Actuator Control Device

Abstract

To provide an actuator control device capable of appropriately performing position determination.SOLUTION: In a park lock system including an electric actuator having a motor 40, a detent mechanism, and a position sensor 55, a control device 60 controls switching of the detent mechanism by driving of the motor 40. A detent roller of the detent mechanism can move between troughs by an output shaft driven by the electric actuator. A control unit 70 of the control device 60 includes a position determining unit 73 for determining that the detent roller is dropped to the lowermost bottom of a target trough when moving the detent roller to the target trough. The position determining unit 73 sets a mask time at which position determination is not performed after load torque is inverted by the detent roller getting over a crest, and executes position determination with the usage of a detection value of the position sensor 55 after the mask time.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an actuator control device. [Background technology]

[0002] Conventionally, there has been known a shift-by-wire system that electrically controls a shift range switching mechanism of an automatic transmission. For example, in Patent Document 1, an output shaft sensor is provided that detects the rotation angle of the output shaft, and the position of the output shaft within a plurality of range determination ranges is determined based on the output signal of the output shaft sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-179142 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when determining whether the locking portion has moved to the bottom of the recess in the detent plate based on the rotation speed or elapsed time, if there is a relatively large amount of play between the motor shaft and the output shaft and vibration occurs within the play, it may not be possible to properly determine that the locking portion is at the bottom of the recess.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an actuator control device that can appropriately perform position determination. [Means for solving the problem]

[0006] An actuator control device (60) of the present invention controls switching of the detent mechanism by driving the actuator in a drive system (1) including an actuator (10) having a drive source (40), a detent mechanism (20), and a position sensor (55). The detent mechanism has a detent member (21) and an engagement member (26). The detent member is formed with a plurality of valleys (211, 212) and ridges (215) separating the valleys. The engagement member is movable between the valleys when the output shaft (15) is driven by the actuator. The position sensor is capable of detecting the position of the output shaft.

[0007] The actuator control device includes a position determination unit (73) that, when moving the engaging member to the target valley portion, determines when the engaging member has fallen to the bottom of the target valley portion. The position determination unit provides a mask time during which position determination is not performed after the engaging member overcomes the peak portion and the load torque reverses, and after the mask time, performs position determination using the detection value of the position sensor. This masks transient changes due to the load torque reversal, allowing for appropriate position determination. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram showing a parking lock system according to a first embodiment. [Figure 2] 1 is a perspective view showing an electric actuator according to a first embodiment. [Figure 3] FIG. 2 is a block diagram showing a control device according to the first embodiment. [Figure 4] FIG. 2 is a schematic diagram showing a motor and a detent mechanism according to the first embodiment. [Figure 5] (a) shows the results of a simulation of the behavior of the motor angle, sensor angle, and output shaft angle, and (b) is an enlarged view of part Vb in FIG. 5(a). [Figure 6] FIG. 4 is a diagram illustrating a sensor angle and a maximum sensor angle value according to the first embodiment. [Figure 7] 4 is a flowchart illustrating a drive mode switching process according to the first embodiment. [Figure 8] 10 is a flowchart illustrating a valley position determination process according to the first embodiment. [Figure 9] 10 is a flowchart illustrating a valley position determination process according to the first embodiment. [Figure 10] (a) is a diagram showing the relationship between current and mask time, (b) is a diagram showing the relationship between temperature and mask time, (c) is a diagram showing the relationship between voltage and mask time, and (d) is a diagram showing the relationship between sensor rotation speed and mask time. [Figure 11] FIG. 4 is a diagram illustrating the relationship between the range switching direction and detent torque. [Figure 12] FIG. 10 is a diagram showing the relationship between the range switching direction and the mask time. [Figure 13] 5 is a time chart illustrating a valley position determination process according to the first embodiment. [Figure 14] 5 is a time chart illustrating a valley position determination process according to the first embodiment. [Figure 15] 10 is a flowchart illustrating a valley position determination process according to the second embodiment. [Figure 16] 10 is a flowchart illustrating a valley position determination process according to the second embodiment. [Figure 17] 10 is a time chart illustrating a valley position determination process according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An actuator control device according to the present invention will be described below with reference to the accompanying drawings. In the following, substantially identical components in a plurality of embodiments will be designated by the same reference numerals, and the description thereof will be omitted.

[0010] (First embodiment) The first embodiment is shown in Figs. 1 to 14. As shown in Fig. 1, an electric actuator 10 is applied to a parking lock system 1. The park lock system 1 includes the electric actuator 10, a detent mechanism 20, and a parking lock mechanism 30. The electric actuator 10 is a rotary type and is configured, for example, with a brushed DC motor and a reduction gear mechanism. The electric actuator 10 drives the detent mechanism 20 by rotating an output shaft 15.

[0011] The detent mechanism 20 has a detent plate 21, a detent spring 25, etc., and transmits the rotational driving force output from the electric actuator 10 to the parking lock mechanism 30.

[0012] The detent plate 21 is fixed to the output shaft 15 and driven by the electric actuator 10. On the side of the detent spring 25 of the detent plate 21, two valleys 211, 212 and a peak 215 separating the valleys 211, 212 are provided.

[0013] The detent spring 25, which is a biasing member, is an elastically deformable plate-like member, and has a detent roller 26 at its tip. The detent spring 25 biases the detent roller 26 toward the rotation center of the detent plate 21.

[0014] When a rotational force greater than or equal to a predetermined value is applied to the detent plate 21, the detent spring 25 elastically deforms, and the detent roller 26 moves between the valleys 211 and 212. When the detent roller 26 fits into either of the valleys 211 or 212, the oscillation of the detent plate 21 is restricted, and the state of the parking lock mechanism 30 is fixed.

[0015] The parking lock mechanism 30 has a parking rod 31, a cone 32, a parking lever 33, a shaft 34, and a parking gear 35. The parking rod 31 is formed in a generally L-shape, and one end 311 is fixed to the detent plate 21. The other end 312 of the parking rod 31 is provided with a cone 32. The cone 32 is formed so that its diameter decreases toward the other end 312. When the detent plate 21 rotates in a direction in which the detent roller 26 fits into the valley 211 corresponding to the P range, the cone 32 moves in the direction of arrow P.

[0016] The parking lever 33 abuts against the conical surface of the cone 32 and is provided so as to be able to swing around a shaft 34. A protrusion 331 that can mesh with the parking gear 35 is provided on the parking lever 33 on the parking gear 35 side. When the cone 32 moves in the direction of arrow P due to rotation of the detent plate 21, the parking lever 33 is pushed up and the protrusion 331 meshes with the parking gear 35. On the other hand, when the cone 32 moves in the direction not indicated by arrow P, the meshing between the protrusion 331 and the parking gear 35 is released.

[0017] The parking gear 35 is connected to a drive shaft (not shown) and is provided so as to be able to mesh with a protrusion 331 of the parking lever 33. When the parking gear 35 meshes with the protrusion 331, rotation of the drive shaft is restricted. When the shift range is a range other than P, i.e., a not P range, the parking gear 35 is not locked by the parking lever 33, and rotation of the drive shaft is not prevented by the parking lock mechanism 30. Furthermore, when the shift range is P range, the parking gear 35 is locked by the parking lever 33, and rotation of the drive shaft is restricted.

[0018] Hereinafter, the valley portion 211 into which the detent roller 26 fits when in the P range will be referred to as the "P valley," the valley portion 212 into which the detent roller 26 fits when in the not P range will be referred to as the "not P valley," and the bottom of the valley portions 211 and 212 will be referred to as the "bottom."

[0019] 2, the electric actuator 10 includes a motor 40, a reduction gear mechanism 42, a case 51, and a board cover 57. The motor 40 is placed horizontally on the board cover 57 so that the motor shaft is approximately parallel to the bottom surface of the case 51.

[0020] The reduction mechanism 42 has a worm gear 43, a helical gear 44, an intermediate gear 45, a driven plate 46, and a driven shaft 47. The worm gear 43 rotates integrally with the motor shaft of the motor 40. The helical gear 44 meshes with the worm gear 43 and large diameter portions of the intermediate gear 45. The intermediate gear 45 has a large diameter portion and a small diameter portion, and the large diameter portion meshes with the helical gear 44 and the small diameter portion meshes with the driven plate 46.

[0021] The driven plate 46 and the driven shaft 47 are formed integrally, but may be separate bodies. The driven shaft 47 and the output shaft 15 are connected by a splined shaft coupling. As a result, the rotation of the motor 40 is transmitted to the output shaft 15 via the worm gear 43, the helical gear 44, the intermediate gear 45, the driven plate 46, and the driven shaft 47.

[0022] The case 51 is made of, for example, resin, and has a cylindrical portion 54 formed in a location corresponding to the driven shaft 47. The cylindrical portion 54 is formed in a cylindrical shape that opens toward the driven shaft 47, and is provided so that its end face can abut against the driven shaft 47. The abutment between the driven shaft 47 and the cylindrical portion 54 causes the cylindrical portion 54 to bear the axial load of the driven shaft 47.

[0023] A sensor magnet (not shown) is provided on the driven shaft 47. A position sensor 55 (see FIG. 3) is provided inside the cylindrical portion 54 at a location facing the driven shaft 47. In this embodiment, the driven shaft 47 is used as the "sensor shaft," and the position sensor 55 detects the rotational position of the output shaft 15. The board cover 57 is fixed to the case 51, and a board (not shown) is provided inside. Various electronic components that constitute the control device 60 are mounted on the board.

[0024] As shown in Fig. 3, the control device 60 includes a drive circuit 61 and a control unit 70. The drive circuit 61 includes drive elements (not shown). The control unit 70 is mainly configured with a microcomputer or the like, and includes a CPU, ROM, RAM, I / O, and bus lines connecting these components (all not shown). Each process in the control unit 50 may be software processing in which the CPU executes a program stored in advance in a physical memory device (i.e., a readable non-transitory tangible recording medium) such as a ROM, or may be hardware processing using a dedicated electronic circuit.

[0025] The control unit 70 acquires the requested shift range, sets a target range, and controls the driving of the electric actuator 10 so that the detent roller 26 is positioned at the valleys 211, 212 corresponding to the target range. The control unit 70 has, as functional blocks, a signal acquisition unit 71, a rotation calculation unit 72, a position determination unit 73, a threshold setting unit 74, and a drive control unit 75. The signal acquisition unit 71 acquires a position detection signal from the position sensor 55, a signal related to the requested shift range from a higher-level ECU (not shown), and sensor signals related to the current, voltage, temperature, etc. of the motor 40.

[0026] The rotation calculation unit 72 calculates a sensor angle θs, which is the rotation angle of the driven shaft 47, and a sensor rotation speed Ns, which is the rotation speed of the driven shaft 47, based on the detection value of the position sensor 55. When the driven shaft 47 and the output shaft 15 rotate together with no backlash, the sensor angle θs and the sensor rotation speed Ns can be considered to be values ​​related to the output shaft 15.

[0027] The position determination unit 73 determines the position of the detent roller 26 in the detent mechanism 20. The threshold setting unit 74 sets a threshold for determining the position of the detent roller 26. The position determination of the detent roller 26 and the setting of the threshold for the position determination will be described later. The drive control unit 75 controls the on / off operation of the drive element of the drive circuit 61, thereby controlling the drive of the motor 40.

[0028] 4 schematically shows the play between the motor 40 and the output shaft 15, with the left-right direction on the page regarded as the direction of rotation, and illustrates how the detent roller 26 moves between the valleys 211 and 212. In reality, the detent roller 26 moves between the valleys 211 and 212 as the detent plate 21, which rotates integrally with the output shaft 15, rotates. In FIG. 4, the operation of the motor 40, etc., is indicated by dashed arrows.

[0029] A reduction gear mechanism 42 is provided between the motor 40 and the output shaft 15, and there is play between them. Hereinafter, the total play between the motor shaft and the driven shaft 47, which is the sensor shaft, will be referred to as the internal play Gm, and the play between the driven shaft 47 and the output shaft 15 will be referred to as the spline play Gs, and the total of the internal play Gm and the spline play Gs will be simply referred to as the "play."

[0030] When the shift range is switched from P to not P, the internal backlash Gm and spline backlash Gs are reduced in the direction of travel, and the detent roller 26 is pushed up toward the crest 215 with the motor shaft leading. When the detent roller 26 passes over the crest 215, the spring force of the detent spring 25 causes the output shaft 15 to move ahead toward the valley 212. When the detent roller 26 passes over the crest 215, the direction of the torque is reversed and the backlash is reduced all at once on the opposite side, causing a sudden change in the detection value of the position sensor 55.

[0031] Furthermore, in this embodiment, the worm gear 43 is used in the reduction mechanism 42, and the driven torque is relatively large. Specifically, the driven torque in the reduction mechanism 42 is larger than the biasing torque of the detent spring 25 that biases the detent roller 26 toward the bottom of the valley. Therefore, when switching ranges, if the motor 40 is turned off after passing the peak portion 215 but before reaching the bottom, depending on the amount of backlash, the detent roller 26 may stop at the position where power was turned off, and may not be able to drop to the bottom. Therefore, in this embodiment, power is turned off after it is determined that the detent roller 26 has stopped at the bottom.

[0032] FIG. 5 shows the simulation results of the motor angle θm, sensor angle θs, and output shaft angle θd when switching from P range to notP range, with the horizontal axis representing time and the vertical axis representing angle.

[0033] In this embodiment, because there is a spline play Gs between the output shaft 15 and the sensor shaft, even if the detent roller 26 is stopped at the valley portion 212, if the driven shaft 47 vibrates within the range of the spline play Gs, the detection value of the position sensor 55 will vibrate. If the sensor shaft oscillates due to the influence of such mechanical play, accurate angle calculation will not be possible until the oscillation settles down.

[0034] Here, focusing on the fact that the driven shaft 47 does not move beyond the range of the spline backlash Gs after the detent roller 26 falls into the valley portion 212, the maximum or minimum value of the sensor angle θs after the detent roller 26 gets over the peak portion 215 is held, and by detecting that the sensor shaft does not move beyond the width of the backlash, it is determined that the detent roller 26 has fallen into the valley bottom. Hereinafter, the maximum value of the sensor angle θs is referred to as the maximum sensor angle θmax, and the minimum value of the sensor angle θs is referred to as the minimum sensor angle θmin.

[0035] 6 shows the sensor angle θs and the maximum sensor angle θmax when switching from the P range to the notP range, with the horizontal axis representing time and the vertical axis representing angle. In the example of Fig. 6, the sum of the internal backlash Gm and the spline backlash Gs is greater than the angle between the peak portion 215 and the valley portion 212, so when the detent roller 26 overcomes the peak portion 215, the output shaft 15 rotates within the backlash, causing the detent roller 26 to move toward the valley portion 212 in a substantially unloaded state.

[0036] 6, when switching from the P range to the notP range, the maximum sensor angle θmax is held, and if the maximum change amount Δθmax, which is the amount of change in the maximum sensor angle θmax, becomes smaller than the position determination threshold Nth, it is determined that the detent roller 26 has dropped into the valley portion 212. Furthermore, when switching from the notP range to the P range, the sensor angle θs is set to decrease as the output shaft 15 rotates, so a similar determination is made by holding the minimum sensor angle θmin.

[0037] Furthermore, when the detent roller 26 passes over the ridge 215 and the backlash-reducing direction is reversed, the kinetic energy of the detent roller 26 causes the driven shaft 47 to vibrate, causing the detection value of the position sensor 55 to vibrate. In this embodiment, the sensor axis is the driven shaft 47, and the behavior of the output shaft 15 cannot be directly detected. Therefore, if the sensor angle θs vibrates after the backlash-reducing direction is reversed, there is a risk of an erroneous determination being made as to whether the detent roller 26 is at the bottom of the valley. Therefore, in this embodiment, a mask time Xmc is provided during which no valley position determination is performed for a predetermined time after the detent roller 26 passes over the ridge 215 and the backlash-reducing direction is reversed.

[0038] The drive mode switching process of this embodiment will be described with reference to the flowchart of Fig. 7. The processes of Fig. 5 and the like are executed at predetermined intervals by the control unit 70. Hereinafter, the "step" in step S101 and the like will be omitted and simply referred to as the symbol "S".

[0039] In S101, the control unit 70 determines whether the driving mode is the standby mode. If it is determined that the driving mode is not the standby mode (S101: NO), the process proceeds to S104. If it is determined that the driving mode is the standby mode (S101: YES), the process proceeds to S102.

[0040] In S102, the control unit 70 determines whether the target range has been switched. If it is determined that the target range has not been switched (S102: NO), the standby mode continues. If it is determined that the target range has been switched (S102: YES), the control unit 70 proceeds to S103, where the drive mode is changed from the standby mode to the switching mode, and the drive of the motor 40 is started.

[0041] If it is determined that the driving mode is not the standby mode (S101: NO), the control unit 70 proceeds to S104, where it determines whether the driving mode is the switching mode. If it is determined that the driving mode is not the switching mode (S104: NO), it proceeds to S107. If it is determined that the driving mode is the switching mode (S104: YES), it proceeds to S105.

[0042] In S105, the control unit 70 determines whether the valley position determination flag Fvj is on. Details of the processing related to the valley position determination flag Fvj will be described later. If it is determined that the valley position determination flag Fvj is off (S105: NO), the switching mode is continued. If it is determined that the valley position determination flag Fvj is on (S105: YES), the process proceeds to S106, where the drive mode is changed from the switching mode to the stop mode. In the stop mode, a braking force is generated by circulating the back electromotive force.

[0043] If it is determined that the drive mode is not the switching mode (S104: NO), the control unit 70 proceeds to S107, where it determines whether the drive mode is the stop mode. If it is determined that the drive mode is not the stop mode (S107: NO), the control unit 70 skips the processing from S108 onwards. If it is determined that the drive mode is the stop mode (S107: YES), it proceeds to S108.

[0044] In S108, the control unit 70 determines whether the stop mode duration Xst has elapsed since the start of the stop mode. If it is determined that the stop mode duration Xst has not elapsed (S108: NO), the control unit 70 increments the stop mode timing counter. If it is determined that the stop mode duration Xst has elapsed (S108: YES), the control unit 70 proceeds to S109, where it changes the drive mode from the stop mode to the standby mode. It also resets the stop mode timing counter.

[0045] The valley position determination process of this embodiment will be described with reference to the flowcharts of Figures 8 and 9. In S201, the control unit 70 determines whether the drive mode is the switching mode. If it is determined that the drive mode is not the switching mode (S201: NO), the process proceeds to S222. If it is determined that the drive mode is the switching mode (S201: YES), the process proceeds to S202.

[0046] In S202, the position determination unit 73 determines whether the mountain crossing determination flag Fmj is on. If it is determined that the mountain crossing determination flag Fmj is on (S202: YES), the process proceeds to S206 in Fig. 9. If it is determined that the mountain crossing determination flag Fmj is off (S202: NO), the process proceeds to S203.

[0047] In S203, the position determination unit 73 determines whether the angle change amount Δθ, which is the amount of change between the previous value and the current value of the sensor angle θs, which is the angle detected by the position sensor 55, is equal to or greater than the sudden change determination threshold θth. The sudden change determination threshold θth is a value corresponding to the rotation angle at which the backlash is reduced on the opposite side when the detent roller 26 overcomes the peak 215, and is set depending on the shape of the detent plate 21 and the magnitude of the backlash. The sudden change determination threshold θth may be different values ​​when switching from the P range to the notP range and when switching from the notP range to the P range, depending on the shape of the detent plate 21. If it is determined that the angle change amount Δθ is smaller than the sudden change determination threshold θth (S203: NO), the detent roller 26 is climbing the peak, and the current driving state is maintained. If it is determined that the angle change amount Δθ is equal to or greater than the sudden change determination threshold θth (S203: YES), the process proceeds to S204.

[0048] In S204, the position determination unit 73 determines that the detent roller 26 has passed over the hill portion 215 and turns on the hill-crossing determination flag Fmj. The control unit 70 stores information related to the sensor rotation speed Ns up to the time when the hill-crossing determination flag Fmj is turned on, in association with time information. In S205, the control unit 70 acquires the sensor rotation speed Ns a predetermined time Xc before the hill-crossing determination flag Fmj is turned on as the hill-climbing rotation speed Nc. The predetermined time Xc is set so that the value when the sensor rotation speed Ns is stable while the detent roller 26 is climbing the hill can be acquired as the hill-climbing rotation speed Nc. It is preferable to acquire the value as close as possible to the time when the rotation speed suddenly changes as the detent roller 26 passes over the hill as the hill-climbing rotation speed Nc. Alternatively, the hill-climbing rotation speed Nc may be calculated by averaging multiple values ​​acquired during the section where the sensor rotation speed Ns is stable.

[0049] As shown in FIG. 9, if it is determined that the mountain crossing determination flag Fmj is on (S202: YES), the process proceeds to S206, where a mask time Xmc is set. The mask time Xmc is set according to the vibration state of the driven shaft 47 caused by the kinetic energy of the driven shaft 47 when the backlash reverses after crossing a mountain. Specifically, the mask time Xmc is set to, for example, 5 ms as a reference time and is varied according to the environmental conditions. For example, when the load torque is large, the torque required for switching is large, so the motor current increases. Furthermore, since the suction force is large, the speed at which the detent roller 26 moves toward the bottom of the valley increases. Therefore, as shown in FIG. 10(a), the mask time Xmc is set to be longer as the motor current increases.

[0050] As shown in Figure 10(b), the higher the temperature, the smaller the viscous resistance and the more likely it is to vibrate, so the mask time Xmc is set to be longer as the temperature increases. As shown in Figure 10(c), the higher the voltage, the more likely it is that switching torque will be generated, so the mask time Xmc is set to be longer as the voltage applied to the motor 40 increases. Also, as shown in Figure 10(d), the higher the rotation speed, the more likely it is to vibrate, so the mask time Xmc is set to be longer as the rotation speed increases.

[0051] Furthermore, as shown in Figure 11, the detent torque differs depending on the drive direction, and the detent torque is greater when switching from P range to notP range than when switching from notP range to P range, resulting in greater vibration.

[0052] Therefore, in this embodiment, the mask time Xmc is made variable depending on the drive direction. Specifically, as shown in FIG. 12, the mask time Xmc is set to be longer when switching from the P range to the not-P range than when switching from the not-P range to the P range. The mask time Xmc is obtained from a map corresponding to the motor current, temperature, applied voltage, motor rotation speed, and drive direction. For example, a value is obtained using a map individually set for each parameter, and the largest value is set as the mask time Xmc.

[0053] 9, in S207, the position determination unit 73 determines whether the mask time Xmc has elapsed since the mountain crossing determination flag Fmj was turned on. If it is determined that the mask time Xmc has not elapsed since the mountain crossing determination flag Fmj was turned on (S207: NO), the process proceeds to S208, where the mask time counter is incremented. If it is determined that the mask time Xmc has elapsed since the mountain crossing determination flag Fmj was turned on (S207: YES), the process proceeds to S209.

[0054] In S209, the position determination unit 73 determines whether the current driving direction is a direction in which the sensor angle θs increases. In this embodiment, a positive determination is made when switching from the P range to the notP range, and a negative determination is made when switching from the notP range to the P range. If it is determined that the current driving direction is a direction in which the sensor angle θs decreases (S209: NO), the process proceeds to S215. If it is determined that the current driving direction is a direction in which the sensor angle θs increases (S209: YES), the process proceeds to S210.

[0055] In S210, the position determination unit 73 determines whether the current sensor angle value θs(n) is greater than the held maximum sensor angle θmax. Hereinafter, the current value is given a subscript (n) and the previous value is given a subscript (n-1), as appropriate. If it is determined that the current sensor angle value θs(n) is greater than the held maximum sensor angle θmax (S210: YES), the process proceeds to S210, where the current sensor angle value θs(n) is held as the maximum sensor angle θmax. If it is determined that the current sensor angle value θs(n) is equal to or less than the held maximum sensor angle θmax (S210: NO), the maximum sensor angle θmax is not updated, and the process proceeds to S212.

[0056] In S212, the position determination unit 73 determines whether the maximum value change amount Δθmax (see equation (1-1)), which is the absolute value of the difference between the current value and the previous value of the held maximum sensor angle θmax, is smaller than the position determination threshold value Nth. In this embodiment, the position determination threshold value Nth is set for each range change. The position determination threshold value Nth is a value obtained by multiplying the mountain-climbing rotation speed Nc by a safety coefficient k, which is a value smaller than 1 (see equation (2)). If necessary, a conversion may be performed to match the scale. In this embodiment, the position determination threshold value Nth is set for each range change.

[0057] Δθmax=|θmax(n)-θmax(n-1)| ···(1-1) Nth=Nc×k (2)

[0058] The safety factor k is set to an arbitrary value equal to or less than 1 (e.g., 0.7). The safety factor k may be variable depending on environmental conditions so that it is equal to or less than an arbitrary reference value (e.g., 0.7). For example, the safety factor when the maximum voltage drop occurs is set as the reference value, and the safety factor k is set to a smaller value as the voltage applied to the motor 40 increases. Furthermore, since the rotation speed of the motor 40 increases at high temperatures, the safety factor k is set to a smaller value as the temperature increases. Furthermore, since the sensor rotation speed Ns increases as the load torque before crossing the peak decreases, the safety factor k is set to a smaller value as the load torque decreases. The safety factor k is obtained, for example, from a map corresponding to the voltage, temperature, and load torque. For example, a value is obtained using a map individually set for each parameter, and the smallest value is set as the safety factor k.

[0059] If it is determined that the maximum value change amount Δθmax is smaller than the position determination threshold Nth (S212: YES), the process proceeds to S213, where the counter related to timing the determination wait time Xh is incremented.If it is determined that the maximum value change amount Δθmax is equal to or greater than the position determination threshold Nth (S212: NO), the process proceeds to S214, where the counter related to timing the determination wait time Xh is reset.

[0060] If it is determined that the current drive direction is a direction in which the sensor angle θs is decreasing (S209: NO), the process proceeds to S215, where the position determination unit 73 determines whether the current sensor angle value θs(n) is smaller than the held minimum sensor angle value θmin. If it is determined that the current sensor angle value θs(n) is smaller than the held minimum sensor angle value θmin (S215: YES), the process proceeds to S216, where the current sensor angle value θs(n) is held as the minimum sensor angle value θmin. If it is determined that the current sensor angle value θs(n) is equal to or greater than the held minimum sensor angle value θmin (S215: NO), the minimum sensor angle θmin is not updated, and the process proceeds to S217.

[0061] In S217, the position determination unit 73 determines whether the minimum value change amount Δθmin (see equation (1-2)), which is the difference between the current value and the previous value of the held sensor angle minimum value θmin, is smaller than the position determination threshold value Nth. If it is determined that the minimum value change amount Δθmin is smaller than the position determination threshold value Nth (S217: YES), the process proceeds to S218, where the counter related to timing the determination wait time Xh is incremented. If it is determined that the minimum value change amount Δθmin is equal to or greater than the position determination threshold value Nth (S217: NO), the process proceeds to S219, where the counter related to timing the determination wait time Xh is reset.

[0062] Δθmin=|θmin(n)-θmin(n-1)| ···(1-2)

[0063] In S220, which follows S213, S214, S218, or S219, the position determination unit 73 determines whether the determination wait time Xh is equal to or longer than the valley position determination time Xv. If it is determined that the determination wait time Xh is shorter than the valley position determination time Xv (S220: NO), S221 is skipped. If it is determined that the determination wait time Xh is equal to or longer than the valley position determination time Xv (S220: YES), the process proceeds to S221, where the valley position determination flag Fvj is set to ON.

[0064] 8, in S222, which is reached when it is determined that the drive mode is not the switching mode (S201: NO), the position determination unit 73 turns off the valley position determination flag Fvj and the mountain crossing determination flag Fmj. In S223, the position determination unit 73 resets the held maximum sensor angle value θmax or minimum sensor angle value θmin. The position determination unit 73 also resets the counters for the determination wait time Xh and the mask time Xmc.

[0065] The valley position determination process of this embodiment will be described with reference to the time charts in FIGS. 13 and 14. FIG. 13 illustrates the transition from the P range to the not-P range. The horizontal axis represents a common time axis, and from the top to bottom, the diagram shows the target shift range, rotation angle, rotation speed, mountain-crossing determination flag Fmj, position determination threshold Nth, maximum sensor angle θmax, maximum value change Δθmax, valley position determination flag Fvj, and duty command value. Regarding the rotation angle and rotation speed, the sensor angle θs based on the detection value of the position sensor 55 is indicated by a solid line, the motor angle θm corresponding to the behavior of the motor 40 is indicated by a two-dot chain line, and the output shaft angle θd corresponding to the behavior of the output shaft 15 is indicated by a dashed line. The scales are aligned by gear ratio conversion. The rotation speed of the motor 40 is designated as motor rotation speed Nm. The motor angle when the detent roller 26 is at the bottom of the valley portion 211 is designated as "P," and the motor angle when the detent roller 26 is at the bottom of the valley portion 212 is designated as "not-P."

[0066] As shown in Figure 13, when the target shift range switches from P to not P at time x10, the motor 40 is driven, and at time x11 when the backlash is eliminated, the sensor shaft also begins to rotate, and the sensor angle θs increases as the motor rotates. In this embodiment, the sensor rotation speed Ns is stored in association with time information, at least until the mountain crossing determination flag Fmj is set. While Figure 13 and other figures show a duty command value of 100% when the motor is driven, any value may be used.

[0067] At time x12, when the detent roller 26 passes over the peak 215, the torque reverses and the backlash is quickly eliminated on the opposite side, causing a large change in the detection value of the position sensor 55. In this embodiment, if the angle change amount Δθ, which is the difference between the previous and current sensor angle θs, is equal to or greater than the sudden change determination threshold θth, it is determined that the detent roller 26 has passed over the peak 215, and the peak-crossing determination flag Fmj is turned on. In addition, the sensor rotation speed Ns at a timing a predetermined time Xc before time x12 is obtained as the peak-crossing rotation speed Nc, and the position determination threshold Nth is set (see equation (2)).

[0068] If the sum of the internal backlash Gm and the spline backlash Gs is greater than the angle between the peaks 215 and the valleys 212, the output shaft 15 rotates within the backlash width in a substantially unloaded state, causing the detent roller 26 to be sucked down to the valley bottom. Even when the detent roller 26 reaches the valley bottom, the sensor angle θs oscillates. The vibration is particularly large immediately after the detent roller 26 moves over the peaks 215. Therefore, the maximum sensor angle θmax is not held until the mask time Xmc has elapsed after it is determined that the detent roller 26 has moved over the peaks 215.

[0069] At time x13, when the mask time Xmc has elapsed since it was determined that the detent roller 26 had cleared the ridge 215, the hold process for the maximum sensor angle θmax begins. That is, to mask the hold process from time x12 to time x13, the maximum values ​​MAX1 and MAX2 detected during this period are not held, and the maximum value MAX3 detected after the mask time Xmc has elapsed is held. Note that after the mask time Xmc, the transition up to the first peak is left to chance.

[0070] At time x14, when the maximum value change amount Δθmax becomes smaller than the position determination threshold Nth, measurement of the determination wait time Xh begins. At time x15, when the maximum value change amount Δθmax remains smaller than the position determination threshold Nth throughout the valley position determination time Xv, the valley position determination flag Fvj is turned on. Then, the duty command value is set to 0% and power to the motor 40 is turned off. At time x15, the vibration at the sensor angle θs has not yet subsided, but as long as the vibration amplitude is within the range of the spline backlash Gs, the detent roller 26 does not move. Therefore, it is possible to determine that the detent roller 26 has stopped at the bottom of the valley portion 212 without waiting for the vibration at the sensor angle θs to subside.

[0071] 14 shows the process of switching from notP range to P range, with the horizontal axis representing a common time axis and, from the top, showing the target shift range, rotation angle, rotation speed, mountain crossing determination flag Fmj, position determination threshold Nth, sensor angle minimum value θmin, minimum value change amount Δθmin, valley position determination flag Fvj, and duty command value. The valley position determination process of switching from notP range to P range is generally the same as the process of switching from P range to notP range, except for the rotation direction.

[0072] When the target shift range switches from not P to P at time x20, the motor 40 is driven, and at time x21 when the backlash is eliminated, the sensor shaft also starts to rotate, and the sensor angle θs decreases as the shaft rotates. In addition, the sensor rotation speed Ns is stored in association with the time information, at least until the mountain crossing determination flag Fmj is set.

[0073] At time x22, when the detent roller 26 passes over the peak 215, the sensor angle θs changes significantly. If the angle change Δθ becomes equal to or greater than the sudden change determination threshold θth, it is determined that the detent roller 26 has passed over the peak 215, and the peak-crossing determination flag Fmj is turned on. In addition, the sensor rotation speed Ns at a timing a predetermined time Xc before time x22 is obtained as the peak-crossing rotation speed Nc, and the position determination threshold Nth is set (equation (2)).

[0074] At time x23, when the mask time Xmc has elapsed since time x22, the hold process for the minimum sensor angle θmin begins. That is, since the hold process from time x22 to time x23 is masked, the minimum values ​​MIN1 and MIN2 detected during this period are not held, and the minimum value MIN3 detected after the mask time Xmc has elapsed is held.

[0075] At time x24, the minimum value change amount Δθmin becomes smaller than the position determination threshold Nth, and at time x25 when the valley position determination time Xv has elapsed, the valley position determination flag Fvj is turned on, the duty command value is set to 0% and power to the motor 40 is turned off.

[0076] In this embodiment, since the sensor angle θs is not updated to an amount equal to or greater than the backlash width after the detent roller 26 has fallen into the valley bottom, the maximum sensor angle θmax or minimum sensor angle θmin with respect to the direction of travel of the sensor angle θs is held to determine whether the detent roller 26 has fallen into the valley bottom. This makes it possible to appropriately determine whether the detent roller 26 has fallen into the valley, even if, for example, there is a relatively large backlash and the sensor shaft continues to vibrate after the detent roller 26 has fallen into the valley.

[0077] Also, immediately after the detent roller 26 reaches the valley portions 211 and 212, the detent roller 26 may oscillate at the valley position and not stop. In this embodiment, to prevent the motor 40 from being turned off while the detent roller 26 is oscillating, a mask time Xmc is provided during which the maximum sensor angle θmax and the minimum sensor angle θmin are not held after the detent roller 26 has passed over the peak portion 215. Furthermore, by varying the mask time Xmc depending on the environmental conditions, it is possible to more appropriately determine whether the detent roller 26 has fallen into the valley bottom.

[0078] As described above, in the parking lock system 1 that includes the electric actuator 10 having the motor 40, the detent mechanism 20, and the position sensor 55, the control device 60 controls the switching of the detent mechanism 20 by driving the motor 40.

[0079] The detent mechanism 20 has a detent plate 21 and a detent roller 26. The detent plate 21 is formed with a plurality of valleys 211, 212 and peaks 215 separating the valleys 211, 212. The detent roller 26 is movable between the valleys 211, 212 when the output shaft 15 is driven by the electric actuator 10. The position sensor 55 is capable of detecting the position of the output shaft 15. Here, the position sensor 55 is not limited to a sensor that directly detects the position of the output shaft 15, but also includes a sensor that detects a shaft connected to the output shaft 15, a detection target that can be converted by a gear ratio, etc.

[0080] The control unit 70 of the control device 60 includes a position determination unit 73 that determines when the detent roller 26 reaches the bottom of the target valley when the detent roller 26 is moved to the target valley. "The detent roller reaches the bottom of the target valley" refers to a state in which the oscillation of the detent roller 26 has converged and the detent roller 26 has stopped at the valley bottom, regardless of the state of the sensor shaft.

[0081] After the load torque is reversed as the detent roller 26 passes over the peak 215, the position determination unit 73 sets a mask time during which it does not perform position determination, and after the mask time, it performs position determination using the detection value of the position sensor 55. This masks transient changes due to backlash reversal, allowing for appropriate position determination.

[0082] The position determination unit 73 determines that the detent roller 26 has reached the bottom of the target valley based on the most advanced value, which is the detection value of the position sensor 55 when the detent roller 26 has advanced furthest in the travel direction in accordance with the drive direction of the output shaft 15. In this embodiment, the target valley when switching from the P range to the notP range is valley 212, and the most advanced value is the maximum sensor angle value θmax. Similarly, the target valley when switching from the notP range to the P range is valley 211, and the most advanced value is the minimum sensor angle value θmin. This makes it possible to quickly determine the state of the detent roller 26 even if, for example, there is play between the detection unit of the position sensor 55 and the output shaft 15 and the detection value of the position sensor 55 fluctuates.

[0083] The masking time Xmc is set according to the current supplied to the motor 40 before the load torque reversal. The masking time Xmc is set according to the voltage applied to the motor 40 before the load torque reversal. The masking time Xmc is also set according to the temperature before the load torque reversal. Furthermore, the masking time Xmc is set according to the sensor rotation speed Ns before the load torque reversal. This allows the masking time Xmc to be set appropriately according to the environmental conditions.

[0084] Furthermore, the mask time Xmc is set to a different value depending on the drive direction of the output shaft 15. Since the load torque differs depending on the drive direction, the mask time Xmc can be set more appropriately.

[0085] (Second embodiment) 15 to 17 show a second embodiment. In this embodiment, the valley position determination process differs from the above embodiment, and this point will be mainly described. In this embodiment, the mask time is determined according to the amplitude after the detent roller 26 has passed over the peak.

[0086] The valley position determination process of this embodiment will be described with reference to the flowcharts of FIGS. 15 and 16. The processes of S301 to S303 are the same as the processes of S201 to S203 in FIG. 8. In S304, which is reached when it is determined that the angle change amount Δθ is equal to or greater than the sudden change determination threshold θth (S303: YES), the position determination unit 73 turns on the mountain crossing determination flag Fmj and the mask flag Fmc. In this embodiment, the maximum sensor angle value θmax or the minimum sensor angle value θmin is not held while the mask flag Fmc is on. The process of S305 is the same as the process of S205 in FIG. 8.

[0087] If it is determined that the mountain crossing determination flag Fmj is on (S302: YES), the process proceeds to S306, where the position determination unit 73 determines whether the slope of the sensor angle θs has reversed. If it is determined that the slope of the sensor angle θs has not reversed (S306: NO), the process proceeds to S310. If it is determined that the slope of the sensor angle θs has reversed (S306: YES), the process proceeds to S307. In S307, the position determination unit 73 stores the sensor angle θs immediately before the reversal as the current peak value.

[0088] In S308, the position determination unit 73 determines whether the amplitude Δθp (see Equation 3), which is the absolute value of the difference between the current peak value θp(n) and the previous peak value θp(n-1) of the sensor angle θs, is equal to or less than the vibration determination threshold Ath. If it is determined that the amplitude Δθp is greater than the vibration determination threshold Ath (S308: NO), the process proceeds to S310. If it is determined that the amplitude Δθp is equal to or less than the vibration determination threshold Ath (S308: YES), the process proceeds to S309, where the mask flag Fmc is turned off.

[0089] Δθp=θp(n)-θp(n-1) ···(3)

[0090] As shown in Fig. 16, in S310, the position determination unit 73 determines whether the mask flag Fmc is off. If it is determined that the mask flag Fmc is on (S310: NO), the process from S310 onwards is skipped. If it is determined that the mask flag Fmc is off (S310: YES), the process proceeds to S311. The processes of S311 to S323 are the same as the processes of S209 to S221 in Fig. 9. Furthermore, the processes of S324 and S325 in Fig. 15 are the same as the processes of S222 and S223 in Fig. 8.

[0091] The valley position determination process of this embodiment will be described based on the time chart in Figure 17. Here, switching from P range to notP range will be described as an example. In Figure 17, the horizontal axis represents a common time axis, and from the top, the horizontal axis shows the target shift range, rotation angle, rotation speed, mountain crossing determination flag Fmj, oscillation amplitude Δθp, mask flag Fmc, maximum sensor angle θmax, maximum value change amount Δθmax, valley position determination flag Fvj, and duty command value.

[0092] The processing from time x20 to time x22 is the same as the processing from time x10 to time x12 in Fig. 10. Furthermore, at time x22, when the angle change amount Δθ becomes equal to or greater than the sudden change determination threshold θth and it is determined that the detent roller 26 has passed over the peak portion 215, the mask flag Fmc is turned on in addition to the peak pass determination flag Fmj.

[0093] When the mountain-crossing determination flag Fmj is set at time x22, each time a reversal of the slope of the sensor angle θs is detected, the value immediately before the reversal is detected is stored as the peak value θp, and an oscillation amplitude Δθp, which is the difference from the previous value, is calculated. To avoid complexity, in Figure 17, the oscillation amplitudes on the increasing side of the sensor angle are denoted as Δθp1, Δθp2, Δθp3, and Δθp4, in order from time x22.

[0094] At time x23, when the vibration amplitude Δθp3 becomes equal to or less than the vibration determination threshold Ath, the mask flag Fmc is turned off and the maximum sensor angle θmax is held. At time x24, when the maximum value change amount Δθmax becomes smaller than the valley position determination threshold Nth, measurement of the determination wait time Xh begins, and at time x25 when the valley position determination time Xv has elapsed, the valley position determination flag Fvj is turned on. Then, the duty command value is set to 0[%] and power to the motor 40 is turned off.

[0095] In this embodiment, the position determination unit 73 determines that the mask time Xmc has elapsed when the oscillation amplitude Δθp of the detection value of the position sensor 55 becomes equal to or less than the vibration determination threshold Ath. In other words, the mask time Xmc is the period until the oscillation amplitude Δθp of the detection value of the position sensor 55 becomes equal to or less than the vibration determination threshold Ath. This allows the mask time Xmc to be set appropriately depending on the environmental conditions.

[0096] In the embodiment, the parking lock system 1 corresponds to the "drive system," the electric actuator 10 corresponds to the "actuator," the detent plate 21 corresponds to the "detent member," the detent roller 26 corresponds to the "engagement member," the motor 40 corresponds to the "drive source," the driven shaft 47 corresponds to the "shaft," and the control device 60 corresponds to the "actuator control device." Also, the sensor rotation speed Ns corresponds to the "drive change rate."

[0097] When switching from P range to notP range, the target valley is valley 212, the most advanced value is the maximum sensor angle value θmax, and the amount of change in the most advanced value is the maximum change amount Δθmax. Also, when switching from notP range to P range, the target valley is valley 211, the most advanced value is the minimum sensor angle value θmin, and the amount of change in the most advanced value is the minimum change amount Δθmin.

[0098] (Other embodiments) In the above embodiment, the position determination threshold is variable depending on the motor applied voltage, motor current, and load torque. In other embodiments, some of these may be omitted, or the position determination threshold may be changed depending on other parameters.

[0099] In the first embodiment, the mask time is variable depending on the current, voltage, temperature, and drive change rate. In other embodiments, some of these may be omitted, or the mask time may be changed depending on other parameters.

[0100] In the above embodiment, the position determination threshold is set for each range change. In other embodiments, the position determination threshold does not need to be set for each range change. For example, the position determination threshold is set at the first range change after a start switch, such as an ignition switch of a vehicle, is turned on, and the position determination threshold set at the first change is used until the start switch is turned off. The same applies to the mask time.

[0101] In the above embodiment, the reduction mechanism is configured with a worm gear, a helical gear, an intermediate gear, or the like. In other embodiments, the configuration of the reduction mechanism and the number of reduction stages may differ from those in the above embodiment. In the above embodiment, the drive source is a brushed DC motor. In other embodiments, the drive source may be a motor other than a brushed DC motor, or may be a solenoid, or the like. In the above embodiment, the electric actuator is a rotary type, but in other embodiments, it may be a linear type.

[0102] In the above embodiment, the electric actuator is applied to a parking lock system. In other embodiments, the electric actuator may be applied to an in-vehicle system other than a parking lock system or a drive system other than an in-vehicle system.

[0103] The present invention may be characterized as follows, for example: "An actuator control device according to any one of claims 1 to 6, wherein the mask time is set to a different value depending on the drive direction of the output shaft."

[0104] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer. As described above, the present invention is not limited to the above embodiments and can be embodied in various forms without departing from the spirit of the invention. [Explanation of symbols]

[0105] 1. Parking lock system (drive system) 10. Electric actuator (actuator) 15 Output shaft 20: Detent mechanism 21: Detent plate (detent member) 221, 222... Valley 215... Peak 26 Detent roller (engagement member) 40 Motor (drive source) 55 Position sensor 60...Control device (actuator control device) 73: Position determination unit 74: Threshold setting unit

Claims

1. an actuator (10) having a drive source (40); a detent mechanism (20) including a detent member (21) having a plurality of valleys (211, 212) and peaks (215) separating the valleys, and an engaging member (26) that is movable between the valleys when the output shaft (15) is driven by the actuator; a position sensor (55) capable of detecting the position of the output shaft; In a drive system (1) comprising: an actuator control device that controls switching of the detent mechanism by driving the actuator, a position determination unit (73) for determining when the engaging member has reached the bottom of the target valley portion when the engaging member is moved to the target valley portion, the position determination unit provides a mask time during which no position determination is performed after the load torque is reversed as the engaging member overcomes the ridge, and performs position determination using the detection value of the position sensor after the mask time.

2. 2. The actuator control device according to claim 1, wherein the position determination unit determines that the engagement member has fallen to the bottom of the target valley portion based on an advance value that is a detection value of the position sensor when the engagement member has advanced furthest in the advance direction, in accordance with a drive direction of the output shaft.

3. 3. The actuator control device according to claim 1, wherein the mask time is set in accordance with a current supplied to the actuator before a load torque reversal.

4. 3. The actuator control device according to claim 1, wherein the mask time is set in accordance with the voltage applied to the actuator before the load torque is reversed.

5. 3. The actuator control device according to claim 1, wherein the mask time is set in accordance with the temperature before the load torque is reversed.

6. 3. The actuator control device according to claim 1, wherein the mask time is set in accordance with a rate of change in drive of the output shaft before a load torque reversal occurs.

7. 3. The actuator control device according to claim 1, wherein the position determination unit determines that the mask time has elapsed when a vibration amplitude of the detected value of the position sensor becomes equal to or less than a vibration determination threshold value.

8. The actuator control device according to claim 1 or 2, wherein the mask time is set to a different value depending on the drive direction of the output shaft.

Images