Shift range control device

A shift range control device includes a drive circuit, a voltage detector, and a controller. The drive circuit includes switching elements, and is shared by a plurality of winding sets. The voltage detector detects terminal voltages of respective phases. The controller controls energization of the winding sets by controlling on and off operations of the switching elements, and controls interruption units each capable of switching between conduction and interruption of power from a power supply to a corresponding winding set. The controller performs disconnection diagnosis based on the terminal voltage during energization of the winding sets in a control state where one of the interruption units is controlled to conduct the power and a remaining interruption unit is controlled to interrupt the power.

TECHNICAL FIELD

The present disclosure relates to a shift range control device.

BACKGROUND

A shift range switching device switches a shift range by driving an actuator such as a motor. The shift range switching device, for example, includes two winding units, and two drive circuits provided correspondingly to the two winding units.

SUMMARY

The present disclosure describes a shift range control device configured to control driving of an actuator including a plurality of winding sets for controlling a shift range switching system. The shift range control device includes a drive circuit, a voltage detector, and a controller. The drive circuit includes a plurality of switching elements, and is shared by the plurality of winding sets. The voltage detector detects terminal voltages of respective phases. The controller controls energization of the winding sets by controlling on and off operations of the switching elements, and controls interruption units, each of which is capable of switching between conduction and interruption of power from a power supply to a corresponding one of the winding sets. The controller further performs a disconnection diagnosis based on the terminal voltages that occur during energization of the winding sets in a control state where one of the interruption units is controlled to conduct the power and a remaining interruption unit is controlled to interrupt the power.

DESCRIPTION OF EMBODIMENTS

A shift range switching device, which switches a shift range by driving an actuator such as a motor, may include two winding units, and two drive circuits provided correspondingly to the two winding units. In a case where the drive circuit is provided for each winding unit, an abnormality such as a disconnection is detectable based on a detection signal generated from a current detection circuit provided in each energization path from the drive circuit to a corresponding phase of the winding unit. However, it is conceivable to share one drive circuit by a plurality of winding sets for simplification of a configuration.

The present disclosure provides a shift range control device capable of appropriately detecting a disconnection abnormality.

According to an aspect of the present disclosure, a shift range control device is configured to control driving of an actuator including a plurality of winding sets for controlling a shift range switching system. The shift range control device includes a drive circuit, a voltage detector, and a controller. The drive circuit includes a plurality of switching elements, and is shared by the plurality of winding sets. The voltage detector detects terminal voltages of respective phases. The controller includes an energization control section, an interruption unit control section, and an abnormality monitoring section. The energization control section controls energization of the winding sets by controlling on and off operations of the switching elements. The interruption unit control section controls interruption units, each of which is capable of switching between conduction and interruption of power from a power supply to a corresponding one of the winding sets. The abnormality monitoring section monitors an abnormality of the shift range switching system.

The abnormality monitoring section performs a disconnection diagnosis based on the terminal voltages that occur during energization of the winding sets in a control state where one of the interruption units is controlled to conduct the power and a remaining interruption unit is controlled to interrupt the power.

In such a configuration, a disconnection abnormality can be appropriately detected even when the drive circuit is shared by the winding sets of the plurality of systems for simplification of the configuration.

Embodiment

A shift range control device will be hereinafter described with reference to the drawings.FIGS. 1 to 13each show a shift range control device according to one embodiment. As shown inFIGS. 1 to 3, a shift-by-wire system1functioning as a shift range switching system includes a motor10functioning as an actuator, a shift range switching mechanism20, a parking lock mechanism30, a shift range control device40, and others.

The motor10rotates when receiving electric power from a battery90, which is mounted on a vehicle (not shown) as a power supply, and serves as a drive source of the shift range switching mechanism20. The motor10is capable of changing current intensity by feedback control, and capable of changing a command for each phase. The motor10of the present embodiment is an SR (switched reluctance) motor. As shown inFIG. 3, the motor10includes two winding sets11and12. The first winding set11has a U-phase winding111, a V-phase winding112, and a W-phase winding113. The second winding set12has a U-phase winding121, a V-phase winding122, and a W-phase winding123.

As shown inFIG. 2, an encoder13functioning as a rotation angle sensor detects a rotational position of a rotor (not shown) of the motor10. For example, the encoder13is a magnetic rotary encoder, and includes a magnet which rotates with the rotor as one body, a Hall integrated circuit (IC) for detecting a magnetic field, and the like. The encoder13outputs pulse signals of A phase and B phase at predetermined angular intervals in synchronization with rotation of the rotor.

A speed reducer14is provided between a motor shaft of the motor10and an output shaft15to reduce a rotation speed of the motor10and output the rotation to the output shaft15. In this manner, the rotation of the motor10is transmitted to the shift range switching mechanism20. The output shaft15is provided with an output shaft sensor16for detecting an angle of the output shaft15. The output shaft sensor16of the present embodiment has four switches each turned on in a rotation angle range of corresponding one of P, R, N, and D ranges. The current range is detectable by determining which switch of the output shaft sensor16has been turned on. Accordingly, the output shaft sensor16is also considered as a transmission range sensor. The output shaft sensor16may be constituted by a potentiometer or the like instead of the switches corresponding to the respective ranges.

As shown inFIG. 1, the shift range switching mechanism20includes a detent plate21, a detent spring25, and the like. The shift range switching mechanism20transmits a rotational driving force output from the speed reducer14to a manual valve28and the parking lock mechanism30.

The detent plate21is fixed to the output shaft15and driven by the motor10. In the present embodiment, a direction in which the detent plate21moves away from a base portion of the detent spring25is defined as a positive rotation direction, and a direction in which the detent plate21moves toward the base portion is defined as a negative rotation direction. The detent plate21includes a pin24projecting in parallel with the output shaft15. The pin24is connected to the manual valve28. When the detent plate21is driven by the motor10, the manual valve28reciprocates in an axial direction. More specifically, the shift range switching mechanism20converts rotational movement of the motor10into linear movement, and transmits the linear movement to the manual valve28. The manual valve28is included in a valve body29. When the manual valve28reciprocates in the axial direction, a hydraulic pressure supply path to a hydraulic clutch (not shown) is switched to change an engagement state of the hydraulic clutch. In this manner, switching of the shift range is achieved.

Four recesses22each holding the manual valve28in a position corresponding to an associated range are formed in the detent plate21on the detent spring25side. The recesses22are formed corresponding to ranges of D, N, R, and P from the base portion side of the detent spring25, respectively.

The detent spring25is an elastically deformable plate-shaped member. A detent roller26is provided at a tip of the detent spring25. The detent roller26is fitted to one of the recesses22. The detent spring25urges the detent roller26toward the rotation center of the detent plate21. When a rotational force equal to or larger than a predetermined force is applied to the detent plate21, the detent spring25is elastically deformed. As a result, the detent roller26moves along the recesses22. When the detent roller26is fitted to any of the recesses22, swing of the detent plate21is regulated. Accordingly, the axial position of the manual valve28and the state of the parking lock mechanism30are determined to fix a shift range of an automatic transmission5.

The parking lock mechanism30includes a parking rod31, a cone32, a parking lock pole33, a shaft portion34, and a parking gear35. The parking rod31has a substantially L shape. One end311of the parking rod31is fixed to the detent plate21. The cone32is provided at an opposite end312of the parking rod31. The cone32has a diameter which decreases toward the opposite end312. When the detent plate21swings in the negative rotation direction, the cone32moves in a direction of an arrow P.

The parking lock pole33abuts a conical surface of the cone32and swings around the shaft portion34. The parking lock pole33includes a protrusion331engageable with the parking gear35and located at the parking lock pole33on the parking gear35side. When the cone32moves in the direction of the arrow P by rotation of the detent plate21in the negative rotation direction, the parking lock pole33is pushed up to achieve engagement between the protrusion331and the parking gear35. On the other hand, when the cone32moves in a direction of an arrow NotP by rotation of the detent plate21in the positive rotation direction, the engagement between the protrusion331and the parking gear35is released.

The parking gear35is provided on an axle (not shown) in such a manner as to be engageable with the protrusion331of the parking lock pole33. Rotations of the axle are regulated during engagement between the parking gear35and the protrusion331. At the time of a shift range other than P range, i.e., non-P range, the parking gear35is not locked by the parking lock pole33. In this condition, rotations of the axle are not regulated by the parking lock mechanism30. During the shift range of P range, the parking gear35is locked by the parking lock pole33. In this condition, rotations of the axle are regulated.

As shown inFIGS. 2 and 3, the shift range control device40includes a drive circuit41, a voltage detector43, a current detector45, a controller50, and the like. The drive circuit41has three switching elements411,412, and413. In the present embodiment, the switching elements411to413are metal-oxide silicon field-effect transmitters (MOSFETs). In place of the MOSFETs, the switching elements411to413may be provided by insulated gate bipolar transistors (IGBTs) or the like.

The U-phase switching element411is provided between a connecting portion421at which the U-phase windings111and121are connected, and the ground. The V-phase switching element412is provided between a connecting portion422at which the V-phase windings112and122are connected, and the ground. The W-phase switching element413is provided between a connecting portion423at which the W-phase windings113and123are connected, and the ground.

The windings111to113of the first winding set11are connected to each other at a wiring connection portion115. Power is supplied from the battery90to the wiring connection portion115via a first power supply line901. A first relay unit91is provided on the first power supply line901. Power is supplied to the wiring connection portion115while the first relay unit91is in an on state.

The windings121to123of the second winding set12are connected to each other at a wiring connection portion125. Power is supplied from the battery90to the wiring connection portion125via a second power supply line902. A second relay unit92is provided on the second power supply line902. Power is supplied to the wiring connection portion125while the second relay unit92is in an on state.

In the present embodiment, each of the relay units91and92corresponds to an “interruption unit”. In the following description, where appropriate, a group of the first power supply line901, the first relay unit91, and the first winding set11is referred to as a first system, and a group of the second power supply line902, the second relay unit92, and the second winding set12is referred to as a second system.

The voltage detector43includes a U-phase terminal voltage detection section431, a V-phase terminal voltage detection section432, and a W-phase terminal voltage detection section433. The U-phase terminal voltage detection section431is provided between the connecting portion421of the U-phase windings111and121and the U-phase switching element411. The V-phase terminal voltage detection section432is provided between the connecting portion422of the V-phase windings112and122and the V-phase switching element412. The W-phase terminal voltage detection section433is provided between the connecting portion423of the W-phase windings113and123and the W-phase switching element413. In the following description, a value detected by the U-phase terminal voltage detection section431is referred to as a U-phase terminal voltage Vu, a value detected by the V-phase terminal voltage detection section432is referred to as a V-phase terminal voltage Vv, and a value detected by the W-phase terminal voltage detection section433is referred to as a W-phase terminal voltage Vw.

The controller50includes an energization control section51, a relay control section52as an interruption unit control section, and an abnormality monitoring section53. The energization control section51controls energization of the winding sets11and12by controlling on and off operations of the switching elements411to413of the drive circuit41. In this manner, driving of the motor10is controlled. The relay control section52has a first relay control section521and a second relay control section522, and controls on and off operations of the relay units91and92. More specifically, on and off operations of the first relay unit91are controlled based on a signal from the first relay control section521, while on and off operations of the second relay unit92are controlled based on a signal from the second relay control section522. The abnormality monitoring section53detects an abnormality of the shift-by-wire system1.

Disconnection diagnosis performed by the abnormality monitoring section53will be described. In the present embodiment, the winding sets11and12are provided by two systems, while the drive circuit41is provided by one system. Accordingly, the winding sets11and12of a plurality of systems are connected to the drive circuit41of one system. In other words, the one drive circuit41is shared by the winding sets11and12of a plurality of systems. In this case, even if a phase in one of the systems is disconnected, power is supplied from the other system via the connecting portions421to423. Accordingly, a disconnection abnormality is difficult to detect in this state based on the terminal voltages Vu, Vv, and Vw.

In the present embodiment, therefore, a circuit configuration is provided in such a manner that the power supply lines901and902are connected to the wiring connection portions115and125of the winding sets11and12of the respective systems, and power is supplied to each of the systems by controlling the relay units91and92provided on the power supply lines901and902. In this case, a disconnection abnormality can be detected, as well as a disconnection portion can be specified. The disconnection abnormality herein is not limited to a disconnection of harness or winding itself, but includes an abnormality such as separation of a connector or the like which causes a conduction failure, for example.

A disconnection diagnosis method will be described with reference toFIGS. 4 to 7. InFIGS. 4 to 7, the switching elements411to413which are turned on are indicated by matte patterns, while current paths are indicated by one-dot chain arrows. InFIG. 5andFIG. 7, a portion where a disconnection has occurred is indicated by an “x” mark.FIGS. 4 and 5each explain a disconnection diagnosis by two-phase energization, whileFIGS. 6 and 7each explain a disconnection diagnosis by one-phase energization.

In the disconnection diagnosis by two-phase energization, initially, the first relay unit91is turned on, and the second relay unit92is turned off. In this state, energized phases are switched at a predetermined time interval as shown in an upper part ofFIG. 4. Subsequently, as shown in a lower part ofFIG. 4, the first relay unit91is turned off, and the second relay unit92is turned on. In this state, the energized phases are switched at a predetermined time interval. The predetermined time interval is set to a time interval sufficient for detecting a voltage after switching on and off of the switching elements411to413. In the example ofFIG. 4, the energized phases are switched in the order of the W and U phases, the U and V phases, and the V and W phases in a state where one of the relay units91and92is turned on. The order of the relay units91and92to be turned on, and the order of switching of the energized phases may be different orders. The same applies to the disconnection diagnosis by one-phase energization. The switching elements411to413are provided on the ground side. When the switching elements411to413are turned on, the terminal voltages Vu, Vv, and Vw are each substantially at the ground potential. In the present embodiment, each of states where the terminal voltages Vu, Vv, and Vw are equal to or lower than a voltage determination threshold Vth, which is a reference for determining the ground potential, is referred to as Lo, and each of states where the terminal voltages Vu, Vv, and Vw are higher than the voltage determination threshold Vth is referred to as Hi.

In the absence of disconnection abnormality, the U-phase terminal voltage Vu and the W-phase terminal voltage Vw are each Lo, while the V-phase terminal voltage Vv is Hi when the switching elements411and413are turned on. When the switching elements411and412are turned on, the U-phase terminal voltage Vu and the V-phase terminal voltage Vv are each Lo, and the W-phase terminal voltage Vw is Hi. When the switching elements412and413are turned on, the V-phase terminal voltage Vv and the W-phase terminal voltage Vw are each Lo, and the U-phase terminal voltage Vu is Hi.

As shown in an upper part ofFIG. 5, in the presence of a disconnection in the U phase on the first system side, when the first relay unit91is turned on and the V and W phases are energized, the U phase terminal voltage Vu is Lo. Thus, the terminal voltages Vu, Vv, and Vw of all the systems are Lo. As such, a disconnection abnormality can be detected. As shown in a lower part ofFIG. 5, when the second relay unit92is turned on and the V and W phases are energized, voltage is supplied from the second relay unit92side even in the presence of a disconnection in the U phase of the first system. In this case, the U-phase terminal voltage Vu is Hi. As such, an abnormality is difficult to detect. Namely, it is possible to determine that the first system has a disconnection abnormality, if all the terminal voltages Vu, Vv, and Vw are Lo when the energized phases are switched in a state where the first relay unit91is in the on state and the second relay unit92is in the off state. Likewise, it is possible to determine that the second system has a disconnection abnormality, if all the terminal voltages Vu, Vv, and Vw are Lo when the energized phases are switched in a state where the first relay unit91is in the off state and the second relay unit92is in the on state.

In the disconnection diagnosis by one-phase energization, as shown in an upper part ofFIG. 6, initially, the first relay unit91is turned on, and the second relay unit92is turned off. In this state, the energized phase is switched at a predetermined time interval. As shown in a lower part ofFIG. 6, the first relay unit91is turned off, and the second relay unit92is turned on. In this state, the energized phase is switched at a predetermined time interval. In the example ofFIG. 6, the energized phase is switched in the order of the U phase, the V phase, and the W phase.

In the absence of disconnection abnormality, when the switching element411is turned on, the U-phase terminal voltage Vu is Lo, and the V-phase terminal voltage Vv and W-phase terminal voltage Vw are each Hi. When the switching element412is turned on, the V-phase terminal voltage Vv is Lo, and the U-phase terminal voltage Vu and the W-phase terminal voltage Vw are each Hi. When the switching element413is turned on, the W-phase terminal voltage Vw is Lo, and the U-phase terminal voltage Vu and the V-phase terminal voltage Vv are each Hi.

As shown in an upper part ofFIG. 7, in the presence of a disconnection in the U phase on the first system side, when the first relay unit91is turned on and the V phase is energized, the U phase terminal voltage is Lo. Thus, an abnormality can be detected. As shown in a lower part ofFIG. 7, when the second relay unit92is turned on and the V phase is energized, voltage is supplied from the second relay unit92side even in the presence of a disconnection in the U phase of the first system. In this case, the U-phase terminal voltage Vu is Hi. Thus, an abnormality is difficult to detect.

Accordingly, in a state where one of the relay units91and92is in an on state, the terminal voltage of the disconnected phase of the system in which the relay unit is in the on state is Lo when the switching element is in an off state. In this case, therefore, the disconnection portion can be specified. Specifically, suppose that the first relay unit91is in the on state, the second relay unit92is in the off state, the switching element411is in the off state, and at least one of the switching elements412and413is in the on state. In this situation, when the U-phase terminal voltage Vu is at a voltage determination threshold Vth or lower, it is specified that a disconnection abnormality has occurred in the U phase on the first system side, that is, on a path from the wiring connection portion115to the connecting portion421.

Suppose that the first relay unit91is in the off state, the second relay unit92is in the on state, the switching element411is in the off state, and at least one of the switching elements412and413is in the on state. In this situation, when the U-phase terminal voltage Vu is at the voltage determination threshold Vth or lower, it is specified that a disconnection abnormality has occurred in the U phase on the second system side, that is, on a path from the wiring connection portion125to the connecting portion421. A disconnection abnormality can be similarly specified for the V phase and the W phase.

In the disconnection detection by the one-phase energization, disconnections of the V-phase and the W-phase can be detected when the U-phase is energized. Disconnections of the U-phase and the W-phase can be detected when the V-phase is energized. Disconnections of the U-phase and the V-phase can be detected when the W-phase is energized. Accordingly, in the disconnection detection when the first relay unit91is in the on state, energization of any two of the three phases is only required, and energization to the remaining one phase may be omitted. The same applies to disconnection detection when the second relay unit92is in the on state. The detection time can be reduced by performing the disconnection detection by the one-phase energization. On the other hand, an erroneous determination due to noise or the like can be reduced by performing the disconnection detection by the two-phase energization.

FIGS. 8 and 9each show the time to execute the disconnection diagnosis. As shown inFIG. 8, the disconnection diagnosis is not performed during a present trip from turning-on of an ignition switch (hereinafter referred to as “IG”) of a vehicle at a time x1to turning-off of the IG at a time x2. When the IG is turned off at the time x2, the disconnection diagnosis is performed in a period before a shutdown of the system. When a disconnection abnormality is detected, execution of a failsafe measure is allowed immediately after a time x3at which the next IG is turned on. Since the disconnection diagnosis is performed in the period where the IG is off, a rapid shift to a shift range switchable state is achievable in the next trip.

As shown inFIG. 9, the disconnection diagnosis is performed in an initial check before execution of the shift range switching when the IG is turned on at a time x5. When a disconnection abnormality is detected, execution of a failsafe measures is allowed in the present trip from a time x6after completion of the disconnection diagnosis. In the on-state of the IG, execution of the disconnection diagnosis is allowed at any timing while shift range switching is not performed. In the example described above, the IG is the start switch of the vehicle. Alternatively, the IG may be a power switch or the like in a hybrid vehicle, for example. The disconnection diagnosis performed after the IG is turned off, and the disconnection diagnosis performed in the on-state of the IG may be both performed.FIGS. 8 and 9each show a case where a disconnection abnormality is detected by way of example. In these figures, the failsafe measure is indicated as “FS”.

A disconnection diagnosis process performed after the IG is turned off will be described with reference to a flowchart ofFIG. 10. This process is a process executed when the IG is turned off. Step S101is hereinafter simply expressed as S101, using only a symbol “S” without “step”. The same applies to the other steps.

When the IG is turned off in S101, the disconnection diagnosis is performed in S102. In the disconnection diagnosis, one of the relay units91and92is turned on, and the energized phase(s) are switched in a mode of the two-phase energization or the one-phase energization. The abnormality monitoring section53acquires the terminal voltages Vu, Vv, and Vw to detect a disconnection abnormality and specify a disconnection portion.

In S103, the abnormality monitoring section53determines whether or not a disconnection abnormality has been detected. When it is determined that the disconnection abnormality has not been detected (S103: NO), the process proceeds to S104. When it is determined that the disconnection abnormality has been detected (S103: YES), the process proceeds to S105.

In S104, the abnormality monitoring section53resets a disconnection flag.

In S105, the abnormality monitoring section53sets the disconnection flag and stores abnormality information including the specified disconnection portion. The disconnection flag is a flag indicating that a disconnection abnormality has occurred. In the following description, the state where the flag is set is referred to as “1”, and the state where the flag is not set is referred to as “0” where appropriate. The presence or absence of the disconnection abnormality may be retained as information other than the flag. The disconnection flag and the abnormality information are stored in a storage unit such as a static random access memory (SRAM) (not shown), which retains stored items even in the off-state of the IG.

A process performed after the IG is turned on in a case of execution of the disconnection diagnosis process after turning off of the IG will be described with reference to a flowchart ofFIG. 11. When the IG is turned on in S151, the abnormality monitoring section53in S152determines whether or not the disconnection flag has been set. When it is determined that the disconnection flag has not been set (S152: NO), the process proceeds to S153. When it is determined that the disconnection flag has been set (S152: YES), the process proceeds to S154.

In S153, the controller50energizes the winding sets11and12to drive the motor10using the two systems.

In S154, the controller50performs a failsafe measure. In the present embodiment, the motor10is driven using the system where the disconnection abnormality has not occurred. In this case, the relay unit91or92of the system where the abnormality has occurred is turned off. In the present embodiment, the relay unit91or92of the system where the disconnection abnormality has occurred is turned off in view of safety. However, the motor10can be driven only by the normal system even when both the relay units91and92are turned on. Moreover, a warning lamp indicating the presence of the disconnection abnormality is lit to warn a user that the abnormality has occurred in the shift-by-wire system1. The method for warning the user is not limited to the lighting of the warning light, but may be any methods such as voice guidance.

The disconnection diagnosis process performed in the on-state of the IG will be described with reference to a flowchart ofFIG. 12. This processing may be executed at any timing while the IG is in the on state. In the present embodiment, a standby state is produced when a microcomputer is initialized after turning-on of the IG.

When the process proceeds from the standby state in S201to S202, the disconnection diagnosis is executed. In S203, the abnormality monitoring section53determines whether or not a disconnection abnormality has been detected. When it is determined that a disconnection abnormality has been detected (S203: YES), the process proceeds to S204. In this case, the abnormality monitoring section53specifies that the abnormality having occurred is a disconnection abnormality. In S205, the controller50performs a failsafe measure similar to that in S154inFIG. 11. When it is determined that the disconnection abnormality has not been detected (S203: NO), the process proceeds to S206.

In S206, the abnormality monitoring section53determines whether or not the current state is a shift range switching state where the shift range is being switched. When it is determined that the current state is not the shift range switching state (S206: NO), this routine ends. When it is determined that the current state is the shift range switching state (S206: YES), the process proceeds to S207.

In S207, the abnormality monitoring section53determines whether or not an encoder temporary abnormality flag has been set. In the figure, the encoder temporary abnormality flag is indicated as “FIgE”. When it is determined that the encoder temporary abnormality flag has been set (S207: YES), the process proceeds to S212. When it is determined that the encoder temporary abnormality flag has not been set (S207: NO), the process proceeds to S208.

In S208, the abnormality monitoring section53determines whether or not the actual range matches the target shift range. When it is determined that the actual range matches the target shift range (S208: YES), this routine ends based on completion of the shift range switching. When it is determined that the actual range does not match the target shift range (S208: NO), the process proceeds to S209.

In S209, the abnormality monitoring section53determines whether or not a count value of the encoder13is stagnant. It is determined herein that the encoder count value is stagnant when the encoder count value does not change for a stagnation determination time or longer. When it is determined that the encoder count value is not stagnant (S209: NO), this routine ends. When it is determined that the encoder count value is stagnant (S209: YES), the process proceeds to S210to set the encoder temporary abnormality flag. In S211, the controller50switches a drive mode of the motor10to an open control mode which does not use a detection value of the encoder13.

When it is determined that the encoder temporary abnormality flag has been set (S207: YES), the process proceeds to S212, where the abnormality monitoring section53determines whether or not a switching completion determination time Xd has elapsed since the shift to the open control mode. The switching completion determination time Xd is set to a time longer than a time required to switch the shift range when the motor10is driven by open driving. When it is determined that the switching completion determination time Xd has not elapsed (S212: NO), the open control is continued with an end of this routine. When it is determined that the switching completion determination time Xd has elapsed (S212: YES), the process proceeds to S213.

In S213, the abnormality monitoring section53determines whether or not the actual range matches the target shift range based on a detection value of the output shaft sensor16. When it is determined that the actual range matches the target shift range (S213: YES), the process proceeds to S214to confirm an encoder abnormality. When it is determined that the actual range does not match the target shift range (S213: NO), the process proceeds to S215to confirm a mechanical lock abnormality. In S216, the controller50performs a failsafe measure in accordance with the abnormal situation.

An abnormality determination process performed at the time of range switching will be described with reference to a time chart ofFIG. 13.FIG. 13shows, from the upper side, a motor control, a motor angle, a switch on-off signal of the output shaft sensor16, an abnormality determination state of the shift-by-wire system1, and disconnection detection.FIG. 13does not show the on-off signal of the output shaft sensor16in the normal condition.

When the target shift range switches from the P range to the D range at a time x10, a target rotation position θ* corresponding to the range is established. In this case, driving of the motor10is started by feedback control or the like based on a detection value of the encoder13. With the start of driving of the motor10, the motor angle approaches the target rotation position θ* in the normal condition. Moreover, a switch constituting the output shaft sensor16is switched on or off in accordance with rotation of the motor10.

When the value of the encoder13becomes stagnant at a time x11, the abnormality monitoring section53determines an encoder temporary abnormality at a time x12after an elapse of a stagnation determination time Xs since the start of the stagnation. When the encoder temporary abnormality is determined, the control of the motor10is switched to such a control which does not use a detection value of the encoder13, such as open drive control which switches the energized phase at a predetermined time interval.

When the motor10is controlled without using the detection value of the encoder13, it is recognized that the motor10is in a rotatable state based on a change of a signal from the output shaft sensor16as indicated by a solid line. When a switch of the output shaft sensor16corresponding to the D range is turned on by rotating the motor10under open driving, the motor10is brake-controlled in a period from a time x13to a time x14(e.g., 100 [ms]). Thereafter, the current state returns to the standby state. Furthermore, an encoder actual abnormality is confirmed at a time x15after an elapse of the switching completion determination time Xd since the shift to open driving.

On the other hand, when the signal from the output shaft sensor16does not change even under control of the motor10without using the detection value of the encoder13as indicated by a one-dot chain line, it is considered that the motor10is not rotating. In this case, the abnormality monitoring section53determines that not an abnormality of the encoder13but an abnormality prevents rotation of the motor10has occurred. InFIG. 13, a mechanical lock abnormality is confirmed at the time x15after an elapse of the switching completion determination time Xd since the shift to open driving on assumptions that the disconnection abnormality determination has been performed before the start of the shift range switching, and that no disconnection has occurred during range switching. When determination of an encoder temporary abnormality is made in the absence of the rotation of the motor10, the disconnection diagnosis described above may be performed to specify whether the disconnection abnormality is a mechanical lock abnormality. For example, when a negative determination is made in S213inFIG. 12, the disconnection diagnosis may be performed. Moreover, when the abnormality of the encoder13is temporary as indicated by a two-dot chain line, the encoder13may be returned to the normal condition.

As described above, the shift range control device40according to the present embodiment is configured to control driving of the motor10including the plurality of winding sets11and12, to thereby control the shift-by-wire system1, and includes the drive circuit41, the voltage detector43, and the controller50. The drive circuit41includes the switching elements411to413, and is shared by the plurality of winding sets11and12. The voltage detector43detects the terminal voltages Vu, Vv, and Vw of the respective phases.

The controller50includes the energization control section51, the relay control section52, and the abnormality monitoring section53. The energization control section51controls energization of the winding sets11and12by controlling on and off operations of the switching elements411to413. The relay control section52controls the relay units91and92each of which is capable of switching between conduction and interruption of power from the battery90to corresponding one of the winding sets11and12. The abnormality monitoring section53monitors an abnormality of the shift-by-wire system1. The abnormality monitoring section53performs disconnection diagnosis based on the terminal voltages Vu, Vv, and Vw that are generated during energization of the winding sets11and12in a control state where one of the relay units is controlled to conduct the power and the other of the relay units is controlled to interrupt the power. In this manner, a disconnection abnormality is appropriately detected even when the drive circuit41is shared by the winding sets11and12of the plurality of systems for simplification of the configuration.

One-side ends of the windings111to113of the first winding set11are connected to each other at the wiring connection portion115. One-side ends of the windings121to123of the second winding set12are connected to each other at the wiring connection portion125. The other ends of the windings111to113of the first winding set11are correspondingly connected to the windings121to123of the second winding set12in the corresponding phases at the connecting portions421to423. The relay units91and92are provided on the power supply lines901and902connecting the wiring connection portions115and125and the battery90. The switching elements411to413are provided between the connecting portions421to423and the ground. In this configuration, the winding sets are independently energized by turning on the respective relay units91and92one by one, and thus a disconnection abnormality can be appropriately detected.

The winding sets11and12have the windings111to113and121to123of three phases, respectively. When the switching elements411to413of one phase or two phases are turned on in the disconnection diagnosis, and the terminal voltage Vu, Vv, Vw of an energization off phase in which the switching element is in the off state is equal to or lower than the voltage determination threshold Vth, the abnormality monitoring section53determines that a disconnection abnormality has occurred in the energization off phase. For example, when the switching element411is in the off state and the U-phase terminal voltage Vu is lower than the voltage determination threshold Vth, it is specified that a disconnection abnormality has occurred in the U-phase of the first winding set11. In this manner, the disconnection portion can be appropriately specified.

The abnormality monitoring section53performs the disconnection diagnosis when the IG as the start switch of the vehicle is turned off. In this case, the shift range can be rapidly switched after the start, at the start of the next trip.

The abnormality monitoring section53performs the disconnection diagnosis when the shift range is not switched in the on-state of the IG. In this case, a shift to the failsafe action is rapidly achievable after detection of the abnormality.

In the presence of an abnormality that a detection value of the encoder13configured to detect the rotational position of the motor10is stagnant during the shift range switching, when the motor10can be driven without using the detection value of the encoder13, the abnormality monitoring section53determines an abnormality of the encoder13. When the motor10cannot be driven even under control for driving the motor10without using the detection value of the encoder13, it is determined whether the abnormality is a disconnection abnormality or a mechanical lock abnormality other than the disconnection abnormality based on a result of the disconnection diagnosis. In this manner, the type of abnormality can be appropriately specified.

Other Embodiments

In the embodiment described above, the actuator is provided by an SR motor. In another embodiment, the actuator may be any devices capable of driving members associated with shift range switching, such as a DC brushless motor. In the embodiment described above, the winding sets and the interruption units of two systems are provided. In another embodiment, the number of systems of the winding sets and the interruption units may be three or more. In the embodiment described above, the windings of three phases are Y-connected in each winding set. In another embodiment, the winding connection method of the windings may be any connection methods, such as Δ connection. Moreover, in the embodiment described above, each of the winding sets is constituted by the windings of three phases. However, each of the winding sets may be constituted by windings of four or more phases. The rotation angle sensor of the embodiment described above is provided by an encoder. In another embodiment, the rotation angle sensor may be of any types such as a resolver, rather than an encoder.

In the embodiment described above, the rotating member is a detent plate, while the engaging member is a detent roller. In another embodiment, the rotating member and the engaging member are not limited to the detent plate and the detent roller, respectively, but may be any other members such as members having different shapes, for example. In the embodiment described above, four recesses are formed in the detent plate. In another embodiment, the number of the recesses is not limited to four, but may be any number. For example, two recesses may be formed in the detent plate to allow switching between P range and non-P range. The shift range switching mechanism, the parking lock mechanism, and the like may be different from the corresponding mechanisms of the above embodiment.

In the embodiment described above, a speed reducer is provided between the motor shaft and the output shaft. While details of the speed reducer are not mentioned in the above embodiment, the speed reducer may have any configurations, such as a configuration including a cycloid gear, a planetary gear, a gear using a spur gear which transmits torque from a speed reduction mechanism substantially coaxial with the motor shaft to a drive shaft, and a combination of these gears. In a different embodiment, the speed reducer between the motor shaft and the output shaft may be eliminated, or a mechanism other than the speed reducer may be provided. The present disclosure is not limited to the embodiments described herein. The present disclosure may be practiced in various modes in the scope without departing from the gist of the disclosure.