Electric brake device

Abstract

The purpose of the present invention is to provide an electric brake device capable of high-precision control at low cost. The present invention is provided with a motor control device (11) for controlling the rotation of an electric motor (8) for pressing brake pads (5a, 5b). A motor control device (11) is provided with: a motor position / current relationship generation unit (43) that acquires the relationship between the rotational position of an electric motor (8) and the current of the electric motor (8); a brake torque estimation unit (41) that estimates the brake torque for pressing the brake pads (5a, 5b) on the basis of the rotational position of the electric motor (8); and a brake torque positional relationship generation unit (42) that acquires the relationship between the rotational position of the electric motor (8) and the brake torque on the basis of information from the motor position current relationship generation unit (43) and the brake torque estimation unit (41). The rotation of the electric motor (8) is controlled on the basis of information from the brake torque positional relationship generation unit (42).

Description

Technical Field

[0001] The invention relates to an electric brake device for vehicle braking. Background Art

[0002] In an electric brake device, by controlling the braking force by estimating the braking force with high accuracy, more detailed control can be achieved. Although the estimation accuracy can be improved by using a thrust sensor for estimation, the cost will increase. As a method for estimating the braking force without using a thrust sensor, for example, the technology described in Patent Document 1 has been proposed.

[0003] In Patent Document 1, a driving force is applied to a driving wheel while a braking force is applied to the wheel, and control parameters of an electric motor for driving a brake mechanism provided on the wheel are corrected based on the driving force when the driving force of the driving wheel exceeds the braking force. Prior art literature Patent Literature

[0004] Patent Document 1: International Publication No. 2020 / 262278 Summary of the invention Problem that the invention aims to solve

[0005] In the technology described in Patent Document 1, since it is necessary to compare the braking force with the driving force when estimating the braking force, it is necessary to generate the driving force to correct the control parameters. In order to obtain the correct driving force information, a high-precision sensor needs to be installed, which increases the cost. In addition, in order to obtain the correct driving force information without using a high-precision sensor, the driving wheel needs to perform a special action, which complicates the control.

[0006] An object of the present invention is to provide an electric brake device capable of high-precision control at low cost. Technical means of solving problems

[0007] Effects of the Invention In order to achieve the above-mentioned purpose, the electric control device of the present invention comprises: an electric motor; a direct-acting part, which moves by the rotation of the electric motor; a brake pad, which presses a disc brake that rotates together with the wheel by the thrust generated by the movement of the direct-acting part; and a motor control device, which controls the rotation of the electric motor. The electric control device is characterized in that the motor control device comprises: a motor position-current relationship generating unit, which obtains the relationship between the rotational position of the electric motor and the current of the electric motor; a braking torque estimating unit, which estimates the braking torque pressing the brake pad according to the rotational position of the electric motor at a specified time; and a braking torque position relationship generating unit, which obtains the relationship between the rotational position of the electric motor and the braking torque based on information from the motor position-current relationship generating unit and the braking torque estimating unit, and the motor control device controls the rotation of the electric motor based on the information from the braking torque position relationship generating unit.

[0008] According to the present invention, it is possible to provide an electric brake device capable of performing high-precision control at low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of an electric brake device according to a first embodiment of the present invention. Figure 2 This is a control block diagram of the electric brake device according to the first embodiment of the present invention. Figure 3 This is a diagram showing the relationship between the motor current and the motor position acquired by the motor position-current relationship generating unit according to the first embodiment of the present invention. Figure 4 This is a diagram showing the relationship between the motor position and the braking torque generated by the braking torque-position-current relationship generating unit according to the first embodiment of the present invention. Figure 5 This is a diagram showing the relationship between the motor current and the motor position acquired by the motor position-current relationship generating unit during the release operation according to the second embodiment of the present invention. Figure 6 This is a diagram showing the relationship between the motor position and the braking torque at the time of release generated by the braking torque position relationship generating unit according to the second embodiment of the present invention. Figure 7 This is a diagram showing the relationship between the motor position and the braking torque at the time of release generated by the braking torque position relationship generating unit according to the second embodiment of the present invention. Figure 8 This is a diagram showing the relationship between the motor position and the motor current used in the braking torque position command conversion unit according to the third embodiment of the present invention. Fig. 9 This is a diagram showing the relationship between the motor position and the braking torque generated by the braking torque position relationship generating unit according to the third embodiment of the present invention. DETAILED DESCRIPTION

[0010] Hereinafter, embodiments of the present invention will be described using the drawings. In addition, substantially the same or similar structures are given the same reference numerals, and when the description is repeated, the repeated description may be omitted. Example 1

[0011] First, the electric brake device described in the first embodiment will be described. Figure 1 This is a schematic diagram of an electric brake device according to a first embodiment of the present invention. Figure 2 This is a control block diagram of the electric brake device according to the first embodiment of the present invention.

[0012] Generally, a vehicle such as a car is composed of four wheels, namely, left and right front wheels and left and right rear wheels, and a brake device is provided on each wheel. Figure 1 As shown, the brake device 1 is composed of the following: a housing 4, which is supported by a bracket (not shown) fixed to a non-rotating part of the vehicle located on the vehicle inner side of the disc brake 2 (rotating member) and can float in the axial direction of the disc brake 2; brake pads 5a, 5b (pressing members) arranged on the left and right sides of the disc brake 2; a piston 6 (linear motion part) that can linearly move in the housing 4; and an electric motor 8 that drives the piston 6. The electric motor 8 applies thrust to the brake pads 5a, 5b through the rotation-to-linear motion conversion mechanism 10 and the piston 6, and the brake pads 5a, 5b press the disc brake 2 that rotates together with the wheel from the left and right directions, and apply braking force through clamping force (pad thrust).

[0013] The output shaft of the electric motor 8 is connected to the speed reducer 9, and the output shaft of the speed reducer 9 is connected to the rotation-to-linear conversion mechanism 10. The piston 6 can move in the linear direction through the rotation-to-linear conversion mechanism 10. The piston 6 moves in the linear direction by the rotation of the electric motor 8.

[0014] In the first embodiment, the caliper 3 is composed of the disc brake 2, the housing 4, the brake pads 5a and 5b, the piston 6, the electric motor 8, the speed reducer 9, and the rotation-to-linear motion conversion mechanism 10. The rotation-to-linear motion conversion mechanism 10 and the piston 6 constitute a linear motion unit.

[0015] The electric motor 8 is connected to a motor control device 11 (controller) via an electric wire 12. The rotation of the electric motor 8 is controlled by the motor control device 11. Figure 1 In the embodiment, the electric motor 8 and the motor control device 11 are described as separate bodies, but they may be an integrated structure. Figure 2 As shown, the electric motor 8 includes a current detection unit 31 for detecting a current during driving, and a position detection unit 32 .

[0016] The motor control device 11 receives a brake torque command 29 from a higher-level control device (vehicle control ECU) and issues a current command to the electric motor 8 based on the detection values ​​of the current detector 31 and the position detector 32 according to a preset control program.

[0017] The motor control device 11 is connected to a control signal line 21 and communication lines 22 and 23. The control signal line 21 is used to input control instructions from a higher-level control device such as an ECU (Electronic Control Unit) for vehicle control to the motor control device 11. The communication lines 22 and 23 are used to communicate information other than control instructions with the higher-level control device. In addition, here, the higher-level control device and the motor control device 11 are configured separately, but it may also be a control device that integrates the two.

[0018] Figure 2 1 shows the calculation method of the motor control device 11. When the brake torque command 29 is received from the vehicle control ECU via the control signal line 21, the brake torque position command conversion unit 36 ​​converts it into a position command value and inputs it to the position current control unit 44. The position current control unit 44 feeds back the position information obtained from the position detection unit 32 and the current value of the electric motor 8 obtained from the current detection unit 31 based on the position command, and provides a current command to the electric motor 8 in the brake caliper 3.

[0019] The braking torque position command conversion unit 36 ​​converts the input braking torque command into a motor position command and outputs it based on the relationship between the motor position and the braking torque generated by the braking torque position relationship generation unit 42 (for example, the braking torque position is represented by a braking torque position map represented on a map). The braking torque position relationship generation unit 42 generates the relationship between the motor position and the motor current based on the relationship between the motor position and the motor current generated by the motor position current relationship generation unit 43 and the output of the braking torque estimation unit 41.

[0020] Next, the motor-position-current relationship generating unit 43 will be described. Figure 3 1 is a diagram showing the relationship between the motor current and the motor position obtained by the motor position current relationship generating unit of the first embodiment of the present invention. The motor position current relationship generating unit 43 obtains the rotational position of the electric motor 8 and the current of the electric motor 8, and generates the relationship between the rotational position of the electric motor 8 and the current of the electric motor 8.

[0021] Since the electric motor 8 is provided with the current detection unit 31 and the position detection unit 32, for example, when the brake is applied during driving, the motor position (rotational position of the electric motor 8) and the motor current (current of the electric motor 8) are measured simultaneously by pressing the brake pads 5a and 5b against the disc brake 2 (application action), so that the vehicle can be operated as follows. Figure 3As shown, the relationship between the motor position x and the motor current I is obtained 51. At this time, since the motor current I usually has a noise component, it can be filtered using a low-pass filter or the like. The motor current I includes a friction component generated in the rotary direct-acting part or the like (the motor current I0 of the friction component). The friction component can be estimated from the current in the gap area before the pad contacts, etc., and the effective motor current Ia is extracted by subtracting this component to obtain the relationship 52 between the motor position and the current. In addition, when the acceleration and deceleration of the motor action are large, if the inertia component is subtracted as needed, the effective motor current component can be extracted with higher accuracy.

[0022] The conditions for obtaining this relationship are explained here. During normal driving, the braking force is only used within a small range, for example Figure 3 It operates within the range of states I and II shown. Figure 3 In the state of I, there is a pad gap in which the braking force has not yet been generated. In the state of I, the motor current I0 of the friction part is obtained.

[0023] Next, in the state II, the characteristics of the low thrust region are obtained. The state II is a state in which the brake pads 5a, 5b are in contact with the disc brake 2 during normal driving to obtain a braking force. In order to obtain the characteristics of the high thrust range that occurs less frequently during normal driving, when stopping, by further performing the action III of increasing the thrust, the relationship between the motor position and the motor current can be obtained within the range of the thrust generated by the parking brake. In addition, by temporarily increasing the thrust to a greater thrust than that required for parking, the relationship between the motor position and the motor current can be obtained in the IV region with a higher thrust.

[0024] As described above, the motor position current relationship generating unit 43 obtains the relationship between the rotational position of the electric motor 8 and the current of the electric motor 8 when the vehicle is running and when the vehicle is stopped. In this embodiment, the relationship between the motor position x and the motor current I having nonlinear characteristics in the entire range of the braking force desired to be generated, including high thrust, can be obtained.

[0025] Next, the braking torque estimating unit 41 for estimating the braking torque pressing the brake pads 5a and 5b will be described. The braking torque can be estimated, for example, based on the vehicle state. Here, the braking torque is estimated during braking.

[0026] Tire fore-aft force Ftx, which is a force that attempts to stop the vehicle by braking force, is represented by a function of tire load Ftz, can be linearly approximated in a small braking force range, and is represented by the following equation 1 in proportion to slip ratio λ.

[0027] [Equation 1] Ftx = λ / Kw × Ftz [Equation 2]λ=(Vb-Vw) / Vb Here, Vb represents the vehicle body speed, Vw represents the value obtained by converting the wheel speed into the center of gravity position, and Kw represents a proportionality coefficient determined by tire characteristics and the like. Therefore, if the vehicle body speed Vb, wheel speed Vw, tire load Ftz, and proportional coefficient Kw are determined, the tire front and rear force Ftx can be estimated. Since the tire front and rear force Ftx includes the braking driving force Fd generated by the engine on the engine vehicle or the main driving motor of the electric vehicle, the value obtained by subtracting the braking driving force Fd from the tire load Ftz becomes the braking force generated by the braking torque as shown in Formula 3. Therefore, by subtracting (removing) the braking driving force generated by the engine or motor from the estimated value, the braking force Fb can be estimated.

[0028] [Formula 3] Fb = Ftx - Fd The tire load Ftz is estimated using the vehicle weight and taking into account a portion that varies due to the rolling motion or pitching motion of the vehicle body.

[0029] Here, by multiplying the braking force Fb by the tire radius R, the braking torque Tb can be estimated. At this time, since the rotational position x (motor position) of the electric motor 8 is measured at the same time, the relationship between this value and the estimated braking torque can be known. Here, the electric motor rotational position is represented as position x, but the position obtained by measuring or estimating the direct displacement of the direct moving part such as the piston 6 that has converted the position by the rotational direct moving part can also be used. Thus, for example, it can be estimated Figure 4 Braking torque Tbx0 at motor position x0. Figure 4 This is a diagram showing the relationship between the motor position and the braking torque generated by the braking torque-position-current relationship generating unit according to the first embodiment of the present invention.

[0030] When the braking torque is estimated in the braking torque estimating unit 41 , it is necessary to estimate the tire load Ftz, the wheel speed Vw, and the braking-driving force Fd as described above. The timing of these estimations will be described below.

[0031] First, if the connection between the engine driving the wheels or the main engine motor driving the wheels and the wheels is disconnected by a clutch or the like, the braking-driving force Fd can be made 0, and there is no need to estimate the braking-driving force Fd, and the error caused by this can be eliminated. Alternatively, if the influence of the braking-driving force Fd is small, the relationship between the tire load Ftz and the braking-driving force Fd is Fd>>Fd, and the influence of the estimated error of the braking-driving force Fd can be reduced.

[0032] In addition, during a turn, the tire load Ftz changes left and right and needs to be estimated, and the wheel speed of each wheel needs to be converted to the center of gravity position and needs to be estimated. Therefore, by limiting the time to straight driving, the estimation error can be reduced.

[0033] In addition, when there is an inclination, the estimation error may become larger due to the acceleration and deceleration caused by the inclination. Therefore, by limiting the estimation to the time when the inclination is small, the estimation error can be reduced.

[0034] As described above, by selecting several conditions for reducing error factors at a predetermined time, it is possible to eliminate various factors of estimation error, thereby improving estimation accuracy.

[0035] In addition, as a method of estimating the braking torque, in addition to the above method, it is also possible to estimate based on information from various sensors that obtain information from the vehicle. As various sensors, for example, there can be cited acceleration sensors, yaw angle sensors, steering angle sensors, GPS (Global Positioning System), etc., and at least one of them can be used. This information is used as Figure 2 The sensor information 40 is input to the braking torque estimating unit 41 .

[0036] Next, the braking torque position relationship generating unit 42 will be described. The braking torque position relationship generating unit 42 acquires the relationship between the rotational position of the electric motor 8 and the braking torque based on information from the motor position current relationship generating unit 43 and the braking torque estimating unit 41 .

[0037] Since the relationship between the motor current I and the motor position x can be understood by the motor position-current relationship generating unit 43 , the motor current Iax0 at the motor position x0 estimated by the braking torque estimating unit 41 can be calculated based on the relationship obtained by the motor position-current relationship generating unit 43 .

[0038] Generally, since the effective motor current component is proportional to the torque generated by the motor and the braking torque generated thereby, the proportionality coefficient Ktia can be calculated using the following formula.

[0039] [Formula 4] Ktia = Tbax0 / Iax0 The proportional coefficient Ktia can be improved in accuracy by using data from multiple points, for example. Moreover, it can be made more accurate by calculating and finding the average of data from multiple points. In addition, if noise values ​​that deviate greatly from other values ​​exist in multiple points, the accuracy can be further improved by removing them. Using this Ktia, the braking torque Tba is expressed as follows.

[0040] [Formula 5] Tba=Ktia×Ia Therefore, we can get the proportionality factor Ktia multiplied by Figure 3 The relationship between the motor current Ia and the braking torque Tba after the motor position characteristics and the motor position x is shown in 53 ( Figure 4 ).

[0041] The following is a description of the braking torque control method. When the braking torque command 29 from the upper level is input, in the braking torque position command conversion unit 36, Figure 4 When the braking torque instruction 29 is Tbref, the motor position xref is obtained based on the relationship 53 between the braking torque Tb and the motor position x. Then, xref is input to the position current control unit 44 as a position instruction, and compared with the value detected by the position detection unit 32, feedback control is performed, and it is converted into a current instruction and output to the electric motor 8. In addition, the braking force applied to the tire can be directly used as the instruction value instead of the braking torque instruction 29.

[0042] According to this embodiment, by detecting the difference in characteristics between the position and the braking torque, which usually have large individual differences due to the difference in rigidity of each component and the difference in motor characteristics, during normal braking action, it is possible to perform high-precision braking torque control that also takes into account the characteristics between the motor position and the braking torque that change over time. In addition, in this embodiment, since no thrust sensor is used in the braking torque control, low cost can be achieved. Example 2

[0043] Next, a second embodiment of the present invention will be described. In the first embodiment, the map generation in the application action was described, and in the second embodiment, the map generation method in the release action will be described. Figure 5 This is a diagram showing the relationship between the motor current and the motor position acquired by the motor position-current relationship generating unit during the release operation according to the second embodiment of the present invention. Figure 6 This is a diagram showing the relationship between the motor position and the braking torque at the time of release generated by the braking torque position relationship generating unit according to the second embodiment of the present invention. Figure 7 This is a diagram showing the relationship between the motor position and the braking torque at the time of release generated by the braking torque position relationship generating unit according to the second embodiment of the present invention.

[0044] Figure 5 The relationship between the motor current and the motor position obtained during the release action is shown. As described in the first embodiment, since the electric motor is operated to the region IV with a thrust higher than that required for the parking brake during the stop, and then the action of temporarily returning to the thrust required for the parking brake is performed, the relationship 61 between the motor current I and the motor position x in the region IV is obtained at this time. Then, by releasing the parking brake during the stop, the relationship 62 between the motor current and the motor position during the release can be obtained in the order of III, II, and I, and the relationship between the effective current Ir of the motor current I0 taking into account the friction amount and the motor position x can be obtained in the same manner as during the application.

[0045] On the other hand, when driving, in the scenario where the release action is performed after the application action, Figure 5The II to I condition moves in the direction of reducing the current, and the relationship 61 between the motor position x and the motor current I is obtained. Then, if a gap is generated on the brake pad, the current in the area I is basically constant, and the motor current I0 equivalent to the friction is obtained.

[0046] Next, the braking torque estimation unit 41 is described. The braking torque can be estimated, for example, based on the vehicle state, as in the case of application. Here, the braking torque is estimated when the brake is released. At this time, by simultaneously measuring the motor position, the braking torque Tbx0 at the motor position x0 can be estimated.

[0047] Same as when applying, you can Figure 5 The effective motor current Ir at the motor position x0 is obtained. Since the effective motor current Ir is proportional to the generated braking torque, the proportionality coefficient can be calculated.

[0048] [Equation 6] Ktir = Tbx0 / Ix0 This proportionality coefficient Ktir can be obtained from a plurality of points in the same manner as when applying. Using this Ktir, the braking torque is expressed as follows.

[0049] [Equation 7] Tbr = Ktir × Ir That is, by multiplying Ktir by Figure 5 The characteristics of the motor current Ir and the motor position x shown in FIG. 6 can provide the relationship 63 between the braking torque Tb and the motor position x ( Figure 6 ).

[0050] Therefore, the forward efficiency and reverse efficiency are usually not necessarily the same, so Figure 7 As shown, two characteristics, a characteristic (Tba-x) 53 on the application side and a characteristic (Tbr-x) 63 on the release side, are obtained.

[0051] Based on this characteristic, when the braking torque command Tbref is input, the braking torque position command conversion unit 36 ​​converts it into a motor position command xref based on whether it is an applying action or a releasing action, and outputs it to the position current control unit 44. In the position current control unit 44, the motor position command xref is compared with the value detected by the position detection unit 32, feedback control is performed, and it is converted into a current command and output to the electric motor 8.

[0052] According to the present embodiment, by distinguishing between the applying action and the releasing action and issuing a command, it is possible to perform high-precision braking torque control corresponding to the action. Example 3

[0053] Next, use Figure 8 and Fig. 9 Embodiment 3 of the present invention will be described. Figure 8This is a diagram showing the relationship between the motor position and the motor current used in the braking torque position command conversion unit according to the third embodiment of the present invention. Fig. 9 This is a diagram showing the relationship between the motor position and the braking torque generated by the braking torque position relationship generating unit according to the third embodiment of the present invention.

[0054] In Example 3, an example is shown that takes into account the following situations: the environment (environment A) in which the relationship between the motor position and the motor current is obtained by the motor position-current relationship generating unit 43 described in Examples 1 and 2, the environment (environment B) in which the braking torque is estimated by the braking torque estimating unit 41, and the environment (environment C) in which control is performed based on the result, and the situation in which the characteristics change at different times.

[0055] For example, the rigidity changes due to the shrinkage and expansion of the brake pad or the device due to temperature, and the relationship between the motor current I and the motor position x changes due to changes in the torque constant of the electric motor 8 .

[0056] The friction coefficient of the brake pad when the torque generated by the electric motor 8 or the thrust through the rotation-to-linear conversion is converted into the braking torque may also change depending on the temperature or the rotation speed.

[0057] Therefore, in the third embodiment, the relationship for environmental changes is stored or formulated in advance in the motor position current relationship generation unit 43. For example, a conversion formula as shown in Formula 8 is prepared. As an example, the case where the motor position x that generates the same thrust changes as shown in the following formula is formulated.

[0058] [Equation 8] x = a × Tpad + b Here, Tpad represents the brake pad temperature, and a and b represent the slope and intercept with respect to the temperature, respectively. The characteristics under the standard state (for example, set to normal temperature) are estimated from these values.

[0059] For example, Figure 8 As shown, it is assumed that the characteristic shown in (1) is obtained when the brake pad temperature is 300°C and the motor temperature is 60°C in the environment A. In this case, the brake pads 5a and 5b are first converted to the normal temperature according to equation 8, and (2) is obtained as the characteristic. In addition, regarding the motor temperature, the lower the motor temperature, the smaller the torque constant. Therefore, at the location where the same torque is generated, the motor current decreases, and the characteristics at the motor normal temperature and the brake pad normal temperature as shown in (3) are obtained.

[0060] Here, the brake pad temperature and the motor temperature may be directly measured or estimated based on the number of operations or the like.

[0061] On the other hand, the braking torque is the product of the thrust generated by the electric motor 8 and the friction coefficient between the brake pads 5a, 5b and the disc brake 2. However, the friction coefficient varies depending on the environment such as the temperature and relative speed of the contacting object. Therefore, in the braking torque estimation unit 41, when the environment changes from the acquired environment to a different environment, the temperature and relative speed of the brake pads 5a, 5b are estimated or measured. In this case, the standard state (for example, normal temperature and speed V0) is also predetermined, and the calculation is performed as follows. Fig. 9 As shown, the braking torque and motor position (Tbx0, x0) are in a standard state relative to the actually measured braking torque and motor position (Tbx0m, x0m).

[0062] The value under the standard state is divided into the application state and the release state as needed, and the proportionality coefficient is calculated according to Formula 4 or Formula 6.

[0063] Then, yes Figure 8 The characteristic of (3) is multiplied by the proportionality coefficient Ktir, for example, to obtain Fig. 9 The solid line 71 shows the relationship between the motor position x and the braking torque Tba or Tbr.

[0064] When further implementing the control, the relationship between the braking torque and the motor position under the control environment (environment C) (motor temperature, brake pad temperature, relative speed) is calculated based on the relationship between the braking torque and the motor position under the standard state 71. The motor position when the braking torque command is calculated based on this relationship is output as a motor position command to the position current control unit.

[0065] According to this embodiment, even if the environment (environment A) when the motor position-current relationship is obtained by the motor position-current relationship generating unit 43, the environment (environment B) when the braking torque estimation unit 41 estimates the braking torque, and the environment (environment C) in which control is performed based on the result are different, the braking torque can be controlled with high precision. Example 4

[0066] Next, a fourth embodiment will be described. In the fourth embodiment, the timing of updating the relationship between the braking torque and the motor position in the braking torque-position relationship generating unit 42 described in the first to third embodiments will be described.

[0067] Regarding the proportional coefficient Ktia or Ktir between the effective motor current and the generated braking torque calculated in the first to third embodiments, the ratio of change over time is actually very small. In particular, when converted to the standard state as described in the third embodiment, the change is small. Therefore, when the Ktia or Ktir detected during the braking torque estimation is greatly changed from the previous value (for example, a change of 10% or more), it is treated as noise and the value is not adopted, and the previous value is adopted. This can reduce the error.

[0068] In addition, the braking torque position relationship generating unit 42 obtains the braking torque value estimated by the braking torque estimating unit 41 multiple times, averages or filters the obtained braking torque value, obtains the relationship between the rotation position of the electric motor 8 and the braking torque as the filtered value Ktia or Ktir, and can also be updated. In this way, the error factor can be reduced and the accuracy can be improved.

[0069] In addition, in each embodiment, an electric brake using a disc brake is described as an example, but various brakes may be used, such as a drum brake in which a braking force is generated by moving a piston using an electric motor or the like to push a brake pad against a brake drum as a rotating body. Explanation of symbols

[0070] 1…brake device, 2…disc brake, 3…brake caliper, 4…housing, 5a, 5b…brake pad, 6…piston, 8…electric motor, 9…reducer, 10…rotation-to-direct motion conversion mechanism, 11…motor control device, 29…brake torque instruction, 31…current detection unit, 32…position detection unit, 36…brake torque-position instruction conversion unit, 41…brake torque estimation unit, 42…brake torque-position relationship generation unit, 43…motor-position-current relationship generation unit, 44…position-current control unit.

Claims

1. An electric brake device comprising an electric motor; a linear motion part that moves by the rotation of the electric motor; a brake pad that presses a disc brake that rotates together with a wheel by a thrust generated by the movement of the linear motion part; and a motor control device that controls the rotation of the electric motor, wherein the electric brake device is characterized in that: The motor control device comprises: a motor position-current relationship generating unit for acquiring a relationship between a rotational position of the electric motor and a current of the electric motor; a braking torque estimating unit that estimates a braking torque pressing the brake pad based on a rotational position of the electric motor at a predetermined time; and a braking torque position relationship generating unit that obtains a relationship between a rotational position of the electric motor and the braking torque based on information from the motor position current relationship generating unit and the braking torque estimating unit, The motor control device controls rotation of the electric motor based on information from the braking torque-position relationship generating unit.

2. The electric brake device according to claim 1, characterized in that: The braking torque estimating unit estimates the braking torque when the vehicle is traveling straight.

3. The electric brake device according to claim 2, characterized in that: When the braking torque is estimated by the braking torque estimating unit, the connection between the engine driving the wheel or the main engine motor driving the wheel and the wheel is disconnected.

4. The electric brake device according to claim 1, characterized in that: The motor position-current relationship generating unit acquires a relationship between a rotational position of the electric motor and a current of the electric motor when the vehicle is traveling and when the vehicle is stopped.

5. The electric brake device according to claim 1, characterized in that: The motor position-current relationship generating unit acquires the relationship between the rotational position of the electric motor and the current of the electric motor during an applying operation and a releasing operation.

6. The electric brake device according to claim 1, characterized in that: The motor position-current relationship generating unit acquires a relationship between a rotational position of the electric motor and a current of the electric motor during an applying operation or a releasing operation.

7. The electric brake device according to claim 3, characterized in that: The braking torque estimating unit estimates the braking torque excluding a braking driving force of the engine or the main motor.

8. The electric brake device according to claim 1, characterized in that: The braking torque estimating unit estimates the braking torque based on information from a sensor that acquires information about the vehicle.

9. The electric brake device according to claim 8, characterized in that: The sensor is at least one of an acceleration sensor, a yaw angle sensor, a steering angle sensor, and a GPS (Global Positioning System).

10. The electric brake device according to claim 1, characterized in that: The braking torque estimating unit estimates the braking torque based on the tire load and the slip ratio.

11. The electric brake device according to claim 1, characterized in that: The braking torque position relationship generating unit acquires the braking torque values ​​estimated by the braking torque estimating unit a plurality of times, performs filtering processing on the acquired braking torque values, and acquires the relationship between the rotational position of the electric motor and the braking torque.

12. The electric brake device according to claim 1, characterized in that: The motor position-current relationship generating unit estimates characteristics when an environment changes from an environment when the relationship between the rotational position of the electric motor and the current of the electric motor is acquired to a different environment, thereby acquiring the relationship between the position and the motor current.

13. The electric brake device according to claim 1, characterized in that: The braking torque estimating unit estimates the braking torque when the environment changes from the environment when the acquired environment is different from the environment.

14. The electric brake device according to claim 1, characterized in that: A braking torque position command conversion unit is provided that outputs a position command of the electric motor based on the information from the braking torque position relationship generation unit.

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