Electric brake device

Abstract

To provide an electric brake device capable of highly accurate control at a low cost.SOLUTION: An electric brake device includes a motor control device 11 that controls the rotation of an electric motor 8 for pressing brake pads 5a, 5b. The motor control device 11 includes: a motor position-current relation creation unit 43 that acquires a relation between a rotational position of the electric motor 8 and a current of the electric motor 8; a braking torque estimation unit 41 that estimates braking torque for pressing the brake pads 5a, 5b from the rotational position of the electric motor 8; and a braking torque-position relation creation unit 42 that acquires a relation between the rotational position of the electric motor 8 and the braking torque, based on information from the motor position-current relation creation unit 43 and the braking torque estimation unit 41. The rotation of the electric motor 8 is controlled based on information from the braking torque-position relation creation unit 42.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric brake device used for braking a vehicle. [Background technology]

[0002] In an electric brake device, more precise control is possible by accurately estimating the braking force. Estimation accuracy can be improved by using a thrust sensor, but this increases costs. For example, a technique described in Patent Document 1 has been proposed as a method for estimating braking force without using a thrust sensor.

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

[0004] [Patent Document 1] International Publication No. 2020 / 262278 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology described in Patent Document 1, when estimating braking force, it is necessary to compare it with driving force, so it is necessary to generate that driving force and correct the control parameters. Obtaining accurate driving force information requires the installation of a high-precision sensor, which increases costs. Furthermore, obtaining accurate driving force information without using a high-precision sensor requires the drive wheels to perform special operations, which complicates control.

[0006] An object of the present invention is to provide an electric brake device that can be controlled with high precision at low cost. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides an electric brake device comprising an electric motor, a linear motion part that moves due to rotation of the electric motor, brake pads that press against a disc rotor that rotates together with a wheel by 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 motor control device comprises: a motor position-current relationship creation unit that obtains a relationship between the rotational position of the electric motor and a current of the electric motor; a braking torque estimation unit that estimates a braking torque that presses against the brake pad from the rotational position of the electric motor at a predetermined timing; and a braking torque position relationship creation unit that obtains the relationship between the rotational position of the electric motor and the braking torque based on information from the motor position-current relationship creation unit and the braking torque estimation unit; The braking torque estimating unit disconnects the engine that drives the wheels or the main motor that drives the wheels from the wheels, and estimates the braking torque when the vehicle is traveling straight, and the motor control device The rotation of the electric motor is controlled based on information from the braking torque position relationship creation unit. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an electric brake device that is low-cost and capable of highly accurate control. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an electric brake device according to a first embodiment of the present invention. [Figure 2] 1 is a control block diagram of an electric brake device according to a first embodiment of the present invention. [Figure 3] 4 is a diagram showing a relationship between a motor current and a motor position acquired by a motor position-current relationship creation unit according to the first embodiment of the present invention. FIG. [Figure 4] FIG. 3 is a diagram showing the relationship between the motor position and braking torque created by a braking torque position-current relationship creating unit according to the first embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing the relationship between the motor current and the motor position acquired by the motor position-current relationship creation unit during the release operation according to the second embodiment of the present invention. [Figure 6] FIG. 10 is a diagram showing the relationship between the motor position and braking torque at the time of release created by a braking torque position relationship creating unit according to the second embodiment of the present invention. [Figure 7] FIG. 10 is a diagram showing the relationship between the motor position and braking torque at the time of release created by a braking torque position relationship creating unit according to the second embodiment of the present invention. [Figure 8] FIG. 10 is a diagram showing the relationship between the motor position and braking torque used in a braking torque position command conversion unit according to a third embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing the relationship between motor position and braking torque created by a braking torque position relationship creating unit according to the third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that substantially the same or similar components are designated by the same reference numerals, and where explanations are redundant, redundant explanations may be omitted. [Example]

[0011] First, an electric brake device according to a first embodiment will be described. Fig. 1 is a schematic diagram of the electric brake device according to the first embodiment of the present invention. Fig. 2 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 an automobile has four wheels, one each for the front and rear wheels, and a brake device is installed on each wheel. As shown in FIG. 1, the brake device 1 is composed of a housing 4 supported on a carrier (not shown) fixed to a non-rotating portion of the vehicle located inside the vehicle of the disc rotor 2 (rotating member) so as to be able to float in the axial direction of the disc rotor 2, brake pads 5a, 5b (pressing members) arranged on both the left and right sides of the disc rotor 2, a piston 6 (linearly moving portion) that can move linearly within 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 via a rotary-to-linear motion conversion mechanism 10 and the piston 6, and the brake pads 5a, 5b press the disc rotor 2, which rotates together with the wheel, from the left and right, thereby applying a braking force by squeezing it together (pad thrust).

[0013] The output shaft of the electric motor 8 is connected to a reducer 9, and the output shaft of the reducer 9 is connected to a rotary-to-linear motion conversion mechanism 10, which enables the piston 6 to move in the linear motion direction. The piston 6 moves in the linear motion direction as the electric motor 8 rotates.

[0014] In the first embodiment, the brake caliper 3 is made up of the disc rotor 2, the housing 4, the brake pads 5a, 5b, the piston 6, the electric motor 8, the reducer 9, and the rotary-to-linear motion conversion mechanism 10. The rotary-to-linear motion conversion mechanism 10 and the piston 6 make up a linear motion part.

[0015] The electric motor 8 is connected to a motor control device 11 (controller) by an electric wire 12. The rotation of the electric motor 8 is controlled by the motor control device 11. In FIG. 1, the electric motor 8 and the motor control device 11 are shown as separate entities, but they may also be configured as an integrated unit. As shown in FIG. 2, the electric motor 8 is also provided with a current detection unit 31 that detects the current when the motor is driven, and a position detection unit 32.

[0016] The motor control device 11 receives a braking torque command 29 from a higher-level control device (vehicle control ECU) or the like, and provides a current command to the electric motor 8 based on a preset control program or the like, which is based on the detection values ​​of the current detection unit 31 and the position detection unit 32.

[0017] A control signal line 21 and communication lines 22 and 23 are connected to the motor control device 11. The control signal line 21 inputs control commands from a higher-level control device such as a vehicle control ECU (Electronic Control Unit) to the motor control device 11. The communication lines 22 and 23 communicate information other than the control commands with the higher-level control device. Note that although the higher-level control device and the motor control device 11 are shown here as being separately located, they may also be integrated into a single control device.

[0018] The calculation method of the motor control device 11 is shown in Fig. 2. When a braking torque command 29 is given from the vehicle control ECU via control signal line 21, it is converted into a position command value by braking torque position command conversion unit 36 ​​and input to position current control unit 44. Position current control unit 44 feeds back position information obtained from position detection unit 32 based on the position command and the current value of electric motor 8 obtained by current detection unit 31, and a current command is given to electric motor 8 in brake caliper 3.

[0019] When a braking torque command is input, braking torque position command conversion unit 36 ​​converts it into a motor position command and outputs it based on the relationship between motor position and braking torque (for example, expressed as a braking torque position map that shows braking torque position on a map) created by braking torque position relationship creation unit 42. Braking torque position relationship creation unit 42 is created from the relationship between motor position and motor current created by motor position current relationship creation unit 43 and the output of braking torque estimation unit 41.

[0020] Next, the motor position-current relationship creation unit 43 will be described. Fig. 3 is a diagram showing the relationship between the motor current and the motor position acquired by the motor position-current relationship creation unit according to the first embodiment of the present invention. The motor position-current relationship creation unit 43 acquires the rotational position of the electric motor 8 and the current of the electric motor 8, and creates the relationship between the rotational position of the electric motor 8 and the current of the electric motor 8.

[0021] The electric motor 8 is equipped with a current detector 31 and a position detector 32. For example, when applying the brakes while driving, the brake pads 5a, 5b are pressed against the disc rotor 2 (applying the brakes), which simultaneously measures the motor position (the rotational position of the electric motor 8) and the motor current (the current of the electric motor 8). This allows the relationship 51 between the motor position x and the motor current I to be obtained, as shown in Figure 3. Because the motor current I typically contains noise, filtering using a low-pass filter or similar is recommended. The motor current I includes a friction component (friction-component motor current I0) generated by rotary-linear components, etc. The friction component can be estimated from the current in the clearance region before pad contact, and by subtracting this component to extract the effective motor current Ia, the motor position-current relationship 52 can be obtained. Furthermore, when the motor accelerates or decelerates significantly, subtracting the inertia component as necessary allows for more accurate extraction of the effective motor current component.

[0022] Here are the conditions for obtaining this relationship. During normal driving, braking force is only used within a small range, and it can only operate within the range of states I and II shown in Figure 3, for example. State I in Figure 3 is a state where there is pad clearance and no braking force is being generated yet. In state I, the motor current I0 for friction is obtained.

[0023] Next, in state II, the characteristics in the low thrust range are obtained. State II is the state during normal driving when the brake pads 5a, 5b are in contact with the disc rotor 2 and braking force is being applied. In order to obtain characteristics in the high thrust range, which is less frequent during normal driving, operation III is performed to further increase the thrust when the vehicle is stopped, making it possible to obtain the relationship between motor position and motor current in the range up to the thrust generated by the parking brake. Furthermore, by temporarily increasing the thrust to an even greater level than that required for parking, it is possible to obtain the relationship between motor position and motor current in region IV of higher thrust.

[0024] As described above, the motor position-current relationship creation unit 43 acquires the relationship between the rotational position of the electric motor 8 and the current of the electric motor 8 separately when the vehicle is running and when the vehicle is stopped. In this embodiment, it is possible to acquire a relationship between the motor position x and the motor current I that exhibits nonlinear characteristics over the entire range of braking forces that are desired to be generated, including high thrust.

[0025] Next, the braking torque estimation unit 41 that estimates the braking torque that presses the brake pads 5a and 5b will be described. The braking torque can be estimated from the vehicle state, for example. Here, the braking torque is estimated during braking.

[0026] The tire longitudinal force Ftx, which acts as a braking force to stop the vehicle, is expressed as a function of the tire load Ftz, can be approximated linearly in the range of small braking forces, and is proportional to the slip ratio λ, as shown in the following equation 1.

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

[0028] [Formula 3] Fb=Ftx-Fd The tire load Ftz is estimated using the vehicle weight, taking into account fluctuations due to the roll and pitch movements of the vehicle body.

[0029] Here, braking torque Tb can be estimated by multiplying braking force Fb by tire radius R. At this time, the rotational position x (motor position) of electric motor 8 is measured at the same time, so the relationship between this value and estimated braking torque can be determined. Here, the motor rotational position is shown as position x, but this may also be converted by a rotary-linear part, and the linear displacement of the linear part, for example, the piston 6, measured or estimated, may be used. This makes it possible to estimate braking torque Tbx0 at motor position x0 in FIG. 4, for example. FIG. 4 is a diagram showing the relationship between motor position and braking torque created by a braking torque position-current relationship creation unit according to the first embodiment of the present invention.

[0030] As described above, tire load Ftz, wheel speed Vw, and braking / driving force Fd must be estimated when estimating braking torque in braking torque estimator 41. The timing for estimating these will be described below.

[0031] First, by disconnecting the engine that drives the wheels or the main motor that drives the wheels from the wheels using a clutch or the like, the braking / driving force Fd can be set to 0, making it unnecessary to estimate the braking / driving force Fd and eliminating any resulting errors. Alternatively, by reducing the influence of the braking / driving force Fd, the relationship between the tire load Ftz and the braking / driving force Fd becomes Ftz>>Fd, and the influence of estimation errors in the braking / driving force Fd can be reduced.

[0032] In addition, when turning, the tire load Ftz changes between the left and right, and this estimation is necessary because the wheel speed of each wheel needs to be converted into the center of gravity position. Therefore, by limiting the estimation to when the vehicle is traveling straight, the estimation error can be reduced.

[0033] Furthermore, when there is an incline, the estimation error may become large due to acceleration or deceleration caused by the incline, so the estimation error can be reduced by limiting the estimation to when the incline is small.

[0034] As described above, by selecting several conditions that reduce error factors at a predetermined timing, it is possible to eliminate each factor of estimation error, thereby improving estimation accuracy.

[0035] In addition to the above-described methods, the braking torque may be estimated based on information from various sensors that acquire vehicle information. The various sensors include, for example, an acceleration sensor, a yaw rate sensor, a steering angle sensor, and a GPS (Global Positioning System), and at least one of these sensors is used. This information is input to the braking torque estimation unit 41 as sensor information 40 in FIG. 2.

[0036] Next, we will explain the braking torque positional relationship creation unit 42. The braking torque positional relationship creation unit 42 acquires the relationship between the rotational position and braking torque of the electric motor 8 based on information from the motor position-current relationship creation unit 43 and the braking torque estimation unit 41.

[0037] Since the motor position-current relationship creation unit 43 is able to grasp the relationship between the motor current I and the motor position x, the motor current Iax0 at the motor position x0 when estimated by the braking torque estimation unit 41 can also be calculated from the relationship obtained by the motor position-current relationship creation unit 43.

[0038] Normally, the effective motor current component, the torque generated by the motor, and the braking torque generated by it are proportional, so the proportionality coefficient ktia can be calculated using the following equation.

[0039] [Formula 4] ktia=Tbax0 / Iax0 It is advisable to increase the accuracy of this proportionality coefficient ktia by using data from multiple points, for example. Then, it can be calculated from the average of the data from multiple points, etc. Furthermore, accuracy can be improved by removing any noise values ​​that deviate significantly from the other values ​​among the multiple points. Using this Ktia, the braking torque Tba can be written as follows:

[0040] [Formula 5] Tba = Ktia × Ia Therefore, a relationship 53 (FIG. 4) between the braking torque Tba and the motor position x can be obtained by multiplying the entire characteristic of the motor current Ia and the motor position shown in FIG. 3 by ktia.

[0041] Next, the braking torque control method will be explained again. When braking torque command 29 is input from a higher level, if braking torque command 29 shown in FIG. 4 is Tbref, braking torque position command conversion unit 36 ​​determines motor position xref based on relationship 53 between braking torque Tb and motor position x. Then, xref is input as a position command to position current control unit 44, which compares it with the value detected by position detection unit 32 for feedback control, converts it into a current command, and outputs it to electric motor 8. Note that instead of braking torque command 29, the braking force applied to the tires may be used directly as the command value.

[0042] According to this embodiment, it is possible to perform highly accurate braking torque control that takes into account differences in the characteristics between the position and braking torque, which usually vary greatly depending on the individual differences in rigidity of each part and differences in motor characteristics, and the characteristics between the motor position and braking torque, which change over time by detecting them during normal braking operation.In addition, this embodiment does not use a thrust sensor for braking torque control, which makes it possible to reduce costs. [Example]

[0043] Next, a second embodiment of the present invention will be described. In the first embodiment, map creation in the apply operation was described, but in the second embodiment, a map creation method in the release operation will be described. FIG. 5 is a diagram showing the relationship between motor current and motor position acquired in the release operation by a motor position-current relationship creation unit according to the second embodiment of the present invention. FIG. 6 is a diagram showing the relationship between motor position and braking torque at the time of release created by a braking torque position relationship creation unit according to the second embodiment of the present invention. FIG. 7 is a diagram showing the relationship between motor position and braking torque at the time of release created by a braking torque position relationship creation unit according to the second embodiment of the present invention.

[0044] The relationship between motor current and motor position obtained during the release operation is shown in Figure 5. As explained in Example 1, when the electric motor is stopped, it is operated up to region IV, which is even higher than the thrust required for the parking brake, and then temporarily returned to the thrust required for the parking brake, and at that time a relationship 61 between motor current I and motor position x in region IV is obtained. After that, by releasing the parking brake during parking, a relationship 62 between motor current and motor position during release can be obtained in the order III, II, and I, and the relationship between active current Ir and motor position x, which takes into account the motor current I0 due to friction, can be obtained, just as when the parking brake was applied.

[0045] Meanwhile, when the vehicle is running, after the apply operation, the release operation is performed, and the current decreases from state II to state I in Figure 5, resulting in a relationship 61 between motor position x and motor current I. When clearance occurs in the brake pads, the current in region I becomes almost constant, and a motor current I0 equivalent to friction is obtained.

[0046] Next, the braking torque estimation unit 41 will be described. The braking torque can be estimated from the vehicle state, for example, in the same way as when applying the braking torque. 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] As with the application, the effective motor current Ir at motor position x0 can also be obtained from Figure 5. Since the effective motor current Ir and the generated braking torque are proportional, the proportionality coefficient can be calculated.

[0048] [Formula 6] ktir=Tbx0 / Ix0 This proportionality coefficient ktir can be calculated from multiple points, just as when applying. Using this Ktir, the braking torque can be written as follows:

[0049] [Formula 7] Tbr=Ktir×Ir That is, by multiplying ktir by the entire characteristic of motor current Ir and motor position x shown in FIG. 5, a relationship 63 (FIG. 6) between braking torque Tb and motor position x can be obtained.

[0050] As a result, since the normal efficiency and the reverse efficiency generally do not necessarily coincide, two characteristics are obtained: the apply-side characteristic (Tba-x) 53 and the release-side characteristic (Tbr-x) 63, as shown in Figure 7.

[0051] Based on this characteristic, when a braking torque command Tbref is input, the braking torque position command conversion unit 36 ​​determines whether it is an apply operation or a release operation, converts it into a motor position command xref, and outputs it to the position current control unit 44. The position current control unit 44 compares the motor position command xref with the value detected by the position detection unit 32, performs feedback control, converts it into a current command, and outputs it to the electric motor 8.

[0052] According to this embodiment, by issuing separate commands for the apply operation and the release operation, highly accurate braking torque control according to the operation becomes possible. [Example]

[0053] Next, a third embodiment of the present invention will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a diagram showing the relationship between motor position and braking torque used in a braking torque position command conversion unit according to the third embodiment of the present invention. Fig. 9 is a diagram showing the relationship between motor position and braking torque created by a braking torque position relationship creation unit according to the third embodiment of the present invention.

[0054] In the third embodiment, an example is shown in which it is taken into consideration that the characteristics change due to differences in the environment (environment A) when the motor position-current relationship creation unit 43 described in the first and second embodiments acquires the relationship between the motor position and the motor current, the environment (environment B) when the braking torque estimation unit 41 estimates the braking torque, and the environment (environment C) when control is performed based on these results.

[0055] For example, the stiffness of brake pads and devices changes due to contraction and expansion caused by 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, etc.

[0056] The friction coefficient of the brake pads when the torque generated by the electric motor 8 or the thrust converted through rotational linear motion is converted into braking torque may also change depending on the temperature and rotational speed.

[0057] Therefore, in the third embodiment, the relationship with respect to environmental changes is stored or formulated in advance in the motor position-current relationship creation unit 43. For example, a conversion formula such as that shown in Equation 8 is prepared. As an example, it is formulated that the motor position x at which the same thrust is generated changes as shown in the following formula.

[0058] [Formula 8] x=a×Tpad+b Here, Tpad is the brake pad temperature, and a and b are the slope and intercept, respectively, relative to the temperature. From this value, the characteristics under standard conditions (e.g., room temperature) can be estimated.

[0059] For example, as shown in Figure 8, let us assume that the characteristics shown in (1) are obtained when the brake pad temperature is 300°C and the motor temperature is 60°C in environment A. In this case, the brake pads 5a and 5b are converted to normal temperatures based on equation 8, and the characteristics are calculated as (2). Also, with regard to motor temperature, since the torque constant usually decreases as the temperature drops, the motor current decreases at the point where the same torque is generated, and the characteristics at normal motor and brake pad temperatures are calculated as shown in (3).

[0060] Here, the brake pad temperature and the motor temperature may be measured directly or may be estimated from the number of times of operation.

[0061] On the other hand, the braking torque is calculated by multiplying the thrust generated by the electric motor 8 by the coefficient of friction between the brake pads 5a, 5b and the disc rotor 2. However, the coefficient of friction changes depending on the environment, such as the temperature and relative speed of the contacting object. Therefore, the braking torque estimation unit 41 estimates or measures the temperature and relative speed of the brake pads 5a, 5b when the environment changes from the acquired environment. In this case, too, a standard condition (e.g., room temperature, speed V0) is determined, and the braking torque and motor position (Tbx0, x0) that would be obtained in the standard condition are calculated based on the actually measured braking torque and motor position (Tbx0m, x0m) as shown in Figure 9.

[0062] The values ​​under these standard conditions are divided into those at the time of application and those at the time of release as necessary, and the proportionality coefficient is calculated based on Equation 4 or Equation 6.

[0063] Then, the characteristic of (3) in FIG. 8 is multiplied by, for example, a proportional coefficient Ktir to obtain a relationship 71 between the motor position x and the braking torque Tba or Tbr shown by a solid line in FIG.

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

[0065] According to this embodiment, even if the environment (environment A) when the motor position-current relationship is acquired by the motor position-current relationship creation unit 43, the environment (environment B) when the braking torque estimation unit 41 estimates the braking torque estimation value, and the environment (environment C) when control is performed based on this result are different, it is possible to control the braking torque with high accuracy. [Example]

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

[0067] The proportional coefficient ktia or ktir between the effective motor current and the generated braking torque calculated in the first to third embodiments actually changes very little over time. In particular, as explained in the third embodiment, the change is small when converted to standard conditions. Therefore, if the ktia or ktir detected during braking torque estimation differs significantly from the previous value (for example, by 10% or more), the new value is not adopted as noise, and the previous value is used instead. This reduces errors.

[0068] Furthermore, the braking torque positional relationship creation unit 42 may acquire the braking torque value estimated by the braking torque estimation unit 41 multiple times, average or filter the acquired braking torque value, and acquire and update the relationship between the rotational position of the electric motor 8 and the braking torque using the filtered value ktia or ktir. This makes it possible to reduce error factors and improve accuracy.

[0069] In each embodiment, an electric brake using a disc brake has been described as an example, but various types of brakes, such as drum brakes, may be configured to generate braking force by operating a piston using an electric motor or the like to press the brake lining against a brake drum, which is a rotating body. [Explanation of symbols]

[0070] 1...brake device, 2...disc rotor, 3...brake caliper, 4...housing, 5a, 5b...brake pads, 6...piston, 8...electric motor, 9...reduction gear, 10...rotation-to-linear motion conversion mechanism, 11...motor control device, 29...braking torque command, 31...current detection unit, 32...position detection unit, 36...braking torque position command conversion unit, 41...braking torque estimator, 42...braking torque position relationship creation unit, 43...motor position-current relationship creation unit, 44...position current control unit

Claims

1. An electric brake device comprising: an electric motor; a linear motion part that moves due to rotation of the electric motor; brake pads that press a disc rotor that rotates together with a wheel by thrust generated by the movement of the linear motion part; and a motor control device that controls rotation of the electric motor, The motor control device includes: a motor position-current relationship creation unit that acquires 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 that presses the brake pads from the rotational position of the electric motor at a predetermined timing; a braking torque position relationship creation unit that acquires the relationship between the rotational position of the electric motor and the braking torque based on information from the motor position-current relationship creation unit and the braking torque estimation unit, the braking torque estimating unit disconnects the wheels from an engine that drives the wheels or a main motor that drives the wheels, and estimates braking torque when the vehicle is traveling straight; The electric brake device is characterized in that the motor control device controls the rotation of the electric motor based on information from the braking torque positional relationship creation unit.

2. In claim 1, The electric brake device, wherein the braking torque estimating unit estimates the braking torque excluding the braking / driving force by the engine or the main motor.

3. An electric brake device comprising an electric motor, a linear motion part that moves due to the rotation of the electric motor, brake pads that press a disc rotor that rotates together with the wheel with thrust generated by the movement of the linear motion part, and a motor control device that controls the rotation of the electric motor, The motor control device includes: a motor position-current relationship creation unit that acquires 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 that presses the brake pads from the rotational position of the electric motor at a predetermined timing; a braking torque position relationship creation unit that acquires the relationship between the rotational position of the electric motor and the braking torque based on information from the motor position-current relationship creation unit and the braking torque estimation unit, the braking torque estimation unit estimates a braking torque from a tire load and a slip ratio; The electric brake device is characterized in that the motor control device controls the rotation of the electric motor based on information from the braking torque positional relationship creation unit.

4. An electric brake device comprising an electric motor, a linear motion part that moves due to the rotation of the electric motor, brake pads that press a disc rotor that rotates together with the wheel with thrust generated by the movement of the linear motion part, and a motor control device that controls the rotation of the electric motor, The motor control device includes: a motor position-current relationship creation unit that acquires 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 that presses the brake pads from the rotational position of the electric motor at a predetermined timing; a braking torque position relationship creation unit that acquires the relationship between the rotational position of the electric motor and the braking torque based on information from the motor position-current relationship creation unit and the braking torque estimation unit, the motor position-current relationship creation unit acquires a relationship between the rotational position of the electric motor and the current of the electric motor separately when the vehicle is running and when the vehicle is stopped; The electric brake device is characterized in that the motor control device controls the rotation of the electric motor based on information from the braking torque positional relationship creation unit.

5. An electric brake device comprising an electric motor, a linear motion part that moves due to the rotation of the electric motor, brake pads that press a disc rotor that rotates together with the wheel with thrust generated by the movement of the linear motion part, and a motor control device that controls the rotation of the electric motor, The motor control device includes: a motor position-current relationship creation unit that acquires 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 that presses the brake pads from the rotational position of the electric motor at a predetermined timing; a braking torque position relationship creation unit that acquires the relationship between the rotational position of the electric motor and the braking torque based on information from the motor position-current relationship creation unit and the braking torque estimation unit, the motor position-current relationship creation unit acquires a relationship between the rotational position of the electric motor and the current of the electric motor separately for an apply operation and a release operation, The electric brake device is characterized in that the motor control device controls the rotation of the electric motor based on information from the braking torque positional relationship creation unit.

6. In claim 4 or 5, The electric brake device is characterized in that the braking torque estimation unit estimates the braking torque based on information from a sensor that acquires information about the vehicle.

7. In claim 6, The electric brake device is characterized in that the sensor is at least one of an acceleration sensor, a yaw rate sensor, a steering angle sensor, and a GPS (Global Positioning System).

8. In any one of claims 1 to 5, the braking torque positional relationship creation unit acquires the braking torque value estimated by the braking torque estimation unit multiple times, filters the acquired braking torque value, and acquires the relationship between the rotational position of the electric motor and the braking torque.

9. In any one of claims 1 to 5, an electric brake device, characterized in that the motor position-current relationship creation unit acquires the relationship between position and motor current by estimating characteristics when the environment is different from the environment when the relationship between the rotational position of the electric motor and the current of the electric motor was acquired.

10. In any one of claims 1 to 5, The electric brake device, wherein the braking torque estimation unit estimates braking torque when the environment changes from the environment when the braking torque was acquired.

11. In any one of claims 1 to 5, an electric brake device comprising a braking torque position command conversion unit that outputs a position command for the electric motor based on information from the braking torque position relationship creation unit;

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