control device

Abstract

The present application relates to a control device. The control device (10) is applied to a friction brake device (20) of a vehicle. The friction brake device (20) generates a friction braking force of the vehicle by starting driving of an electric motor (41). The control device (10) has a motor control section (11) that controls the electric motor (41). The control device (10) has an acquisition section (12) that acquires an index value corresponding to the magnitude of a target value of the friction braking force. A value for determining the magnitude of the index value is used as a limit determination value. The motor control section (11) limits the increase speed of the rotational speed of the electric motor (41) when the index value is below the limit determination value, and releases the limitation when the index value exceeds the limit determination value.

Description

Technical Field

[0001] This invention relates to a control device for controlling a vehicle's friction braking system. Background Technology

[0002] Patent Document 1 describes a friction braking device that generates friction braking force by adjusting the hydraulic pressure within the wheel cylinder. This friction braking device includes a pressurization mechanism for supplying brake fluid to the wheel cylinder. The pressurization mechanism has the function of driving a pump powered by an electric motor to increase the hydraulic pressure within the wheel cylinder.

[0003] Regarding such pressurization mechanisms, there are known structures that omit the energy storage device. In this case, the pressurization mechanism does not have the function of storing high-pressure brake fluid. Therefore, when friction braking force is requested, the vehicle generates friction braking force by driving the electric motor from that moment.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-73164

[0005] To ensure responsiveness when requesting friction braking force in a friction braking system without an energy storage device, the rotational speed of the electric motor is increased. However, this increased speed also increases the noise generated by the electric motor's operation. Therefore, the noise generated by the electric motor in the friction braking system during friction braking is sometimes transmitted to the driver. This noise can cause discomfort to the driver. Summary of the Invention

[0006] A control device for solving the above-mentioned problem is applied to a friction braking device having an electric motor. By starting the drive of the electric motor, a friction braking force is generated in the vehicle. The control device includes: a motor control unit that controls the electric motor; and an acquisition unit that acquires an index value corresponding to the magnitude of the target value of the friction braking force. The value used to determine the magnitude of the index value is used as a limit determination value. When the index value is below the limit determination value, the motor control unit limits the rate of increase of the rotational speed of the electric motor. When the index value exceeds the limit determination value, the limit is lifted.

[0007] Based on the above structure, the increase in the electric motor's rotational speed can be suppressed from the time the vehicle begins braking until the index value exceeds the limit threshold. This suppresses the increase in noise associated with the electric motor's operation, making it less likely for the driver to experience discomfort. Attached Figure Description

[0008] Figure 1 This is a schematic diagram illustrating one embodiment of the control device and a friction braking device that is the controlled object of the control device.

[0009] Figure 2 It is a flowchart representing the process executed by the control device.

[0010] Figure 3 It is a timing diagram showing the motor speed limited by the control device.

[0011] Figure 4 It is a timing diagram showing the motor speed limited by the control device.

[0012] Figure 5 This is a timing diagram showing the motor speed limited by the control device of the modified example.

[0013] Figure 6 This is a schematic diagram showing a control device with other variations and a friction braking device that is the object controlled by the control device. Detailed Implementation

[0014] The following is for reference Figures 1-4 One embodiment of the control device will be described.

[0015] Figure 1 This refers to a vehicle equipped with a control device 10 and a friction braking device 20. The control device 10 controls the friction braking device 20. The friction braking device 20 enables the vehicle to generate friction braking force. The vehicle equipped with the friction braking device 20 has a brake operating component 92. The brake operating component 92 can be operated by the driver of the vehicle. An example of the brake operating component 92 is a brake pedal. The vehicle may also have an automatic driving control unit 80 that calculates command values ​​for enabling the vehicle to drive automatically. The automatic driving control unit 80 can send and receive information with the control device 10.

[0016] (Friction braking device)

[0017] The friction braking device 20 will be described below. The friction braking device 20 includes a braking mechanism 30 corresponding to each wheel 91 of the vehicle. Figure 1 The diagram illustrates one of the wheels 91 of a vehicle and the corresponding braking mechanism 30. Other wheels 91 and braking mechanisms 30 are omitted from the diagram.

[0018] One example of a friction braking device 20 is a hydraulic braking device. In a hydraulic braking device, frictional braking force can be generated based on the hydraulic pressure (WC) within the wheel cylinder 31 of the braking mechanism 30. The braking mechanism 30 is configured such that the higher the WC pressure, the greater the force that presses the friction material 32 against the rotating body 33 that rotates integrally with the wheel 91. The higher the WC pressure, the greater the braking force that each braking mechanism 30 can impart to the wheel 91.

[0019] The friction brake device 20 is capable of supplying brake fluid to each wheel cylinder 31. Although not shown in the figure, the friction brake device 20 includes a master cylinder that supplies brake fluid to the wheel cylinders 31 according to the operation of the brake operation component 92. The friction brake device 20 includes a pressurizing mechanism 40 for pressurizing the brake fluid, which includes an electric motor 41 and a pump 42. The pump 42 is an electric pump that uses the electric motor 41 as a power source. Brake fluid discharged from the pump 42 is supplied to each wheel cylinder 31. The pump 42 is the pressurizing source that increases the WC pressure. The greater the driving force of the power source of the pump 42, i.e., the electric motor 41, the higher the WC pressure can be.

[0020] As a hydraulic braking device, the friction braking device 20 generates frictional braking force by transmitting the driving force of the electric motor 41 to the braking mechanism 30 via the brake fluid. For example, the friction braking device 20 does not have a accumulator for storing high-pressure brake fluid. When frictional braking force is requested, the vehicle generates frictional braking force by starting the drive of the electric motor 41. The WC pressure increases because the brake fluid is pressurized by starting the drive of the electric motor 41.

[0021] (Sensors and other equipment equipped in the vehicle)

[0022] The vehicle is equipped with various sensors. Figure 1 As examples of various sensors, a brake sensor 93 and a wheel speed sensor 94 are shown. Detection signals from various sensors are input to the control unit 10.

[0023] The brake sensor 93 can detect the amount of operation of the brake operating component 92. One example of the amount of operation of the brake operating component 92 is the pedal travel, which is the amount of movement of the brake operating component 92. In addition, the amount of operation of the brake operating component 92 can be listed as the pedal force, which is the pressure applied to the brake operating component 92 in order to operate the brake operating component 92.

[0024] The wheel speed sensor 94 can detect the wheel speed of the wheel 91. The wheel speed sensor 94 is installed on each wheel 91. The vehicle speed can be calculated based on the wheel speed.

[0025] The vehicle may also be equipped with a noise meter. The meter can be installed inside or outside the vehicle. Additionally, the vehicle may be equipped with an indoor microphone. Information related to the sound acquired by the meter or microphone can be input to the control device 10.

[0026] (Control device)

[0027] The control device 10 will be described below. The control device 10 consists of multiple functional units that perform various controls. Figure 1As an example of a functional unit, the motor control unit 11 and the acquisition unit 12 are shown.

[0028] The control device 10 may be any one of the following structures (a) to (c): (a) It has one or more processors that execute various processes according to a computer program. The processor includes a CPU and memories such as RAM and ROM. The memories store program code or instructions configured to enable the CPU to execute processes. The memories, i.e., computer-readable media, include all usable media that can be accessed by a general-purpose or special-purpose computer. (b) It has one or more dedicated hardware circuits that execute various processes. The dedicated hardware circuits are, for example, application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs). (c) It has a processor that executes a portion of the various processes according to a computer program, and dedicated hardware circuits that execute the remaining processes.

[0029] The acquisition unit 12 can calculate the vehicle's state quantities based on detection signals from various sensors. For example, the acquisition unit 12 can calculate the operation quantity of the brake operating component 92 based on the detection signal from the brake sensor 93. That is, the acquisition unit 12 can calculate pedal travel, pedal force, etc. In addition, the acquisition unit 12 can calculate the vehicle's travel speed, i.e., vehicle speed, based on the detection signal from the wheel speed sensor 94.

[0030] The acquisition unit 12 can acquire the background noise level BN obtained by inferring the magnitude of the background noise. Here, background noise refers to the noise other than the driving sound from the electric motor 41 that is transmitted to the driver of the vehicle. Sometimes this background noise is also referred to as background noise relative to the driving sound from the electric motor 41.

[0031] The background noise level BN is explained below. The background noise level BN is a value that is inferred to be higher as the background noise level increases. When the background noise level BN is high, it can be said that the background noise relative to the driving sound from the electric motor 41 is relatively large, and the driving sound from the electric motor 41 is not easily transmitted to the driver. Conversely, when the background noise level BN is low, it can be said that the background noise relative to the driving sound from the electric motor 41 is relatively small, and the driving sound from the electric motor 41 is easily transmitted to the driver.

[0032] For example, background noise increases when the vehicle is in motion compared to when it is stationary. Furthermore, background noise increases with higher vehicle speeds. Therefore, as an example, the higher the vehicle speed, the higher the background noise level BN calculated by the acquisition unit 12. Additionally, if the vehicle's power source is an engine, the higher the engine speed, the higher the calculated background noise level BN. Furthermore, the higher the road noise, the higher the calculated background noise level BN. For example, if the coefficient of friction of the road surface is high, it can be inferred that road noise is high. Therefore, as an example, the higher the coefficient of friction of the road surface, the higher the calculated background noise level BN calculated by the acquisition unit 12.

[0033] For example, when the vehicle's air conditioning is working, the background noise increases. Alternatively, when the air conditioning is working, the acquisition unit 12 may calculate the background noise level BN to be higher than when the air conditioning is not working.

[0034] For example, when sound is output from a car audio system, the background noise also increases. Alternatively, when sound is output from an audio system, the acquisition unit 12 may calculate a larger background noise level BN compared to when sound is not output from an audio system.

[0035] Alternatively, the acquisition unit 12 can also calculate the background noise level BN based on the sound pressure level of the noise. For example, the acquisition unit 12 can also use the sound pressure level acquired from a measuring device or microphone to calculate the background noise level BN. Furthermore, even when the sound pressure level of the background noise is the same, it is difficult for the driver to distinguish the operating sound when the difference between the frequency of the operating sound and the frequency of the background noise is small, compared to when the difference is large. Therefore, in particular, the background noise level BN can also be calculated based on the sound pressure level of a frequency in the detected noise that is the same as the frequency of the sound driven by the electric motor 41. The background noise level BN can also be calculated based on the sound pressure level of a predetermined frequency that is close to the frequency of the sound driven by the electric motor 41.

[0036] The acquisition unit 12 can acquire the target pressure PT as a target value of the pressure that presses the friction material 32 against the rotating body 33 in the braking mechanism 30. For example, the acquisition unit 12 can calculate the target pressure PT based on the pedal travel. The target pressure PT is an example of an index value corresponding to the magnitude of the target value of the friction braking force.

[0037] Other examples of index values ​​are target braking force as the target value of friction braking force. Furthermore, index values ​​can include the vehicle's target deceleration, the actual braking force actually generated by the vehicle, the actual deceleration actually generated by the vehicle, and the WC pressure representing the pressure of the brake fluid or the servo pressure representing the pressure generated by pump 42. When the vehicle is not moving automatically, i.e., when the vehicle is moved by the driver's operation, the pedal travel and pedal force can also be used as index values.

[0038] The motor control unit 11 is capable of controlling the electric motor 41. The motor control unit 11 controls the electric motor 41 by adjusting its rotational speed, i.e., the motor speed Nm. The motor control unit 11 drives the electric motor 41 so that the motor speed Nm follows a target value, i.e., a target speed NT. The target speed NT is the rotational speed of the electric motor 41 required to pressurize the brake fluid to the pressure needed to generate friction braking force.

[0039] The motor control unit 11 can also perform a limiting process that restricts the motor speed Nm to a value smaller than the target speed NT. This limiting process suppresses the increase in noise that accompanies the driving of the electric motor 41 when frictional braking force begins to be generated. Details of the limiting process will be described later.

[0040] (Processing performed by the control device)

[0041] Figure 2 This describes the process flow executed by the control device 10. This process begins when a request for friction braking force is made. For example, this process begins when the brake operation component 92 is first operated. In the case of automatic vehicle operation, this process can begin when braking is requested by the automatic driving control unit 80.

[0042] When this processing procedure begins, firstly, in step S101, the control device 10 causes the acquisition unit 12 to perform an acquisition process. During this acquisition process, the acquisition unit 12 acquires the target pressure PT and the background noise level BN. Then, the control device 10 transfers the processing to step S102.

[0043] In step S102, the control device 10 causes the motor control unit 11 to set a limit judgment value PTth. The limit judgment value PTth is a value used to determine the magnitude of the index value, i.e., the target pressure PT.

[0044] The setting of the limit judgment value PTth will be explained. For example, the motor control unit 11 can calculate the limit judgment value PTth based on the background noise level BN. In this case, the higher the background noise level BN, the lower the limit judgment value PTth calculated by the motor control unit 11. The motor control unit 11 can also calculate the limit judgment value PTth based on the brake fluid temperature. In this case, the lower the brake fluid temperature, the lower the limit judgment value PTth calculated by the motor control unit 11. Alternatively, the motor control unit 11 can calculate the limit judgment value PTth based on the temperature of the friction material 32. In this case, the lower the temperature of the friction material 32, the lower the limit judgment value PTth calculated by the motor control unit 11. Furthermore, the brake fluid temperature and the friction material 32 temperature can, for example, be values ​​detected by a temperature sensor. The brake fluid temperature and the friction material 32 temperature can also be calculated based on the duration of operation of the friction braking device 20, etc.

[0045] When the limit determination value PTth is set in the process of step S102, the control device 10 transfers the process to step S103.

[0046] In step S103, the control device 10 causes the motor control unit 11 to set a limit value for the motor speed Nm. Here, the motor control unit 11 sets a gradient limit value to limit the rate of increase of the motor speed Nm. The gradient limit value is a value corresponding to the slope of the increase of the motor speed Nm. When the gradient limit value is decreased to limit the rate of increase of the motor speed Nm, the period until the motor speed Nm increases becomes longer.

[0047] The setting of the gradient limit value will be explained. For example, the motor control unit 11 can calculate the gradient limit value based on the background noise level BN. In this case, the higher the background noise level BN, the higher the calculated gradient limit value. That is, the higher the background noise level BN, the more lenient the speed increase limitation. The motor control unit 11 can also calculate the gradient limit value based on the brake fluid temperature. In this case, the lower the brake fluid temperature, the higher the calculated gradient limit value. The motor control unit 11 can also calculate the gradient limit value based on the temperature of the friction material 32. In this case, the lower the temperature of the friction material 32, the higher the calculated gradient limit value. The gradient limit value can also be calculated as a value that can suppress the instantaneous increase in brake fluid pressure as the motor speed Nm increases when the electric motor 41 is started.

[0048] When the motor speed limit value Nm is set in the process of step S103, the control device 10 transfers the process to step S104.

[0049] In step S104, the control device 10 initiates the limiting process of the motor control unit 11. As a result, the electric motor 41 is driven with the motor speed Nm limited based on the limit value set in step S103. When the motor control unit 11 initiates the limiting process, the control device 10 transfers the process to step S105.

[0050] In step S105, the control device 10 instructs the motor control unit 11 to determine whether the target pressure PT is below the limit determination value PTth. If the target pressure PT is greater than the limit determination value PTth (S105: "No"), the control device 10 transfers the processing to step S107. In step S107, the control device 10 instructs the motor control unit 11 to end the limit processing. As a result, the limitation on the motor speed Nm is released. That is, the electric motor 41 is driven so that the motor speed Nm follows the target speed NT. When the motor control unit 11 ends the limit processing, the control device 10 terminates this processing procedure.

[0051] On the other hand, in the process of step S105, if the target pressure PT is below the limit determination value PTth (S105: "Yes"), the control device 10 transfers the process to step S106. In step S106, the control device 10 causes the acquisition unit 12 to update the target pressure PT. The acquisition unit 12 calculates and updates the target pressure PT at the time of executing the process of step S106. Then, the control device 10 transfers the process back to step S105. That is, through the processes of steps S105 and S106, the limitation on the motor speed Nm continues until the target pressure PT exceeds the limit determination value PTth. In other words, when the target pressure PT exceeds the limit determination value PTth, the limitation on the motor speed Nm is released.

[0052] (Functions and effects)

[0053] The function and effects of this embodiment are explained.

[0054] Figure 3 This indicates the change in motor speed (Nm) when the vehicle begins braking. Figure 3 In the example shown, frictional braking force is generated from a timer t11.

[0055] like Figure 3 As shown in (a), the target pressure PT begins to increase from the timing t11 when the friction braking force is requested. According to the control device 10, a limit judgment value PTth is set by requesting the generation of friction braking force (S102). Furthermore, the larger the background noise level BN, the larger the gradient limit value is set (S103), and the limitation of the motor speed Nm begins (S104). By limiting the rate of increase of the motor speed Nm, thus... Figure 3As shown in (b), the motor speed Nm is suppressed to be smaller than the target speed NT.

[0056] exist Figure 3 In the example shown, the target pressure PT increases at a constant rate after time t11. Before time t12, the target pressure PT does not exceed the limit judgment value PTth. Therefore, during the period from time t11 to time t12, the motor speed limit Nm continues (S105, S106).

[0057] When the target pressure PT exceeds the limit judgment value PTth at time t12, the limitation on the motor speed Nm is released (S107). Therefore, after time t12, the motor speed Nm is controlled based on the target speed NT. Figure 3 In the example shown, the period from time t11 to time t12 is the period during which the increase in motor speed Nm is limited.

[0058] According to the control device 10, the motor speed Nm can be suppressed from increasing during the period from the start of vehicle braking until the target pressure PT exceeds the limit judgment value PTth. Therefore, the increased noise generated during the driving of the electric motor 41 during this period can be suppressed, making it less likely for the driver to experience discomfort.

[0059] However, even if the drive sound of the electric motor 41 increases while the background noise is also high, it is believed that the driver will not easily be able to determine that the noise is coming from the electric motor 41. That is, even if the drive sound of the electric motor 41 increases when the background noise is high, the driver will hardly feel uncomfortable.

[0060] In the control device 10, the higher the background noise level BN, the smaller the limit judgment value PTth is calculated. Therefore, the higher the background noise level BN, the shorter the period until the target pressure PT exceeds the limit judgment value PTth is. That is, the period for limiting the rate of increase of motor speed Nm is more likely to be shorter. Therefore, when the background noise level BN is high but the drive sound of the electric motor 41 is allowed, the period for limiting the rate of increase of motor speed Nm can be shortened to ensure responsiveness. Thus, it is possible to suppress the increase of motor speed Nm during the initial braking phase and shorten the period for limiting the rate of increase of motor speed Nm to ensure responsiveness.

[0061] According to the control device 10, the rate of increase of the motor speed Nm during the period when the target pressure PT is below the limit judgment value PTth is limited by a gradient limit value that increases with the background noise level BN. Therefore, when the background noise is presumed to be high, the limitation on the rate of increase of the motor speed Nm can be mitigated. Thus, when the background noise is presumed to be high, the motor speed Nm can increase earlier compared to when the background noise is presumed to be low. This ensures the discharge pressure of the pump 42, which uses the electric motor 41 as a power source, and ensures the responsiveness of pressurizing the brake fluid. That is, it ensures the responsiveness of generating friction braking force.

[0062] In the friction braking device 20, when the temperature of the brake fluid or the friction material 32 is low, the responsiveness of generating the friction braking force tends to decrease. Therefore, limiting the rate of increase of the motor speed Nm is sometimes not preferable. In the control device 10, the lower the temperature of the brake fluid and the friction material 32, the smaller the limit determination value PTth can be calculated. This shortens the period for limiting the rate of increase of the motor speed Nm, thus ensuring responsiveness. Furthermore, in the control device 10, the lower the temperature of the brake fluid or the friction material 32, the larger the gradient limit value, which can mitigate the limitation on the rate of increase of the motor speed Nm. This reduces the decrease in responsiveness caused by the limitation of the motor speed Nm, thus ensuring responsiveness.

[0063] Figure 4 Indicates and Figure 3 Compared to the examples shown, the examples exhibit a greater rate of increase in target pressure PT. Figure 4 In the example shown, the friction braking force is requested starting from time t21. Figure 4 As shown in (a), the target pressure PT increases at a relatively high rate, thus shortening the period until the target pressure PT exceeds the limit threshold PTth. That is, the period during which the rate of increase of the motor speed Nm is limited is shortened. If, at time t22, the target pressure PT exceeds the limit threshold PTth, the limitation on the motor speed Nm is lifted. Then, as... Figure 4 As shown in (b), the motor speed Nm increases with the increase of the target speed NT. Thus, according to the control device 10, when the target pressure PT increases rapidly, the period limiting the increase rate of the motor speed Nm can be shortened, and the motor speed Nm can be increased earlier. This ensures the period for suppressing the increase in noise associated with the driving of the electric motor 41, and ensures responsiveness by driving the pump 42 at a higher motor speed Nm. Therefore, in the event of an emergency braking request, a friction braking force corresponding to the request can be generated.

[0064] In addition, in relation to Figure 3Compared to the example shown, when the rate of increase of the target pressure PT is smaller, the period until the target pressure PT exceeds the limit judgment value PTth becomes longer. That is, the period for limiting the rate of increase of the motor speed Nm becomes longer. Therefore, when the rate of increase of the target pressure PT is smaller, it is possible to further suppress the increase in noise generated by the driving of the electric motor 41.

[0065] exist Figure 3 as well as Figure 4 The example shown illustrates a situation where the rate of increase of the target pressure PT remains constant after braking begins. Here, for example, consider the case where the amount of operation of the brake operating component 92 increases during braking, leading to a greater rate of increase in the target pressure PT. In this case, compared to the case where the target pressure PT remains constant, the target pressure PT exceeds the limit judgment value PTth at an earlier moment. Therefore, when the rate of increase of the target pressure PT increases, the limitation on the rate of increase of the motor speed Nm is released more quickly. Thus, according to the control device 10, responsiveness corresponding to the target pressure PT can be ensured. On the other hand, when the rate of increase of the target pressure PT decreases during braking, compared to the case where the target pressure PT remains constant, the period until the target pressure PT exceeds the limit judgment value PTth is longer. Therefore, when the rate of increase of the target pressure PT decreases, discomfort to the driver caused by the noise from the electric motor 41 can be further suppressed.

[0066] Furthermore, when setting a target pressure PT based on the driver's operation, the rate of change of the target pressure PT during operation may sometimes be inconsistent, resulting in deviations. For example, the rate of change may sometimes vary, such as noise. Therefore, if the motor speed Nm is controlled based on the rate of change of the target pressure PT to identify emergency braking and gentle braking, the rate of increase of the motor speed Nm may differ from the assumption due to the deviation in the rate of change of the target pressure PT. In contrast, in the control device 10, the rate of increase of the motor speed Nm is limited based on the target pressure PT being below the limit determination value PTth. Therefore, the rate of increase of the motor speed Nm can be controlled in accordance with both emergency braking and gentle braking, regardless of the deviation in the rate of change of the target pressure PT.

[0067] As an example of the friction braking device 20, the brake operating component 92 is engaged with the master cylinder, and the pressurizing mechanism 40 is integrally formed with the master cylinder. In this case, the pressurizing mechanism 40 is necessarily located near the driver who operates the brake operating component 92. Moreover, the pressurizing mechanism 40 is firmly connected to the vehicle body. Therefore, the sound and vibration generated by the drive of the electric motor 41 are more easily transmitted to the driver. With the friction braking device 20 configured in this way, the control device 10 of this embodiment is more effective in suppressing the discomfort caused by the sound from the electric motor 41.

[0068] (Example of Change)

[0069] This embodiment can be modified and implemented as follows. This embodiment and the following modifications can be combined and implemented with each other within the scope of technical inconsistency.

[0070] In the above embodiment, the rate of increase of the motor speed Nm is limited by a limiting process. In addition, an upper limit value can be set for the motor speed Nm.

[0071] use Figure 5 Explanation will be provided. In Figure 5 In the example shown, such as Figure 5 As shown in (a), a friction braking force is requested starting at time t31. At time t33, the target pressure PT exceeds the limit judgment value PTth.

[0072] like Figure 5 As shown in (b), an upper limit motor speed NL is set as the upper limit of the motor speed Nm. During the period until the target pressure PT exceeds the limit judgment value PTth, the motor control unit 11 can limit the motor speed Nm to a value lower than the smaller of the upper limit motor speed NL and the target speed NT. Therefore, when the motor speed Nm reaches the upper limit motor speed NL at time t32 before time t33, the motor speed Nm remains constant. Then, when the target pressure PT exceeds the limit judgment value PTth at time t33, the limitation on the motor speed Nm is released, and the electric motor 41 is driven so that the motor speed Nm follows the target speed NT.

[0073] At this time, the motor control unit 11 is Figure 2 In step S103, in addition to the gradient limit value, an upper limit motor speed NL can also be set. For example, the upper limit motor speed NL can also use a value calculated in advance through experiments, etc. The larger the background noise level BN, the larger the upper limit motor speed NL can be calculated to be. Furthermore, the upper limit motor speed NL can also be a variable value during braking. For example, the upper limit motor speed NL can also be calculated by multiplying the target speed NT by a value greater than "0" and less than "1".

[0074] In the above embodiments, the limiting determination value PTth is used in... Figure 2 The value calculated in step S102. Instead, the constant value calculated in advance through experiments and stored in the motor control unit 11 can be used as the limit determination value PTth. In this case, it can also be omitted. Figure 2 The processing of step S102.

[0075] In the above embodiment, a control device 10 is shown that controls a hydraulic braking device, i.e., a friction braking device 20. The friction braking device is not limited to a hydraulic braking device. The control device can control a mechanical friction braking device that generates friction braking force by mechanically transmitting the driving amount of an electric motor.

[0076] Figure 6 The control device 110 and the friction braking device 120, which is controlled by the control device 110, are described. The friction braking device 120 includes a braking mechanism 130. The braking mechanism 130 includes an electric motor 141. The braking mechanism 130 includes, for example, a reduction gear. The braking mechanism 130 includes, for example, a direct-drive conversion mechanism. The braking mechanism 130 is capable of pressing the friction material 132 against the rotating body 133 according to the driving amount of the electric motor 141 transmitted by the reduction gear and the direct-drive conversion mechanism. The control device 110 controls the friction braking device 120 and has the function of performing a limiting process to limit the rate of increase of the rotational speed of the electric motor 141.

[0077] According to the control device 110, similar to the control device 10 in the above embodiment, the rate of increase in the rotational speed of the electric motor 141 can be limited during the initial stage of braking. More specifically, the control device 110 can suppress the increase in the rotational speed of the electric motor 141 during the period from the start of vehicle braking until the index value exceeds the limit determination value. As a result, the increase in noise generated during the driving of the electric motor 141 during this period can be suppressed, making it less likely for the driver to feel uncomfortable.

[0078] Furthermore, the gradient limit value set in this case can be calculated as a value that can reduce the collision between gears as the rotational speed increases when the electric motor 141 is started to drive.

Claims

1. A control device applied to a friction brake device having an electric motor, which generates a friction braking force of a vehicle by starting driving of the electric motor, wherein, The aforementioned control device includes: The motor control unit controls the aforementioned electric motor; and The acquisition unit acquires the index value corresponding to the magnitude of the target value of the aforementioned frictional braking force. The value used to determine the magnitude of the above indicator will be used as the limiting judgment value. When the aforementioned indicator value is below the aforementioned limit judgment value, the motor control unit limits the rate of increase of the electric motor's rotational speed; when the aforementioned indicator value exceeds the aforementioned limit judgment value, the restriction is lifted. The aforementioned acquisition unit acquires the background noise level obtained by inferring the magnitude of the background noise relative to the sound of the drive from the aforementioned electric motor. The higher the background noise level, the lower the limit determination value will be set by the motor control unit.

2. The control device according to claim 1, wherein, The aforementioned acquisition unit acquires the background noise level obtained by inferring the magnitude of the background noise relative to the sound of the drive from the aforementioned electric motor. When the above-mentioned index value is below the above-mentioned limit judgment value, the lower the background noise level, the smaller the increase rate is caused by the motor control unit.

3. The control device according to claim 1 or 2, wherein, The higher the speed of the vehicle, the higher the background noise level will be for the acquisition unit.

4. A control device applied to a friction braking device having an electric motor, wherein friction braking force is generated in a vehicle by activating the electric motor, wherein... The aforementioned control device includes: The motor control unit controls the aforementioned electric motor; and The acquisition unit acquires the index value corresponding to the magnitude of the target value of the aforementioned frictional braking force. The value used to determine the magnitude of the above indicator will be used as the limiting judgment value. When the aforementioned indicator value is below the aforementioned limit judgment value, the motor control unit limits the rate of increase of the electric motor's rotational speed; when the aforementioned indicator value exceeds the aforementioned limit judgment value, the restriction is lifted. The aforementioned acquisition unit acquires the background noise level obtained by inferring the magnitude of the background noise relative to the sound of the drive from the aforementioned electric motor. When the above-mentioned index value is below the above-mentioned limit judgment value, the lower the background noise level, the smaller the increase rate is caused by the motor control unit.

5. The control device according to claim 4, wherein, The higher the speed of the vehicle, the higher the background noise level will be for the acquisition unit.

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