Electric parking system

Abstract

To enable detection of deterioration in the components of the actuator that generates parking pressure. [Solution] The electric parking device 30 includes a parking actuator 31 that generates a parking pressure by driving an electric motor 32 to press a friction part 23 against a rotating body 22 that rotates integrally with the wheels 11, and a processing circuit 41 that controls the electric motor 32. The processing circuit 41 performs an acquisition process to acquire operating information of the parking actuator 31 when the electric motor 32 is being driven, and a determination process to determine whether or not the components of the parking actuator 31 have deteriorated based on the operating information acquired in the acquisition process.

Description

Technical Field

[0001] The present invention relates to an electric parking device provided in a vehicle.

Background Art

[0002] Patent Document 1 discloses an example of a device for predicting the failure of periodic movable machine parts such as bearings.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] If an actuator of an electric parking device mounted on a vehicle is used over a long period of time, components such as bearings included in the actuator deteriorate. Therefore, an object of the present invention is to be able to detect that the components have deteriorated to some extent before the actuator becomes inoperable.

Means for Solving the Problems

[0005] The electric parking device for solving the above problems includes an actuator that generates a parking pressing force by pressing a friction part against a rotating body that rotates integrally with a wheel by driving an electric motor, and a processing circuit that controls the electric motor. The processing circuit executes an acquisition process for acquiring operation information of the actuator when the electric motor is being driven, and a determination process for determining whether or not components of the actuator have deteriorated based on the operation information acquired in the acquisition process.

Effects of the Invention

[0006] The above-mentioned electric parking device has the effect of being able to detect when the components of the actuator that generates the parking pressure have deteriorated. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a cross-sectional view showing a schematic configuration of an electric parking device capable of applying parking pressure to the wheels of a vehicle in a first embodiment. [Figure 2] In Figure 2, (a) shows the change in motor current when the components of the parking actuator in Figure 1 are not deteriorated, (b) shows the change in motor current when the components have deteriorated to some extent, and (c) shows the change in motor current and an approximate straight line of that change. [Figure 3] Figure 3 is a flowchart showing a series of processes performed when determining whether or not a component has deteriorated in the control device of the electric parking system shown in Figure 1. [Figure 4] In Figure 4, (a) is a diagram of the operation in the first embodiment, and (b) is an enlarged view of a part of Figure 4(a). [Figure 5] Figure 5 is a flowchart showing a part of the series of processes performed when determining whether or not a component has deteriorated in the electric parking system of the second embodiment. [Figure 6] Figure 6 is a block diagram showing a schematic of the control device for the electric parking system in the third embodiment. [Figure 7] Figure 7 is a schematic diagram showing a vehicle equipped with an electric parking device and a server installed outside the vehicle in the fourth embodiment. [Modes for carrying out the invention]

[0008] (First Embodiment) The first embodiment will be described with reference to Figures 1 to 4. Figure 1 illustrates a part of a vehicle equipped with an electric parking device 30. The vehicle is equipped with friction brakes 20 that apply braking force to the wheels 11.

[0009] The friction brake 20 comprises a wheel cylinder 21, a rotating body 22, and a friction part 23. The rotating body 22 rotates integrally with the wheel 11. Therefore, by pressing the friction part 23 against the rotating body 22, a braking force is generated at the wheel 11. The force pressing the friction part 23 against the rotating body 22 increases with increasing wheel pressure, which is the hydraulic pressure inside the wheel cylinder 21. Therefore, the higher the wheel pressure, the greater the braking force generated at the wheel 11.

[0010] <Electric parking system> The electric parking system 30 comprises a parking actuator 31 and a control device 40 that controls the parking actuator 31.

[0011] The parking actuator 31 is integrated with the friction brake 20 of the corresponding wheel 11. When the parking actuator 31 is activated, the friction part 23 can be pressed against the rotating body 22 even if no wheel pressure is generated. The force that presses the friction part 23 against the rotating body 22 is referred to as the "pressing force". The pressing force generated by the operation of the parking actuator 31 is referred to as the "parking pressing force Fpb".

[0012] The parking actuator 31 comprises an electric motor 32, a reduction mechanism 33, and a conversion mechanism 34. The reduction mechanism 33 reduces the rotation of the rotating shaft 321 of the electric motor 32 and outputs it to the conversion mechanism 34. The reduction mechanism 33 includes, for example, an input member 331 that rotates integrally with the rotating shaft 321, and an output member 332 that rotates synchronously with the input member 331.

[0013] The conversion mechanism 34 converts the rotational motion of the output member 332 of the reduction mechanism 33 into linear motion and transmits it to the piston 211 of the wheel cylinder 21. An example of the conversion mechanism 34 is a screw mechanism. In this case, the conversion mechanism 34 has a rotating member 341 that rotates integrally with the output member 332, and a linear motion member 342 connected to the rotating member 341. The rotating member 341 is rotatably supported by a plurality of bearings. The plurality of bearings are fixed, for example, to the housing of the friction brake 20. Among the plurality of bearings, the thrust bearing that receives the force acting in the axial direction of the rotating member 341 is referred to as "bearing 35". The linear motion member 342 moves linearly in a direction corresponding to the rotation direction of the rotating member 341 supported by the bearing 35. Then, the linear motion member 342 pushes the piston 211, causing the piston 211 to move linearly.

[0014] When the piston 211 moves in a linear motion due to the driving of the electric motor 32, the friction part 23 of the friction brake 20 approaches the rotating body 22. When the friction part 23 is pressed against the rotating body 22, a parking pressure Fpb is generated. In other words, the parking actuator 31 can generate a parking pressure Fpb by driving the electric motor 32.

[0015] The conversion mechanism 34 has a self-locking function. In other words, if the driving force of the electric motor 32 is not transmitted to the conversion mechanism 34, the components of the conversion mechanism 34 will not operate. Therefore, even if the power supply to the electric motor 32 is stopped while the parking pressure Fpb has increased due to the operation of the electric motor 32, the parking pressure Fpb can be maintained by the self-locking function of the conversion mechanism 34.

[0016] Note that a flange 341a is provided on the rotating member 341. Therefore, when the parking pressing force Fpb is generated, a reaction force caused by pressing the friction portion 23 against the rotating body 22 is applied to the bearing 35 via the flange 341a. Therefore, such a reaction force continues to be applied to the bearing 35 during the driving of the electric motor 32. As a result, if the parking actuator 31 is used for a long time, the components of the bearing 35 gradually wear out. That is, the deterioration of the bearing 35 gradually progresses.

[0017] The control device 40 includes a processing circuit 41 that controls the parking actuator 31. An example of the processing circuit 41 is an electronic control unit. In this case, the processing circuit 41 has a CPU 42, a first memory 43, and a second memory 44. The first memory 43 stores a control program executed by the CPU 42, various maps, tables, arithmetic expressions, etc. that the CPU 42 refers to. The second memory 44 stores the calculation results of the CPU 42 and the like. By the CPU 42 executing the control program in the first memory 43, the processing circuit 41 controls the electric motor 32 of the parking actuator 31.

[0018] The processing circuit 41 executes an apply process and a release process. The apply process is a process executed when generating the parking pressing force Fpb. The release process is a process executed when releasing the state in which the parking pressing force Fpb is generated.

[0019] FIG. 2 illustrates the transition of the motor current Imt when the apply process is executed. The motor current Imt is the current flowing through the electric motor 32. The solid line in FIG. 2(a) shows an example of the transition of the motor current Imt when the components of the parking actuator 31 such as the bearing 35 have not yet deteriorated. The solid line in FIG. 2(b) shows an example of the transition of the motor current Imt when the deterioration of the components has progressed to a certain extent. The "deterioration of the components" referred to here means that although the parking actuator 31 can still operate, the deterioration of the components has progressed to a certain extent.

[0020] As shown in Figures 2(a) and 2(b), when the apply process starts at timing t11, an inrush current flows through the electric motor 32. After that, during the period when the friction part 23 is not yet in contact with the rotating body 22, the load applied to the electric motor 32 is small. Therefore, the motor current Imt is low.

[0021] When the friction part 23 comes into contact with the rotating body 22 at timing t12, a parking pressure Fpb begins to be generated. After timing t12, as the parking pressure Fpb increases, the load applied to the electric motor 32 increases. As a result, the motor current Imt increases almost proportionally to the increase in load. When the motor current Imt reaches the current determination value Imtth at timing t13, the apply process is terminated, and the driving of the electric motor 32 is stopped.

[0022] Figures 2(a) and 2(b) show a dashed current transition line, Limt, which represents the ideal relationship between the motor current Imt and time from the point at which the parking pressure Fpb is generated. The current transition line Limt can be expressed as a linear function. The motor current shown by the current transition line Limt is referred to as the "reference motor current Imtk".

[0023] As shown in Figure 2(a), when the components have not yet deteriorated, the discrepancy between the actual motor current Imt and the current transition line Limt (i.e., the transition of the reference motor current Imtk) is small during periods when the parking pressure Fpb is increasing, such as from timing t12 to timing t13. On the other hand, as shown in Figure 2(b), when the deterioration of the components has progressed to some extent, a discrepancy between the reference motor current Imtk and the actual motor current Imt is likely to occur during periods when the parking pressure Fpb is increasing.

[0024] When the reaction force applied to a bearing 35 that has deteriorated relatively significantly increases, the rotating member 341 supported by the bearing 35 becomes less able to rotate smoothly. As a result, a discrepancy between the reference motor current Imtk and the actual motor current Imt is likely to occur.

[0025] Therefore, the processing circuit 41 acquires time-series data of the motor current Imt, which shows the change in motor current Imt from the time the parking pressure Fpb is generated, as operating information for the parking actuator 31 during the execution of the apply process. This operating information is time-series data of the motor current Imt when the parking pressure Fpb is increasing due to the driving of the electric motor 32. Based on this operating information, the processing circuit 41 determines whether or not the components of the parking actuator 31, such as the bearing 35, have deteriorated.

[0026] The first memory 43 of the processing circuit 41 stores normative operation information. Normative operation information is operation information for when the components of the parking actuator 31 are not deteriorated. In other words, normative operation information is time-series data of the normative motor current Imtk, shown by the current transition line Limt, between timing t12 and timing t13.

[0027] When the processing circuit 41 acquires operational information, it compares the operational information with reference operational information to determine whether or not a component has deteriorated. For example, the processing circuit 41 calculates the difference ΔImt between the motor current Imt indicated by the operational information and the reference motor current Imtk indicated by the reference operational information at regular intervals. The processing circuit 41 then determines that a component has deteriorated if the average value ΔImtave of the absolute values ​​of multiple differences ΔImt is greater than the difference threshold ΔImtth. On the other hand, the processing circuit 41 determines that a component has not deteriorated if the average value ΔImtave is less than or equal to the difference threshold ΔImtth. In this case, the difference threshold ΔImtth is the criterion for determining whether or not a component has deteriorated.

[0028] <Degradation detection process> Referring to Figure 3, a series of processes for determining whether or not the bearing 35, one of the components of the parking actuator 31, has deteriorated will be explained. The processing circuit 41 starts executing this series of processes when the parking actuator 31 is activated.

[0029] In step S11, the processing circuit 41 determines whether or not it is performing the apply process. If the processing circuit 41 is performing the apply process (S11: YES), the processing circuit 41 proceeds to step S13. On the other hand, if the processing circuit 41 is performing the release process (S11: NO), the processing circuit 41 terminates the series of processes. In step S13, the processing circuit 41 determines whether or not the friction part 23 has come into contact with the rotating body 22 as a result of the application process. In other words, the processing circuit 41 determines whether or not the parking pressure Fpb has started to be generated. For example, the processing circuit 41 can determine whether or not the friction part 23 has come into contact with the rotating body 22 by monitoring the change in the motor current Imt. If the processing circuit 41 determines that the friction part 23 is not in contact with the rotating body 22 (S13: NO), the processing circuit 41 repeats the determination in step S13 until it can determine that the friction part 23 has come into contact with the rotating body 22. On the other hand, if the processing circuit 41 determines that the friction part 23 has come into contact with the rotating body 22 (S13: YES), the processing circuit 41 proceeds to step S15.

[0030] In step S15, the processing circuit 41 acquires operational information. For example, the processing circuit 41 acquires the elapsed time since the judgment in step S13 became positive (YES) and the motor current Imt, relating them to each other. At this time, the processing circuit 41 stores the acquired operational information in the second memory 44.

[0031] In the next step, S17, the processing circuit 41 determines whether the apply process has been completed. When the apply process is completed, the motor current Imt becomes 0 (zero). Therefore, if the motor current Imt is greater than 0 (zero), the processing circuit 41 determines that the apply process is not complete (S17: NO). Then, the processing circuit 41 moves on to step S15. That is, the processing circuit 41 continues to acquire operating information. On the other hand, if the motor current Imt is 0 (zero), the processing circuit 41 determines that the apply process is complete (S17: YES). Then, the processing circuit 41 moves on to step S19. That is, the processing circuit 41 terminates the acquisition of operating information.

[0032] In step S19, the processing circuit 41 calculates multiple differences ΔImt based on the acquired operating information and the reference operating information. In the subsequent step S21, the processing circuit 41 calculates the average value ΔImtave of the absolute values ​​of the multiple differences ΔImt.

[0033] Then, in step S23, the processing circuit 41 determines whether the average value ΔImtave is greater than the difference threshold ΔImtth. If the average value ΔImtave is greater than the difference threshold ΔImtth (S23: YES), the processing circuit 41 proceeds to step S25. On the other hand, if the average value ΔImtave is less than or equal to the difference threshold ΔImtth (S23: NO), the processing circuit 41 proceeds to step S27.

[0034] In step S25, the processing circuit 41 determines that the bearing 35 has deteriorated. Subsequently, the processing circuit 41 completes the series of processes shown in Figure 3. In step S27, the processing circuit 41 determines that the bearing 35 is not deteriorated. Subsequently, the processing circuit 41 completes the series of processes shown in Figure 3.

[0035] In this embodiment, steps S15 and S17 correspond to an "acquisition process" for acquiring operating information when the electric motor 32 is being driven. Steps S23, S25, and S27 correspond to a "determination process" for determining whether or not the bearing 35 has deteriorated. Furthermore, the completion of the apply process, that is, the determination in step S17 becoming "YES", corresponds to "a predetermined condition being met". Therefore, it can be said that in the determination process, the processing circuit 41 determines whether or not the bearing 35 has deteriorated based on the operating information acquired in the acquisition process before the predetermined condition is met.

[0036] <Operation of this embodiment> Referring to Figure 4, the operation when the deterioration of bearing 35 has progressed to a certain extent will be explained. As shown in Figure 4(a), the parking pressure Fpb begins to be generated at timing t21 during the execution of the apply process. In the initial section from timing t21 to timing t22, there is almost no discrepancy between the reference motor current Imtk and the motor current Imt. However, from timing t22 onward, the reaction force applied to the bearing 35 increases, making it difficult for the rotating member 341 supported by the bearing 35 to rotate. As a result, as shown in Figure 4(b), a discrepancy between the reference motor current Imtk and the motor current Imt is more likely to occur.

[0037] When the electric motor 32 is stopped at timing t23, the processing circuit 41 determines whether the bearing 35 has deteriorated based on the operating information, which is time-series data of the motor current Imt acquired in the interval from timing t21 to timing t23.

[0038] For example, if the processing circuit 41 determines that the bearing 35 has deteriorated, it may notify the vehicle's occupants that it would be advisable to take the vehicle to a repair shop such as a dealer. Also, if a vehicle equipped with an electric parking device 30 can communicate with a server installed outside the vehicle, the processing circuit 41 may be configured to send a message to the server indicating that the deterioration of the bearing 35 of the parking actuator 31 has progressed to a certain extent.

[0039] <Effects of this embodiment> (1-1) When the deterioration of the bearing 35 progresses to a certain extent, the operating information is superimposed with the effect of the deterioration of the bearing 35, as shown in Figure 4(b). Therefore, the processing circuit 41 determines whether or not the bearing 35 of the parking actuator 31 has deteriorated based on the operating information acquired while the electric motor 32 is being driven.

[0040] Furthermore, the processing circuit 41 makes the above determination based on the operating information when the parking actuator 31 is operating normally due to the drive of the electric motor 32. Therefore, the electric parking device 30 can detect deterioration of the bearing 35, which is one of the components of the parking actuator 31, before the parking actuator 31 fails.

[0041] (1-2) The greater the reaction force applied to the bearing 35, the more likely the effects of bearing 35 deterioration are to be superimposed on the operating information. Therefore, the processing circuit 41 acquires the change in motor current Imt as operating information when the parking pressure Fpb is increased by the apply process. By using this operating information, the processing circuit 41 can accurately determine whether or not the bearing 35 has deteriorated.

[0042] (1-3) The processing circuit 41 determines whether the bearing 35 has deteriorated by comparing the operating information acquired while the electric motor 32 is being driven with the reference operating information. The reference operating information is information that shows the ideal progression of the motor current when the bearing 35 has not deteriorated. Therefore, by using this reference operating information in the above determination, the processing circuit 41 can accurately determine whether the bearing 35 has deteriorated.

[0043] (Second Embodiment) The second embodiment will be described with reference to Figures 2 and 5. The second embodiment differs from the first embodiment in that it creates normative operation information after the acquisition process is executed. In the following description, the parts that differ from the first embodiment will be mainly described, and the same reference numerals will be used for components that are the same as or equivalent to those in the first embodiment, and redundant explanations will be omitted.

[0044] Referring to Figure 5, we will now explain the differences between the series of processes used to determine whether or not the bearing 35 has deteriorated and those of the first embodiment described above. Note that Figure 5 illustrates only a portion of the series of processes.

[0045] In step S17, if the processing circuit 41 determines that the apply process is complete (S17:YES), the processing circuit 41 terminates the acquisition of operation information. Then, the processing circuit 41 proceeds to step S18.

[0046] In step S18, the processing circuit 41 creates standard operation information using the operation information acquired during the execution of the current apply process. In Figure 2(c), the transition of the motor current Imt, as indicated by the acquired operating information, is shown by a solid line. For example, as shown in Figure 2(c), the processing circuit 41 creates a linear function equation that represents the approximate linear line of the transition of the motor current Imt, as indicated by the acquired operating information. In Figure 2(c), the linear line LimtA, which represents the equation of this linear function, is shown by a dashed line. The transition of the motor current Imt shown by this linear line LimtA can be said to represent the transition of the reference motor current Imtk. Therefore, in this embodiment, the linear line LimtA corresponds to the "reference operating information".

[0047] Returning to Figure 5, once the processing circuit 41 has created the normative operation information, it proceeds to step S19 in Figure 3. The processing flow from step S19 onward is the same as in the first embodiment described above, so a detailed explanation is omitted.

[0048] In this embodiment, step S18 corresponds to a "creation process" in which, after the acquisition process is executed, normative operation information, which is a standard for operation information, is created based on the operation information acquired in the acquisition process.

[0049] <Effects of this embodiment> In this embodiment, in addition to the effects (1-1) and (1-2) of the first embodiment described above, the following effects can be further obtained.

[0050] (2-1) Once the processing circuit 41 has completed acquiring the operation information through the acquisition process, it creates normative operation information based on that operation information. Therefore, unlike the first embodiment described above, the first memory 43 does not need to store normative operation information in advance. Consequently, the control device 40 can reduce the amount of storage in the first memory 43.

[0051] (Third embodiment) A third embodiment will be described with reference to Figure 6. The third embodiment differs from the above-described embodiments in that it can determine whether or not the components of the parking actuator 31 have deteriorated without using normative operation information. In the following description, the parts that differ from the above-described embodiments will be mainly described, and the same reference numerals will be used for components that are the same as or equivalent to those in the above-described embodiments, and redundant explanations will be omitted.

[0052] Figure 6 illustrates the control device 40A of the electric parking system 30. The control device 40A includes a processing circuit 41 and a learner 45. The learning device 45 has a trained model 46 that has undergone machine learning to output an index Y indicating the degree of deterioration of the components of the parking actuator 31 based on the operational information acquired during the execution of the apply process. The trained model 46 is composed of, for example, a neural network.

[0053] During the execution of the apply process, the processing circuit 41 performs an acquisition process to acquire operating information, i.e., time-series data of the motor current Imt. The processing circuit 41 executes a determination process after the application process is completed, that is, after the electric motor 32 has stopped driving. In the determination process, the processing circuit 41 inputs the operation information acquired in the acquisition process as an input variable to the trained model 46. The trained model 46 outputs an index Y corresponding to the input operation information as an output variable. Based on this index Y, the processing circuit 41 determines whether or not the component has deteriorated. For example, the processing circuit 41 determines that the component has deteriorated if the estimated value of the degree of deterioration indicated by index Y is greater than or equal to a threshold. On the other hand, the processing circuit 41 determines that the component has not deteriorated if the estimated value of the degree of deterioration is less than the threshold.

[0054] <Methods for generating pre-trained models> The pre-trained model generator prepares multiple training data sets, including operating information and ground truth data. The ground truth data represents the degree of deterioration of a component when the corresponding operating information is obtained.

[0055] The generator obtains an index Y output from a learning model when operational information is input to the learning model. The generator adjusts the variables of the trained model so that the discrepancy between the estimated degree of degradation indicated by index Y and the ground truth data corresponding to the input operational information is minimized. If the trained model 46 is a neural network, the generator updates the weights of the connections between each neuron and the threshold of each neuron so that the estimated degree of degradation indicated by index Y approaches the ground truth data. By repeatedly performing this machine learning process, the generator can generate a trained model 46.

[0056] <Effects of this embodiment> In addition to the effects (1-1) and (1-2) of the above-described embodiments, this embodiment can further obtain the following effects.

[0057] (3-1) The control device 40A has a learner 45. The control device 40A determines whether or not a component has deteriorated by inputting operating information into the learned model 46 of the learner 45. Therefore, the control device 40A can determine whether or not a component has deteriorated without using normative operating information.

[0058] (Fourth Embodiment) The fourth embodiment will be described with reference to Figure 7. In the following description, the differences from the above embodiments will be mainly explained, and the same reference numerals will be used for components that are the same as or equivalent to those in the above embodiments, and redundant explanations will be omitted.

[0059] Figure 7 illustrates a vehicle 10 equipped with an electric parking device 30 and a server 200 installed outside the vehicle. Vehicle 10 is equipped with a communication device 50 for sending and receiving various types of information with the server 200. The communication device 50 transmits information output from the control device 40B of the electric parking device 30 to the server 200 via an external communication network 100. The communication device 50 also receives information transmitted by the server 200 via the communication network 100. The communication network 100 may be a wireless communication network or a wired communication network.

[0060] When the control device 40B of the electric parking system 30 acquires operation information of the parking actuator 31, it transmits the operation information to the communication device 50. The communication device 50 then transmits the operation information to the server 200.

[0061] Server 200 includes a communication device 201 and a diagnostic device 202. The communication device 201 receives operational information transmitted by the vehicle 10 via the communication network 100. The communication device 201 then outputs this operational information to the diagnostic device 202. Furthermore, the communication device 201 transmits the information output by the diagnostic device 202 to the vehicle 10, or to an information terminal owned by the owner of the vehicle 10, via the communication network 100. Examples of such information terminals include smartphones and tablet devices.

[0062] An example of the diagnostic device 202 is an electronic control unit. The diagnostic device 202 performs a determination process to determine whether or not the components of the parking actuator 31 have deteriorated based on the acquired operating information. In the determination process, the diagnostic device 202 may determine whether or not the components have deteriorated by comparing the operating information with reference operating information, as described in the first or second embodiment above. Alternatively, for example, the diagnostic device 202 may determine whether or not the components have deteriorated by inputting the operating information into a learned model 46, as described in the third embodiment above. The diagnostic device 202 then outputs information indicating the determination result of the determination process to the communication device 201.

[0063] In this embodiment, as in the above-described embodiments, it is possible to determine whether or not the components of the parking actuator 31 have deteriorated. (Example of change) The above embodiments can be implemented with the following modifications. The above embodiments and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0064] In the first and second embodiments described above, the processing circuit 41 obtains the number of differences ΔImt whose absolute value is greater than the difference threshold ΔImtth among a plurality of differences ΔImt. The processing circuit 41 may then determine that the components of the parking actuator 31 have deteriorated if this number is greater than or equal to a predetermined value. The predetermined value is a positive number of 2 or greater.

[0065] If the components of the parking actuator 31 deteriorate to a certain extent, it can be inferred that the rate of change of the motor rotation angle when the electric motor 32 is being driven will fluctuate. Therefore, the processing circuit 41 may acquire time-series data of the motor rotation angle when the electric motor 32 is being driven as operating information. The processing circuit 41 may then determine whether or not the components have deteriorated based on the time-series data of the motor rotation angle.

[0066] The processing circuit 41 may terminate the acquisition process, i.e., the acquisition of operating information, while the parking pressure Fpb is increasing. For example, if the processing circuit 41 can acquire a sufficient amount of data to determine whether or not the components of the parking actuator 31 have deteriorated, it may terminate the acquisition process before the increase in the parking pressure Fpb is complete.

[0067] In the above embodiments, the processing circuit 41 acquires operational information when the parking pressure Fpb increases due to the driving of the electric motor 32, but it is not limited to this. For example, the processing circuit 41 may acquire operational information when the parking pressure Fpb decreases due to the driving of the electric motor 32, and determine whether or not the components have deteriorated based on said operational information.

[0068] The parking actuator does not have to be the parking actuator 31 applied to a disc brake as shown in Figure 1. For example, the parking actuator may be an actuator applied to a drum brake.

[0069] The processing circuit 41 is not limited to one that includes a CPU and ROM and executes software processing. In other words, the control device 40 may have any of the following configurations: (a), (b), and (c).

[0070] (a) The processing circuit 41 comprises one or more processors that perform various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to perform the processes. The memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or dedicated computer.

[0071] (b) The processing circuit 41 includes one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits, i.e., ASICs or FPGAs. ASIC is an abbreviation for "Application Specific Integrated Circuit". FPGA is an abbreviation for "Field Programmable Gate Array".

[0072] (c) The processing circuit 41 comprises one or more processors that execute a portion of the various processes according to a computer program, and one or more dedicated hardware circuits that execute the remaining processes of the various processes.

[0073] (Other technological ideas) This section describes the technical concepts that can be understood from the above-mentioned multiple embodiments and modifications. [Note 1] A method for determining the deterioration of components of an actuator in an electric parking system, which includes an actuator that generates a parking pressure by pressing a friction part against a rotating body that rotates integrally with the wheel by driving an electric motor, The operation information of the actuator when the electric motor is in operation is to be obtained by the computer, A method for determining deterioration, comprising causing the computer to determine whether or not the components of the actuator have deteriorated based on the operating information acquired by the computer. [Explanation of Symbols]

[0074] 10... Vehicles 11...Wheel 22…Rotational body 23...Friction part 30…Electric parking system 31…Parking Actuator 32… Electric motor 35…Bearing (an example of a component) 40, 40A, 40B… Control devices 41…Processing circuit

Claims

1. An actuator generates parking pressure by driving an electric motor to press a friction part against a rotating body that rotates integrally with the wheel, The system includes a processing circuit for controlling the aforementioned electric motor, The aforementioned processing circuit is An acquisition process for acquiring operating information of the actuator when the electric motor is being driven, Based on the operation information acquired in the acquisition process, a determination process is performed to determine whether or not the components of the actuator have deteriorated. Electric parking system.

2. The aforementioned processing circuit is In the acquisition process described above, when the parking pressure is increased by driving the electric motor, the operating information of the actuator is acquired. In the determination process, it is determined whether or not the actuator components have deteriorated based on the operation information acquired in the acquisition process before the predetermined conditions are met. The electric parking device according to claim 1.

3. In the determination process, the processing circuit determines whether or not the actuator components have deteriorated by comparing the operation information acquired in the acquisition process with the reference operation information. The electric parking device according to claim 1.

4. The processing circuit, in the acquisition process, acquires time-series data of the motor current flowing to the electric motor when the electric motor is in operation as the operation information. The time-series data of the motor current indicated by the aforementioned normative operating information is the time-series data of the normative motor current. The processing circuit determines, in the determination process, that the actuator components have deteriorated if the average of the absolute values ​​of the differences between the multiple motor currents included in the operation information and the multiple reference motor currents included in the reference operation information is greater than a threshold. The electric parking device according to claim 3.

5. The aforementioned processing circuit is After the acquisition process is executed, a creation process is executed to create normative operation information, which is the normative operation information, based on the operation information acquired in the acquisition process. The determination process is executed after the operation of the electric motor is stopped. The electric parking device according to claim 4.

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