Park lock system and control method for park lock system

Abstract

The purpose of the present invention is to control an actuator on the basis of the rotational speed of a rotary element in a drive power transmission path, even in situations in which information correlated to the speed of a vehicle cannot be acquired. Provided is a park lock system (1) for an electric vehicle, said part lock system (1) comprising: a lock wheel (41); a lock section (44) that is capable of engaging an engagement section (42) of the lock wheel (41); an actuator (45) that switches between the engagement and the disengagement of the engagement section (42) and the lock section (44); and a controller (50) that controls the operation of the actuator (45), wherein the controller (50) causes the lock section (44) to engage with the engagement section (42) when the shift range of the electric vehicle is a park range (P), causes the lock section (44) to disengage from the engagement section (42) when the shift range of the electric vehicle is a range (nP) other than the park range, determines whether the rotational speed of a drive motor (10) is equal to or less than a prescribed engagement permissible threshold value on the basis of the power generated according to the rotational speed of the drive motor (10), and prohibits the engagement of the lock section (44) to the engagement section (42) when the rotational speed of the drive motor (10) exceeds the prescribed engagement permissible threshold value.

Description

[0001] [Document name] Statement

[0002] [Title of invention] Park lock system and control method for park lock system

[0003] [Technical Field]

[0004]

[001] The present invention relates to a park lock system and a control method for the park lock system.

[0005] [Background technology]

[0006] [. 0 0 2] A park lock system is provided in the drivetrain of a vehicle and locks the rotating elements of the drivetrain to prevent the wheels from rotating when the vehicle is parked. For example, Patent Document 1 discloses a parking lock system that includes a parking rod, a parking lever, and a parking gear, where the parking lever is swingable around its axis by an actuator, and the parking gear side of the parking lever is provided with a convex portion that can engage with the parking gear, and the system can be switched between a state in which the convex portion and the parking gear are engaged and a state in which the engagement is released. The parking gear is connected to the driveshaft and is provided so as to be able to engage with the convex portion of the parking lever, and when the parking gear and the convex portion engage with each other, rotation of the driveshaft is restricted.

[0007]

[0003] In the parking lock system described in Patent Document 1, when the shift range is switched from parking range (P range) to a range other than P range (not P range) and from not P range to P range, an actuator is driven to engage or disengage the parking gear and the convex portion of the parking lever. Regardless of the shift range, the parking lock system may also be used to ensure safety when a vehicle malfunction occurs or the ignition switch is turned off. For example, if a malfunction of a specific component in the vehicle system is detected or if an off signal is detected from the ignition switch, the park lock system will engage the parking gear and the convex portion of the parking lever to restrict wheel rotation. If the drive shaft is rotating at high speed at this time, there is a risk of damage to the components of the parking lock system. In response to this, Patent Document 2 proposes a parking lock system that allows the parking gear and the protrusion of the parking lever to engage when the vehicle speed or acceleration is below a predetermined value.

[0008] [Prior art documents]

[0009] [Patent documents]

[0010]

〇 0 0 4

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-159723

[0012] [Patent Document 2] German Patent Application Publication No. 102020211436

[0013] Summary of the Invention

[0014] [Problem to be solved by the invention]

[0015] [0 0 5] However, depending on the vehicle system configuration, the parking lock system may not be configured to obtain information correlated with vehicle speed from other control devices. Furthermore, even if a sensor that measures information correlated with vehicle speed fails, the parking lock system may not be able to obtain the information. In such a case, the actuator may be activated to engage the parking gear with the protrusion on the parking lever, even though the driveshaft is rotating at high speed, potentially damaging the parking lock system.

[0016]

[0006] The present invention has been made in consideration of the above problems, and provides a parking lock system and a control method for a parking lock system that can control an actuator based on the rotational speed of a rotating element in a driving force transmission path even in a situation where information correlated with the vehicle speed cannot be obtained.

[0017] [Means for Solving the Problems]

[0007] In order to solve the above problem, according to one aspect of the present invention, a parking lock system that holds wheels in a state where they cannot rotate when an electric vehicle is parked comprises: a lock wheel having at least one engaging portion and fixed to a rotation shaft provided in a driving force transmission path that transmits rotational torque of a drive motor to the wheels; a locking portion that can engage with the engaging portion of the lock wheel; an actuator that switches between engagement and disengagement of the locking portion with the engaging portion; and a control device that controls the operation of the actuator, wherein the control device engages the locking portion with the engaging portion when the shift range of the electric vehicle is in a parking range, and disengages the locking portion from the engaging portion when the shift range of the electric vehicle is in a range other than the parking range, and determines whether the rotation speed of the drive motor is equal to or less than a predetermined engagement allowance value based on electric power generated in accordance with the rotation speed of the drive motor, and A parking lock system is provided that prohibits the locking portion from locking with the engaging portion while the degree of locking exceeds the predetermined engagement allowance value.

[0018]

[0008] To solve the above problem, according to another aspect of the present invention, there is provided a control method for a parking lock system which holds the wheels in an unrotatable state when the electric vehicle is parked, the control method comprising: a lock wheel having at least one engaging portion, the lock wheel being fixed to a rotation shaft provided in a driving force transmission path which transmits the rotational torque of a drive motor to wheels of an electric vehicle; a locking portion engageable with the engaging portion of the lock wheel; an actuator which switches between engagement and disengagement of the locking portion with the engaging portion; and a control device which controls operation of the actuator, the control device engaging the locking portion with the engaging portion when the shift range of the electric vehicle is in a parking range, and disengaging the locking portion from the engaging portion when the shift range of the electric vehicle is in a range other than the parking range, and determining whether the rotational speed of the drive motor is equal to or less than a predetermined engagement allowance value based on electric power generated in accordance with the rotational speed of the drive motor, There is provided a control method for a parking lock system that prohibits the locking portion from locking with the engaging portion while the rotational speed of the drive motor exceeds the predetermined engagement allowance value.

[0019] [Effects of the Invention]

[0020]

[0009] As described above, according to the present invention, even in a situation where information correlated with the vehicle speed cannot be obtained, it is possible to control the actuator based on the rotational speed of the rotating element in the driving force transmission path.

[0021] [Brief explanation of the drawings]

[0022] [ 0 0 1 0 ]

[0023] [Figure 1] An explanatory diagram showing an example configuration of a parking lock system according to an embodiment of the present invention.

[0024] [Figure 2] An explanatory diagram showing the disengaged state of the park lever and lock wheel of the parking lock system of the same embodiment.

[0025] [Figure 3] An explanatory diagram showing the engaged state of the park lever and lock wheel of the parking lock system of the same embodiment.

[0026] [Figure 4] A block diagram showing an example configuration of a control device of the parking lock system according to the same embodiment.

[0027] [Figure 5] A flowchart showing a control method for the parking lock system according to the same embodiment.

[0028] [Figure 6] An explanatory diagram showing the relationship between the rotation speed of the drive motor and the active short circuit current value.

[0029] [Figure 7] An explanatory diagram showing the relationship between the rotational speed of the drive motor and the back electromotive force voltage.

[0030] [Figure 8] An explanatory diagram showing an example configuration of a parking lock system related to the first modified example.

[0031] [Fig. 9] An explanatory diagram showing a configuration example of a parking lock system according to a second modified example. [Fig. 10] An explanatory diagram showing a configuration example of a parking lock system according to a third modified example.

[0032] DETAILED DESCRIPTION OF THE INVENTION

[0033]

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0034] [ 0 0 1 2 ]

[0035] <1. Park Lock System> First, a configuration example of a parking lock system according to an embodiment of the present disclosure will be described. FIG. 1 is a schematic diagram showing a configuration example of a parking lock system. The illustrated parking lock system 1 is a parking lock system 1 applied to an electric vehicle that uses a drive motor 10 as a driving force source. The park lock system 1 includes a lock mechanism 40 attached to a transmission 20 that transmits driving torque output from the drive motor 10 to axles 33a, 33b connected to left and right wheels 35a, 35b, and a control device 50 that controls the operation of the lock mechanism 40.

[0036]

[0013] The drive motor 10 is, for example, a permanent magnet three-phase AC motor including a rotor 13 attached to a motor shaft 15 that outputs rotational torque, and a stator 11 arranged on the outer periphery of the rotor 13. The drive motor 10 is driven by three-phase AC power supplied from an inverter 19. The inverter 19 is controlled by a motor controller 80, and converts DC power output from a battery (high-voltage battery) 70 into three-phase AC power for output. The drive motor 10 is equipped with a rotation speed sensor 17 that measures the rotation speed of the motor shaft 15. The rotation speed sensor 17 is, for example, a resolver, and corresponds to a sensor that outputs a state value correlated to the rotation speed of the motor shaft 15.

[0037]

[0014] The transmission 20 includes a gear mechanism that transmits rotational torque output via the motor shaft 15, and a differential gear 31 that distributes the rotational torque to left and right wheels 35a, 35b. The gear mechanism includes a drive gear 21 that is fixed to the motor shaft 15 and rotates synchronously with the motor shaft 15, a driven gear 23 that is fixed to the intermediate shaft 25, meshes with the drive gear 21, and rotates synchronously with the intermediate shaft 25, and an output gear 27 that is fixed to the intermediate shaft 25, meshes with the ring gear 29 of the differential gear 31, and rotates synchronously with the intermediate shaft 25.

[0038]

[0015] The lock mechanism 40 includes a lock wheel 41, a park lever 43, and an actuator 45. The lock wheel 41 has at least one engagement portion on its outer circumferential surface, is fixed concentrically to the motor shaft 15, and rotates synchronously with the motor shaft 15. The park lever 43 has a locking portion that can engage with the engagement portion of the lock wheel 41, and is supported so as to be displaceable so that the engagement and disengagement of the locking portion with the engagement portion can be switched. The actuator 45 displaces the park lever 43 to switch the engagement and disengagement of the locking portion with the engagement portion. The actuator 45 includes a component that is driven by controlling the supply of power, such as an electric motor, and is an actuator that can displace the park lever 43.

[0039]

[0016] The control device 50 is configured with a microcomputer and peripheral components, and controls the operation of the actuator 45. The control device 50 is configured to be able to acquire a sensor signal from the rotation speed sensor 17. The control device 50 is also configured to be able to acquire a sensor signal from the shift position sensor 3, which detects the position of the shift range selected by the driver operating the shift lever or shift switch. Furthermore, the control device 50 is connected to the motor controller 80 so as to be able to communicate with it.

[0017]

[0040] <2. Locking mechanism> Next, we will explain in detail the locking mechanism 40 of the Park Lock System 1.

[0041]

[0018] Fig. 2 and Fig. 3 are schematic diagrams showing an example of the configuration of the locking mechanism 40. Fig. 2 shows the configuration of the locking mechanism 40.

[0042] FIG. 1 shows an unlocked state of the locking mechanism 40, and FIG. 2 shows a locked state of the locking mechanism 40. In this specification, the state in which the rotation of the motor shaft 15 is restricted is referred to as the "locked state." In addition, the state in which the restriction on the rotation of the motor shaft 15 is released is referred to as the "unlocked state."

[0043]

[0019] The lock mechanism 40 shown in FIG. 1 includes a lock wheel 41, a park lever 43, and an actuator 45. The lock wheel 41 has at least one engaging portion 42 on its outer circumferential surface. The lock wheel 41 is fixed concentrically to the motor shaft 15. The lock wheel 41 transmits the rotational torque of the drive motor 10 to the wheels 35a, 35b, etc. via the intermediate shaft 25.

[0044] The parking lever 43 may be fixed to a rotating shaft provided in a driving force transmission path that transmits the driving force to the lock wheel 41. The parking lever 43 has a locking claw (locking portion) 44 that can enter and engage with the engaging portion 42 of the lock wheel 41. The parking lever 43 is supported so as to be swingable around the rotating shaft 43a.

[0045]

[0020] The actuator 45 includes an electric motor 46 and a lock piston 47. The lock piston 47 is moved toward and away from the park lever 43 by the electric motor 46. When the lock piston 47 moves toward the park lever 43, the locking claw 44 of the park lever 43 enters the engaging portion 42 of the lock wheel 41, restricting the rotation of the motor shaft 15. On the other hand, when the lock piston 47 moves in a direction away from the park lever 43, the locking claw 44 of the park lever 43 disengages from the engaging portion 42 of the lock wheel 41, and the restriction on the rotation of the motor shaft 15 is released.

[0046]

[0021] When the shift range is in parking range (P), the locking claw 44 of the park lever 43 enters the engaging portion 42 of the lock wheel 41, thereby locking the vehicle (see Figure 3). On the other hand, when the shift range is in a range other than parking range (nP), the locking claw 44 of the park lever 43 disengages from the engaging portion 42 of the lock wheel 41, thereby unlocking the vehicle (see Figure 2).

[0047] [ 0 0 2 2 ]

[0048] <3. Control device> Next, we will explain the control device 50 of the parking lock system 1 according to this embodiment.

[0049]

[0023] Figure 4 is a block diagram showing the functional configuration of the control device 50. The control device 50 includes a processing unit 61 and a memory unit 63. The processing unit 61 includes a microcomputer. The memory unit 63 includes storage media such as RAM (Random Access Memory) and ROM (Read Only Memory). The memory unit 63 stores programs executed by the processing unit 61, various parameters used in calculations, calculation results, detection results, etc. A portion of the memory unit 63 is used as a work area for the processing unit 61.

[0050]

[0024] The processing unit 61 includes a shift range determination unit 51, a lock state determination unit 52, a sensor abnormality determination unit 53, an inverter control command unit 55, a rotation speed determination unit 57, and an actuator control unit 59. Each of these units is realized by, for example, a microcomputer executing a program. However, part of the control device 50 may be configured by hardware such as an analog circuit.

[0051]

[0025] The shift range determination unit 51 acquires a sensor signal transmitted from the shift position sensor 3, which detects the position of the shift range selected by the driver operating the shift lever or shift switch, and determines the shift range. For example, the shift range determination unit 51 determines whether or not a sensor signal is output from the shift position sensor 3 when the parking range is selected, and determines whether the shift range is the parking range or a range other than the parking range.

[0052]

[0026] The lock state determination unit 52 determines whether the lock mechanism 40 is locked or unlocked. For example, the lock state determination unit 52 determines the lock state of the lock mechanism 40 based on a sensor signal from an angle sensor provided in the actuator 45 that detects the rotation angle of the motor shaft of the electric motor 46.

[0053]

[0027] The sensor abnormality determination unit 53 determines whether or not there is an abnormality in the rotation speed sensor 17. For example, the sensor abnormality determination unit 53 may determine whether or not there is an abnormality in the rotation speed sensor 17 based on a sensor signal from the rotation speed sensor 17, or may obtain a signal indicating the occurrence of an abnormality in the rotation speed sensor 17 output from a processing device (not shown) and determine whether or not there is an abnormality in the rotation speed sensor 17. The method for determining whether or not there is an abnormality in the rotation speed sensor 17 is not particularly limited.

[0054]

[0028] When the shift range is a range other than the parking range and the sensor abnormality determination unit 53 determines that the rotation speed sensor 17 is abnormal, the inverter control command unit 55 outputs a command to the motor controller 80 to put the inverter 19 into a predetermined state. The inverter control command unit 55 puts the rotation speed of the drive motor 10 into a state where it can be estimated based on the power generated according to the rotation speed of the drive motor 10. For example, the inverter control command unit 55 outputs a command to the motor controller 80 to execute active short circuit control of the inverter 19. Alternatively, the inverter control command unit 55 outputs a command to the motor controller 80 to stop driving the inverter 19 and put the drive motor 10 into a freewheeling state.

[0055]

[0029] When the sensor abnormality determination unit 53 determines that the rotation speed sensor 17 is not abnormal, the rotation speed determination unit 57 determines the rotation speed of the drive motor 10 based on the sensor signal of the rotation speed sensor 17. On the other hand, when the sensor abnormality determination unit 53 determines that the rotation speed sensor 17 is abnormal, the rotation speed determination unit 57 determines the rotation speed of the drive motor 10 based on information about the power flowing through the inverter 19 obtained from the motor controller 80.

[0056]

[0030] The actuator control unit 59 controls the driving of the actuator 45. When the shift range is in the parking range, the actuator control unit 59 locks the locking mechanism 40 to restrict the rotation of the motor shaft 15 and prevent the wheels 35a and 35b from rotating. When the shift range is in a range other than the parking range, the actuator control unit 59 releases the locking mechanism 40 from its locked state to allow the motor shaft 15 to rotate and allow the wheels 35a and 35b to rotate.

[0057]

[0031] Furthermore, when the actuator control unit 59 receives a command to lock the lock mechanism 40 when the shift range is in a range other than the parking range and the lock mechanism 40 is unlocked, it determines whether the rotational speed of the drive motor 10 is equal to or less than a predetermined engagement permission threshold. The actuator control unit 59 prohibits the lock mechanism 40 from being locked while the rotational speed of the drive motor 10 exceeds the predetermined engagement permission threshold. The predetermined engagement permission threshold is set to any appropriate value as a rotational speed value that will not damage the lock mechanism 40 even if the locking claw 44 of the park lever 43 enters the engagement portion 42 of the lock wheel 41. In other words, the actuator control unit 59 puts the locking mechanism 40 into the locked state after the rotational speed of the drive motor 10 becomes low.

[0058] <4. Control Method> Next, the control method by the control device 50 of the parking lock system 1 according to this embodiment will be explained in detail.

[0059]

[0033] Figure 5 is a flowchart showing an example of a control method for the parking lock system 1 executed by the control device 50. First, after the park lock system 1 is activated, the shift range determination unit 51 of the processing unit 61 determines whether the position of the shift range selected by the driver operating the shift lever or shift switch is the parking range based on the sensor signal of the shift position sensor 3 (step S11). If the shift range determination unit 51 determines that the shift range is the parking range (S11 / Yes), the lock state determination unit 52 determines whether the lock mechanism 40 is in a locked state (step S13). If the lock state determination unit 52 determines that the lock mechanism 40 is in a locked state (S13 / Yes), the process returns to step S11. In this case, the locking mechanism 40 is in a locked state, and the rotation of the wheels 35a and 35b is restricted when the shift range is in the parking range.

[0060]

[0034] On the other hand, if the lock state determination unit 52 does not determine that the lock mechanism 40 is in a locked state (S13 / NO), the process proceeds to step S23 described later, and a process is executed to switch the lock mechanism 40 to a locked state.

[0061]

[0035] In the above step S11, if the shift range determination unit 51 does not determine that the shift range is the parking range (S11 / NO), the lock state determination unit 52 determines whether the lock mechanism

[0062] The lock state determination unit 52 determines whether the lock mechanism 40 is in an unlocked state (Step S15). If the lock state determination unit 52 determines that the lock mechanism 40 is in an unlocked state (S15 / Yes), the process proceeds directly to Step S19. On the other hand, if the lock state determination unit 52 does not determine that the lock mechanism 40 is in an unlocked state (S15 / N), the actuator control unit 59 drives the actuator 45 to disengage the locking claw 44 of the park lever 43 from the engaging portion 42 of the lock wheel 41 (Step S17). This causes the wheels 35a, 3

[0063] The restriction on the rotation of the actuator 45 is released, allowing the electric vehicle to travel. When the locking mechanism 40 is in the unlocked state, the actuator control unit 59 stops driving the actuator 45. This keeps the locking mechanism 40 in the unlocked state.

[0064]

[0036] Next, the shift range determination unit 51 determines whether the shift range has been switched to the parking range (step S19). If the shift range determination unit 51 determines that the shift range has been switched to the parking range (S19 / Yes), the process proceeds to step S23.

[0065]

[0037] On the other hand, if the shift range determination unit 51 does not determine that the shift range has been switched to the parking range (S19 / NO), the actuator control unit 59 determines whether the situation requires the locking mechanism 40 to be locked (step S21). For example, the actuator control unit 59 determines that the situation requires the locking mechanism 40 to be locked when it cannot acquire a sensor signal from the rotation speed sensor 17, when it receives a signal or message indicating a malfunction in the electric vehicle system, or when it receives a signal indicating that the ignition switch of the electric vehicle has been forcibly turned off, or when the CAN (Controller Area Network) signal that communicates with the electric vehicle system is interrupted. A situation in which the locking mechanism 40 should be locked when the shift range is in a range other than the parking range means that the electric vehicle needs to be stopped.

[0066]

[0038] Next, the actuator control unit 59 is in a state where the lock mechanism 40 should be locked. The relationship between the value of the active short circuit current A_m and the rotational speed N_m of the drive motor 1 can be determined in advance by experiments, simulations, etc.

[0067]

[0041] Figure 6 is an explanatory diagram showing the relationship between the rotational speed N_m of the drive motor 10 and the current value A_m of the active short circuit current. The current value A_m of the active short circuit current changes depending on the rotational speed N_m of the drive motor 10. The current value A_m of the active short circuit current depends on the rotational speed N_m of the drive motor 10 as well as the temperature. However, the closer the rotational speed N_m of the drive motor 10 is to zero, the closer the current value A_m of the active short circuit current is to zero. Therefore, by executing active short circuit control of the inverter 19, it is possible to obtain information on the active short circuit current that can be used to determine whether the rotational speed N_m of the drive motor 10 is equal to or less than a predetermined engagement permission threshold.

[0068]

[0042] In the active short circuit control, it is possible to prevent the generation of counter electromotive force, so that even if the rotation speed N_m of the drive motor 10 is high, it is possible to prevent the generation of high voltage power. Therefore, when an abnormality occurs in the high voltage system, it is advantageous in that it can prevent electric shock, etc.

[0069]

[0043] The inverter control command unit 55 instructs the motor controller 80 to stop driving the inverter 19 and enter a freewheeling state, and acquires the measured back electromotive force voltage value from the motor controller 80. When the drive motor 10 is in a freewheeling state, the drive motor 10 functions as a generator and generates back electromotive force. The relationship between the generated back electromotive force voltage V_m and the rotational speed N_m of the drive motor 10 can be determined in advance by experiments, simulations, etc.

[0070]

[0044] Figure 7 is an explanatory diagram showing the relationship between the rotational speed N_m of the drive motor 10 and the back electromotive force voltage value V_m. The back electromotive force voltage value V_m changes linearly according to the rotational speed N_m of the drive motor 10. The back electromotive force voltage value V_m depends on the rotational speed N_m of the drive motor 10 as well as temperature. However, the closer the rotational speed N_m of the drive motor 10 is to zero, the closer the back electromotive force voltage value V_m is to zero. Therefore, by putting the drive motor 10 into a freewheeling state, it is possible to obtain back electromotive force voltage information that can be used to determine whether the rotational speed N_m of the drive motor 10 is equal to or less than a predetermined engagement allowance value.

[0071]

[0045] Next, the rotational speed determination unit 57 acquires information on the active short circuit current or back electromotive force voltage from the motor controller 80, and estimates the rotational speed of the drive motor 10 by referring to the characteristic data shown in Figure 6 or Figure 7 (step S29).

[0072]

[0046] Next, the actuator control unit 59 determines whether the rotational speed of the drive motor 10 measured in step S25 or the rotational speed of the drive motor 10 estimated in step S29 is equal to or less than a predetermined engagement permission threshold (step S31). Instead of determining whether the rotational speed of the drive motor 10 estimated in step S29 is equal to or less than a predetermined engagement permission threshold, the actuator control unit 59 may determine whether the acquired active short circuit current or back electromotive force voltage is equal to or less than the current value or voltage value at the rotational speed that is the engagement permission threshold.

[0073]

[0047] If the actuator control unit 59 does not determine that the rotational speed of the drive motor 10 is equal to or lower than the predetermined engagement permission threshold (S31 / N), it prohibits the locking claw 44 of the park lever 43 from engaging with the engagement portion 42 of the lock wheel 41 (step S33), and returns to step S31 to repeat the determination of the rotational speed of the drive motor 10.

[0074]

[0048] On the other hand, if the actuator control unit 59 determines that the rotational speed of the drive motor 10 is equal to or lower than a predetermined engagement permission threshold (S31 / Yes), it drives the actuator 45 to engage the locking claw 44 of the park lever 43 with the engaging portion 42 of the lock wheel 41 (step S35). This allows the rotational speed of the drive motor 10 to decrease before the locking claw 44 of the park lever 43 can be engaged with the engaging portion 42 of the lock wheel 41.

[0075] [ 0 0 4 9 ]

[0076] <5. Effects> As described above, the parking lock system 1 of this embodiment has at least one engagement portion 42 and includes a lock wheel 41 fixed to a motor shaft 15 provided in a drive force transmission path that transmits the rotational torque of the drive motor 10 to the wheels 35a, 35b, a locking pawl 44 that can engage with the engagement portion 42 of the lock wheel 41, an actuator 45 that switches the engagement and disengagement of the locking pawl 44 with the engagement portion 42, and a control device 50 that controls the operation of the actuator 45. The control device 50 engages the locking claw 44 with the engagement portion 42 when the shift range of the electric vehicle is in the parking range, and disengages the locking claw 44 from the engagement portion 42 when the shift range of the electric vehicle is in a range other than the parking range.The control device 50 determines whether the rotation speed of the drive motor 10 is below a predetermined engagement permission threshold based on the power generated according to the rotation speed of the drive motor 10, and prohibits the locking claw 44 from engaging with the engagement portion 42 while the rotation speed of the drive motor 10 exceeds the predetermined engagement permission threshold.

[0077] According to the parking lock system 1 of this embodiment, when switching the lock mechanism 40 from the unlocked state to the locked state, the rotational speed of the drive motor 10 decreases before the locking pawl 44 of the park lever 43 can be engaged with the engagement portion 42 of the lock wheel 41. Furthermore, even if the rotational speed sensor 17 that measures the rotational speed of the drive motor 10 indicates an abnormality and the rotational speed of the drive motor 10 cannot be measured by the rotational speed sensor 17, it is possible to determine whether the rotational speed of the drive motor 10 is equal to or less than a predetermined engagement allowance threshold based on the electric power generated in accordance with the rotational speed of the drive motor 10. Therefore, when an abnormality occurs in the rotation speed sensor 17, when an error occurs in the system of the electric vehicle, or when the ignition switch is intentionally turned off, the locking mechanism 40 can be put into a locked state without being damaged, and the rotation of the wheels 35a, 35b can be reliably restricted after the electric vehicle has stopped.

[0078]

[0051] Furthermore, the parking lock system 1 according to this embodiment uses the rotational speed of the drive motor 10 measured by the rotational speed sensor 17 to determine whether the rotational speed of the drive motor 10 is equal to or less than the engagement allowable minimum value while the rotational speed of the drive motor 10 measured by the rotational speed sensor 17 can be used. When the rotational speed of the drive motor 10 measured by the rotational speed sensor 17 cannot be used, the state of the inverter 19 is controlled to generate power according to the rotational speed of the drive motor 10, and information on this power is used to determine whether the rotational speed of the drive motor 10 is equal to or less than the engagement allowable minimum value. Therefore, while the rotational speed of the drive motor 10 measured by the rotational speed sensor 17 can be used, it is possible to determine whether the rotational speed of the drive motor 10 has dropped below the engagement allowable minimum value without specially controlling the state of the inverter 19.

[0079]

[0052] Furthermore, when the rotation speed sensor 17 indicates an abnormality, the parking lock system 1 according to this embodiment executes active short circuit control of the inverter 19 or places the drive motor 10 in a freewheeling state, thereby making it possible to acquire an active short circuit current or back electromotive force voltage corresponding to the rotation speed of the drive motor 10. Therefore, without using the rotation speed sensor 17 or acquiring information from other sensors capable of estimating the speed of the electric vehicle, it is possible to estimate the rotation speed of the drive motor 10 and determine whether the rotation speed has dropped below the engagement allowance threshold.

[0080] [ 0 0 5 3 ]

[0081] 6. Modifications The parking lock system according to this embodiment has been described above. The parking lock system according to the above embodiment can be modified in various ways. Some modifications of the parking lock system will be described below.

[0082]

[0054] In the park lock system 1, a situation in which the state value correlated with the rotational speed of the drive motor 10 cannot be acquired may occur when an error occurs in the power system of the electric vehicle. In this case, not only will the state value correlated with the rotational speed of the drive motor 10 not be acquired, but it may also be impossible to drive the actuator 45. This may result in the lock mechanism 40 being unable to be locked.

[0083]

[0055] Fig. 8 shows the configuration of a first modified example that enables the park lock system 1A to be driven even when an abnormality occurs in the main power supply 90 that supplies power to the park lock system 1A. The parking lock system 1A shown in the figure is driven using a low-voltage battery as the main power supply 90, which is the power source for low-voltage power loads 91 such as auxiliary equipment of the electric vehicle. In addition to the main power supply 90, the electric vehicle is equipped with an auxiliary power supply 93. The auxiliary power supply 93 is a power supply with a smaller capacity than the main power supply 90, and is, for example, a capacitor. The auxiliary power supply 93 is connected in parallel to a DC stage that connects the main power supply 90 and the inverter 19.

[0084]

[0056] A switch 95 that electrically disconnects the main power supply 90 is provided between the main power supply 90 and the auxiliary power supply 93. When the switch 95 is connected, the control device 50 receives power from the main power supply 90 and drives the actuator 45. When the switch 95 is disconnected, the control device 50 uses power from the auxiliary power supply 93 to drive the actuator 45 of the locking mechanism 40.

[0085]

[0057] In the first modified example, the control device 50 is connected to the inverter 19 so as to be able to receive a current signal or a voltage signal. When an abnormality occurs in the main power supply 90 or when the control device 50 is unable to receive power from the main power supply 90 due to a disconnection or the like, the control device 50 turns off the switch 95 to electrically disconnect the main power supply 90 and enable power to be supplied from the auxiliary power supply 93. The control device 50 operates using power from the auxiliary power supply 93, receives a current signal or a voltage signal from the inverter 19 according to the rotational speed of the drive motor 10, controls the actuator 45 as described in the above embodiment, and engages the locking claw 44 of the park lever 43 with the engagement portion 42 of the lock wheel 41 after the rotational speed of the drive motor 10 has decreased.

[0086]

[0058] The control device 50 that controls the actuator 45 of the locking mechanism 40 consumes little power, and can drive the actuator 45 even with the output power of a small-capacity auxiliary power supply 93. Furthermore, because the control device 50 is connected to the inverter 19 so as to be able to acquire a current signal or a voltage signal, even when the inverter 19 cannot be driven, it can estimate the rotation speed of the drive motor 10 based on the value of the back electromotive force voltage corresponding to the rotation speed of the drive motor 10. Therefore, even when power cannot be supplied from the main power supply 90, the locking mechanism 40 can be locked without being damaged, and the rotation of the wheels 35a, 35b can be reliably restricted after the electric vehicle has stopped.

[0087]

[0059] Figure 9 shows a second modified configuration in which, when power cannot be received from the main power supply 90, power is received from a high-voltage battery 10 instead of from an auxiliary power supply 93. In the illustrated parking lock system 1B, a battery (high-voltage battery) 70, which is also the power source for the drive motor 10, and a control device 50 are electrically connected via a switch 97. When the switch 95 is connected and the control device 50 is normally powered by the main power supply 90, the switch 97 is disconnected.

[0088]

[0060] When the control device 50 cannot receive power from the main power supply 90, it cuts off the switch 95 to electrically disconnect the main power supply 90, and connects the switch 97 to enable power supply from the battery 70 and reduces the power of the battery 70 to drive the actuator 45 of the locking mechanism 40. Even when configured in this way, when it cannot receive power from the main power supply 90, it is possible to lock the locking mechanism 40 without damaging it, and to reliably restrict the rotation of the wheels 35a, 35b after the electric vehicle has stopped.

[0089]

[0061] Fig. 10 shows the configuration of a third modified example in which an auxiliary actuator 49 is further added to the first modified example. The auxiliary actuator 49 has the function of engaging the locking claw 44 of the park lever 43 with the engaging portion 42 of the lock wheel 41. For example, the park lock system 1C according to the third modified example has a constant lock type configuration in which the locking claw 44 of the park lever 43 is constantly urged toward the lock wheel 41 by the urging force of a spring, and the auxiliary actuator 49 has the function of releasing the urging force of the spring. The auxiliary actuator 49 is an actuator that can operate with less power than the power consumption of the electric motor 46 of the actuator 45, such as an electromagnetic solenoid or a piezoelectric actuator.

[0090]

[0062] In the third modified example, when the control device 50 cannot receive power from the main power supply 90, it turns off the switch 95 to electrically disconnect the main power supply 90 and enables power to be supplied from the auxiliary power supply 93. The control device 50 operates using power from the auxiliary power supply 93, obtains a current signal or voltage signal corresponding to the rotational speed of the drive motor 10 from the inverter 19, controls the auxiliary actuator 49, and engages the locking claw 44 of the park lever 43 with the engaging portion 42 of the lock wheel 41 after the rotational speed of the drive motor 10 has decreased.

[0091]

[0063] In the third modified example, when the control device 50 cannot receive power from the main power supply 90, the control device 50 uses the auxiliary actuator 49, which consumes less power, to lock the lock mechanism 40. This increases the reliability of locking the lock mechanism 40 even when the capacity of the auxiliary power supply 93 is small or the capacity of the circuit that reduces the power from the high-voltage battery 90 is small.

[0092]

[0064] In the third modified example, an example in which an auxiliary actuator 49 is added to the first modified example has been described, but the same effect can be obtained even when an auxiliary actuator 49 is added to the second modified example.

[0093]

[0065] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various changes or modifications within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0094] For example, in the above embodiment, the rotation speed sensor 17 is provided on the motor shaft 15, but the rotation speed sensor may be provided at another position on the driving force transmission path as long as it is capable of measuring a state value correlated with the rotation speed of the drive motor 10. The rotation speed sensor may be, for example, a sensor that measures the rotation speed of the intermediate shaft 25 of the transmission 20.

[0095]

[0067] Furthermore, although the parking lock system according to the above embodiment is configured to drive the actuator when switching the lock mechanism between a locked state and an unlocked state, the present invention is not limited to the above example. For example, the parking lock system may have a constant lock type configuration in which, when the actuator is not driven, the locking claw of the park lever enters the engagement portion of the lock wheel due to the biasing force of the spring, thereby locking the lock mechanism. Even in a constant lock type parking lock system, if the rotation speed of the drive motor cannot be measured by a rotation speed sensor, it can determine whether the rotation speed of the drive motor is equal to or lower than a predetermined engagement allowance value based on the power generated in accordance with the rotation speed of the drive motor, and can lock the lock mechanism without damaging it.

[0096] [Explanation of symbols]

[0097] [ 0 0 6 8 ]

[0098] 1: Parking lock system

[0099] 3: Shift position sensor

[0100] 1 〇: Drive motor

[0101] 1 5: Motor shaft

[0102] 1 7: Rotational speed sensor

[0103] 1 9: Inverter

[0104] 2 〇: Transmission

[0105] 3 1: Differential gear

[0106] 4 〇: Locking mechanism

[0107] 4 1: Locking wheel

[0108] 4 2: Engagement part

[0109] 4 3: Park lever

[0110] 4 4: Locking claw

[0111] 4 5: Actuator 6 Electric motor 7 Lock piston 9 Auxiliary actuator ○ Control device 1 Shift range determination unit 2 Lock state determination unit 3 Sensor abnormality determination unit 5 Inverter control command unit 7 Rotation speed determination unit 9 Actuator control unit 1 Processing unit 3 Memory unit ○ Battery (high voltage battery) ○ Motor controller ○ Main power supply 3 Auxiliary power supply

Claims

[Document name] Scope of claims

1. A parking lock system (1) for holding wheels (35a, 35b) in a non-rotatable state when parking an electric vehicle, comprising: a lock wheel (41) having at least one engaging portion (42) and fixed to a rotating shaft (15) provided in a driving force transmission path for transmitting the rotational torque of a drive motor (10) to the wheels (35a, 35b); a locking portion (44) engageable with the engaging portion (42) of the lock wheel (41); an actuator (45) for switching between engagement and disengagement of the locking portion (44) with the engaging portion (42); and a control device (50) for controlling the operation of the actuator (45), wherein the control device (50) controls the operation of the actuator (45) to lock the locking portion (44) with the engaging portion (42) when the shift range of the electric vehicle is in a parking range (P). and disengaging the locking portion (44) from the engaging portion (42) when the shift range of the electric vehicle is in a range (nP) other than the parking range; determining whether the rotation speed of the drive motor (10) is equal to or less than a predetermined engagement allowance value based on electric power generated in accordance with the rotation speed of the drive motor (10); and prohibiting the locking portion (44) from being engaged with the engaging portion (42) while the rotation speed of the drive motor (10) exceeds the predetermined engagement allowance value.

2. The parking lock system according to claim 1, wherein the control device (50) acquires a state value correlated with the rotational speed of the drive motor (10), determines whether the state value is equal to or less than a predetermined minimum value, prohibits the locking portion (44) from locking with the engagement portion (42) while the state value exceeds the predetermined minimum value, and, when it is not possible to determine whether the state value is equal to or less than the predetermined minimum value, determines whether the rotational speed of the drive motor (10) is equal to or less than the predetermined engagement allowable minimum value based on electric power generated in accordance with the rotational speed of the drive motor (10), and prohibits the locking portion (44) from locking with the engagement portion (42) while the rotational speed of the drive motor (10) exceeds the predetermined engagement allowable minimum value.

3. The parking lock system according to claim 2, wherein the state value is a measurement value of a rotation speed sensor (17) that measures the rotation speed of the drive motor (10), and the control device (50) determines whether or not the rotation speed of the drive motor (i0) is equal to or less than the predetermined engagement allowable minimum value based on the measurement value of the rotation speed sensor (17) when the rotation speed sensor (17) is in a normal state, and determines whether or not the rotation speed of the drive motor (10) is equal to or less than the predetermined engagement allowable minimum value based on electric power generated in accordance with the rotation speed of the drive motor (10) when the rotation speed sensor (17) is in an abnormal state.

4. The parking lock system according to claim 2, wherein, when the control device (50) cannot determine whether the state value is equal to or less than the predetermined minimum value, the control device (50) executes active short circuit control of the inverter (19) that drives the drive motor (10), and determines whether the rotation speed of the drive motor (10) is equal to or less than the predetermined engagement permission minimum value based on the value of the measured active short circuit current.

5. The parking lock system according to claim 2, wherein, when the control device (50) cannot determine whether the state value is equal to or less than the predetermined minimum value, the control device (50) stops driving the inverter (19) that drives the drive motor (10) to bring the drive motor (10) into a freewheeling state, and determines whether the rotation speed of the drive motor (10) is equal to or greater than the predetermined engagement permission minimum value based on the value of the measured back electromotive force voltage.

6. The parking lock system according to claim 1, wherein the electric vehicle includes a main power supply (90) and an auxiliary power supply (93), the control device (50) is connected to an inverter (19) that drives the drive motor (10) so as to be able to acquire a current signal or a voltage signal from the inverter (19), the control device (50) controls the actuator (45) using power from the main power supply (90), and when power cannot be supplied from the main power supply (90), the control device (50) acquires the current signal or the voltage signal corresponding to the rotational speed of the drive motor (10) from the inverter (19) and controls the actuator (45) using power from the auxiliary power supply (93). [Claim ?] The electric vehicle includes an auxiliary actuator that engages the locking portion (44) with the engaging portion (42).

7. The parking lock system according to claim 6, further comprising: a power supply (93) for supplying power from the main power supply (90) to the control device (50), the power supply (93) being configured to control the auxiliary actuator (49) using power from the auxiliary power supply (93) when the control device (50) is unable to receive power from the main power supply (90).

8. The parking lock system according to claim 1, wherein the electric vehicle includes a main power supply (90) which is a low-voltage power source and a high-voltage battery (70) which is a high-voltage power source, the control device (50) is connected to an inverter (19) which drives the drive motor (10) so as to be able to acquire a current signal or a voltage signal, the control device (50) controls the actuator (45) using power from the main power supply (90), and when power cannot be supplied from the main power supply (90), acquires the current signal or the voltage signal from the inverter (19) according to the rotational speed of the drive motor (10) and reduces the power of the high-voltage battery (70) to control the actuator (45).

9. The electric vehicle includes an auxiliary actuator that engages the locking portion (44) with the engaging portion (42).

9. The parking lock system according to claim 8, further comprising: a power supply unit (49) for supplying power from the high-voltage battery (70) to the parking lock system; wherein the control unit (50) controls the auxiliary actuator (49) by reducing the power of the high-voltage battery (70) when power cannot be supplied from the main power supply (90).

10. A lock wheel (41) having at least one engaging portion (42) and fixed to a rotating shaft (15) provided in a driving force transmission path that transmits the rotational torque of a drive motor (10) to wheels (35a, 35b) of an electric vehicle; a locking portion (44) that can be engaged with the engaging portion (42) of the lock wheel (41); and an actuator (44) that switches between engagement and disengagement of the locking portion (44) with the engaging portion (42). and a control device (50) for controlling the operation of the actuator (45), wherein when the electric vehicle is parked, the locking portion (44) is engaged with the engaging portion (42) to lock the wheel (3). a control device (50) that holds a drive motor (10) (35 a, 35 b) in a non-rotatable state when the shift range of the electric vehicle is the parking range, and disengages the locking portion (44) from the engagement portion (42) when the shift range of the electric vehicle is a range other than the parking range, determines whether the rotation speed of the drive motor (10) is equal to or less than a predetermined engagement permission threshold based on electric power generated according to the rotation speed of the drive motor (10), and prohibits the locking portion (44) from being engaged with the engagement portion (42) while the rotation speed of the drive motor (10) exceeds the predetermined engagement permission threshold. 15

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