WO2019159813A1

WO2019159813A1 - Electric brake device and electric brake system

Info

Publication number: WO2019159813A1
Application number: PCT/JP2019/004471
Authority: WO
Inventors: 唯増田
Original assignee: Ntn株式会社
Priority date: 2018-02-13
Filing date: 2019-02-07
Publication date: 2019-08-22
Also published as: JP2019137249A; JP7116551B2

Abstract

The present invention provides an electric brake device and an electric brake system in which power consumption can be reduced without increasing the size of an electric motor. In the present invention, an electric brake control device (2) is provided with a vehicle stop determination means (23d), a brake load commander (22), a brake load controller (24), and a brake power reducer (23). The brake load commander (22) outputs a target brake load Fr on the basis of a required brake force. The brake load controller (24) outputs a command value Ar of brake load retaining power applied to an electric motor (4) according to the target brake load Fr. The brake power reducer (23) reduces the command value Ar of the brake load retaining power, applied to the electric motor (4) on the basis of the required brake force Brk, compared to that in a vehicle stopped state.

Description

Electric brake device and electric brake system

Related applications

This application claims the priority of Japanese Patent Application No. 2018-022836 filed on Feb. 13, 2018, which is incorporated herein by reference in its entirety.

The present invention relates to an electric brake device and an electric brake system installed in an automobile or the like, and relates to a technique for reducing power consumption.

Conventionally, an electric actuator including an electric motor, a speed reducer, and a linear motion mechanism, and an electric brake device including the control device have been proposed (for example, Patent Document 1).

JP 2003-247576 A

In an electric brake device using an electric actuator as in Patent Document 1, when it is mainly mounted on a vehicle such as an automobile, an independent power supply system such as a battery is used except for charging from a charging facility. Must work. For this reason, power consumption that is as low as possible is often required. In the electric brake device, the power consumption ratio due to copper loss of an electric motor or the like may be relatively large. Since the copper loss is basically proportional to the square of the current, it is generally proportional to the square of the torque that is approximately proportional to the current. That is, there are many cases where the power consumption tends to increase as a large brake load that can require a large torque is exhibited.

On the other hand, in the case of the electric brake device mounted on the vehicle as described above, the brake force is determined by the vehicle operator, and the brake load based on the basically required brake force must be generated by the electric brake device. In some cases, it is difficult to reduce the copper loss. At this time, when the copper loss is reduced by the electric motor design, it is necessary to increase the size of the electric motor, and there may be a problem in mountability and cost.

An object of the present invention is to provide an electric brake device and an electric brake system that can reduce power consumption without increasing the size of the electric motor.

Hereinafter, in order to facilitate understanding, the present invention will be described with reference to the reference numerals of the embodiments for convenience.

The electric brake device 1 according to the present invention includes a brake rotor 8, a friction material 9 that contacts the brake rotor 8 to generate a braking force, an electric motor 4, and a rotational operation of the electric motor 4. The friction material operating means (for example, the linear motion actuator 5) that converts the contact operation to the brake rotor 8 and the electric motor 4 based on the required brake force Brk of the brake force command means 21 are used to control the friction material 9. And an electric brake control device 2 that controls a brake load that is a pressing force to the brake rotor 8, and is mounted on a vehicle,
The electric brake control device 2 is
A stop determination means 23d for determining the distinction between the stop state and the travel state of the vehicle from the rotational movement of the wheel 15 on which the brake rotor 8 is disposed;
A brake load command device 22 that outputs a target brake load Fr that is a control target value of the brake load based on the required brake force;
A brake load controller 24 for outputting a command value Ar of brake load holding power to be applied to the electric motor 4 in accordance with the target brake load;
A brake power reducer 23 that reduces the command value Ar of the brake load holding power to be given to the electric motor 4 based on the required brake force Brk when the vehicle is in a stopped state, as compared to when the vehicle is in the running state. 23A.

According to the electric brake device 1 having this configuration, the brake power required by the vehicle operator is increased depending on whether the vehicle is running or the vehicle is stopped by providing the

brake power reducers

23 and 23A. (Pedal operation amount, etc.) The brake load actually generated with respect to Brk has a different relationship, and when the vehicle is stopped, the target brake load Fr with respect to the required brake force Brk is made relatively low.

The brake force is a value obtained by multiplying the brake load, which is the pressing force of the friction material 9 against the brake rotor 8, by the friction coefficient and the effective brake diameter. When the vehicle is stopped, the friction coefficient is larger than the dynamic friction coefficient. The coefficient works. Therefore, even when the same brake load is applied, a larger braking force acts in the stopped state than in the traveling state. Therefore, in the control in which a brake load that is always proportional to the required brake force Brk is generated, an excessive frictional force, that is, an excessive brake force is generated with respect to the required brake force Brk when the vehicle is stopped. Therefore, when the vehicle is stopped, the required braking force for the required brake force Brk is maintained by relatively reducing the target brake load Fr with respect to the required brake force Brk within the excessive range. However, the power consumption of the electric motor 4 by reducing the brake load can be reduced. By reducing unnecessary power supply through control in this way, it is possible to reduce power consumption by suppressing copper loss without increasing the size of the electric motor 4.

The brake power reducer 23 calculates a stationary state target brake load Fst that is a target brake load with respect to the required brake force Brk when the vehicle is in the stopped state (for example, a determination result of the stop determining unit 23d). A load command unit 23b, and a travel brake load command unit 23a that calculates a travel state target brake load Fdy that is a target brake load for the required brake force Brk in the travel state,
The stationary brake load command unit 3b may make the stationary state target brake load Fst smaller than the traveling state target brake load Fdy with respect to the required brake force Brk.
Thus, by providing the stationary brake load command unit 23b and the traveling brake load command unit 23a, the control can be performed simply.

When the stationary brake load command unit 23b and the travel brake load command unit 23a are provided, the stationary brake load command unit 23b uses the stop state target brake load Fst calculated for the required brake force Brk as the travel. For the ratio to be smaller than the state target brake load Fdy,
Based on a predetermined ratio kfr of the static friction coefficient to the dynamic friction coefficient in contact between the friction material 9 and the brake rotor 8, the driving state target brake load Fdy is determined so that Fst = Fdy / kfr. May be.
In this way, if the target brake load is switched based on the dynamic friction coefficient and the static friction coefficient, the brake force (friction coefficient x brake load x brake effective diameter) can be kept substantially constant, while the brake load decreases to reduce the copper loss. Can be reduced.

Vehicle speed estimation for estimating the vehicle speed of the vehicle equipped with the electric brake device based on predetermined information including at least the rotational movement of the wheel 15 as a component of the electric brake control device 1 or separately from the electric brake control device 1 Having a container 29,
The brake power reducer 23 finally determines a target brake load Fr that is determined as the estimated vehicle speed transitions to a value that can be regarded as zero when the estimated vehicle speed is less than a predetermined value. May have a function of transitioning from the travel state target brake load Fdy to the stop state target brake load Fst.
In this way, by switching the target brake load Fr gently to some extent according to the vehicle speed, when the vehicle is not in a strict stop state when the target brake load Fr is switched, the vibration of the vehicle due to a sudden change in the brake load, etc. Can be prevented.

When the required brake force Brk is smaller than a predetermined value, the stationary brake load command unit 23b calculates the stop state target brake load Fst to a value that can be regarded as the same as the travel state target brake load Fdy, When the required brake force Brk is larger than the predetermined value, the stop state target brake load Fst may be calculated to a value smaller than the travel state target brake load Fdy. When the braking force is small, it is easy for the operator to feel a minute change, and there are cases where the difficulty in implementation of the present invention increases, for example, when strict detection of the vehicle speed is required. On the other hand, the copper loss when the braking force is small is very small, so the merit of mounting is relatively small. Therefore, the effect of the invention can be exhibited while reducing the difficulty in mounting by executing the brake load reduction in the stopped state only when the brake force is greater than the predetermined value.

In the case of this configuration, the brake power reducer 23 is
A first predetermined value of the required brake force Brk at which the stop state target brake load Fst and the traveling state target brake load Fdy are not substantially the same, and a second predetermined value of the required brake force greater than the first predetermined value. Value is set,
From the first predetermined value to the second predetermined value, the stop state target brake load Fst and the travel state target brake load Fdy may be gradually separated.
The first predetermined value and the second predetermined value are set to appropriate values by testing or simulation. In the case of this configuration, it is possible to prevent feeling deterioration such as an unintended braking shock.

The brake power reducer 23 sets the target brake load Fr as time elapses within the predetermined time within a predetermined time after the switching from the running state target brake load Fdy to the stop state target brake load Fst. The travel state target brake load Fdy may be changed to the stop state target brake load Fst.
Also in this configuration, it is possible to prevent unintended feeling deterioration such as braking shock.

The electric brake system of the present invention is an electric brake system including a plurality of electric brake devices 1 having any one of the above-described configurations of the present invention,
A brake integrated control device 20 that integrally controls the plurality of electric brake devices 1;
The brake power reducers 23 of at least two electric brake devices 1 in the plurality of electric brake devices 1 are integrated into one and provided in the brake integrated control device 20,
The brake power reducer 23 integrated into this one is that the stationary brake load command unit 23b and the travel brake load command unit 23a in the brake power reducer 23 are integrated with the target in each electric brake device 1 related to integration. Output the total brake load.
In the case of this configuration, it is possible to perform control according to the load ratio and position of each electric brake depending on whether the vehicle is a front wheel or a rear wheel. Here, “each electric brake device related to integration” is, for example, “each electric brake device related to integration” or “electric brake device corresponding to each integrated brake power reducer”.

In this electric brake system, the brake integrated control device 20 may be provided in the host control device 19 of the vehicle. In this case, the configuration is simple.

Further, instead of providing the brake integrated control device 20 in the host control device 19, any one of the electric brake control devices 2 in each electric brake device 1 related to integration may be used. In the case of this configuration, the electric brake control device 2 can be configured independently of the host control device 19.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the invention.

The present invention will be understood more clearly from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.

1 is a block diagram showing a conceptual configuration of an electric brake device according to a first embodiment of the present invention. It is explanatory drawing which mainly shows the linear motion actuator of the same electric brake device. It is a control flowchart of the same electric brake device. It is a time chart which shows the change of each physical quantity of the electric brake device. It is a time chart which shows the change of each physical quantity of the electric brake device of a prior art example. It is a block diagram which shows the conceptual structure of the electric brake device which concerns on other embodiment. 1 is a block diagram showing a conceptual configuration of an electric brake system according to an embodiment of the present invention. It is a block diagram which shows the conceptual structure of each electric brake device in the same electric brake system. It is a block diagram which shows the conceptual structure of the electric brake system which concerns on other embodiment. It is a block diagram which shows the conceptual structure of the electric brake device which concerns on other embodiment.

An electric brake device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4B. This electric brake device is mounted on a vehicle such as an automobile. As shown in FIG. 1, the electric brake device 1 includes a brake mechanism portion 1A composed of a friction brake 7 and a direct acting actuator 5, an electric brake control device 2 that controls the brake mechanism portion 1A, and a power supply device 3. The friction brake 7 is mounted on the wheel 15.

<< Configuration of Friction Brake 7 and Linear Actuator 5 >>
As shown in FIG. 2, the friction brake 7 includes a brake rotor 8 and a friction material 9 that is brought into contact with the brake rotor 8 to generate a braking force. The friction brake 7 is, for example, a disc brake device using a brake disc and a caliper as the brake rotor 8 and the friction material 9. The friction brake 7 may be a drum brake device using a drum and a lining.

The linear motion actuator 5 includes an electric motor 4 and a linear motion mechanism 6 which is a friction material operating means for converting the rotation operation of the electric motor 4 into a contact operation of the friction material 9 to the brake rotor 8. The linear motion actuator 5 further includes a speed reducer 10 (not shown in FIG. 1) in the example of FIG.

The electric motor 4 is composed of, for example, a permanent magnet synchronous motor. In that case, the space-saving, high-efficiency and high-torque is considered suitable, but for example, a DC motor using a brush, a reluctance motor not using a permanent magnet, or An induction motor or the like can also be applied. As the linear motion mechanism 6, various screw mechanisms such as a planetary roller screw and a ball screw, and various mechanisms capable of converting a rotational motion into a straight motion such as a ball ramp can be used.

The speed reducer 10 is a mechanism that decelerates the rotation of the electric motor 4, and includes a primary gear 12, an intermediate (secondary) gear 13, and a tertiary gear 11 in this example. The speed reducer 10 decelerates the rotation of the primary gear 12 attached to the rotor shaft 4 a of the electric motor 4 by the intermediate gear 13, and generates the tertiary gear 11 fixed to the end of the rotating shaft 6 a of the linear motion mechanism 6. It can be transmitted. The speed reducer 10 may use a worm gear, a planetary gear, or the like instead of the configuration using the spur gear of FIG.

As shown in FIG. 1, the linear actuator 5 is provided with an angle sensor Sa for detecting the motor angle of the electric motor 4 and a load sensor Sb for detecting the axial load of the linear motion mechanism 6. As the angle sensor Sa, for example, using a resolver, a magnetic encoder, or the like is considered to be preferable because it is highly accurate and reliable, but various sensors such as an optical encoder may be applied. Alternatively, as another configuration of FIG. 1, angle sensorless estimation in which the motor angle is estimated from the relationship between voltage and current in the electric brake control device 2 described later, for example, can be used without using the angle sensor Sa.

The load sensor Sb can be, for example, a magnetic sensor, a strain sensor, a pressure sensor, or the like that detects displacement or deformation. Alternatively, as another configuration of the figure, the load sensor Sb is not provided, and the load sensorless estimation is performed in the electric brake control device 2 described later from the motor angle and the electric brake device rigidity, the motor current, the linear actuator efficiency, and the like. May be. In addition to the linear motion actuator 5, various sensors such as a thermistor may be separately provided as necessary.

The wheel 15 can be provided with a wheel speed sensor Sd. As the wheel speed sensor Sd, for example, a magnetic pole sensor that detects a magnetic pole of a magnetic encoder that rotates integrally with the wheel 2, a coil that detects an inductance fluctuation of a rotor provided with unevenness, and the like can be used. Alternatively, another type of rotation sensor such as an angle sensor that detects the rotational position of the wheel 2 may be used. The wheel speed sensor Sd and the like may be used in, for example, anti-skid control for preventing the wheel 15 from being locked, in addition to the power consumption reduction used in this embodiment.

<< Power supply 3 >>
The power supply device 3 is a direct current power supply, and may be a battery provided exclusively for the electric brake device 1 or a battery used for driving other devices of the vehicle.

<Control system configuration>
The electric brake control device 2 controls the brake load which is the pressing force of the friction material 9 against the brake rotor 8 in the friction brake 7 by controlling the electric motor 4 based on the required brake force Brk of the brake force command means 21. It is a means to perform, and is comprised from the various control arithmetic units which perform a control calculation, a motor driver, various estimators, and sensors. FIG. 1 shows the concept of the functional configuration, and elements not shown are appropriately provided according to requirements. Each functional block is provided for convenience, and can be appropriately integrated or divided according to mounting convenience. In addition, each of the following embodiments is not limited to any one example, and may be configured to be partially or wholly merged as necessary as long as there is no contradiction in mounting.

<< braking force command means 21 >>
The brake force command means 21 is a means for instructing the required brake force Brk to the electric brake control device 2, and may be a means for the vehicle operator to instruct a brake operation, such as a brake pedal and a stroke sensor, for example. Also, it may be a host ECU such as a vehicle integrated control unit (VCU). In the case of a host ECU (Electronic Control Unit), the host ECU may be configured to detect the operation of a brake pedal or the like by the vehicle operator, and the braking force is applied by the host ECU such as automatic driving. It may be configured as required.

<< Various estimators and sensors >>
Each of the angle estimator 27 and the load estimator 28 has a function of estimating an angle and a brake load used for control calculation from the outputs of the angle sensor Sa and the load sensor Sb. In addition, as described above, the angle estimator 27 and the load estimator 28 may be means having an angle sensorless estimation function and a load sensorless estimation function without using sensors such as the angle sensor Sa and the load sensor Sb. it can. Further, the angle estimator 27 has a function of appropriately obtaining necessary physical quantities based on the configuration of the brake load controller 24 such as an electrical angle phase used for current control and an integrated value of angles used for position control. In addition, the angle estimator 27 may have a function of estimating differential amounts such as angular velocity and angular acceleration, disturbances that can be estimated based on angles, and the like. The estimation of the other physical quantity may use, for example, a state estimation observer or the like, or may be a direct calculation such as a back calculation based on differentiation or an inertia equation.

The current sensor Sc is a sensor that detects a current applied to the electric motor 4 from the motor driver 25. For example, a sensor that includes an amplifier that detects a voltage across the shunt resistor, and a non-contact sensor that detects a magnetic flux around the energization path. Etc. can be used. Or it is good also as a structure which detects the terminal voltage etc. of the element etc. which comprise the motor driver 25, for example.

The current estimator 26 has a function of estimating a current used for control calculation from the current sensor output. The estimation of the current may be performed by, for example, a plurality of current sensors provided in the motor phase current supply path, or may be estimated by one current sensor provided on the low side (low voltage side circuit) or the high side (high voltage side circuit). A method of estimating the secondary current and obtaining the phase current based on the motor characteristics or the like may be used. Or you may make it perform feedforward control based on a motor characteristic etc., without providing any current sensor.

<< Brake load commander 22 >>
The brake load command device 22 has a function of deriving a target brake force Fr that is a brake load command value as a control target value based on the required brake force Brk input from the brake force command means 21. The required brake force Brk input from the brake force command means 21 may be a physical quantity considered on the vehicle base such as vehicle deceleration, deceleration torque, braking force, etc., or may be a predetermined brake effective diameter, brake It may be a physical quantity considered on the basis of an actuator such as a brake load derived based on a friction coefficient or the like. The brake load command device 22 determines a target brake load Fr that is finally set as a target value for the required brake force Brk.

<< Brake load controller 24 >>
The brake load controller 24 calculates a command value Ar of the brake load holding power, which is an operation amount of the electric motor 4 so that the estimated brake load follows the target brake load Fr obtained by the brake load command device 22. . The command value Ar for the brake load holding power may be, for example, a motor voltage, or may be a value calculated by providing one or more minor feedbacks for controlling the motor current and the motor angle. In addition, the physical quantity used during the calculation is appropriately selected according to the design convenience such as the actuator position calculated from the motor angle and the actuator equivalent lead, the motor torque obtained from the motor current, and the like. In addition, feedforward control or the like can be used or used in combination as appropriate.

In addition to the brake load control function, the brake load controller 24 includes a friction material 9 of the friction brake 7 and a brake rotor 8 when releasing the brake in order to reduce drag torque. It is preferable to provide a function of controlling the linear actuator 5 at a position where a predetermined clearance is provided therebetween. For example, it is considered that the function is a function for estimating the position of the linear motion actuator 5 from the motor angle and the equivalent lead of the linear motion actuator 5. A sensor may be provided separately.

<< Motor driver 25 >>
The motor driver 25 controls a brake load holding power that is supplied from the power supply device 3 and applied to the electric motor 4 according to the command value Ar of the brake load holding power output from the brake load controller 24. It is. Since the power supply device 3 is a direct current power supply, the motor driver 25 includes an inverter (not shown) that converts direct current power into alternating current power and control means (not shown). The motor driver 25 constitutes the inverter composed of a half-bridge circuit using a switching element such as an FET, for example, and is configured to perform PWM control for determining a motor applied voltage or a motor current according to a predetermined duty ratio. This is preferable because it is inexpensive and has high performance. The motor driver 25 may be configured to perform a PAM control by providing a transformer circuit or the like.

<< Brake power reducer 23, stop determination means 23d >>
The brake power reducer 23 is a means for performing processing for reducing the brake power consumption in the stopped state from the running state, and the brake load applied to the electric motor 4 based on the required brake force Brk in the stopped state. The command value Ar of the holding power is reduced as compared with the case of the traveling state. In this embodiment, the brake power reducer 23 is provided as a part of the brake load command device 22, and includes a travel brake load command unit 23a, a stationary brake load command unit 23b, and a brake load command determination unit 23c. .

The traveling brake load command unit 23a derives a traveling state target brake load Fdy that is a brake load command value based on the required braking force a of the braking force command means 21 in the traveling state. The stationary brake load command unit 23b derives a stop state target brake load Fsy that is a similar brake load command value in the stop state. The stop state target brake load Fsy is set to be a relatively small brake load with respect to the travel state target brake load Fdy. By using a small brake load, the motor current can be made relatively small at the same time, and the motor copper loss when holding the brake is reduced. Therefore, power consumption can be reduced.

The brake load command determination unit 23c is a function for determining which of the travel brake load command unit 23a and the stationary brake load command unit 23b is valid based on the vehicle running state estimated by the vehicle speed estimator 29. Or a function for determining an effective ratio or the like.

The braking force generated by the contact between the brake rotor 8 and the friction material 9 is generated based on the dynamic friction coefficient with the brake rotor 8 when the vehicle is running, that is, when the brake rotor is sliding relative to the vehicle. On the other hand, the braking force in the stopped state is generated based on the static friction coefficient. Therefore, even when the same brake load is exhibited, a relatively large braking force is generated in the stopped state relative to the traveling state. In other words, if the same brake load is exerted with respect to the same required brake force Brk, an excessive braking force is generated when the vehicle is stopped. That is, switching the brake load command value Fr between the stop state and the stop state and setting the brake load to a relatively small brake load in the stop state is considered reasonable for reducing power consumption while keeping the braking force constant.

However, since the ratio between the static friction coefficient and the dynamic friction coefficient can vary depending on, for example, the wear state and temperature of the friction material, it may be difficult to set the accurate friction coefficient ratio. Even in such a case, for example, a conversion coefficient or a conversion table or the like in the static brake load command unit 23b and the travel brake load command unit 23a is set based on a condition that the difference between the static friction coefficient and the dynamic friction coefficient is the smallest. As a result, a braking force larger than that in the traveling state is generated at least in a stopped state. For this reason, it is thought that there is no problem in the safety as a vehicle.

The brake load command determination unit 23c recognizes, for example, whether the vehicle is stopped or running, and in the stopped state, only the stationary brake load command unit 23b is enabled and is running. In a state, the function which makes only the traveling brake load instruction | command part 23a effective may be sufficient.

Whether the vehicle is in a stopped state or in a traveling state is determined by the stop determination unit 23d. The stop determination means 23d may be configured to determine whether the vehicle is in the stopped state or the traveling state from the rotational motion of the wheel 15 on which the brake rotor 8 is disposed, and is provided as a part of the brake load command determination unit 23c. The vehicle speed estimator 29 may also serve as the stoppage determination unit 23d, or may be provided separately from either the brake load command determination unit 23c or the vehicle speed estimator 29.

The stop determination unit 23d may determine, for example, that the wheel speed is detected as zero for a certain period of time as a stop state, and perform a relatively slow deceleration that is clearly not a wheel lock toward the wheel speed of zero. The determination may be made when zero is reached. In this case, the vehicle speed estimator 29 does not need to be configured to perform continuous speed estimation, and may have a function capable of determining whether or not the vehicle is in a stopped state. Even in such a case, the function can be sufficiently exerted even under conditions where it is difficult to accurately estimate the vehicle speed only by the wheel speed of one wheel due to, for example, the slip state with the road surface.

In addition to the above function, the brake load command determination unit 23c is a stationary state target brake load Fst, which is a stationary brake load command value output by the stationary brake load command unit 3b until the vehicle speed becomes low to zero. The vehicle brake load command unit 23a may have a function of adjusting the effective ratio with the travel state target brake load Fdy, which is the travel brake load command value output by the travel brake command unit 23a, according to the vehicle speed. As a specific example, for example, a final target brake load (brake load command value) Fr is expressed by the following equation using a stop state target brake load Fst, a travel state target brake load Fdy, and a coupling coefficient α depending on the vehicle speed. It may be derived as follows.
Fr = α · Fst + (1−α) · Fdy
However, 0 ≦ α ≦ 1 (α1 at zero vehicle speed, α = 0 at low speed of switching start)

In this case, it is possible to reduce the driver's uncomfortable feeling by switching the target brake load (brake load command value) Fr aggressively to some extent and preventing sudden switching of the brake load. However, it is necessary to estimate the vehicle speed with a certain degree of accuracy. The conversion coefficient α may be, for example, a linear coefficient proportional to the vehicle speed, or a curved nonlinear coefficient that changes in a curve with respect to the vehicle speed.

Further, the brake load command determination unit 23c outputs the stop state target brake load Fst output from the stationary brake load command unit 23a and the travel brake load command unit 23b within a predetermined time after the stop state is determined. You may have a function which adjusts an effective ratio with driving state target brake load Fdy according to elapsed time. In this case as well, a similar relational expression can be used by replacing the coupling coefficient α in the previous expression from the vehicle speed to time. Or you may use the relational expression which uses the said vehicle speed and time together.

The brake power reducer 23 may perform a process of switching between the stop state target brake load Fst and the travel state target brake load Fdy only when the required brake force Brk is larger than a predetermined value. In general, the smaller the braking force, the more sensitive the vehicle operator is to changes in the braking force that accompany changes in the brake load. Therefore, when the brake load is small, the switching of the brake load occurs before the vehicle strictly stops. The demerit of feeling worsening due to this will increase. On the other hand, the greater the braking force, that is, the greater the brake load, the greater the copper loss reduction effect by reducing the brake load. Therefore, when the brake load is large, the merit of switching the brake load increases. Therefore, it is reasonable to switch the target brake load only when the required brake force Brk is larger than a predetermined value.

In addition, when the function of switching when the required brake force Brk is larger than a predetermined value is provided, the stationary brake load command unit 23b and the traveling brake load command unit 23a have a predetermined required brake when the brake load is small. The stationary state target brake load Fst and the traveling state target brake load Fdy, which are relatively equal to the force Brk, are respectively calculated, and when the required braking force Brk is large, the stationary state target brake load Fst and the traveling state target brake that are relatively separated from each other. A function for calculating the load Fdy may be used. In this case, the stop state target brake load Fst and the travel state target brake load Fdy may be set so as to deviate as the required brake force Brk increases.

The brake power reducer 23 also includes a first predetermined value and a first predetermined value of the required brake force Brk at which the stop state target brake load Fst and the traveling state target brake load Fdy are not substantially the same. A second predetermined value of a larger required brake force is set, and the stationary state target brake load Fst and the traveling state target brake load Fdy are set from the first predetermined value to the second predetermined value. You may make it diverge gradually. Each predetermined value is set to an appropriate value by testing or simulation.

The above-described various calculation means (brake load command device 22, brake power reducer, brake load control device 24) in the electric brake control device 1 are configured by a calculation unit such as a microcomputer, FPGA, ASIC, and peripheral circuits, for example. It is considered to be suitable because of its low cost and high performance.

<Execution flow of brake load commander 22>
FIG. 3 shows an execution example of the brake load command unit 22 in FIG. In step S.1, a required brake force Brk based on a predetermined specification is acquired. The required brake force Brk can be information corresponding to, for example, vehicle deceleration, braking force derived from vehicle deceleration based on a predetermined correlation including vehicle weight or the like, or brake torque. Alternatively, it may be a brake load that can be derived based on a predetermined brake frictional force calculation formula based on any of the above information.

Step S. 2, it is determined by the stop determination means 23 d whether the vehicle is in a stopped state or a traveling state. The determination may be performed by estimating the vehicle speed using, for example, the wheel speed and longitudinal acceleration of a plurality of wheels, vehicle position information, and the like, and determining the vehicle speed by providing a predetermined threshold. For example, the predetermined wheel speed sensor It may be a simple one that is determined based on the case where the pulse has not changed for a certain time or the like, or a method in which these are used together as appropriate. Further, the stop state may include, for example, a low-speed state that can be regarded as almost stopped, or conversely, the travel state may be immediately after the stop, for example, when the time elapsed after the stop is less than a predetermined time. It may be included.

Step S. 2, if it is determined that the vehicle is in a stopped state, step S. 3, the stop state target brake load Fst is derived as Fst = kst · Brk based on the stop state calculation coefficient kst. The calculation coefficient kst can be a predetermined coefficient determined based on, for example, a static friction coefficient in the characteristics of the friction material 9 and the brake rotor 8. The derived stop state target brake load Fst is set as a target brake load Fr which is a control target value (step S.4).

Step S. If it is determined in step 2 that the vehicle is in a running state, step S. 5, the running state target brake load Fdy is derived based on the running state calculation coefficient kdy. The calculation coefficient kdy may be a predetermined coefficient determined based on, for example, a dynamic friction coefficient in the characteristics of the friction material and the brake rotor. The derived traveling state target brake load Fdy is set as a target brake load Fr that is a control target value (step S.6).

In this way, the target brake load Fr is determined as the stop state target brake load Fst or the traveling state target brake load Fdy (steps S.4 and S.6), and the brake load controller is used by using the determined target brake load Fr. 24 (FIG. 1) controls the brake load by controlling the electric motor 4 (FIG. 3, step S.7).

For example, step S. 2, when the driving state at the previous time changes to the stopping state at the current time, the calculated target brake load is not a discrete change such as a step change but a continuous change that gradually changes The state transition may be performed so that However, the continuous change in this case means that the change between predetermined control sample steps is relatively smoother than a simple binary change, for example, when the target brake load changes stepwise in a plurality of steps. It also includes discrete changes complemented to

The continuous change may be, for example, due to a process in which the coupling coefficient changes from kdy to kst according to the vehicle speed in a predetermined section from the vehicle speed of zero to a predetermined low speed state. In this case, for example, even if the change in the judgment from the running state to the stopped state occurs before the vehicle strictly stops, the brake load can be prevented from changing suddenly. Ring deterioration can be prevented. For example, when the judgment changes from a running state to a stopped state, the continuous change is a process in which the coupling coefficient changes from kdy to kst within a predetermined time after the judgment change occurs. It may be due to. Also in this case, as described above, it is possible to prevent feeling deterioration such as unintended braking shock by preventing the brake load from changing suddenly.

Contrary to the above, when the judgment changes from the stopped state to the traveling state, the same means as described above can be taken. However, since it is considered extremely rare that the vehicle changes from the stopped state to the traveling state in the brake application situation, the continuous change process described above may be performed only when the vehicle changes from the traveling state to the stopped state. Good.

<Time chart of change of each physical quantity in the above operation>
4A shows an operation example of the electric brake device 1 to which the configuration of FIG. 1 is applied, and FIG. 4B shows an operation example of a conventional electric brake device to which the configuration is not applied. In the example (application example) of FIG. 4A, the brake load is reduced when the vehicle speed (second from the top in the figure) becomes zero, compared to the example (non-application example) in FIG. Th). At this time, although the brake load decreases, the friction coefficient between the friction material 9 and the brake rotor 8 increases by changing from the dynamic friction state to the static friction state, and is offset with the decrease in the brake load. Therefore, the generated frictional force of the brake rotor 8 is kept substantially constant without decreasing (fourth from the top in the figure). At this time, when the brake load decreases, the motor torque necessary for holding the brake decreases, and the motor copper loss decreases (fifth from the top in the figure). Each parameter in the figure may be, for example, that of the electric brake device 1 in FIG. 1, or may be the sum of a plurality of electric brake devices 1 in FIG.

<Other embodiments>
5 to 9 show other embodiments of the present invention. In these embodiments, the matters to be specifically described are the same as those in the first embodiment, and the corresponding parts are denoted by the same reference numerals and redundant description is omitted.

FIG. 5 shows an example in which the vehicle speed estimation means 28 is provided outside the electric brake control device 2. The vehicle speed estimation means 28 is a means for estimating the vehicle speed based on, for example, the wheel speed of a plurality of wheels, or an acceleration sensor, GPS (not shown), or the like. The vehicle speed estimation means 28 may be provided in a host ECU such as a vehicle integrated control unit (VCU) or may be provided in another one of the plurality of electric brake control devices 1. It may be.

The arrows in the block diagram are described based on the final destination of the signal, and the transmission path along the way can be selected as appropriate. For example, in the example of FIG. 5, the output of the wheel speed sensor Sd is shown as an example of input to the vehicle speed estimation means 28. For example, the output of the wheel speed sensor Sd is input to the electric brake control device 2, and the electric brake control device The wheel speed may be output to the vehicle speed estimator 28 via 2. For example, when performing wheel speed control such as anti-skid control (not shown) in the electric brake control device 1, it may be necessary to perform wheel speed control calculation in the electric brake control device 1. It may be preferable to do this.

<Electric brake system (further embodiment)>
FIG. 6 shows an example of an electric brake system in which a plurality of electric brake devices 1 (1 ₁ , 1 ₂ ,...) Are integrated and controlled by the brake integrated control device 20. In this electric brake system, one brake load command device 22 provided in the brake integrated control device 20 becomes the brake load command device 22 in the plurality of electric brake devices 1 (1 ₁ , 1 ₂ ,...). . The brake integrated control device 20 is provided in a host control device 19 such as a vehicle integrated control device (VCU) that performs integrated control of the vehicle.

Each block of the first, second,...,

Electric brake devices

1 ₁ , 1 ₂ ,... Shown in FIG. 6 shows the components that omit the brake load command device 22 from the electric brake device 1 shown in FIG. , Each of the first, second,...

Electric brake devices

1 ₁ , 1 ₂ ,... Constitutes the electric brake device 1 including the brake load command device 22 provided in the brake integrated control device 20. To do. The parts indicated by the blocks of the first, second,...

Electric brake devices

1 ₁ , 1 ₂ ,... In FIG. 6 are brake loads in the electric brake device 1 of FIG. All components other than the command device 22, for example, the electric brake control device 2, the electric actuator 5, the friction brake 7, and the like are provided.

The brake power reducer 23 integrated with one of the brake load command devices 22 provided in the brake integrated control device 20 of FIG. 6 includes a stationary brake load command unit 23b and a travel brake load command unit 23a that are related to the integration. The total values of the stationary state target brake load Fst and the traveling state target brake load Fdy in the electric brake device 1 (1 ₁ , 1 ₂ ,...) Are output. Using these total values, the brake load command determination unit 23c selects the stop state target brake load Fst and the travel state target brake load Fdy or totals a predetermined ratio, and then selects or totals the predetermined ratio. The total target brake load performed is applied to each electric brake device 1 (1 ₁ , 1 ₂ ,...) And the brake force sharing ratio determined by these electric brake devices 1 (1 ₁ , 1 ₂ ,...). To output. As for the brake force sharing ratio, the own brake force sharing ratio is set in the electric brake control device 2 in each electric brake device, and the total target brake load is output from the brake integrated control device 20. Also good.

For example, in the case of a general four-wheeled vehicle, the brake load on the front wheel side becomes relatively large with respect to the rear wheel side because the front-wheel load distribution on the front wheel side becomes relatively strong at the time of braking. Often set. In this case, the relationship between the motor copper loss, that is, the brake power consumption with respect to the brake load may be different between the front wheel side electric brake device and the rear wheel side electric brake device. At this time, for example, if the brake load on the front wheel side is more actively reduced, the brake power consumption in the total sum of the four wheels can be reduced, or conversely, the brake load on the rear wheel side is more actively reduced. The brake power consumption in the wheel sum may be reduced.

According to this embodiment, in the stationary brake load command unit 23b, for example, after calculating the sum of the stop state target brake loads Fst of the plurality of electric brake devices 1, the target brake load is distributed so that the power consumption can be further reduced. Fr can be transmitted to the plurality of electric brake devices 1. The distribution that can reduce the power consumption from the above is an appropriate distribution obtained by a test, simulation, or the like, and is determined in the brake load command determination unit 23c of the brake power reducer 23.

The brake integrated control device 20 may be any one of the plurality of electric brake devices 1 (1 ₁ , 1 ₂ ,...). 8, the electric brake control unit 2 of the first electric braking device 1 ₁ shows an example of a brake integrated control apparatus 20 of FIG.

FIG. 9 shows an example in which the brake power reducer 23A is implemented in the brake load estimation for the electric brake device 1 of FIG. In the example of the figure, the brake load command device 22 outputs the target brake load Fr corresponding to the required brake force Brk regardless of whether the vehicle is running or stopped. The brake power reducer 23A is a load sensor when the brake load controller 24 calculates and outputs a command value Ar of brake load holding power corresponding to the target brake load Fr by feeding back the detection value of the load sensor Sb. The estimated value of the load according to the detected value of Sb is set to a larger value in the stopped state of the vehicle than in the traveling state.

The traveling brake load estimating unit 23Aa obtains an estimated value of the load from the detected value of the load sensor Sb in the traveling state, and the stationary brake load estimating unit 23Ab calculates the estimated value of the load from the detected value of the load sensor Sb in the stopped state. Ask. The brake state estimation determination unit 23Ac includes a stop determination unit 23d, and depending on whether the vehicle is in a traveling state or a stopped state, which load estimated value of the traveling brake load estimation unit 23Aa and the stationary brake load estimation unit 23Ab is determined. Is transmitted to the brake load controller 24.

In the case of the embodiment shown in the figure, the brake load in the stopped state is estimated to be large, and the brake load in the traveling state is estimated to be small, thereby obtaining the same power saving effect as that of the first embodiment shown in FIG. be able to.

As described above, the preferred embodiments have been described with reference to the drawings, but various additions, modifications, and deletions are possible without departing from the spirit of the present invention. Therefore, such a thing is also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Electric brake device, 1A ... Brake mechanism part, 2 ... Electric brake control device, 3 ... Power supply device, 4 ... Electric motor, 5 ... Linear actuator, 7 ... Friction brake, 9 ... Friction material, 0 ... Reduction gear, DESCRIPTION OF SYMBOLS 15: Wheel, 19 ... High-order control apparatus of vehicle, 20 ... Brake integrated control apparatus, 21 ... Brake force command means, 22 ... Brake load command device, 23 ... Brake power reducer, 23a ... Travel brake load command part, 23b ... Static brake load command section, 23c ... brake load command determination section, 23d ... stop determination means, 24 ... brake load controller, 25 ... motor driver, 26 ... current estimator, 27 ... angle estimator, 28 ... load estimator, 29 ... Vehicle speed estimator, Sa ... Angle sensor, Sb ... Load sensor, Sc ... Current sensor, Sd ... Wheel speed sensor, Ar ... Brake load holding power command value, Brk ... Required Brake force, Fr ... the final target brake load, Fdy ... traveling state target brake load, Fst ... stop state target brake load

Claims

A brake rotor, a friction material that comes into contact with the brake rotor to generate a braking force, an electric motor, and a friction material operation means that converts a rotational operation of the electric motor into a contact operation of the friction material with the brake rotor; And an electric brake control device that controls a brake load, which is a pressing force of the friction material against the brake rotor, by controlling the electric motor based on a required brake force of a brake force command means, and is mounted on a vehicle. An electric brake device,
The electric brake control device is
Stop determination means for determining the distinction between the stop state and the travel state of the vehicle from the rotational motion of the wheel on which the brake rotor is disposed;
A brake load command device that outputs a target brake load that is a control target value of the brake load based on the required brake force;
A brake load controller that outputs a command value of brake load holding power applied to the electric motor according to the target brake load;
A brake power reducer that reduces the command value of the brake load holding power to be given to the electric motor based on the required brake force when the vehicle is in a stopped state as compared to when the vehicle is in the running state;
Electric brake device.
2. The electric brake device according to claim 1, wherein the brake power reducer includes a stationary brake load command unit that calculates a stop state target brake load Fst that is a target brake load with respect to the required brake force in the stop state. A running brake load command unit that calculates a running state target brake load Fdy that is a target brake load with respect to the required brake force in the running state,
The stationary brake load command unit sets the stop state target brake load Fst to a value smaller than the travel state target brake load Fdy with respect to the required brake force.
Electric brake device.
3. The electric brake device according to claim 2, wherein the stationary brake load command unit sets the stop state target brake load Fst calculated with respect to the required brake force to a value smaller than the travel state target brake load Fdy. Per percentage
Based on a predetermined ratio kfr of a static friction coefficient to a dynamic friction coefficient in contact between the friction material and the brake rotor, calculation is performed so that Fst = Fdy / kfr with respect to the traveling state target brake load Fdy.
Electric brake device.
4. The electric brake device according to claim 2, wherein the electric brake device is a component of the electric brake control device or separately from the electric brake control device, based on predetermined information including at least rotational movement of the wheels. It has a vehicle speed estimator that estimates the vehicle speed of a vehicle equipped with an electric brake device,
The brake power reducer, when the estimated vehicle speed is below a predetermined value, the target brake load that is finally determined as the estimated vehicle speed transitions to a value that can be regarded as zero, An electric brake device having a function of shifting from the travel state target brake load Fdy to the stop state target brake load Fst.
5. The electric brake device according to claim 2, wherein when the required brake force is smaller than a predetermined value, the stationary brake load command unit sets the stop state target brake load Fst. When the required braking force is greater than the predetermined value, the stop state target brake load Fst is set to be greater than the traveling state target brake load Fdy. Electric brake device that calculates small values.
The electric brake device according to claim 5,
The brake power reducer is
A first predetermined value of the required brake force at which the stop state target brake load Fst and the traveling state target brake load Fdy are not substantially the same, and a second predetermined value of the required brake force that is greater than the first predetermined value. And are set,
An electric brake device that gradually separates the stop state target brake load Fst and the travel state target brake load Fdy from the first predetermined value to the second predetermined value.
The electric brake device according to any one of claims 2 to 6, wherein the brake power reducer has switched from the travel state target brake load Fdy to the stop state target brake load Fst. An electric brake device that shifts the target brake load from the running state target brake load Fdy to the stop state target brake load Fst within a predetermined time as time elapses within the predetermined time.
An electric brake system comprising a plurality of the electric brake devices according to any one of claims 2 to 7,
A brake integrated control device for integrated control of the plurality of electric brake devices;
The brake power reducer of at least two electric brake devices in the plurality of electric brake devices is integrated into one and provided in the brake integrated control device,
The brake power reducer integrated into this one is the total value of the target brake load in each electric brake device in which the stationary brake load command unit and the traveling brake load command unit in the brake power reducer are integrated. Output,
Electric brake system.
9. The electric brake system according to claim 8, wherein the brake integrated control device is provided in a host control device of the vehicle.
9. The electric brake system according to claim 8, wherein the brake integrated control device is any one of the electric brake control devices in each electric brake device related to integration.