WO2017026472A1

WO2017026472A1 - Electric brake system

Info

Publication number: WO2017026472A1
Application number: PCT/JP2016/073396
Authority: WO
Inventors: 唯増田
Original assignee: Ntn株式会社
Priority date: 2015-08-11
Filing date: 2016-08-09
Publication date: 2017-02-16
Also published as: JP2017036000A; JP6552910B2

Abstract

According to the present invention, a brake can be operated while appropriately using a parking brake mechanism, power consumption can be reduced, an operating time of the brake can be effectively extended especially when an auxiliary power supply is used, and effects on the performance and feeling of the brake are maximally reduced while using the parking brake. The electric brake system is provided with a parking brake mechanism (5) which maintains braking force through mechanical engagement. The electric brake system is provided with an auxiliary power supply (25) in addition to a main power supply device (19), and a power supply control device (24) which switches whether to use the auxiliary power supply (25). A power monitoring control means (23) is provided which monitors the power supply state and assists in the retention of power supply through the auxiliary power supply (25) when it is determined that the power supply state is below a predetermined state. The parking brake mechanism (5) is configured to be operated without manipulation of a driver while the auxiliary power supply (25) is used.

Description

Electric brake system

Related applications

This application claims the priority of Japanese Patent Application No. 2015-158926 filed on August 11, 2015, and is incorporated herein by reference in its entirety.

This invention relates to an electric brake system having a parking brake function.

Conventionally, the following examples have been proposed as electric brake devices and parking brake mechanisms.
An electric brake device that controls braking force with an electric motor (Patent Document 1).
A disc brake that detects friction pad pressing force (Patent Document 2).
A ball screw type electric brake device using a member having a low thermal conductivity for the ball screw ball (Patent Document 3).
A parking brake mechanism using a solenoid (Patent Document 4).

JP 2003-247576 A JP 2010-270788 A JP 2006-183809 A JP 2012-087889 A

In an electric brake device such as Patent Documents 1 to 4, there is a case where a redundant system against a failure of a power supply device is particularly problematic. At this time, in a redundant system in which an auxiliary power source is provided, the cost and mounting space may be a problem for the auxiliary power source that can brake for a long time. For example, Patent Documents 3 and 4 propose a mechanism that maintains braking force without consuming electric power by engaging each brake component that generates braking force. However, if the braking force is maintained by the mechanism, the engaging portion must be separated once for changing the braking force. For this reason, it takes time to change the braking force, the change cannot be made quickly, and the brake feeling may deteriorate.

An object of the present invention is to perform a necessary brake operation with the assistance of electric power from an auxiliary power source even when the power supply state of the power supply device is reduced, and to perform a brake operation while appropriately using a parking brake mechanism. Electricity that can reduce power consumption, is particularly effective in extending the brake operation time when using an auxiliary power supply, and can minimize the impact on the brake performance and feeling of using the parking brake mechanism. Is to provide a braking system.

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 system includes an electric brake device 1 and a power supply device 19 that supplies electric power to the electric brake device 1.
The electric brake device 1 includes a brake rotor 6, a friction material 7, friction material operation means 8 for bringing the friction material 7 into contact with the brake rotor 6, an electric motor 9 for driving the friction material operation means 8, and the electric motor An electric brake actuator 2 having a parking brake mechanism 5 that retains a predetermined braking force by mechanical engagement in a drive transmission portion 8b from 9 to the friction material 7 and a brake by controlling the electric motor 9 An electric brake system having a main brake control means 21 for controlling the force to follow a target value, and a brake control device 3 having a parking brake control means 22 for controlling the parking brake mechanism 5,
Auxiliary power supply 25 different from the power supply device 19, a power supply control device 24 capable of changing a ratio used between the power of the power supply device 19 and the power of the auxiliary power supply 25, and power supply by the power supply device 19 When the state of power supply is monitored and it is determined that the power supply state falls below a predetermined state, the power supply control device 24 compensates for the shortage of the power supply of the power supply device 19 by the power of the auxiliary power supply 25. And the power supply monitoring control means 23 in the form of connection to be supplied, and the parking brake control means 22 uses the auxiliary power supply 25 for the shortage of power supplied by the power supply device 19 under the control of the power supply control device 24. Therefore, the parking brake mechanism 5 has a function of operating the parking brake mechanism 5 based on a predetermined determination without the operation of the operator of the vehicle on which the electric brake device 1 is mounted. That.

Note that the “predetermined determination” is determined by design as appropriate for the detected value, calculated value, target value, or physical quantity of the control target to be used, and what state to determine. It ’s fine. “The power supply state falls below a predetermined state” includes, for example, that the power supply amount falls below (or below) a predetermined threshold value. The threshold is determined from simulation results, experimental results, actual measurement results, and the like (hereinafter the same).

According to this configuration, by performing a brake operation while using the parking brake mechanism 5 as appropriate, power consumption is reduced, and in particular, it is effective in extending the brake operation time when the auxiliary power supply 25 is used. Further, by changing the frequency of using the parking brake mechanism 5 according to the situation, it is possible to minimize the influence on the brake performance and feeling.

Specifically, the auxiliary power source 25 different from the main power source device 19 (hereinafter sometimes referred to as “main power source device 19”) and the auxiliary power source 25 when the power supply state falls below a predetermined state. Since the power supply control device 24 is used to supplement the power of the power supply 25 and used to drive the electric motor 9, even if the output voltage of the main power supply device 19 decreases due to a decrease in the amount of stored power, the power of the auxiliary power supply 25 Is added to the output of the main power supply device 19, and the normal braking operation can be performed properly. Since the auxiliary power supply 25 is arranged in parallel with the main power supply device 19, if the power capacity is large, an excessive configuration results in an increase in cost and weight, and thus the power capacity needs to be suppressed. In this regard, since the parking brake mechanism 5 is configured to hold the braking force by mechanical engagement in the drive transmission portion, it is possible to hold the braking force with almost no power consumption, and the parking brake. The control means 22 operates the parking brake mechanism 5 in a situation where the auxiliary power supply 25 is used, based on a predetermined determination, without the operation of the driver of the vehicle equipped with the electric brake device 1. Therefore, power consumption can be reduced without any particular attention from the driver.

Thus, the brake operation is performed while using the parking brake mechanism 5 as appropriate, thereby reducing the power consumption, and in particular, extending the grace time until the brake failure due to the power depletion of the auxiliary power supply 25 when the auxiliary power supply 25 is used. In addition, redundancy can be improved. For this reason, even if the output voltage decreases due to a decrease in the amount of power stored in the main power supply device 19 or the like, the vehicle can be driven to a place where repair or maintenance is possible, and the main power supply device 19 can be We can expect charge. While the use of the parking brake mechanism 5 during traveling reduces power consumption, the feeling of braking operation is reduced. However, the parking brake mechanism 5 is used in a situation where the auxiliary power source 25 is used. Based on a predetermined judgment. Thus, since the conditions which use the parking brake mechanism 5 are limited to the limited conditions, the fall of the feeling of brake operation is suppressed compared with the case where the parking brake mechanism 5 is used frequently. The parking brake mechanism 5 can be used only when the braking is important and the operation feeling is not questioned depending on the setting contents of the predetermined judgment.

In the present invention, the predetermined determination is made based on at least one of a target brake force, a change amount of the target brake force, an estimated brake force, and a change amount of the estimated brake force. When the target brake force or the estimated brake force increases, or when the amount of change in any of the target brake force and the estimated brake force decreases below a threshold value, the brake control unit 22 performs the parking in the operation time of the electric brake device 1. You may make it increase the time for which the brake mechanism 5 is functioned.

As the condition for changing the frequency for causing the parking brake control means 22 to function by the parking brake control means 22, for example, any one of the target braking force and the estimated braking force can be used. In general, since the power consumption tends to increase as the braking force increases, it is considered preferable to set the processing in which the frequency of parking braking increases as the braking force increases. The increase in the braking force may be either the target braking force or the estimated braking force. As the frequency change condition, for example, the amount of change in the target brake force or the estimated brake force can be used. The smaller the amount of change, the less the need to change the braking force, and the smaller the amount of change, the smaller the effect on the braking performance when using a parking brake. Conceivable.

In the present invention, the parking brake control means 22 makes the predetermined determination based on the remaining power of the auxiliary power supply 25, and when the remaining power of the auxiliary power supply 25 decreases, the operation time of the electric brake device 1 is reduced. The ratio of the time for executing the parking brake mechanism 5 may be increased. As the remaining power of the auxiliary power source 25 decreases, it is necessary to extend the brake operation possible time even at the expense of brake feeling. Therefore, it is preferable to perform a process in which the frequency of parking braking increases as the remaining power decreases. Conceivable. By adjusting the frequency of applying the parking brake mechanism 5 stepwise in accordance with the remaining power of the auxiliary power supply 25, the grace time until brake failure due to power depletion of the auxiliary power supply 25 is maintained while maintaining the brake feeling as much as possible. And the redundancy can be improved.

In the present invention, the parking brake control means 22 includes a vehicle speed estimation means 29 of a vehicle on which the electric brake device 1 is mounted, and makes the predetermined determination based on the vehicle speed of the vehicle on which the electric brake device 1 is mounted. When the vehicle speed decreases, the ratio of the time during which the parking brake mechanism 5 functions in the operation time of the electric brake device 1 may be increased. The lower the vehicle speed is, the lower the influence of the deterioration of the braking performance on the safety of the vehicle is. Therefore, it is considered that the process of increasing the parking braking frequency as the vehicle speed decreases is considered preferable. In particular, when the vehicle speed is approximately zero, that is, when the vehicle is stopped, it is not necessary to change the braking force. Therefore, it is considered preferable to perform parking braking with a sufficient braking force to stop the vehicle. At that time, for example, when the driving force of the vehicle is lost, it is not necessary to release the parking brake, so it is only necessary to keep the parking brake.

The parking brake control means 22 selects and executes one of the predetermined judgments and the processes based on the judgment results for the processes based on the predetermined judgments and the judgment results. Alternatively, two or more may be executed in appropriate combination.

In the present invention, the parking brake control means 22 follows the operation of the brake operation means 31 by the driver when the parking brake mechanism 5 is caused to function regardless of the operation of the operator based on the predetermined determination. has a normal braking time limit C _ths to limit the continuous operation time of the normal braking operation, and a parking braking time lower limit C _thp to limit the minimum duration at which the parking brake mechanism 5 to function, the parking brake the percentage of time that mechanism 5 to function, may be adjustable by changing the normal braking time limit C _ths and parking braking time lower limit C _thp. As this arrangement, the percentage of time that the parking brake mechanism 5 to function, the case where the normal and adjustable by varying the braking time upper limit value C _ths and parking braking time lower limit C _thp, reduce power consumption The ratio between the degree and the control that places importance on the feeling of operation can be easily changed.

In the present invention, the driving force monitoring means 32 for estimating the state of the driving force of the vehicle on which the electric brake device 1 is mounted is provided, and the parking brake control means 22 When it is determined that the vehicle is equipped with the electric brake device 1 and is substantially stopped, it is determined that the parking brake mechanism 5 remains functioning and the vehicle stopped state is maintained. It may be continued. When the driving force of the vehicle is lost, the vehicle does not travel again after the vehicle has been stopped by the brake. Therefore, the parking brake mechanism 5 is kept functioning so that the vehicle can be safely stopped.

In this invention, the parking brake mechanism 5 engages with each other out of the parts constituting the drive transmission portion 8b from the electric motor 9 to the friction material 7 and the stationary parts, thereby moving the friction member in the loosening direction. Between the parts that prevent movement, the engaging part that engages both parts and the matched part are engaged, and the pressing force of the friction material 7 is maintained regardless of the power of the electric motor 9. May be. As described above, the parking brake mechanism 5 is configured to prevent the movement by engaging the parts, so that the braking force can be maintained with almost no power consumption.

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 system according to an embodiment of the present invention. It is explanatory drawing of schematic structure of the electric brake device in the same electric brake system. It is explanatory drawing of the parking brake mechanism in the same electric brake device. It is a flowchart of the control action of the parking brake control means of the electric brake system.

An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the electric brake system includes an electric brake device 1 and a power supply device 19 that supplies electric power to the electric brake device 1, and is operated by a braking command or the like from the host ECU 20.

The electric brake device 1 includes an electric brake actuator 2 that is a mechanical part, and a brake control device 3 that controls the electric brake actuator 2. The electric brake actuator 2 has a parking brake mechanism 5 that causes the main brake part 4 to function as a parking brake in addition to the main brake part 4 capable of controlling the braking force. Further, the electric brake actuator 2 is provided with a sensor 14 for detecting the state with a predetermined characteristic value such as a rotor angle of an electric motor 9 described later and a degree of distortion in the brake housing.

The brake control device 3 controls the electric motor 9 of the electric brake actuator 2 so as to control the brake force (for example, service brake force) following the target value. And parking brake control means 22 for controlling the parking brake mechanism 5.

In this electric brake system, in the above configuration, an auxiliary power source 25 is provided separately from the power source device 19, and the power control that can change the ratio used between the power of the power source device 19 and the power of the auxiliary power source 25. When the power supply state by the device 24 and the power supply device 19 is monitored and it is determined that the power supply state is lower than a predetermined state based on the result of the monitoring, the power supply control device 24 is powered by the power of the auxiliary power supply 25. And a power supply monitoring control means 23 configured to supply the power supply device 19 by compensating for the shortage of the power supply. The parking brake control means 22 is equipped with the electric brake device 1 on the basis of a predetermined judgment in a situation where the power supply control device 24 compensates for the shortage of the supplied power using the auxiliary power supply 25. A function of operating the parking brake mechanism 5 without the operation of the driver.

Note that the “predetermined determination” is determined by design as appropriate for the detected value, calculated value, target value, or physical quantity of the control target to be used, and what state to determine. It ’s fine. “The power supply state falls below a predetermined state” includes, for example, that the power supply amount falls below (or below) a predetermined threshold value. Moreover, this figure shows only the structure for implement | achieving the proposal of this inventor, and about the other necessary functions, functions other than the one shown in this figure shall be mounted suitably. Hereinafter, each part is demonstrated concretely.

FIG. 2 shows an example of the electric brake actuator 2. In the electric brake actuator 2, a rake rotor 6 that rotates integrally with a wheel (not shown) of a vehicle such as an automobile, a friction material 7, and the friction material 7 are brought into contact with the brake rotor 6 (for example, the friction material 7 The main brake portion 4 is composed of a friction material operating means 8 that moves the friction material operating means 8 in a direction in contact with the brake rotor 6 and an electric motor 9 that drives the friction material operating means 8. The friction material operating means 8 comprises a feed screw mechanism or the like, and drives the linear motion mechanism 8a by decelerating and transmitting the rotation of the electric motor 9 and the linear motion mechanism 8a that can move in the direction of the arrow in the figure. A reduction gear 8b. In the illustrated example, the speed reducer 8 b includes a gear train, and includes a primary gear 12, an intermediate (secondary) gear 13, and a tertiary gear 11. In this example, the speed reduction mechanism 8b is a tertiary gear fixed to the rotation shaft 8aa of the linear motion mechanism 8a via the intermediate gear 13 by rotating the primary gear 12 attached to the rotor shaft 9a of the electric motor 9. 11 can be transmitted.

The parking brake mechanism 5 is a drive transmission portion between the electric motor 9 and the friction material 7, for example, a reduction gear 8b, which is a part of the friction material operating means 8, and a brake housing (not shown). A mechanism for holding a predetermined braking force (described later) by mechanical engagement is provided. For example, among the parts that constitute the drive transmission unit from the electric motor 9 to the friction material 7 and the stationary parts, the parts that prevent the friction member 7 from moving in the loosening direction by engaging each other, The engaging part that engages both parts and the engaged part are engaged, and the pressing force of the friction material 7 is maintained regardless of the power of the electric motor 9.

FIG. 3 is a diagram showing an outline of the parking brake mechanism 5 in a side view. On one side of the main surface of the intermediate gear 13, a plurality (six in this example) of locking holes 17 that are engaged portions are formed at regular intervals in the circumferential direction. Each locking hole 17 is formed in a long hole shape extending along the circumferential direction. In any one of these locking holes 17, an advancing / retracting lock member 15, which is an engaging portion, is configured to be locked. The lock member 15 is driven back and forth by an engagement / disengagement drive source 16 (FIG. 2).

In this example, a solenoid is applied to the engagement / disengagement drive source 16. The locking member 15 is advanced by the engagement / disengagement drive source 16 and is fitted into the bottomed cylindrical hole 17a of the locking hole 17 formed in the intermediate gear 13, thereby being locked to the bottomed cylindrical hole 17a. By preventing the rotation of the intermediate gear 13, the friction material 7 is maintained at the current position in the direction of the arrow in FIG. 2, and a predetermined braking force, that is, the braking force at this time is maintained. That is, a drive transmission part (intermediate gear 13 or the like) including the speed reducer 8b is engaged with a brake housing (not shown) in which the engagement / disengagement drive source 16 is installed. The parking lock state is realized. By retracting part or all of the lock member 15 and detaching it from the locking hole 17 (FIG. 3), the rotation of the intermediate gear 13 is allowed and the unlocked state is established.

Note that the engagement / disengagement drive source 16 of the parking brake mechanism 5 uses a solenoid in this example, but may be constituted by an electric motor such as a DC motor and a linear motion mechanism, for example. It is considered that the parking brake mechanism 5 is inexpensive and suitable when a mechanism that engages the torque transmission unit such as the drive transmission unit 8b (reduction gear 8b) with the housing using the solenoid or the DC motor is used.

When the brushless DC motor is used as the electric motor 9 of the main brake unit 4, a high output can be obtained in a small space, but a brushed DC motor or an induction motor may be used. In addition to the feed screw mechanism, the linear motion mechanism 8a can use a mechanism that converts a rotational motion such as a ramp mechanism into a straight motion. The reduction gear 8b is considered to be inexpensive and suitable if a parallel gear as in the example of FIG. 3 is used, but a planetary gear, a worm gear, or the like can also be used, and the reduction gear 8b may not be used depending on the required thrust. .

In FIG. 1, it is considered preferable that the sensor 14 includes, for example, an angle sensor that detects the angle of the electric motor 9, a brake force sensor, and the like because highly accurate control can be realized. If the power supply device 19 is a low-voltage power supply in an automobile, for example, it can be realized at a low cost and is considered preferable. As the auxiliary power source 25, for example, a power storage device such as a battery or a capacitor can be used. The auxiliary power supply 25, the power supply control device 24, and the power supply monitoring control means 23, which will be described in detail later, are installed in the electric brake actuator 1 of the electric brake device 1 instead of being installed in the electric brake device 1. The electric brake actuator 2 may be provided at a location different from that of the electric brake actuator 2. However, if the brake control device 3 is mounted with a small capacitor and a control circuit around the brake control device 3 as shown in FIG. It can be expected that it is suitable.

The host ECU (also referred to as “VCU”) 20 is operated according to the operation of the brake operation means 31 operated by a driver such as a brake pedal, or the stability such as automatic driving, collision control, attitude control, ABS control, The electronic control unit has a function of giving a braking command to the electric brake device 1 in accordance with a braking command generated by a control means (not shown) for ensuring safety. The host ECU 20 may be, for example, a main electronic control unit that performs overall cooperative control and overall control in an automobile. In this case, the integrated ECU (see FIG. (Not shown) may be provided separately from the main ECU.

The brake control device 3 includes an arithmetic unit 26, and further includes a motor driver 27, a parking brake mechanism drive device 28, and the power supply control device 24. The calculator 26 is provided with the main brake control means 21, the parking brake control means 22, and the power supply monitoring control means 23.

The computing unit 26 may be implemented by, for example, a microcomputer, FPGA, ASIC, DSP, etc., and it is considered preferable because it can easily implement complicated control functions. The motor driver 27 is a circuit that causes a motor current to flow to the electric motor 9 in accordance with the motor drive command output by the main brake control means 21. For example, it is considered to be inexpensive and suitable to be mounted by a half bridge circuit using an FET. The parking brake mechanism driving device 28 is means for supplying driving power for the parking brake mechanism 5 in accordance with the output of the parking brake control means 22. For example, the driving source of the parking brake mechanism 5 in the electric brake actuator 2 is a solenoid. If there is a switch or the like, and an electric motor such as a DC motor is mounted by a half bridge circuit or the like, it is considered inexpensive and suitable.

The power supply control device 24 has a function of supplying the power supplied from the power supply device 19 and the auxiliary power supply 25 to the entire brake control device 3 and the electric brake actuator 2. Each current control circuit may be provided, or a switch that simply switches the outputs of the two may be used. The power supply control device 24 may be provided with a circuit that charges the auxiliary power supply 25 with the power supply device 19.

The calculator 26 is provided with the main brake control means 21, the parking brake control means 22, and the power supply monitoring control means 23 as described above. The main brake control means 21 determines the drive power of the electric motor 9 for causing the brake force to follow the target value by feedforward control or feedback control according to the target value of the brake force given from the host ECU 20 or the like. The motor driver 27 outputs drive power to the electric motor 9 according to the determined drive power.

The parking brake control means 22 uses the above-described engagement method for maintaining the braking force as the parking brake, and controls the brake of the main brake unit 4 so as to maintain the braking force of the service brake at the target braking force. The parking brake mechanism 5 is operated in conjunction. The parking brake control means 22 performs the process specifically shown by the flowchart of FIG. The power supply monitoring control means 23 monitors the power supply status of the power supply device 19 and the auxiliary power supply 25, and uses the auxiliary power supply 25 to reduce the power supply when the power supply from the power supply device 19 drops below a predetermined threshold, for example. The power supply control device 24 changes the ratio of using the power of the auxiliary power supply 25 so as to supplement the power. Further, the power supply monitoring control unit 23 performs a process of appropriately charging the auxiliary power supply 25 with the power of the power supply device 19 using the power supply control device 24 when the power supply from the power supply device 19 is, for example, a threshold value or more. Do.

FIG. 4 shows an example of processing performed by the parking brake control means 22 (FIG. 1) in the electric brake system having the above configuration. First, in step f1, it is determined whether or not the braking mode of the electric brake system is a normal braking mode in which the braking force is controlled to follow the target value. When in the normal braking mode, the counter value C _bs for calculating the duration of the normal braking mode is added by a certain value (for example, 1) (step f2), and the counter value C _bs is calculated from the threshold value (threshold) C _ths . Is also larger (step f3). If it is equal to or less than the threshold value, the braking mode of the electric brake device 1 is maintained in the normal braking mode (step f4), the process is terminated, and the process of FIG.

When the counter value C _bs of the continuation time exceeds a predetermined value, that is, the threshold value C _ths , the braking force of the parking braking force is set to the current braking force F _r (k) (step f5), and the braking mode is set to the parking braking mode. (Step f6). Thereafter, the counter value C _bs is reset to zero (step f7), the process is terminated, and the process of FIG.

If it is determined in step f1 that the vehicle is in the parking braking mode, a counter value _Cps for measuring the duration of parking braking is _added by a certain value (for example, 1) (step f8), and the counter value _Cps is a threshold value (threshold). It is determined whether it is greater than C _thp (step f9). When the duration C _ps is _{equal to} or less than the threshold value C _thp , the processing is terminated while the braking mode is set to the parking braking mode (step f10), and the processing of FIG.

When the parking braking duration C _ps exceeds the threshold value C _thp in step f9, a deviation ΔF between the target brake force F _r (k) and the estimated brake force F _b (k) is obtained (step f11). The estimated brake force F _b (k) is determined from the measured value of the sensor 14 (FIG. 1) included in the electric brake actuator 2.

The absolute value of the deviation ΔF is compared with a threshold value (threshold) _{Fth for} changing the braking force (step f12). If the absolute value of the deviation ΔF is the threshold F _th below the process ends while maintaining the braking mode to the parking brake (step f10), it performs the processing of FIG from the first step f1. Is determined in step f12, the absolute value of the deviation ΔF exceeds the threshold value _{F th,} sets the braking mode to the normal braking mode (step f13), reset to zero the counter value _{C ps} (step f14), the processing Exit. Such processing is always repeated.

In the processing example of the flowchart of the figure, for example, the threshold C _ths of each _counter, by adjusting the value of C _thp, it is possible to change the frequency of entering the parking brake mode. For example, when the frequency is increased, power consumption can be suppressed, and when the frequency is decreased, the brake control accuracy is improved. Therefore, for example, when the above-described processing for increasing the parking braking frequency is performed at the time of redundant control in which power consumption must be suppressed, it is considered preferable that the power of the auxiliary power supply 25 can be used for a long time.

As the condition for changing the frequency of parking braking, for example, either target braking force or estimated braking force can be used. In general, since the power consumption tends to increase as the braking force increases, it is considered preferable to set the processing in which the frequency of parking braking increases as the braking force increases.

For example, the amount of change in the target braking force or the estimated braking force can be used as the condition for changing the parking braking frequency. The smaller the amount of change, the less the need to change the braking force, and the smaller the amount of change, the smaller the effect on the braking performance when using a parking brake. Conceivable.

In summary, as described above, the parking brake control means 22 is used in a situation where the auxiliary power supply 25 is used under the control of the power supply control device 24 in order to compensate for the shortage of the supplied power. The parking brake mechanism 5 is operated based on the determination. As described above, the predetermined determination is at least one of the target brake force, the target brake force change amount, the estimated brake force, and the estimated brake force change amount. The parking brake control means 22 increases the target brake force or the estimated brake force, or the amount of change in either the target brake force or the estimated brake force is greater than the threshold value. Is also decreased, the time for the parking brake mechanism 5 to function during the operation time of the electric brake device 1 is increased. And it may be.

For example, the remaining power of the auxiliary power supply 25 shown in FIG. 1 can be used as the condition for changing the parking braking frequency. For example, the parking brake control means 22 makes a predetermined determination as to whether or not to operate the parking brake mechanism 5 based on the remaining power of the auxiliary power source 25, and the remaining power of the auxiliary power source 25 decreases. The ratio of the time for executing the parking brake mechanism 5 in the operation time of the electric brake device 1 may be increased. As the remaining power of the auxiliary power source 25 decreases, it is necessary to extend the brake operation possible time even at the expense of brake feeling. Therefore, it is preferable to perform a process in which the frequency of parking braking increases as the remaining power decreases. Conceivable.

As a condition for changing the frequency of parking braking, for example, the vehicle speed of a vehicle equipped with an electric brake system can be used. For example, the parking brake control means 22 makes a predetermined determination as to whether or not to operate the parking brake mechanism 5 based on the vehicle speed of the vehicle on which the electric brake device 1 is mounted, and when the vehicle speed decreases, You may make it raise the ratio of the time which makes the said parking brake mechanism 5 function in the operation time of the electric brake device 1. FIG. In this case, as shown in FIG. 1, the vehicle speed estimation means 29 for estimating the vehicle speed is used, and the vehicle speed estimation means 29 is, for example, a means for detecting rotation of a driven wheel and converting it to a vehicle speed. The lower the vehicle speed is, the lower the influence of the deterioration of the braking performance on the safety is. Therefore, it is considered that the process of increasing the parking braking frequency as the vehicle speed decreases is considered preferable. In particular, when the vehicle speed is approximately zero, that is, when the vehicle is stopped, it is not necessary to change the braking force. Therefore, it is considered preferable to perform parking braking with a sufficient braking force to stop the vehicle. At that time, for example, when the driving force of the vehicle is lost, it is not necessary to release the parking brake, so it is only necessary to keep the parking brake.

Further, the parking brake control means 22 performs normal braking following the operation of the brake operation means 31 by the driver when the parking brake mechanism 5 is made to function regardless of the operation of the operator based on the predetermined determination. A normal braking time upper limit value (threshold value C _ths ) for limiting the continuous operation time of the operation (step f3 in FIG. 4) and a parking braking time lower limit value (threshold value) for limiting the minimum duration time when the parking brake mechanism 5 functions. C _thp ) (step f9 in FIG. 4), and the ratio of the time during which the parking brake mechanism 5 functions can be adjusted by changing the normal braking time upper limit value and the parking braking time lower limit value. Also good. As in this configuration, when the ratio of the time during which the parking brake mechanism 5 functions can be adjusted by changing the upper limit value of the normal braking time and the lower limit value of the parking braking time, the power consumption is reduced and the operation is reduced. It is possible to easily change the ratio with the control that places importance on the feeling.

Further, as shown in FIG. 1, the electric brake system includes a driving force monitoring unit 32 that estimates a driving force state of a vehicle on which the electric braking device 1 is mounted, and the parking brake control unit 22 When the driving force monitoring means 32 determines that the driving force of the vehicle is below a predetermined value and it is determined that the vehicle on which the electric brake device 1 is mounted is substantially stopped, the parking brake mechanism 5 is functioned. You may make it continue maintaining a vehicle stop state with letting it be left. The driving force monitoring means 32 is provided in the calculator 26 of the brake control device 3, for example. When the driving force of the vehicle is lost, the vehicle does not travel again after the vehicle has been stopped by the brake. Therefore, the parking brake mechanism 5 is kept functioning so that the vehicle can be safely stopped.

In addition, the frequency of parking braking can be changed by appropriately processing one or more of the above processes. Several processes may be executed in parallel, and any one process may be selected.

The main brake control means 21, the parking brake control means 22, the power supply monitoring control means 23, the current control circuit in the power supply control device 24, and the driving force monitoring means 32 described above are specifically software or hardware. In the LUT (Look Up Table) implemented in, or a predetermined conversion function stored in the software library (Library), equivalent hardware, etc., and if necessary, comparison functions and four arithmetic operations functions It is composed of a hardware circuit or a software function on a processor (not shown) that can perform an operation and output a result using equivalent hardware or the like.

As mentioned above, although the suitable form for implementing this invention based on embodiment was demonstrated referring drawings, embodiment disclosed here is an illustration and restrictive at no points. The scope of the present invention is shown not by the above description but by the claims. Those skilled in the art will readily appreciate various changes and modifications within the obvious scope upon reviewing this specification. Therefore, such changes and modifications should be construed as being within the scope of the invention defined by the claims or within the scope equivalent thereto.

DESCRIPTION OF SYMBOLS 1 ... Electric brake device 2 ... Electric brake actuator 4 ... Main brake part 5 ... Parking brake mechanism 6 ... Brake rotor 7 ... Friction material 8 ... Friction material operation means 8b ... Reducer (drive transmission part)
DESCRIPTION OF SYMBOLS 9 ... Electric motor 19 ... Power supply device 21 ... Main brake control means 22 ... Parking brake control means 23 ... Power supply monitoring control means 24 ... Power supply control device 25 ... Auxiliary power supply

Claims

An electric brake device and a power supply device for supplying electric power to the electric brake device;
The electric brake device includes a brake rotor, a friction material, friction material operation means for bringing the friction material into contact with the brake rotor, an electric motor for driving the friction material operation means, and a space between the electric motor and the friction material. An electric brake actuator having a parking brake mechanism that retains a predetermined brake force by mechanical engagement in a drive transmission unit; a main brake control means that controls the electric motor to follow the target value by controlling the electric motor; and An electric brake system having a brake control device having a parking brake control means for controlling the parking brake mechanism,
Auxiliary power source different from the power source device, a power source control device capable of changing a ratio used between the power of the power source device and the power of the auxiliary power source, and monitoring the power supply state by the power source device When the power supply state is determined to be lower than the predetermined state based on the result of the power supply monitoring, the power supply monitoring device is configured to supply the power supply control device with the power supply of the auxiliary power supply compensated for the shortage of the power supply of the power supply device. The parking brake control means is based on a predetermined determination in a situation where the power supply control device controls to compensate for the shortage of power supplied by the power supply device using the auxiliary power supply. , Having the function of operating the parking brake mechanism without the operation of the operator of the vehicle equipped with the electric brake device,
Electric brake system.
The electric brake system according to claim 1, wherein the predetermined determination is based on at least one of a target brake force, a change amount of the target brake force, an estimated brake force, and a change amount of the estimated brake force. When the target brake force or the estimated brake force increases, or when the amount of change in any of the target brake force and the estimated brake force falls below a threshold value, the parking brake control means An electric brake system that increases a time during which the parking brake mechanism functions during an operation time.
2. The electric brake system according to claim 1, wherein the parking brake control unit makes the predetermined determination based on the remaining power of the auxiliary power source, and when the remaining power of the auxiliary power source decreases, the electric brake device The electric brake system which raises the ratio of the time which performs the said parking brake mechanism in the operating time of.
2. The electric brake system according to claim 1, wherein the parking brake control unit includes a vehicle speed estimation unit of a vehicle on which the electric brake is mounted, and the predetermined determination is based on a vehicle speed of the vehicle on which the electric brake device is mounted. Therefore, when the vehicle speed decreases, the electric brake system increases the ratio of the time for which the parking brake mechanism functions in the operation time of the electric brake device.
The electric brake system according to any one of claims 1 to 4, wherein the parking brake control means causes the parking brake mechanism to function based on the predetermined determination regardless of a driver's operation. A normal braking time upper limit value for limiting a continuous operation time of a normal braking operation following the operation of the brake operation means by the driver, and a parking braking time lower limit value for limiting a minimum duration time when the parking brake mechanism functions. And the ratio of the time for which the parking brake mechanism functions is adjustable by changing the normal braking time upper limit value and the parking braking time lower limit value.
5. The electric brake system according to claim 1, further comprising driving force monitoring means for estimating a driving force state of a vehicle on which the electric brake device is mounted, wherein the parking brake control means is When the driving force monitoring means determines that the driving force of the vehicle is lost or falls below a predetermined value and the vehicle equipped with the electric brake device is determined to be substantially stopped, the parking brake mechanism is An electric brake system that keeps the vehicle stopped while functioning.
The electric brake system according to any one of claims 1 to 6, wherein the parking brake mechanism is engaged with each other among a part and a stationary part that constitute a drive transmission unit from the electric motor to the friction material. By engaging, the engaging portion that engages both components and the engaged portion are engaged between the components that prevent the friction member from moving in the loosening direction, and the engagement is performed regardless of the power of the electric motor. An electric brake system configured to maintain the pressing force of the friction material.