Switching range switching system

Abstract

Switching range switching system, comprising: a motor (10) comprising a plurality of motor windings (11, 12) and generating a cogging torque by means of a permanent magnet; a plurality of control circuits (41, 42) which switch an excitation of the motor windings (11, 12); an output shaft (15) onto which a rotation of a motor shaft (105) is transmitted as a rotating shaft of the motor (10); a switching range switching mechanism (20) comprising a trough-providing element (21) having a plurality of troughs (221 to 224) and a plurality of combs (226 to 228) separating the troughs (221 to 224) from one another and rotating integrally with the output shaft (15), an engagement element (26) that fits into one of the troughs (221 to 224) according to a switching range, and a preloading element (25) that preloads the engagement element (26) in a direction for fitting into one of the troughs (221 to 224); and a control unit (50) comprising at least one calculation unit (51, 52) for performing a calculation with reference to a drive control of the motor (10), wherein a clearance is provided between the motor shaft (105) and the output shaft (15); the intervention element (26) falls into one of the recesses (221 to 224) through the play; the control circuits (41, 42), the motor windings (11, 12) and a plurality of connecting wires (71, 72) which connect the control circuits (41, 42) and the motor windings (11, 12) are defined as a plurality of motor control systems; the cogging torque transmitted to the output shaft (15) is defined as an output shaft cogging torque; an intermediate-range stop anomaly is defined such that the output shaft (15) stops when the output shaft detent torque and a load torque (TL) of the preload element (25) are balanced; if an anomaly occurs in the motor control systems during a climbing process in which the engagement element (26) moves from one of the recesses (221 to 224) to an adjacent one of the ridges, the switching range switching system prevents the occurrence of the intermediate range stop anomaly; If an anomaly occurs in one part of the engine control systems, a normal part of the engine control systems will continue to provide control of the engine (10); when an anomaly occurs in part of the engine control systems, a range switching execution determination is performed and allowing or preventing a range switching operation is selected; the control unit (50) checks a current switching range as the range switching execution determination; the control unit (50) allows the range switching operation when the current switching range is a range other than a P-range; and The control unit (50) prevents the range switching process if the current switching range corresponds to the P range.

Description

Cross-reference to related application

[0001] This application is based on Japanese Patent Application No. 2017-222865 filed on November 20, 2017, the disclosure of which is incorporated herein by reference. Technical area

[0002] The present disclosure relates to a shift range switching system. General state of the art

[0003] Conventionally, a shifting device is known that switches a shift range by controlling a motor in response to a shift range switching request from a driver. For example, in JP 2016-75364 A, the position of a body bottom is learned using a predetermined amount of clearance provided between two idler gears.

[0004] Furthermore, DE 11 2017 002 201 B4 discloses a shift range control device that switches a shift range by controlling a drive of a motor, the shift range control device comprising: an idling determination device configured to determine whether a rotation state of the motor corresponds to an idling state in which the motor rotates within a range of play existing between a motor shaft corresponding to a rotation shaft of the motor and an output shaft to which rotation of the motor is transmitted; and a current limiter configured to limit a current of the motor when it is determined that the rotation state of the motor corresponds to the idling state.

[0005] Furthermore, JP 2016-94949 A discloses that, when a supply voltage detected by a voltage sensor is less than a prescribed voltage value, a motor is determined to be in a torque-free state by reducing the current caused by the supply voltage drop, and switching of a switching range is prohibited. When the supply voltage detected by the voltage sensor is equal to or greater than the prescribed voltage value and a motor current detected by a current sensor is less than a prescribed current value, the motor is determined to be in a torque-free state by the current drop caused by a coil temperature increase, and a switching limit is applied to temporarily prevent switching of the switching range.If the number of shifts by a driver reaches a prescribed number of times during the shift restriction, the shift range switching is permitted only at that time, and thereafter the shift range switching is prohibited again. Summary of the invention

[0006] In JP 2016-75364 A, a biasing force of a detent spring corresponds to a force acting so that a roller or roll portion falls into a groove or recess. In the range switching system, when the range is switched, a state in which a spring load acts in one direction to assist engine torque and a state in which the spring load acts in one direction to inhibit engine torque repeatedly occur as the roller portion moves along the grooves and recesses.

[0007] When a motor in which cogging torque is generated is used as the drive source, a torque balance point is created where the load torque caused by the spring force and the torque caused by cogging torque, motor friction, and the like are balanced. In this example, a new problem was discovered that when a motor-off malfunction occurs during shift range switching, in which the motor cannot be driven, the torque is balanced depending on the motor position at the time the motor-off malfunction occurs, and an output shaft stops in an intermediate range. If the output shaft stops in the intermediate range, proper hydraulic pressure cannot be generated in an automatic transmission, which may lead to a malfunction of the automatic transmission.

[0008] An object of the present invention is to provide a shift range switching system capable of continuing to drive a motor even when an abnormality occurs in a part of a motor drive system.

[0009] The above object is achieved by the subject matter of claim 1. Advantageous developments of the invention are the subject matter of the subsequent dependent claims.

[0010] The shift range switching system according to an illustrative aspect of the present disclosure includes a motor, a drive circuit, an output shaft, a shift range switching mechanism, and a control unit. The motor has motor windings, and cogging torque is generated by permanent magnets. The drive circuit switches the excitation of the motor windings. The rotation of a motor shaft, which corresponds to a rotating shaft of the motor, is transmitted to the output shaft. The shift range switching mechanism includes a well-providing member, an engaging member, and a biasing member. The well-providing member is formed with a plurality of recesses and a plurality of ridges separating the recesses and rotates integrally with the output shaft. The engaging member fits into the well corresponding to a shift range. The biasing member biases the engaging member in a direction to fit into the well.The control unit comprises a calculation unit which performs a calculation with respect to a drive control of the motor.

[0011] A clearance is provided between the motor shaft and the output shaft, and the engagement element can be dropped into the trough using the clearance. The drive circuit, the motor winding, the connecting wiring connecting the drive circuit and the motor winding, and the calculation unit are used as a motor drive system. The plurality of motor drive systems are provided to prevent the occurrence of an intermediate stop abnormality in which the output shaft stops due to the balance of an output shaft cogging torque corresponding to a cogging torque transmitted to the output shaft and a torque including a load torque of a biasing element when an abnormality occurs in a motor drive system during ascent in which an engagement element moves from a trough to a crest.

[0012] Consequently, even if an abnormality occurs in a part of the engine driving systems during a rise of the engagement element, the driving of the engine can be continued, and the inter-range stop abnormality is avoided, so that a malfunction of the automatic transmission can be prevented. Short description of the figures

[0013] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: Fig. 1 is a perspective view showing a shift-by-wire system according to a first embodiment; Fig. 2 is a schematic configuration diagram showing a shift-by-wire system according to the first embodiment; Fig. 3 is a circuit diagram showing a motor and a motor driver according to the first embodiment; Fig. 4 is an illustrative diagram showing the behavior of a locking mechanism according to the first embodiment; Fig. 5 is an illustrative diagram showing a torque applied to the locking mechanism according to the first embodiment; Fig. 6 is an illustrative diagram showing a relationship between an energization period and an output shaft stop position according to the first embodiment; Fig. 7 is a timing chart showing an experimental result in the case where energization is turned off after energization for a predetermined time according to the first embodiment; Fig. 8 is a schematic diagram showing a state in which an inter-range stop abnormality has occurred according to the first embodiment; Fig. 9 is a schematic diagram showing a motor drive system according to the first embodiment; Fig. 10 is a flowchart illustrating an engine control process according to the first embodiment; Fig. 11 is a schematic diagram showing a motor drive system according to a second embodiment; Fig. 12 is a flowchart illustrating an engine control process according to a third embodiment; Fig. 13 is a flowchart illustrating an engine control process according to a fourth embodiment; and Fig. 14 is a flowchart illustrating an engine control process according to a fifth embodiment. Embodiments for carrying out the invention

[0014] A shift range switching system is described below with reference to the figures. In several embodiments, essentially the same components are designated by the same reference numerals, and a description of the same configurations is omitted. (First embodiment)

[0015] The Fig. 1 to 10 show a shift range control device according to a first embodiment. As shown in the Fig. 1 and Fig. 2, a 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.

[0016] The motor 10 rotates when a battery 45 (see Fig. 3) mounted on a vehicle (not shown), and serves as a drive source of the shift range switching mechanism 20. The motor 10 according to the present embodiment corresponds to a permanent magnet type brushless DC motor and generates a cogging torque. In this specification, the cogging torque and a torque caused by motor friction and the like, which are also generated at the time of de-energization, are appropriately referred to as a "motor cogging torque."

[0017] As in Fig. As shown in Figure 3, the motor 10 has two sets of motor windings 11 and 12. The first motor winding 11 includes a U1 coil 111, a V1 coil 112, and a W1 coil 113. The second motor winding 12 includes a U2 coil 121, a V2 coil 122, and a W2 coil 123.

[0018] As in Fig. As shown in Figure 2, an encoder 13 detects a motor angle θm corresponding to 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 A-phase and B-phase pulse signals at every predetermined angle in synchronization with the rotation of the rotor.

[0019] A speed reducer 14 is mounted between the motor shaft 105 (see Fig. 4) corresponding to a rotating shaft of the motor 10 and an output shaft 15, and reduces a rotational speed of the motor 10 to output the rotation of the motor 10 to the output shaft 15. Consequently, 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 output shaft angle θs corresponding to an angle of the output shaft 15. The output shaft sensor 16 is, for example, a potentiometer. In the embodiment, a clearance such as backlash exists between the motor shaft 105 and the output shaft 15. Hereinafter, a total clearance between the motor shaft 105 and the output shaft 15 is appropriately referred to as "backlash."

[0020] As in Fig. 1, the shift range switching mechanism 20 includes a detent plate 21, a detent spring 25, and the like, and transmits a rotational driving force output from the speed reducer 14 to a manual valve 28 and the parking lock mechanism 30.

[0021] The detent plate 21 is fixed to the output shaft 15 and driven by the motor 10. The detent plate 21 is provided with a pin 24 projecting parallel to the output shaft 15. The pin 24 is connected to a manual valve 28. When the detent plate 21 is driven by the motor 10, the manual valve 28 reciprocates in the 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 the 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, thereby changing the shift range.

[0022] As in the Fig. 1 and Fig. As shown in Fig. 5, on the detent spring 25 side of the detent plate 21 corresponding to a trough-providing member, four troughs 221 to 224 for holding the manual valve 28 at positions corresponding to the respective ranges are provided. The troughs 221 to 224 are arranged in the order of a P trough 221 corresponding to a P (Park) range, an R trough 222 corresponding to an R (Reverse) range, an N trough 223 corresponding to an N (Neutral) range, and a D trough 224 corresponding to a D (Drive) range from a tip side of the detent spring 25.

[0023] The detent spring 25, which corresponds to a biasing element, is an elastically deformable plate-shaped member, and a detent roller 26, which corresponds to an engagement element, is provided at a tip of the detent spring 25. The detent spring 25 biases the detent roller 26 toward the rotation center of the detent plate 21. When a predetermined or higher rotational force is applied to the detent plate 21, the detent spring 25 elastically deforms, and the detent roller 26 moves on the grooves 221 to 224. For example, when switching from the P range to the D range, the detent roller 26 moves from the P groove 221 to the D groove 224 as the detent plate 21 rotates in the forward rotation direction and fits into the D groove 224.When the detent roller 26 fits into one of the recesses 221 to 224, the swing 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 the automatic transmission 5 is set.

[0024] As in Fig. 6, a zone Rp corresponds to a zone on a side opposite to the R-well 222 up to a predetermined position on the R-well 222 side from the center of the P-well 221, and this corresponds to a P-lock guarantee range in which parking lock by the parking lock mechanism 30 is ensured when the detent roller 26 is located at an output shaft angle in the zone Rp. A zone Rr corresponds to a predetermined range including the center of the R-well 222, and this corresponds to an R-hydraulic pressure generation range in which hydraulic pressure in the R range is ensured in the automatic transmission 5 when the detent roller 26 is located at the output shaft angle in the zone Rr.A zone Rd corresponds to a predetermined area including the center of the D-well 224, and this corresponds to a D hydraulic pressure generation area in which hydraulic pressure in the D area is ensured in the automatic transmission 5 when the detent roller 26 is located in the zone Rd at the output shaft angle. A zone Rn corresponds to a predetermined area including the center of the N-well 223, and this corresponds to an area in which a friction engagement element (not shown) is not engaged and generation of oil pressure in an oil passage of the automatic transmission 5 is not ensured when the detent roller 26 is located in the zone Rn at the output shaft angle. Hereinafter, the zones Rp, Rr, Rn, and Rd are appropriately defined as area guarantee zones, and zones other than the area guarantee zones are defined as intermediate area zones.

[0025] As in Fig. As shown in Figure 1, the parking lock mechanism 30 includes a parking rod 31, a conical body 32, a parking pawl 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 is fixed to the detent plate 21. The conical body 32 is provided on the other end 312 side of the parking rod 31. A diameter of the conical body 32 decreases toward the other end 312. When the detent plate 21 swings in a reverse rotation direction, the conical body 32 moves in a direction of an arrow P.

[0026] The parking pawl 33 abuts against a conical surface of the conical body 32, and on the parking gear 35 side of the parking pawl 33, which is pivotally provided around the shaft portion 34, a projection portion 331 is provided that can mesh with the parking gear 35. When the detent plate 21 rotates in the reverse rotation direction and the conical body 32 moves in a direction of an arrow P, the parking pawl 33 is pushed upward, and the projection portion 331 and the parking gear 35 mesh with each other. Conversely, when the detent plate 21 rotates in a forward rotation direction and the conical body 32 moves in a direction of an arrow NON-P, the engagement between the projection portion 331 and the parking gear 35 is released.

[0027] The parking gear 35 is provided on an axle (not shown) so that it can be engaged with the protruding portion 331 of the parking pawl 33. When the parking gear 35 and the protruding portion 331 are engaged with each other, the rotation of the axle is restricted. When the shift range is a non-P range other than the P range, the parking gear 35 is not locked by the parking pawl 33, and the rotation of the axle is not obstructed by the parking lock mechanism 30. When the shift range is the P range, the parking gear 35 is locked by the parking pawl 33, and the rotation of the axle is regulated.

[0028] As in the Fig. 2 and Fig. 3, the switching range control device 40 includes motor drivers 41 and 42 as drive circuits, an ECU 50 as a control unit, and the like. The motor driver 41 is a three-phase inverter for switching the excitation of the first motor winding 11, and switching elements 411 to 416 are bridge-connected to each other. One end of the U1 coil 111 is connected to a connection point of the U-phase switching elements 411 and 414 that are paired with each other. One end of the V1 coil 112 is connected to a connection point of the V-phase switching elements 412 and 415 that are paired with each other. One end of the W1 coil 113 is connected to a connection point of the W-phase switching elements 413 and 416 that are paired with each other. The other ends of the coils 111 to 113 are connected to each other by a connecting portion 115.

[0029] The motor driver 42 is a three-phase inverter for switching the excitation of the second motor winding 12, and switching elements 421 to 426 are bridge-connected to each other. One end of the U2 coil 121 is connected to a connection point of the paired U-phase switching elements 421 and 424. One end of the V2 coil 122 is connected to a connection point of the paired V-phase switching elements 422 and 425. One end of the W2 coil 123 is connected to a connection point of the paired W-phase switching elements 423 and 426. The other ends of the coils 121 to 123 are connected to each other by a connecting portion 125. The switching elements 411 to 416 and 421 to 426 according to the present embodiment are MOSFETs, but other elements such as IGBTs may also be used.

[0030] A motor relay 46 is provided between the first motor driver 41 and the battery 45. A motor relay 47 is provided between the second 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 or the like, is turned on and electric power is supplied to the motor 10. The motor relays 46 and 47 are turned off when the start switch is turned off and the supply of electric power to the motor 10 is interrupted. A voltage sensor 48 for detecting a battery voltage Vb is provided on a high-potential side of the battery 45.

[0031] The ECU 50 controls on / off operations of the switching elements 411 to 416 and 421 to 426 and controls the driving of the motor 10, thereby controlling the switching of the shift range. The ECU 50 controls the driving of a hydraulic shift control solenoid 6 based on a vehicle speed, an accelerator opening degree, a driver request shift range, and the like. A shift speed is controlled by controlling the hydraulic shift control solenoid 6. The number of hydraulic shift control solenoids 6 is provided according to the number of shift speeds and the like. In the present embodiment, one ECU 50 controls the driving of the motor 10 and the solenoid 6, but the ECU 50 may be divided into an engine ECU for controlling the motor 10 and an AT ECU for controlling the solenoid. The following mainly describes the drive control of the motor 10.

[0032] The ECU 50 includes microcomputers 51 and 52, and the like, and internally includes a CPU (not shown), a ROM, a RAM, an I / O, a bus line for connecting these components, and the like. Processing in the ECU 50 may correspond to software processing by allowing a CPU to execute a program stored in advance in a tangible storage device such as a ROM (i.e., a readable, non-perishable, tangible recording medium), or to hardware processing by dedicated electronic circuits.

[0033] As in the Fig. 2 and Fig. 9, the first microcomputer 51 is connected to the first motor driver 41 and controls the excitation of the first motor winding 11. In the second microcomputer 52, the second microcomputer 52 is connected to the second motor driver 42 and controls the excitation of the second motor winding 12. The microcomputers 51 and 52 perform calculation related to the drive control of the motor 10 and correspond to a "calculation unit".

[0034] The microcomputers 51 and 52 control the driving of the motor 10 through feedback control or the like based on a motor angle θm, an output shaft angle θs, and the like, so that the motor angle θm stops at a motor angle command value θcmd set according to the required shift range. The details of the drive control of the motor 10 can be arbitrary. The microcomputers 51 and 52 monitor the abnormality in the shift-by-wire system 1. Specifically, in the present embodiment, the intermediate-range stop abnormality in which the detent roller 26 stops in the intermediate range zone is detected by the occurrence of the motor-off malfunction in which the motor 10 stops during range switching.

[0035] In this example, the behavior of the detent mechanism at the time of shift range switching is described with reference to Fig. 4. In Fig. 4 schematically shows the concept of "gap," and the output shaft 15 and the speed reducer 14 are integrated with each other, and the motor shaft 105 is movable within a gap range of the speed reducer 14. The motor shaft 105 and the speed reducer 14 may be integrated with each other so that a "gap" exists between the speed reducer 14 and the output shaft 15. In this example, the "gap" between the motor shaft 105 and the output shaft 15 is mainly described with reference to a gap existing between the gear of the speed reducer 14 and the motor shaft 105, but the "gap" may be regarded as a total of clearance, play, and the like existing between the motor shaft 105 and the output shaft 15.

[0036] The following mainly describes an example in which the shift range is switched from a range other than the P range to the P range. Fig. Fig. 4 schematically shows a state in which the locking roller 26 moves from the R-trough 222 to the P-trough 221 when the motor 10 rotates. In Fig. 4, the rotation directions of the motor 10 and the output shaft 15 are described in the figure as right and left directions, and a state in which the detent roller 26 moves from an upper stage to a lower stage in conjunction with the rotation of the motor 10 is shown. In fact, the detent plate 21 rotates integrally with the output shaft 15 to move the detent roller 26 between the troughs 221 to 224, in Fig. 4, however, for the purpose of description, the locking roller 26 is shown moving together with the output shaft 15.

[0037] Before describing the behavior of the locking mechanism, a torque applied to the locking mechanism is described with reference to Fig. 5. As described in an upper part of Fig. 5, when the detent plate 21 rotates, a state in which a load torque TL generated by a spring load SL of the detent spring 25 acts as a positive torque to assist the driving torque of the motor 10 and a state in which the load torque TL acts as a negative torque to inhibit the driving torque of the motor 10 are repeated. When switching the shift range toward the P range, a torque applied to the detent roller 26 in the P direction is defined as a positive torque, and a torque applied in the D direction is defined as a negative torque. The positive torque is mainly generated by the driving torque of the motor 10 and the spring load SL during the lowering of the detent roller 26. The negative torque is mainly generated by the spring load SL during the ascending of the detent roller 26.

[0038] As in Fig. As shown in Fig. 4, in the shift-by-wire system 1, in the shift range switching mechanism 20, the shift range is switched by the detent roller 26, which moves between the recesses 221 to 224 by the rotation of the detent plate 21. In the present embodiment, the detent roller 26 is dropped into any one of the recesses 221 to 224 corresponding to the required shift range by the spring load SL using the play existing between the motor shaft 105 and the output shaft 15.

[0039] When the detent roller 26 is moved from the R-trough 222 to the P-trough 221, as shown in state a, the motor 10 rotates with backlash, so that the motor shaft 105 and the speed reducer 14 come into contact with each other, and the backlash is inhibited. When the backlash is inhibited, the motor shaft 105 and the output shaft 15 rotate integrally with each other, and the detent roller 26 begins to ascend.

[0040] As shown in a state b, the motor 10 pulls or drags the output shaft 15 when the detent roller 26 is in an ascending state in which the detent roller 26 moves from the R-trough 222 toward a crest 226. At this time, the spring load SL acts as a negative torque.

[0041] As shown in state c, when the detent roller 26 is in a descending state, moving from a crest of the crest 226 toward the P-trough 221, the spring load SL acts as a positive torque, and the output shaft 15 leads the motor 10 and is pulled into the P-trough 221 in play. As shown in state d, the detent roller 26 falls into the P-trough 221.

[0042] In the present embodiment, a DC motor with a permanent magnet is used as the motor 10, and as shown in a lower part of Fig. As shown in Figure 5, the motor cogging torque TC_M is generated periodically. The generation cycle of the cogging torque differs depending on the number of magnetic poles of the motor 10 and the like. The motor cogging torque TC_M is amplified according to a gear ratio of the speed reducer 14 and transmitted to the output shaft 15. Hereinafter, the cogging torque amplified by the speed reducer 14 is referred to as an output shaft cogging torque TC_S.

[0043] As in Fig. 5 is indicated by "x", torque balance points where the load torque TL and the output shaft cogging torque TC_S are balanced occur on the ascending side. Specifically, when a gear ratio of the speed reducer 14 is large and a maximum value of the output shaft cogging torque TC_S is greater than a maximum value of the negative torque by the detent spring 25, the number of torque balance points increases compared to the case where the maximum value of the output shaft cogging torque TC_S is smaller than the maximum value of the negative torque. To avoid complication, parts of the "X" marks indicating the balance points are shown.

[0044] This example describes a case where a motor-off malfunction occurs during range switching, which corresponds to an abnormality in which the motor 10 cannot be driven due to a disconnection or the like. If the motor-off malfunction occurs during the lowering of the detent roller 26, the spring load SL acts as a positive torque, and therefore, the detent roller 26 may be dropped into a depression by the spring load SL if a large clearance is provided.

[0045] On the other hand, if a motor-off malfunction occurs during the ascent of the detent roller, the spring load SL acts as a negative torque. Therefore, if the motor-off malfunction occurs at the torque balance point, the detent roller 26 stops during ascent, and a new problem of the intermediate stop anomaly has been identified (see Fig. 8). When the detent roller 26 stops at the torque balance point, the inter-range stop abnormality is not resolved even if the backlash is large. Furthermore, in the case of a motor that does not use a permanent magnet, such as a switched reluctance motor, no cogging torque is generated, so the torque balance point does not occur, and the detent roller 26 is dropped into one of the troughs 221 to 224 by the spring load SL of the detent spring 25, so no inter-range stop abnormality occurs.

[0046] Fig. 6 shows a stop position of the output shaft 15 when the excitation is turned off after a certain period of time elapses until the detent roller 26 reaches the P-trough 221 after the excitation is started from a state where the detent roller 26 is located in the D-trough 224. Even if the excitation is turned off during range switching, the detent roller 26 is dropped into one of the troughs 221 to 224 by the spring load SL depending on an excitation off time. However, as surrounded by a two-dot chain line, the detent roller 26 may stop in an intermediate range zone upon detent roller 26 ascending.

[0047] The Fig. 7 and Fig. 8 are experimental results when an excitation period of the motor 10 is defined as xa, and correspond to a point A in Fig. 6. In Fig. In Figure 7, a horizontal axis represents a common time axis, and a drive mode and angle are shown from above. P, R, N, and D in the figure correspond to the output shaft angles when the detent roller 26 is located at the centers of the troughs 221 to 224. The motor angle θm and the motor angle command value θcmd are described in terms of the output shaft.

[0048] When the detent roller 26 is energized for a time xa and then de-energized from a state in which the detent roller 26 is located at the D-well 224, it results that the motor angle θm does not reach the motor angle command value θcmd and the output shaft angle θs stops in an intermediate range zone between the R-well 222 and the P-well 221.

[0049] If an abnormality occurs in which the output shaft 15 stops in the intermediate range zone, the manual valve 28 stops at a midway position, so that appropriate hydraulic pressure cannot be generated, which may result in a malfunction of the automatic transmission 5.

[0050] Therefore, in the present embodiment, the plurality of motor drive systems are systematized so that an inter-range stop abnormality does not occur even if disconnection or the like occurs in part of the motor drive systems. The motor drive system includes the motor windings 11 and 12, the motor drivers 41 and 42, the microcomputers 51 and 52, and connecting wiring for connecting these components to each other. The combination of the first motor winding 11, the first motor driver 41, the first microcomputer 51, and connecting wiring 61 and 71 for connecting these components to each other is defined as a first system, and the combination of the second motor winding 12, the second motor driver 42, and the second microcomputer 52 and connecting wiring 62 and 72 for connecting these components to each other is defined as a second system.

[0051] As in Fig. 9, the first motor driver 41 is connected to the first microcomputer 51 via the first microcomputer-side connection wiring 61 and to the first motor winding 11 via the first motor-side connection wiring 71. The first microcomputer 51 controls the on / off operation of the switching elements 411 to 416 (in Fig. 9 not shown) of the first motor driver 41, thereby controlling the excitation of the first motor winding 11.

[0052] The second motor driver 42 is connected to the second microcomputer 52 via the second microcomputer-side connecting wiring 62 and to the second motor winding 12 via the second motor-side connecting wiring 72. The second microcomputer 52 controls the on / off operation of the switching elements 421 to 426 (in Fig. 9 not shown) of the second motor driver 42, thereby controlling the excitation of the second motor winding 12. The range switching request and the like are input to the microcomputers 51 and 52, and they perform various controls based on the input information. Fig. 9 and Fig. 11, the motor windings 11 and 12 are marked with a symbol “M”.

[0053] An engine control process according to the present embodiment will be explained using a flowchart of Fig. 10. This processing is executed by each of the microcomputers 51 and 52 in a predetermined cycle. In this example, the processing in the first microcomputer 51 will be described, and the processing in the second microcomputer 52 is similar to the processing in the first microcomputer 51, and therefore, a description of the processing in the second microcomputer 52 will be omitted. Hereinafter, a "step" of step S101 will be omitted, and reference will simply be made to the symbol "S." The same applies to the other steps. The same applies to the third to fifth embodiments.

[0054] In S101, the first microcomputer 51 determines whether a host system is normal or not. If it is determined that the host system is normal (YES in S101), the process proceeds to S102 and range switching is permitted. In particular, to drive the motor 10 according to the required shift range, the excitation of the first motor winding 11 is controlled. If it is determined that the host system is abnormal (NO in S101), the process proceeds to S103 and range switching in the host system is prohibited. Specifically, the first motor winding 11 is not excited. If the other system is normal at this time, driving of the motor 10 continues using the other system. In addition, in S104, the first microcomputer 51 reports to the second microcomputer 52 and other ECUs (not shown) outside the shift-by-wire system 1, such asa host ECU, which controls the entire vehicle, receives information indicating that a malfunction has occurred in the first system. Information transfer between microcomputers 51 and 52 can be performed directly via inter-microcomputer communication, or it can be performed via a vehicle communication network, such as CAN (Controller Area Network).

[0055] As described above, the shift-by-wire system 1 according to the present embodiment includes the motor 10, the motor drivers 41 and 42, the output shaft 15, the shift range switching mechanism 20, and the ECU 50. The motor 10 has the motor windings 11 and 12, and cogging torque is generated by permanent magnets. The motor drivers 41 and 42 switch the excitation of the motor windings 11 and 12. The rotation of the motor shaft 105, which corresponds to a rotating shaft of the motor 10, is transmitted to the output shaft 15.

[0056] The shift range switching mechanism 20 includes the detent plate 21, the detent roller 26, and the detent spring 25. The detent plate 21 is formed with the plurality of recesses 221 to 224 and the plurality of crests 226 to 228 separating the recesses 221 to 224, and rotates integrally with the output shaft 15. The detent roller 26 fits into each of the recesses 221 to 224 corresponding to the shift range. The detent spring 25 biases the detent roller 26 in a direction to fit into the recesses 221 to 224. The ECU 50 includes the microcomputers 51 and 52 for performing calculations related to the drive control of the engine 10.

[0057] A gap is provided between the motor shaft 105 and the output shaft 15, allowing the locking roller 26 to drop into the recesses 221 to 224. The motor drivers 41 and 42, the motor windings 11 and 12, the connecting wires 71 and 72 connecting the motor drivers 41 and 42 and the motor windings 11 and 12, respectively, and the microcomputers 51 and 52 are defined as a motor drive system. The plurality of motor drive systems are provided so as to prevent the occurrence of an intermediate stop abnormality in which the output shaft 15 stops due to the balance of an output shaft cogging torque, which is a cogging torque transmitted to the output shaft 15, and a torque including a load torque by the detent spring 25, when an abnormality occurs in the motor drive system during ascending in which the detent roller 26 moves from the troughs 221 to 224 toward the crests 226 to 228.Consequently, even if an abnormality occurs in the motor drive system during the ascent of the detent roller 26, the driving of the motor 10 can be continued and the inter-range stop abnormality is avoided, so that a malfunction of the automatic transmission 5 can be prevented.

[0058] The respective microcomputers 51 and 52 independently control the excitation of the respective motor windings 11 and 12 in response to a common range switching request. This allows the motor 10 to be driven using the multiple systems simultaneously, ensuring an output. Even if an abnormality occurs in some of the systems, the motor 10 can be driven as in the normal system, and range switching can continue.

[0059] If an abnormality occurs in any part of the motor drive systems, the driving of the motor 10 continues using the normal motor drive system. As a result, range switching can continue even if an abnormality occurs in any part of the systems.

[0060] If an abnormality occurs in the motor control system, the first microcomputer 51 notifies the second microcomputer 52, which corresponds to the "other computing unit," and the outside of the system of information indicating that an abnormality has occurred. This makes it possible to take appropriate action. Furthermore, the driver, for example, is informed of the abnormality and can initiate early repairs. (Second embodiment)

[0061] A second embodiment is in Fig. 11. As shown in Fig. As shown in Fig. 11, in the present embodiment, microcomputers 51 and 52 perform synchronization control to align control timings. In the present embodiment, clock signals of the respective microcomputers 51 and 52 are synchronized with each other. The synchronization control may be performed by sharing synchronization information between the microcomputers 51 and 52, or information such as external clock signals from outside the microcomputers 51 and 52 may be used.

[0062] In the present embodiment, microcomputers 51 and 52 perform the synchronization process to synchronize the timing of the excitation command with the other microcomputers 52 and 51. This can reduce the deviation in the excitation timing between the motor windings 11 and 12. This can prevent torque from decreasing due to the deviation in the excitation timing. Furthermore, the same effects as in the previous embodiment can be achieved. (Third embodiment)

[0063] A third embodiment is in Fig. 12. In the third to fifth embodiments, as in the first embodiment, a motor control process is performed, so the motor control process will be mainly described. As in the second embodiment, synchronization control can be performed.

[0064] In S201, as in S101 of Fig. 10, the first microcomputer 51 determines whether a host system is normal or not. If it is determined that the host system is abnormal (NO in S201), the process shifts to S206. The processes of S206 and S207 are the same as the processes of S103 and S104 in Fig. 10. If it is determined that the host system is normal (YES in S201), the process goes to S202.

[0065] In S202, the first microcomputer 51 determines whether the other system is normal or not. If it is determined that the other system is normal (YES in S202), the process proceeds to S204 and area switching is permitted. If it is determined that the other system is abnormal (NO in S202), the process proceeds to S203.

[0066] In S203, the first microcomputer 51 determines whether or not a battery voltage Vb is equal to or higher than a voltage determination threshold Vth. In the present embodiment, the battery voltage Vb corresponds to "an input voltage input to the drive circuit." The voltage determination threshold Vth is set to a voltage that can drive the motor 10 in a system. The voltage determination threshold Vth may be the same value regardless of the range, or a different value depending on the current shift range. For example, when the current shift range corresponds to the P range, the voltage determination threshold Vth may be set to a value greater than this when the current shift range corresponds to the other range, or the like.If it is determined that the battery voltage Vb is equal to or higher than the voltage determination threshold Vth (YES in S203), the process proceeds to S204 and range switching is permitted. If it is determined that the battery voltage Vb is less than the voltage determination threshold Vth (NO in S203), the process proceeds to S205 and range switching is prohibited.

[0067] When the motor 10 is driven by one system, the torque that can be output is lower compared to the case of driving by two systems. If the battery voltage is reduced, the torque that can be output is further reduced, and range switching may fail. Therefore, in the present embodiment, when an abnormality occurs in one of the systems and the battery voltage Vb is reduced, switching of the shift range is prohibited. In this way, the range switching malfunction caused by the torque reduction can be prevented.

[0068] In the present embodiment, when an abnormality occurs in part of the motor drive systems, the range switching execution determination is performed to select whether to permit or prohibit the range switching. Specifically, the ECU 50 performs the determination on the battery voltage Vb as the input voltage input to the motor drivers 41 and 42 as the range switching execution determination, permits the range switching when the battery voltage Vb is equal to or higher than the voltage determination threshold Vth, and prohibits or prohibits the range switching when the battery voltage Vb is less than the voltage determination threshold Vth. Consequently, the range switching malfunction due to a torque shortage caused by a malfunction of part of the systems can be prevented, and the occurrence of the inter-range stop abnormality can be avoided.In addition, the same effects as those of the above embodiment can be achieved. (Fourth embodiment)

[0069] A fourth embodiment is in Fig. 13. An engine control process according to the present embodiment is the same as that of the third embodiment, except that the process in S211 is performed instead of S203 in Fig. 12 is performed. In S211, to which the process proceeds upon a negative determination in S202, a first microcomputer 51 determines whether a machine is being driven or not. If it is determined that the machine is being driven (YES in S211), the process proceeds to S204, and area switching is permitted. If it is determined that the machine is not being driven (NO in S211), the process proceeds to S205, and area switching is prohibited.

[0070] In the present embodiment, an ECU 50 determines a driving state of the engine as a range switching execution determination. When the engine is driven, range switching is permitted, and when the engine is stopped, range switching is prohibited. For example, when the engine is stopped due to an idle stop or the like, the battery voltage Vb may be reduced. Therefore, in the present embodiment, when an abnormality occurs in one of the systems and the engine is stopped, switching of the shift range is prohibited. Consequently, the range switching malfunction due to the torque shortage can be prevented, and the occurrence of the inter-range stop abnormality can be avoided. Furthermore, the same effects as those of the above embodiment can be achieved. (Fifth embodiment)

[0071] A fifth embodiment is in Fig. 14. An engine control process according to the present embodiment is the same as that of the third embodiment, except that processes S216 and S217 are performed instead of S203 in Fig. 12. In S216, to which the process proceeds when a negative determination is made in S202, a first microcomputer 51 determines whether or not a current shift range is a range other than a P range. If it is determined that the current shift range is a range other than the P range (YES in S216), the process advances to S204, and range switching is permitted. If it is determined that the current shift range is the P range (NO in S216), the process proceeds to S217.

[0072] In S217, the first microcomputer 51 determines whether a vehicle's inclination angle θi is equal to or less than an angle determination threshold θth. The vehicle's inclination angle θi is calculated, for example, based on a detection value of a tilt angle sensor. If it is determined that the inclination angle θi is equal to or less than the angle determination threshold θth (YES in S217), the process proceeds to S204, and area switching is permitted. If it is determined that the inclination angle θi is greater than the angle determination threshold θth (NO in S217), the process proceeds to S205, and area switching is prohibited.

[0073] When the shift range is switched from the P range to a range other than the P range, that is, at the time of "switching from P," a larger torque is required than at the time of switching the other ranges. Furthermore, when the vehicle is tilted, friction corresponding to the tilt angle θi and vehicle weight are generated at an engagement point between the parking pawl 33 and the parking gear 35, so that a larger torque is required at the time of switching from P. Therefore, in the present embodiment, when an abnormality occurs in one of the systems and the range is switched from P in a tilted vehicle state, the shift range is prohibited from being switched. In this way, the range switching malfunction caused by the torque reduction can be prevented.

[0074] In the engine control process, the process of S217 can be omitted, and when an abnormality occurs in one of the systems, switching from the P range to another range can be prevented regardless of the vehicle's inclination angle θi. In the engine control process, several processes of S203 can be combined into Fig. 12, S211 in Fig. 13 and S216 and S217 in Fig. 14 can be combined with each other.

[0075] In the present embodiment, the ECU 50 determines the current shift range as the range switching execution determination. When the current shift range is a range other than the P range, the range switching is permitted, and when the current shift range is the P range, the range switching is prohibited. Further, the ECU 50 determines the current shift range and the inclination angle θi of the vehicle as the range switching execution determination. When the current shift range is a range other than the P range, and when the current shift range is the P range and the inclination angle θi is equal to or less than the angle determination threshold θth, the range switching is permitted. When the current shift range is the P range and the inclination angle θi is greater than the angle determination threshold θth, the range switching is prohibited.In this way, it is possible to prevent the range switching malfunction caused by a torque shortage and avoid the occurrence of the inter-range stop abnormality at the time of switching from P, which requires a relatively large torque. Moreover, the same effects as those of the above embodiment can be achieved. (Other embodiments)

[0076] In the above embodiments, the motor corresponds to a brushless DC motor. In further embodiments, the motor may be a motor other than a brushless DC motor that generates a cogging torque. In the above embodiments, the motor driver as the drive circuit is a three-phase inverter. In further embodiments, the drive circuit may be configured to be capable of switching the excitation of the motor windings. In the above embodiment, two motor drive systems are provided. In a further embodiment, three or more motor drive systems may be provided.

[0077] In the above embodiments, the motor rotation angle sensor is an encoder. In other embodiments, the motor rotation angle sensor is not limited to the encoder, and any type, such as a resolver, can be used. In the above embodiments, a potentiometer is exemplified as the output shaft sensor. In other embodiments, the output shaft sensor can be any sensor. For example, the output shaft sensor can be configured by a switch turned on in each range guarantee zone, or a non-contact magnetic sensor can be used. The output shaft sensor can be omitted.

[0078] In the above embodiments, the detent plate is provided with four recesses. In other embodiments, the number of recesses is not limited to four and can be arbitrarily high. For example, two recesses may be provided corresponding to a P range and a non-P range different from the P range. The shift range switching mechanism, the parking lock mechanism, and the like may be different from those of the above embodiments.

[0079] In the above embodiments, the 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 embodiments, any configuration may be adopted, such as a cycloidal gear, a planetary gear, a spur gear for transmitting torque from a reduction mechanism substantially coaxial with the motor shaft to the drive shaft, or a combination of these components may be used. In other embodiments, the speed reducer may be omitted between the motor shaft and the output shaft, or a mechanism other than the speed reducer may be provided. As described above, the present disclosure is not limited to the above-described embodiments and may be implemented in various forms without departing from the spirit of the present disclosure.

Claims

[1] Shift range switching system, comprising: a motor (10) comprising a plurality of motor windings (11, 12) and generating a cogging torque by a permanent magnet; a plurality of drive circuits (41, 42) which switch excitation of the motor windings (11, 12); an output shaft (15) to which a rotation of a motor shaft (105) as a rotating shaft of the motor (10) is transmitted; a shift range switching mechanism (20) comprising a recess-providing member (21) having a plurality of recesses (221 to 224) and a plurality of crests (226 to 228) separating the recesses (221 to 224) from each other and rotating integrally with the output shaft (15), an engaging member (26) fitting into one of the recesses (221 to 224) corresponding to a shift range, and a biasing member (25) biasing the engaging member (26) in a direction to fit into one of the recesses (221 to 224); and a control unit (50) comprising at least one calculation unit (51, 52) for performing a calculation with respect to a drive control of the motor (10), wherein a clearance is provided between the motor shaft (105) and the output shaft (15); the engagement element (26) falls into one of the recesses (221 to 224) due to the play; the drive circuits (41, 42), the motor windings (11, 12) and a plurality of connecting wirings (71, 72) connecting the drive circuits (41, 42) and the motor windings (11, 12) are defined as a plurality of motor drive systems; the cogging torque transmitted to the output shaft (15) is defined as an output shaft cogging torque; an intermediate range stop anomaly is defined such that the output shaft (15) stops when the output shaft cogging torque and a load torque (TL) of the biasing element (25) are balanced; when an abnormality occurs in the motor drive systems during a climbing operation in which the engaging element (26) moves from one of the troughs (221 to 224) to an adjacent one of the ridges, the shift range switching system prevents the inter-range stop abnormality from occurring; when an abnormality occurs in a part of the motor drive systems, a normal one of the motor drive systems continues to provide control of the motor (10); when an abnormality occurs in any part of the motor drive systems, a range switching execution determination is made and allowing or prohibiting a range switching operation is selected; the control unit (50) checks a current switching range as the range switching execution determination; the control unit (50) permits the range switching operation when the current shift range is a range other than a P range; and the control unit (50) prevents the range switching process if the current switching range corresponds to the P range. [2] A shift range switching system according to claim 1, wherein a plurality of calculation units included in the at least one calculation unit independently and accordingly control the excitation of the motor windings (11, 12) in response to a common range switching request. [3] The shift range switching system according to claim 1, wherein one of a plurality of calculation units included in the at least one calculation unit performs a synchronization process for synchronizing an energization instruction time with another of the calculation units. [4] A shift range switching system according to any one of claims 1 to 3, wherein: the control unit (50) checks an input voltage to be input to the drive circuits (41, 42) as the range switching execution determination; the control unit (50) allows the range switching operation when the input voltage is equal to or higher than a voltage determination threshold (Vth); and the control unit (50) prevents the range switching operation when the input voltage is lower than the voltage determination threshold (Vth). [5] A shift range switching system according to any one of claims 1 to 4, wherein: the control unit (50) checks a driving state of an engine of a vehicle as the range switching execution determination; the control unit allows the range switching operation when the machine is in operation; and the control unit (50) prevents the range switching operation when the machine stops operating. [6] A shift range switching system according to any one of claims 1 to 5, wherein: the control unit (50) checks the current shift range and a tilt angle (θi) of a vehicle as the range switching execution determination; the control unit (50) permits the range switching operation when the current shift range is a range other than the P range or when the current shift range corresponds to the P range and the inclination angle (θi) is less than or equal to an angle determination threshold (θth); and the control unit (50) prevents the range switching operation when the current switching range corresponds to the P range and the inclination angle (θi) is greater than the angle determination threshold (θth). [7] The shift range switching system according to any one of claims 1 to 6, wherein, when the abnormality occurs in the motor drive systems, the at least one calculation unit reports information indicating that the abnormality occurs to the outside.

Images