermined time, the standby mode is switched to at time t16.

Here, as in the reference example shown in FIG. 7, when the motor 10 is driven at a duty of 100% without performing duty limitation during low-speed rotation immediately after the start of driving, for example, when the motor 10 is driven, the period from time tx1 to time tx2, the upper limit value. A motor current Im exceeding Illim flows. Further, even during deceleration, if the motor 10 is driven with a duty of -100% without limiting the duty, a current exceeding the upper limit Illim flows during the period from the time ty1 to the time ty2.

When switching the shift range, the motor 10 is started to be driven in response to the switching request, and the motor 10 is stopped at the target count value θcmd according to the target shift range. Therefore, when the drive count θA and the remaining count θB are small, the motor 10 is rotating at a low speed and the motor current Im may increase. Therefore, the duty limit value Dlim is set small. Thereby, the motor drivers 41 and 42 can be protected. On the other hand, when the drive count θA and the remaining count θB are large, the motor 10 is rotating at a high speed of a certain level or more and the motor current Im is small, so that the duty is not limited. As a result, it is possible to secure responsiveness without suppressing torque.

Specifically, as shown in FIG. 6, at time t10, the drive count θA = 0, so the duty limit value Dlim is set to 50%. Further, since the rotation speed of the motor 10 increases as the drive count θA increases by one count, the duty limit value Dlim is gradually increased to 60%, 70%, 80%, and 90%. When the drive count θA becomes 5 or more at time t11, the duty limit value Dlim is set to 100% and the duty limit is released. Further, the duty limit is not limited until the remaining count θB becomes 5.

When the remaining count θB reaches 4 at time t14, the duty limit value Dlim is set to 80%. Further, since the rotation speed of the motor 10 decreases each time the remaining count θB decreases by one count, the duty limit value Dlim is reduced to 70%, 60%, and 50%. As a result, the motor current Im from the start to the completion of the shift range switching can be suppressed to less than the upper limit value Illim.

As described above, the shift range control device 40 of the present embodiment controls the switching of the shift range by controlling the drive of the motor 10 having the motor windings 11 and 12, and the motor driver 41. 42 and ECU 50 are provided. The motor drivers 41 and 42 include switching elements 411 to 416 and 421 to 426 that switch the energization of the motor windings 11 and 12.

The ECU 50 has a motor angle calculation unit 51, a drive control unit 53, and a duty limiting unit 55. The motor angle calculation unit 51 calculates the encoder count value θen based on the encoder signal acquired from the encoder 13 that detects the rotational position of the motor 10. The drive control unit 53 controls the drive of the motor 10 so that the encoder count value θen becomes the target count value θcmd according to the target shift range. The duty limiting unit 55 determines a duty limit value Dlim that limits the duty D, which is the ratio of the on-time of the switching elements 411 to 416 and 421 to 426 in a predetermined period, according to the encoder count value θen.

In the present embodiment, the duty limit value Dlim is made variable based on the encoder count value θen, which is easily monitorable information, so that overcurrent is suppressed without changing the circuit, and the motor drivers 41 and 42. Can be protected and range switching responsiveness can be ensured.

The duty limit unit 55 increases the duty limit value Dlim as the drive count θA, which is the difference between the encoder count value θen_init at the start of driving of the motor 10 and the current encoder count value θen, increases during motor acceleration. In addition, the duty limit value Dlim is determined. This makes it possible to prevent overcurrent during low-speed rotation when the motor is started.

The duty limit unit 55 determines the duty limit value Dlim so that the smaller the remaining count θBg, which is the difference between the target count value θcmd and the current encoder count value θen, the smaller the duty limit value Dlim during motor deceleration. do. This makes it possible to prevent overcurrent during low-speed rotation before the motor is stopped.

In this embodiment, the motor drivers 41 and 42 correspond to the "drive circuit", the ECU 50 corresponds to the "control unit", and the encoder 13 corresponds to the "rotation angle sensor". Further, the encoder count value θen corresponds to the “motor angle” and the target count value θcmd corresponds to the “target rotation angle”.

(Second Embodiment)
The second embodiment is shown in FIGS. 8 to 10. In the present embodiment, the overcurrent due to the lock current is prevented by the duty limit according to the encoder count value θen. The duty limit value calculation process of this embodiment will be described with reference to the flowchart of FIG. This processing is executed in a predetermined cycle during the period from the switching of the target shift range to the start of the stop control, and can be executed in parallel with the duty limit value calculation processing described with reference to FIG. be.

In S201, the duty limiting unit 55 determines whether or not the encoder count value θen has changed. When it is determined that the encoder count value θen has changed (S201: YES), the process proceeds to S202, the continuous count value Ct is cleared, and this routine is terminated. When it is determined that the encoder count value θen has not changed (S201: NO), the process proceeds to S203. In S203, the duty limiting unit 55 increments the continuous count value Ct that measures the time when the encoder count value θen is not switched.

In S204, the duty limiting unit 55 calculates the estimated rotation speed Ne. The estimated rotation speed Ne is a value when the motor 10 is rotating normally, and is calculated by map calculation or the like based on the drive count θA.

In S205, the continuation determination time T_th is set based on the estimated rotation speed Ne. The continuation determination time T_th is set to a value equal to or greater than the same energized phase continuation time Te, which is the time during which the same energized phase is continued when the motor 10 is rotating at the estimated rotation speed Ne. Further, the count value corresponding to the continuation determination time T_th is defined as the determination count value Ct_th.

In S206, it is determined whether or not the continuous count value Ct is equal to or greater than the determination count value Ct_th. When it is determined that the continuous count value Ct is less than the determination count value Ct_th (S206: NO), the process of S207 is not performed and this routine is terminated. When it is determined that the continuous count value Ct is equal to or greater than the determination count value Ct_th (S206: YES), the process proceeds to S207, and the duty limit value Dlim is set to 50%. The duty limit value Dlim set here is an arbitrary value in which the motor current Im does not exceed the upper limit value Ilim when the lock is energized and the energized phase can be switched when the lock is energized.

Here, the drive control process according to the reference example is shown in FIG. The processing from the time t10 to the time t11 is the same as that of the first embodiment, and the duty limit is released at the time t11, and thereafter, the duty limit value Dlim = 100%. Under normal conditions, if the energized phases are switched in sequence, the current will decrease (see FIG. 6). On the other hand, if an abnormality occurs in which the motor 10 stops at the time tz1 which is the timing before the time t12 which becomes the constant speed range in the normal state, when the lock energization is applied to the same energizing phase, the motor current larger than the upper limit value Illim Im may flow. If the motor current Im, whose duty is not limited, continues to flow, there is a risk that the circuit failure of the motor drivers 41 and 42 will occur until the abnormality is confirmed.

Therefore, in the present embodiment, as shown in FIG. 9, the estimated rotation speed Ne is calculated based on the drive count θA. Then, the same energized phase duration time Te when the motor 10 is rotating at the estimated rotation speed Ne is calculated (S204 in FIG. 8), and the continuation determination time T_th is set (S205). For example, when the estimated rotation speed Ne is 4000 [rpm] and the calculation is such that the energized phase is switched at 0.625 [ms], the continuation determination time T_th is set to 1 [ms]. Then, the duty limit value Dlim is set to 50% at the time tz2 when the continuation determination time T_th has elapsed from the time tz1 when the abnormality in which the motor 10 is stopped occurs (S207). Further, at the time tz3 when a predetermined time has elapsed from the occurrence of the abnormality, the abnormality is confirmed and the mode shifts to the fail mode.

As a result, even if an abnormality occurs in which the motor 10 is stopped, the motor current Im exceeding the upper limit value Illim does not flow before the abnormality is confirmed, so that it is possible to prevent circuit failures of the motor drivers 41 and 42. ..

In the present embodiment, the duty limiting unit 55 makes the duty limiting value Dlim smaller than the normal time when the state in which the encoder count value θen does not change continues over the continuation determination time T_th during the drive control of the motor 10. .. As a result, the overcurrent when a failure occurs in which the motor 10 is stopped is suppressed, and the motor drivers 41 and 42 can be protected.

The continuation determination time T_th is set according to the estimated rotation speed Ne estimated based on the drive count θA, which is the difference between the encoder count value θen_init at the start of motor drive and the current encoder count value θen. As a result, the duty can be appropriately limited when a failure occurs in which the motor 10 is stopped. Moreover, the same effect as that of the above-described embodiment is obtained.

(Other embodiments)
In the first embodiment, the duty is limited according to the drive count θA and the remaining count θB. In another embodiment, for example, in the deceleration region, if the motor current does not exceed the upper limit value without performing the duty limit, the duty limit at the time of motor deceleration according to the remaining count θB may be omitted. Further, in the above embodiment, (1) the duty limit during acceleration, (2) the duty limit during deceleration, and (3) the duty limit when a failure occurs in which the motor stops are described. In other embodiments, some of the above (1) to (3) may be omitted. In the second embodiment, the continuation determination time is variable according to the drive count. In another embodiment, the continuation determination time may be fixed regardless of the drive count.

In the above embodiment, two sets of motor windings and motor drivers are provided. In another embodiment, the motor winding and the motor driver may be one set or three or more sets.

In the above embodiment, the motor rotation angle sensor that detects the rotation angle of the motor is a three-phase encoder. In another embodiment, the motor rotation angle sensor may be a two-phase encoder, and not limited to the encoder, any resolver or the like may be used. In the above embodiment, a potentiometer is exemplified as an output shaft sensor. In other embodiments, the output shaft sensor may be any. Further, the output shaft sensor may be omitted.

In the above embodiment, the detent plate is provided with two recesses. In other embodiments, the number of recesses is not limited to two, and for example, recesses may be provided for each range. Further, the shift range switching mechanism, the parking lock mechanism, and the like may be different from those in the above embodiment.

In the above embodiment, a speed reducer is provided between the motor shaft and the output shaft. Although the details of the speed reducer are not mentioned in the above embodiment, for example, cycloid gears, planetary gears, spur gears that transmit torque from a speed reduction mechanism substantially coaxial with the motor shaft to the drive shaft, and these Any configuration may be used, such as a combination of the above. Further, in another embodiment, the speed reducer between the motor shaft and the output shaft may be omitted, or a mechanism other than the speed reducer may be provided. As described above, the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the invention.

10 ... Motor 11, 12 ... Motor winding 13 ... Encoder (motor rotation angle sensor)
40 ... Shift range control device 41, 42 ... Motor driver (drive circuit)
411 to 416, 421 to 426 ... Switching element 50 ... ECU (control unit)
51 ... Angle calculation unit 53 ... Drive control unit 55 ... Duty limit unit

Claims (5)

A shift range control device that controls switching of a shift range by controlling the drive of a motor (10) having motor windings (11, 12).
A drive circuit (41, 42) having a switching element (411 to 416, 421 to 426) for switching the energization of the motor winding, and a drive circuit (41, 42).
The motor angle calculation unit (51) that calculates the motor angle based on the signal acquired from the rotation angle sensor (13) that detects the rotation position of the motor, and the motor angle becomes the target rotation angle according to the target shift range. As described above, the drive control unit (53) that controls the drive of the motor and the duty limit value that limits the duty, which is the ratio of the on-time of the switching element in a predetermined period, are determined according to the motor angle. A control unit (50) having a limiting unit (55) and
A shift range control device. The duty limiting unit determines the duty limiting value so that the duty limiting value increases as the difference between the motor angle at the start of driving of the motor and the current motor angle increases during motor acceleration. The shift range control device according to claim 1. The duty limiting unit determines the duty limiting value in claim 1 or 2 so that the duty limiting value becomes smaller as the difference between the target rotation angle and the current motor angle becomes smaller during motor deceleration. The shift range controller described. The shift according to claim 1, wherein the duty limiting unit makes the duty limiting value smaller than the normal time when the state in which the motor angle does not change continues for the continuation determination time during the drive control of the motor. Range control device. The shift range control device according to claim 4, wherein the continuation determination time is set according to an estimated rotation speed estimated based on the difference between the motor angle at the start of driving of the motor and the current motor angle. ..

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