JP2000110865A - Motor-driven brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of drag to a brake during disengagement of brake operation even when a motor fails in operation during operation of a brake, in a motor-driven brake driven by a motor serving as a drive source. SOLUTION: A motor-driven brake 10 causes a motor 40 to be linked to an inner pad 20a through a planetary roller screw 80, a ball screw 96, and a pressure shaft 64 and a ball screw 96 is provided with a selector 110 to selectively allow relative rotation between a nut 98 and a pressure shaft. Normally, the relative rotation is blocked by the selector and the function of a ball screw is rendered ineffective. Meanwhile, when, during release of brake operation, the pressure shaft is not moved in a direction in which the shaft is separated from the inner pad, relative rotation is allowed by the selector and the function of the ball screw is rendered effective. This constitution allows the inner pad to move in a direction, in which the inner pad is separated away from the disc 12, without rotation of the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric brake for a vehicle driven by a motor.

[0002]

2. Description of the Related Art Japanese Patent Application Publication No. 10-504876 discloses a conventional example of the electric brake. this is,
(a) a rotating body that rotates with the wheel, (b) a friction material pressed against the rotating body to suppress rotation of the wheel, (c) a motor, and (d) a rotating member that is rotated by the motor. ,
(e) a linear motion member that is linearly moved to move the friction material toward and away from the rotating body, and (f) a motion conversion mechanism that converts rotation of the rotary member into linear motion of the linear motion member. Is configured.

In this type of electric brake, a motion conversion mechanism is interposed between a motor and a friction material.
This motion conversion mechanism generally has a function of allowing transmission of a force in a direction from a motor to a friction material, while suppressing transmission of a force in the opposite direction. Therefore, in this type of electric brake, even if the power supply to the motor is interrupted due to power failure, disconnection, etc. during the operation of the brake, the friction material is retained by the force holding function of the motion conversion mechanism. However, it cannot be easily moved in the pressing force decreasing direction in which the pressing force applied to the rotating body decreases. As a result, the wheel braking force is maintained to some extent.

However, in some cases, the driver desires to release the brake operation, and in this case, the friction material cannot be moved in the direction of decreasing the pressing force, so that the brake is dragged when the motor fails. Can occur.

On the other hand, in the above-mentioned conventional example, a return spring is provided between the rotating member and the housing of the electric brake, and the rotating member is constantly biased by the return spring in the direction of decreasing the pressing force. . Motors are generally configured to include a rotor and a stator, the rotor being adapted to rotate with a rotating member. Therefore, the return spring eventually urges the rotor in the direction of decreasing the pressing force.

Therefore, in this conventional example, even if the power supply to the motor is interrupted during the braking operation, the motor is rotated by the return spring to move the friction material in the direction of decreasing the pressing force. Can be Therefore, according to this conventional example, when the motor fails, it is possible to prevent the electric brake from continuing to operate despite the brake operation being released. That is, dragging of the brake is prevented.

[0007]

However, in this conventional example, regardless of whether the motor has failed or not, the return member applies the rotating member and the rotor in the direction of decreasing the pressing force regardless of whether or not the motor has failed. Be inspired. Therefore, in this conventional example, when increasing the wheel braking force in response to the brake operation, an extra force must be generated by the motor to overcome the return spring. Therefore, when the conventional example is implemented, there is a problem that the motor is enlarged and power consumption is increased.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent a brake from being dragged when a motor fails while avoiding an increase in the size and power consumption of the motor. It is to provide an electric brake.

This problem is solved by the following aspects of the present invention. In the following description, each aspect of the present invention will be described in the same format as in the claims, with each section numbered. This is to clarify the possibility of adopting a combination of the features described in each section, excluding the possibility of adopting a combination other than the combinations described here, or excluding the features described here. It does not exclude the possibility of combining the features.

(1) A rotating body that rotates with a wheel, a friction material pressed by the rotating body to suppress the rotation of the wheel, a motor, and the rotation of the motor causes the friction material to be rotated by the rotating body. And a friction material driving device for moving the friction material closer to and away from the rotating member, and selectively moving the friction material in a pressing force decreasing direction in which a pressing force of the friction material pressed against the rotating body is reduced without rotation of the motor. An electric brake including a selective permitting device for permitting the electric brake (claim 1). In this electric brake, if the selective permitting device is operated, the friction material can be moved in the direction of decreasing the pressing force without rotating the motor. Therefore, according to this electric brake, even if the power supply to the motor is interrupted during the brake operation, the frictional material is moved in the pressing force decreasing direction by the force applied from the friction material by the operation of the selective permitting device. Thus, the brake can be prevented from being dragged when the motor fails. Also, according to this electric brake, the friction material can be moved in the direction of decreasing the pressing force without rotating the motor, so even if the motor breaks down and is mechanically locked,
Brake drag can be prevented. In the electric brake, when the friction material is moved in the pressing force decreasing direction, it is not essential to forcibly rotate the motor by the external force or to move the friction material in the pressing force decreasing direction by the external force. In this electric brake, by the operation of the selective permitting device, by the force acting from the friction material,
This is because the friction material can be moved in the pressing force decreasing direction. Therefore, in this electric brake, as in the above-described conventional example, in order to prevent the brake from being dragged in the event of a motor failure, the rotating member, the friction material, and the like are always urged by the return spring in the pressing force decreasing direction. Not essential. Therefore, according to this electric brake, it is not necessary to generate an unnecessarily large force on the motor when the motor is normal, and therefore, it is possible to prevent the motor from increasing in size and increasing power consumption, and at the same time, to prevent the motor from malfunctioning when the motor fails. Dragging can be prevented. The electric brake described in this section may be of a disk type or a drum type. (2) The selective allowance device prevents the friction material from moving in the direction of decreasing the pressing force without rotation of the motor when the electric brake is normal, and allows the friction material to move in an abnormal state (1). The electric brake according to the item. According to this electric brake, when the electric brake is normal, the friction material is prevented from moving in the direction of decreasing the pressing force without rotation of the motor, so that the wheel braking force is generated normally. Since the friction material is allowed to move in the direction in which the pressing force decreases without rotation of the motor, the occurrence of dragging of the brake due to an abnormality in the electric brake is prevented. (3) the friction material driving device, (a) a rotating member that is rotated by the motor, and (b) a linear motion member that is linearly moved to move the friction material toward and away from the rotating body. (C) a motion conversion mechanism that converts the rotation of the rotating member into a linear motion of the linear motion member, and
The selective permitting device is a force transmitting device for transmitting a force between the linear motion member and the friction material, and prevents relative movement of the linear motion member and the friction material in the pressing force decreasing direction. (2) The electric brake according to the above (1) or (2), including one that switches between an engaged state and an allowed state. In this electric brake, a force transmitting device for transmitting a force between a linear motion member and a friction material is in a state in which relative movement between the linear motion member and the friction material in a direction of decreasing the pressing force is permitted and a condition in which the force transmission device is permitted. The friction material can be moved in the direction in which the pressing force decreases, regardless of the rotation of the motor. (4) The force transmitting device (a) transmits force between the linear motion member and the friction material, and is relatively rotatable with respect to any of the linear motion member and the friction material. A combined force transmitting member, which is moved in one direction by a force acting from the friction material, thereby being moved in the pressing force decreasing direction together with the friction material without the linear motion of the linear motion member, (b) The electric brake according to item (3), including a state switching device that switches between a state in which rotation of the force transmission member is permitted and a state in which rotation of the force transmission member is blocked.
In this electric brake, a force transmitting member for transmitting a force between the linear motion member and the friction material is moved in one direction by a force applied from the friction material, thereby being moved in a pressing force decreasing direction. As a result, regardless of the rotation of the motor, the friction material is moved in the pressing force decreasing direction. Therefore, according to this electric brake, since the force acting on the force transmitting member from the friction material can be positively used, a mechanism for exclusively generating a driving force for moving the friction material in the pressing force decreasing direction is provided. It becomes unnecessary. Therefore, according to this electric brake, it is possible to suppress an increase in the number of components due to the addition of the drag prevention measure. (5) the force transmission device is a slope formed on at least one of the force transmission member and the linear motion member,
At least one of the force transmitting member and the linear motion member has an inclined surface with respect to a plane perpendicular to the axis of the linear motion member, and the inclined surface allows one-direction rotation of the force transmitting member in the direction of decreasing the pressing force of the force transmitting member. The electric brake according to item (4), wherein the electric brake is converted to the movement of (4). According to the electric brake, the brake can be prevented from being dragged when the motor fails, with a relatively simple configuration. (6) The force transmitting device includes a first screw mechanism in which the linear motion member and the force transmitting member are screwed (4) or (5).
An electric brake according to claim [Claim 5]. According to this electric brake, the conversion of the one-way rotation of the force transmitting member to the movement of the force transmitting member in the pressing force decreasing direction can be performed with a relatively simple configuration. (7) The motion conversion mechanism includes a second screw mechanism in which the rotating member and the linear motion member are screwed together, the screw conversion efficiency of which is lower than that of the first screw mechanism. The electric brake according to claim 6. According to this electric brake, not only the conversion of the one-way rotation of the force transmitting member into the movement of the force transmitting member in the pressing force decreasing direction, but also the conversion of the rotation of the rotating member into the linear motion of the linear motion member can be compared. It can be performed with a simple configuration. Furthermore, in this electric brake, the first screw mechanism for converting one-way rotation of the force transmitting member into movement in the direction of decreasing the pressing force of the force transmitting member despite the fact that two screw mechanisms are provided in series with each other. , The screw reverse efficiency is higher than in the second screw mechanism that converts the rotation of the rotating member into the linear motion of the linear motion member. here,
In general, the screw reverse efficiency means a ratio of work in which the torque output from the screw mechanism increases with respect to the work input to the screw mechanism, and as a result, the rotation angle of the movable member increases. In brief, the higher the screw reverse efficiency, the longer the motion stroke output from the movable member when the same magnitude of force is input to the movable member that is a component of the screw mechanism. . For example, the meaning of the screw reverse efficiency will be specifically described by taking the relationship between the screw reverse efficiency of the first screw mechanism and the electric brake as an example. The higher the screw reverse efficiency, the higher the force acting on the force transmitting member from the friction material. As a result, the force transmitting member can be easily moved. In the electric brake described in this section, as described above, the screw reverse efficiency is set higher in the first screw mechanism than in the second screw mechanism. Cannot be restored but can be forcibly restored, or cannot be restored electrically or forcibly). As a result, even if the second screw mechanism becomes inoperable, the first screw mechanism becomes inoperable. The screw mechanism can operate. Therefore, according to this electric brake, the relationship of the screw reversal efficiency between the two screw mechanisms in series with each other is optimized, so that even if the motor fails and cannot be restored, the frictional material is pressed in the direction of decreasing the pressing force. To prevent the brakes from dragging. (8) The electric brake according to (6) or (7), wherein the first screw mechanism is configured such that the force transmitting member is coaxially screwed into a hollow portion formed in the linear motion member. Item 7]. In this electric brake, the linear motion member and the force transmission member are overlapped in a common axial direction. Therefore, according to this electric brake, it is easy to shorten the axial dimension of the linear motion member and the force transmitting member as a whole, and as a result, the electric brake becomes larger with the addition of the drag prevention measure. Can be suppressed. (9) the state switching device, (a) a moving member that is moved to a rotation allowable position for allowing rotation of the force transmitting member and a rotation preventing position for preventing, and (b) the moving member by electromagnetic force, The electric brake according to any one of (4) to (8), further including a moving member driving device that drives the moving member to be selectively moved to a rotation allowing position and a rotation preventing position. ]. According to this electric brake, it is possible to electromagnetically switch between a state in which the friction material is allowed to move in the direction of decreasing the pressing force and a state in which the friction material is blocked, so that the state switching timing can be set more freely in the case of mechanical switching. It can be set. Here, the movement of the “moving member” includes both a linear motion and a rotational motion. (10) The state switching device, wherein the moving member is positioned at the rotation preventing position in a state where the electromagnetic force generator of the moving member driving device is not energized, and moves to the rotation allowable position when energized. The electric brake according to item (9), wherein (11) The state switching device, in a state where the electromagnetic force generator of the moving member driving device is not energized, positions the moving member at a rotation allowable position, and when energized, moves the moving member to a rotation preventing position. The electric brake according to item (9), wherein (12) the moving member drive device, even if the brake operation by the driver is released, if the wheel braking force by the electric brake does not decrease, moves the moving member to a rotation allowable position, thereby And (9) permitting the friction material to move in the pressing force decreasing direction.
An electric brake according to any one of the above items (11) to (11). (13) The moving member driving device includes an abnormality determining unit that determines that the electric brake is abnormal when the wheel braking force by the electric brake does not decrease even though the brake operation by the driver is released. The electric brake according to item (12), including: (14) The abnormality determining means, when the brake operation by the driver is released, the brake operation-related amount related to the brake operation by the driver and the wheel braking force-related amount related to the wheel braking force by the electric brake. The electric brake according to item (13), wherein when the two do not properly correspond to each other, it is determined that the electric brake is abnormal. Here, the "brake operation-related amount" can be, for example, an operation stroke of a brake operation member or an operation force, and the "wheel braking force-related amount" can be, for example, a wheel braking force or a vehicle body deceleration. The operating stroke or operating force of the friction material, the operating stroke or operating force of the force transmitting member, the operating stroke or operating force of the linear motion member, or the rotation angle or the rotating force of the rotating member. be able to. (15) When the force transmitting member is moved by a set distance or more in the pressing force decreasing direction in a state where the force transmitting member is allowed to move in the pressing force decreasing direction without the linear movement of the linear motion member. , The force transmitting member abuts the linear motion member,
When the linear motion member is moved in the direction in which the pressing force increases in that state, the force transmitting member is linearly moved integrally with the linear motion member, thereby increasing the pressing force (4). The electric brake according to any one of (14) to (14). When implementing the electric brake according to any one of the above (4) to (14), in order to prevent the rotation of the force transmitting member, it is necessary that the phase of the force transmitting member is a specific phase. There are cases. In this case, if rotation is initially blocked and rotation is permitted if necessary, then rotation cannot be prevented due to improper phase, even if it is necessary to prevent rotation. There is. If rotation cannot be prevented, even if it is necessary to increase the pressing force, the pressing force can be increased normally because there is a first screw mechanism having a higher screw reversal efficiency than the second screw mechanism. It will be difficult. On the other hand, according to the electric brake described in this section, when the force transmitting member is moved by the set distance or more in the pressing force decreasing direction, the force transmitting member contacts the linear motion member, and in that state, the linear motion member However, when the pressing force is moved in a direction in which the pressing force increases, the force transmitting member is linearly moved integrally with the linear motion member, thereby increasing the pressing force. Therefore, according to this electric brake, a necessary wheel braking force can be secured even if the rotation of the force transmitting member cannot be prevented in a case where it is appropriate to prevent the rotation.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some specific embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an electric brake device including an electric brake 10 according to a first embodiment of the present invention. This electric brake device is mounted on a vehicle provided with left and right front wheels FL and FR and left and right rear wheels RL and RR, and four electric brakes 10 are respectively attached to the four wheels.

FIG. 2 representatively shows one electric brake 10. The electric brake 10 is of a disk type in the present embodiment. Therefore, the electric brake 10 includes a disk 12 (an example of a rotating body) that rotates together with the wheels. Both sides of the disk 12 are friction surfaces 14. The electric brake 10 further includes a pair of friction pads 20a and 20b (an example of a friction material).
Are provided at a pair of positions facing each other with the disk 12 interposed therebetween. Among the pair of friction pads 20a and 20b, the one located on the inside of the vehicle body is the inner pad 20a, and the one located on the outside of the vehicle body is the outer pad 20b. The electric brake 10 further includes a mounting bracket 22 fixed to a vehicle body (not shown), and a caliper 24 is mounted on the mounting bracket 22 so as to be movable in a direction substantially parallel to the rotation axis of the disk 12. A pair of friction pads 20 are attached to the caliper 24.
a and 20b are slidably supported in a direction substantially parallel to the rotation axis of the disk 12.

The caliper 24 includes a pressing portion 30 for pressing the inner pad 20a against the disk 12, a reaction portion 32 for pressing the outer pad 20b against the disk 12, and a connection between the pressing portion 30 and the reaction portion 32. And a connecting portion 34 to be provided. The outer pad 20b is configured such that the reaction force from the inner pad 20a is
By being transmitted to the outer pad 20b via the connection portion 34 and the reaction portion 32, the disc 12 is pressed.

The pressing portion 30 includes a pair of friction pads 20.
A design reference line extending in parallel to the moving direction of a, 20b is set, and the motor 40 is mounted coaxially with the design reference line. The motor 40 is a DC motor, but may be another motor, for example, an ultrasonic motor. The motor 40 is a hollow motor housing 4
2, a stator 44 housed in the motor housing 42, and a rotor 46 passing through a hollow hole of the stator 44. The motor housing 42 has the pressing portion 3
0 is fitted and fixed substantially airtightly. Wires 50 extend outward from the motor housing 42, and the gap between the wires 50 and the motor housing 42 is substantially airtightly filled by an elastic seal member 52. The stator 44 is configured by winding a coil 54 around a laminated core 56. Rotor 46
Is configured such that a plurality of permanent magnets 58 are attached to the outer peripheral surface of the stator 44 facing the coil 54 so that the polarity is alternately different in the circumferential direction. Pressing part 3
A hollow portion 60 is formed in the hollow portion 0, and an end portion of the both ends of the rotor 46 which is closer to the inner pad 20 a is located in the hollow portion 60. And the rotor 46 is
It is rotatably supported across the pressing portion 30 and the motor housing 42 via a pair of bearings 62 and 63.

The pressing portion 30 further houses a pressure shaft 64 coaxially with the design reference line. The pressure shaft 64 has a shaft portion 66, and a large-diameter portion 68 is formed at one end (the right end in the figure). The pressing shaft 64 has a large diameter portion 6.
At 8, it is brought into contact with the back surface of the inner pad 20 a. It is desirable that the large-diameter portion 68 and the inner pad 20a be brought into contact with each other so that their relative rotation is performed smoothly.
It is desirable that the inner pad 20a and the inner pad 20a be brought into contact with each other via a bearing such as a thrust bearing.
For example, it is desirable that the large diameter portion 68 and the inner pad 20a be in contact with each other via a rolling element such as a bolt.
An annular seal member 70 is provided between the large diameter portion 68 and the pressing portion 30.
Is installed. The seal member 70 is made of rubber,
Thereby, it can be easily elastically deformed.

Between the rotor 46 and the pressure shaft 64,
A planetary roller screw 80 as a second screw mechanism is mounted. Since the planetary roller screw 80 is of the same type as the planetary roller roller screw spindle described in Japanese Patent Application Laid-Open No. 8-33841, it will be briefly described. Planetary roller screw 80
Are a nut 82 formed integrally with the rotor 46, a plurality of rollers 84 (planetary rollers), and a pair of retainers 86.
And a screw shaft 88.
The nut 82 has an annular groove 89 formed on the inner peripheral surface, and has at least one (a plurality of roller receiving ribs 90 in the example in the figure) projecting radially inward from the inner peripheral surface and extending in the circumferential direction. Have. The roller receiving rib 9
0 (at least both sides in the example in the figure)
A roller receiving surface 92 is a slope inclined with respect to the diameter direction of the hole of the nut 82. The plurality of rollers 84
Annular groove 9 having a slope corresponding to roller receiving surface 92
3 and an annular groove 94 (a screw thread is also possible) on each outer peripheral surface. The plurality of rollers 84 frictionally engage with the roller receiving ribs 90 of the nut 82 in the annular groove 93. The pair of retainers 86 are provided with the plurality of rollers 8.
4 are held at both ends of the rollers 84 so as to be rotatable around the axis of the rollers 84 and that the axes of the rollers 84 are located at equal distances from the center line of the hole of the nut 82. The rotation and revolution of the plurality of rollers 84 can be realized by the pair of retainers 86. The screw shaft 88 has a thread 95 on an outer peripheral surface, and the thread 95 is frictionally engaged with the annular groove 94 of the plurality of rollers 84 at the thread 95. Screw shaft 88
As will be described in detail later, axial movement is allowed, but rotation is prevented.

A ball screw 96 as a first screw mechanism is mounted between the screw shaft 88 and the pressure shaft 64. The ball screw 96 has a screw shaft 88.
And a screw shaft 100 formed integrally with the pressure shaft 64, and the nut 98 and the screw shaft 100 are provided with a plurality of balls 10
2 and screwed together.

That is, in this embodiment, the motor 40 and the pressure shaft 64 are connected to each other by the planetary roller screws 8.
0 and the ball screw 96 are connected to each other in series. The screw reverse efficiency of the ball screw 96 is higher than the screw reverse efficiency of the planetary roller screw 80.

In the ball screw 96, the nut 98 and the screw shaft 100 are switched between a state where relative rotation is prevented and a state where relative rotation is allowed. In a state where the relative rotation is prevented, the nut 98 and the screw shaft 100 can linearly move integrally with each other. The state switching is performed by the selector 110 using a solenoid (an example of an electromagnetic force generator) as a driving source. Selector 1
Reference numeral 10 denotes a selector housing 112 as shown in FIG.
And a solenoid 114 housed in the selector housing 112, and a plunger 116 driven based on the magnetic force of the solenoid 114. The selector housing 112 is fixed to the pressing portion 30.
The plunger 116 has an engagement protrusion 120 as an engagement portion at a portion protruding from the selector housing 112. The plunger 116 is connected to the solenoid 11
In the OFF state of No. 4, the spring 12 as an elastic member
2 urges the selector housing 112 toward the most protruding position.

The screw shaft 100 and the nut 98 include
Engagement grooves 124 and 126 are formed as engagement portions extending in the axial direction, respectively. The engagement grooves 124, 12
Reference numeral 6 denotes a size that allows the engagement protrusion 120 to engage. In the engagement state, relative rotation between the screw shaft 100 and the nut 98 is prevented, and furthermore, they rotate with respect to the pressing portion 30. Is also blocked. In FIG. 3, the engagement protrusion 120 is shown at a position most protruded from the selector housing 112, but does not engage with the screw shaft 100 but engages with the nut 98 at the most retracted position. Are adapted. Therefore, the nut 98 (and the screw shaft 88 of the planetary roller screw 80) is always prevented from rotating.

The screw shaft 100 and the nut 98
The axial position at the time of the non-braking operation does not remain unchanged, but changes with wear of the friction pads 20a and 20b. Despite such a change in the axial position, the axial dimension of the engagement grooves 124 and 126 is reduced so that the friction pads 20a and 20b are worn so that the engagement protrusions 120 are properly engaged with the engagement grooves 124 and 126. It is set in consideration of the amount.

As shown in FIG. 1, the electric brake device comprises:
A brake pedal 130 as a brake operation member, a controller 132, a driver 134, and various sensors are provided. The brake pedal 130 is connected to a stroke generator 136 that generates a stroke according to the operation force applied thereto.

The controller 132 includes a CPU 140, R
Computer 14 including OM 142 and RAM 144
6 as a main component. The ROM 142 stores various routines such as a brake control routine and a solenoid control routine shown by flowcharts in FIGS. 4 and 5, respectively. These routines are executed by the CPU 140 while using the RAM 144. As a result, the electric brake control and the solenoid control are performed. These controls will be described later in detail.

As shown in FIG. 1, the driver 134 includes an output section of the controller 132 and the electric brake 10 for four wheels.
The motor 40 and the solenoids 114 for the four wheels are further connected to a battery 150 as a vehicle power supply. The driver 134 supplies a current from the battery 150 to each motor 40 and each solenoid 114 in an amount corresponding to a signal from the controller 132.

Various sensors include an operation stroke sensor 1
52 and a motor rotation position sensor 1 provided for each wheel
54, and a motor current sensor 156 provided for each wheel.
There is. The operation stroke sensor 152 detects the operation stroke of the brake pedal 130 as a brake operation amount. Each motor rotation position sensor 154 detects the rotation position of the rotor 46 of the corresponding motor 40. Each motor current sensor 156 detects an actual current flowing through the corresponding motor 40.

The brake control routine of FIG. 4 is executed by the computer 146 sequentially and repeatedly for four wheels. In each execution, first, in step S1 (hereinafter simply referred to as “S1”; the same applies to other steps), the operation stroke of the brake pedal 130 is detected by the operation stroke sensor 152. Next, in S2, based on the detected operation stroke, a target motor current value to be supplied to the motor 40 corresponding to the execution target wheel of the present execution of this routine among the four wheels is determined. Specifically, the relationship between the operation stroke and the target motor current value is calculated by using a table, an equation, or the like.
This is stored in the OM 142, and the current target motor current value is determined according to the relationship. Thereafter, in S3, the actual motor current value of the motor 40 corresponding to the execution target wheel is controlled. Specifically, the actual motor rotation position is detected by the motor rotation position sensor 154 corresponding to the execution target wheel, and the actual motor current value is detected by the motor current sensor 156 corresponding to the execution target wheel. Based on this, the actual motor current value is controlled in a feedback manner so that the determined target motor current value is realized. This completes one execution of this routine.

The solenoid control routine of FIG. 5 is also executed by the computer 146 sequentially for four wheels and repeatedly for each wheel. At the time of each execution, first, S11
In, it is determined whether or not the operation stroke has decreased from the previous time, and thereby it is determined whether or not the brake operation has been released by the driver. Specifically, the current value of the operation stroke detected by the operation stroke sensor 152 is the previous value (stored in the RAM 144).
It is determined whether the number has decreased further. This time, if it is assumed that it has not decreased, the determination is NO, and one cycle of this routine is immediately terminated. Since the solenoid 114 is always designed to be in the OFF state, this time, the solenoid 114 is maintained in the OFF state.

The fact that the solenoid 114 is in the OFF state means that the relative rotation of the nut 98 and the screw shaft 100 is prevented, and that the function of the ball screw 96 is eventually invalidated. Therefore, when the solenoid 114 is in the OFF state, the nut 98 and the screw shaft 1
00 are linearly moved by the motor 40 integrally with each other, whereby the wheel braking force is controlled.

On the other hand, if it is assumed that the operation stroke has decreased this time, the determination in S11 is YES.
And the process proceeds to S12. In this S12, it is determined whether or not the operation stroke of the pressurizing shaft 64 of the electric brake 10 corresponding to the execution target wheel has decreased from the previous stroke, whereby the pressurizing shaft 64 according to the release operation of the brake pedal 130 is determined. Is normally moved (retracted) in a direction away from the disk 12.
There is no voltage drop of the battery 150, no disconnection of the motor 40, and the like, and it is determined whether the motor 40 is normally rotated.

More specifically, the present value of the operating stroke of the pressurizing shaft 64 is estimated based on the output signal of the motor rotational position sensor 154 corresponding to the wheel to be executed, and the estimated current value is used as the previous estimated value ( It is determined whether or not the number has decreased. In the present embodiment, noting that a certain relationship is established between the rotation of the motor 40 and the operation stroke of the pressure shaft 64, the motor rotation position sensor 154
The number of sensors is smaller than when the motor rotation position and the operation stroke of the pressure shaft 64 are detected by separate sensors. However, it is possible to implement the present invention by performing detection by separate sensors.

In this case, assuming that the operation stroke of the pressurizing shaft 64 is smaller than the previous stroke, the determination in S12 is Y
It becomes ES and one execution of this routine ends immediately. Eventually, this time, the solenoid 114 is maintained in the OFF state.

On the other hand, if it is assumed that the operation stroke of the pressurizing shaft 64 has not decreased from the previous time even though the operation stroke has decreased from the previous time, this time, S11
Is YES, and the determination in S12 is NO, and in S13, it is determined that the motor 40 is abnormal, and a signal for turning it ON is output to the solenoid 114. As a result, the plunger 116 is moved from the most protruded position to the most retracted position, and the engagement protrusion 120 is disengaged from the engagement groove 124. This completes one execution of this routine.

When the engagement protrusion 120 is disengaged from the engagement groove 124, the screw shaft 100 and the pressure shaft 6
4 are allowed, thereby enabling the function of the ball screw 96. On the other hand, a reaction force acts on the pressing shaft 64 from the inner pad 20a in a direction to separate the pressing shaft 64 from the inner pad 20a. Here, the reaction force from the inner pad 20a also depends on the elasticity (compression) of the inner pad 20a itself, but also on the elasticity (deflection) of the caliper 24. Therefore, the reaction force from the inner pad 20a causes the screw shaft 100
The pressing shaft 64 is moved in a direction away from the inner pad 20a while being rotated. As shown in FIG. 2, an axial gap 160 is provided between the nut 98 and the pressing shaft 64 during the non-braking operation, so that the pressing shaft 64 approaches the nut 98. Is acceptable. However, the axial gap 160 decreases as the pressure shaft 64 is retracted, and eventually disappears. The dimension of the axial gap 160 is set to be equal to or greater than the amount of movement required to move the inner pad 20a from the state where the inner pad 20a is pressed by the disk 12 to the state where no drag occurs.

Therefore, in the present embodiment, even if the motor 40 is in an abnormal condition that the motor 40 cannot be restored in the brake operating state, the inner pad 20a is
Is allowed to move in the direction in which the pressing force decreases, so that dragging of the brake is prevented.

Further, in the present embodiment, the axial gap 160 is set to a length necessary to prevent the drag of the brake as described above, and a sufficient distance and additional distance are required to prevent the drag. If the pressure shaft 64 is retracted,
Unnecessary retraction of the pressure shaft 64 is prevented by contact with the nut 98. On the other hand, the screw shaft 88
Regardless of the operation of the selector 110, the rotation is always prevented by the cooperative action of the engagement protrusion 120 and the engagement groove 126, while the linear movement is allowed. Therefore,
When a new brake operation is performed and the motor 40 has returned to the normal state at that time, the screw shaft 88 is advanced by the motor 40, and the nut 98 is advanced by the axial force of the screw shaft 88. Become. When the nut 98 is advanced, the nut 98 presses the pressing shaft 64 toward the inner pad 20a, and the electric brake 10 is operated.

As is clear from the above description, in the present embodiment, the nut 82 constitutes a “rotating member”, the screw shaft 100 constitutes a “linear motion member”, and the planetary roller screw 80 constitutes a “motion converting member”. , A nut 82, a screw shaft 100 and a planetary roller screw 80.
Constitutes a “friction material driving device”, and a portion of the selector 110, the nut 98, the screw shaft 100, the ball screw 96, the operation stroke sensor 152, the motor rotation position sensor 154, and the controller 132 which executes the solenoid control routine of FIG. Form a "selective permitting device" in cooperation with each other. The nut 98, the screw shaft 100, the pressure shaft 64, and the ball screw 96 cooperate with each other to form a “force transmission device”, and the pressure shaft 64 and the screw shaft 100 cooperate with each other to form a “force transmission member”. It constitutes. Also, the ball screw 9
6 constitutes a “first screw mechanism”, and the planetary roller screw 80 constitutes a “second screw mechanism”. Further, the selector 110 constitutes a “state switching device”, and the plunger 1
16 constitutes the “moving member”, and the portion of the selector 110 other than the plunger 116 constitutes the “moving member driving device”.

It should be noted that, in this embodiment,
After the pressure shaft 64 and the screw shaft 100 are integrally formed, the relative rotation between the pressure shaft 64 and the inner pad 20a is performed at a position where the pressure shaft 64 and the inner pad 20a are in contact with each other. However, for example, after the pressure shaft 64 and the screw shaft 100 are separately formed, the shafts 64 and 100 are relatively rotatably engaged with each other, whereby the inner pad 20a is retracted without the nut 98 being retracted. A function that can be performed may be realized.

Next, an electric brake device including an electric brake 178 according to a second embodiment of the present invention will be described. However, the present embodiment differs from the first embodiment only in the configuration related to solenoid control, and other configurations are common. Therefore, only the configuration related to solenoid control will be described in detail.
The other components are denoted by the same reference numerals, and detailed description is omitted.

In the first embodiment, as described above,
The selector 110 engages the engagement protrusion 120 with the engagement groove 124 when the solenoid 114 is in the OFF state, thereby preventing the relative rotation between the nut 98 and the screw shaft 100 in the ball screw 96, and If the solenoid 114 is turned on at the time of an abnormality, the engaging protrusion 120 is engaged with the engaging groove 1 by the magnetic force of the solenoid 114.
The ball screw 96 allows the nut 98 and the screw shaft 100 to rotate relative to each other.

On the other hand, in this embodiment, when the selector 180 is in the OFF state of the solenoid 182,
As shown in FIGS. 6 and 7, the elastic protrusion of the spring 184 as an elastic member causes the engaging protrusion 120 to engage with the engaging groove 1.
24, the ball screw 96 allows relative rotation between the nut 98 and the screw shaft 100, and if the solenoid 182 is turned on,
The engagement protrusion 120 is engaged with the engagement groove 124 by the magnetic force of the solenoid 182, and the relative rotation between the nut 98 and the screw shaft 100 in the ball screw 96 is prevented. Therefore, in the present embodiment, the solenoid 182 is always in the ON state, and when the motor 40 is abnormal, the solenoid 182 is switched to the OFF state.

FIG. 8 is a flowchart showing a solenoid control routine for performing such a solenoid control. Hereinafter, this routine will be described.
The steps common to the solenoid control routine of FIG. 4 in the embodiment will be briefly described.

This routine is also executed sequentially for the four wheels and repeatedly for each wheel. At each run,
In S31, similarly to S21, it is determined whether the operation stroke has decreased from the previous stroke. This time, assuming that it has not decreased, the determination is NO,
Immediately, one execution of this routine ends. In the present embodiment, the key switch of the vehicle is turned off by the driver.
When the solenoid 182 is operated from ON to OFF, the solenoid 182 is switched from OFF to ON. Therefore, this time, assuming that the motor 40 is in a normal state,
Solenoid 182 is maintained in the ON state, so that nut 98 and screw shaft 100
Relative rotation is prevented. Thereby, the ball screw 9
Function 6 is disabled.

On the other hand, if it is assumed that the operation stroke has decreased this time, the determination in S31 is YES.
In S32, similarly to S22, it is determined whether the operation stroke of the pressurizing shaft 64 has decreased from the previous stroke. In this case, assuming that the number has decreased, the determination is YES, and one cycle of this routine is immediately terminated. This time, too, assuming that the motor 40 is normal, the solenoid 182 is maintained in the ON state, and as a result, the relative rotation between the nut 98 and the screw shaft 100 in the ball screw 96 is prevented.

On the other hand, if it is assumed that the operation stroke of the pressurizing shaft 64 has not decreased from the previous time even though the operation stroke has decreased from the previous time, the process proceeds to S31.
Is YES, and the determination at S32 is NO. At S33, a signal is output to the solenoid 182 to determine that the motor 40 is abnormal, and to turn it off.
Thereby, the engagement protrusion 120 is disengaged from the engagement groove 124, and the relative rotation between the nut 98 and the screw shaft 100 in the ball screw 96 is allowed. As a result, the pressing shaft 64 is caused to retreat while rotating by the reaction force from the inner pad 20a, thereby preventing the drag of the brake.

In this embodiment, the electric brake 17
8 when there is no current supply to the solenoid 182,
Brake drag can be prevented. Therefore, in this embodiment, the battery 150 is connected to the motor 40 and the solenoid 1
The power supply is common to the power supply 82 and the electric brake 178 has an advantage that the brake can be prevented from being dragged even when the abnormality of the electric brake 178 is caused by the failure of the battery 150. However, in the present embodiment, since the engagement protrusion 120 is about to be engaged with the engagement groove 124 in a state where the screw shaft 100 is rotatable in the ball screw 96, the phase of the screw shaft 100 is a specific. If it is not the same (the same phase as the nut 98), the engaging projection 120 cannot be engaged with the engaging groove 124. Therefore, in the present embodiment, a situation may occur in which the engagement protrusion 120 cannot be engaged with the engagement groove 124 in a state where the abnormality of the motor 40 has never occurred. However, even if the engagement is not realized, the retraction limit of the pressure shaft 64 is defined by the nut 98, so that the brake may be dragged, but the braking by the electric brake 178 does not occur.

On the other hand, in the first embodiment,
In the state where the abnormality of the motor 40 has never occurred, since the engagement protrusion 120 is engaged with the engagement groove 124,
A situation in which the engagement protrusion 120 cannot be engaged with the engagement groove 124 does not occur. However, when the motor 40 recovers after becoming abnormal, a situation may occur in which the engagement protrusion 120 cannot be engaged with the engagement groove 124 as in the second embodiment. But also in this case,
For the same reason as in the second embodiment, although the brake may be dragged, the situation where the braking by the electric brake 10 becomes impossible does not occur.

Next, an electric brake device including an electric brake 198 according to a third embodiment of the present invention will be described. However, this embodiment differs from the first embodiment only in the position of the selector, and is common to other elements. Therefore, only the position of the selector will be described in detail, and the same reference numerals will be used for the other elements. A detailed description will be omitted.

In the first embodiment, as shown in FIG. 2, the selector 110 is arranged in the pressing portion 30 near the inner pad 20a. On the contrary,
In the present embodiment, as shown in FIG.
00 is located at one position in the motor housing 42 as one of positions away from the inner pad 20a, and is located at a position close to an end of the pressure shaft 64 that is farther from the inner pad 20a. I have. On the other hand, the inner pad 20a is a portion that becomes high in heat due to friction with the disk 12. Therefore, according to the present embodiment, since the selector 200 is disposed at a position away from the high-temperature portion of the electric brake 198, the countermeasures to be taken for the selector 200 may be reduced or unnecessary.

Next, an electric brake device including an electric brake according to a fourth embodiment of the present invention will be described. However, this embodiment is different from the first embodiment only in the force transmission device, and other configurations are common. Therefore, only the force transmission device will be described in detail, and the same reference numerals will be used for other configurations. A detailed description will be omitted.

In the first embodiment, as shown in FIG. 2, the nut 98, the screw shaft 100, and the pressure shaft 6
4 and the ball screw 96 cooperate with each other to form a "force transmission device".
Specifically, a ball screw 96 is used to realize the retreat of the pressure shaft 64 without the retreat of the nut 98. On the other hand, in the present embodiment, as shown in FIG. 10, a hollow portion 220 is formed in the screw shaft 100 of the planetary roller screw 80, and the shaft portion 66 of the pressure shaft 64 is formed in the hollow portion 220. Are fitted coaxially so as to be relatively rotatable and axially movable.

At least one ball guide groove 222 for guiding the ball 221 is formed as an inclined guide on the end face of the both ends of the screw shaft 100 which is closer to the inner pad 20a. The ball guide groove 222 is shown in FIG.
As shown in FIG. 1, it extends in the circumferential direction of the screw shaft 100 and is inclined with respect to a plane perpendicular to the axis of the screw shaft 100 as shown in FIG. In the present embodiment, the number of the ball guide grooves 222 is plural. The plurality of ball guide grooves 222 are arranged in the circumferential direction of the screw shaft 100, and as shown in FIG.
22 are arranged so that the depth changes in the same direction when the plurality of ball guide grooves 222 are traced in one direction. Each ball guide groove 222 accommodates one ball 221. On the other hand, of the two end surfaces of the large diameter portion 68 of the pressure shaft 64, the end surface facing the screw shaft 100 has a ball support surface 224 for supporting the ball 221.
Are formed as support portions. Each ball 221 is sandwiched between its ball support surface 224 and each ball guide groove 222 and is rolled therebetween. Each ball 221 is
In a state where the relative rotation between the pressing shaft 64 and the screw shaft 100 is blocked by the selector 110, the shallowest part (the ball supporting surface 22) of each ball guide groove 222 is formed.
(The part closest to No. 4).

Therefore, in a state where the relative rotation between the pressing shaft 64 and the screw shaft 100 is permitted by the selector 110, the force acting on the screw shaft 100 from the pressing shaft 64 and the slope of each ball guide groove 222 Of each ball 221 causes each ball guide groove 222 to roll from a shallow portion to a deep portion. As a result, the large diameter portion 68 of the pressure shaft 64 approaches the screw shaft 100, and the inner pad 20a
Is moved away from the disk 12. Thus, when the electric brake is abnormal, dragging of the brake is prevented.

In the present embodiment, the ball guide groove 222 as an inclined guide portion and the ball support surface 2 as a support portion
24, the ball 221 is interposed therebetween, whereby the relative rotation between the inclined guide portion and the support portion is smoothly performed. However, the interposition of the ball 221 is not limited to implementing the present invention. Is not indispensable in

As is clear from the above description, in the present embodiment, the screw shaft 100 and the pressure shaft 64
, Ball 221, ball guide groove 222, and ball support surface 2
24 together form a "force transmission device".

Next, an electric brake device including an electric brake according to a fifth embodiment of the present invention will be described. However, this embodiment is different from the first embodiment only in a part of the motor.
Since other parts are common, only the different parts will be described in detail, and the other parts will be denoted by the same reference numerals and detailed description thereof will be omitted.

In the first embodiment, as shown in FIG. 2, a wire 50 extends from the motor housing 42. The airtightness between the wire 50 and the motor housing 42 made of metal This is realized by attaching an elastic seal member 52 to the motor housing 42 and the motor housing 42.

On the other hand, in the present embodiment, as shown in FIG. 12, a sealing member 240 is made up of a rigid first portion 242 and an elastic second portion 244 adhered to the first portion 242. And is configured to include: First
The part 242 is press-fitted into the motor housing 42, whereby the sealing member 52 is firmly attached to the motor housing 42. On the other hand, the second portion 244 is in close contact with the motor housing 42 at a contact area 246 extending along a closed line surrounding the wire 50, whereby the sealing member 240 is hermetically attached to the motor housing 42. ing.

Specifically, in the present embodiment, the first
The portion 242 is made of metal, and is formed by adding a flange portion 252 to one end of a generally cylindrical tubular portion 250. Also, the first portion 242 is
It is located outside portion 244 and substantially hermetically contacts second portion 244 on the inner peripheral surface of tubular portion 250 thereof. Further, the first portion 242 is substantially airtightly bonded to the second portion 244 by an adhesive. On the other hand, the second portion 224 is formed of a rubber-like elastic material, and is formed by adding a flange portion 256 to an axially intermediate portion of a generally cylindrical tubular portion 254. A stepped hole 258 is formed in the motor housing 42 as a hole through which the wire 50 passes, and an end surface 260 at one end of the cylindrical portion 254 substantially substantially airtightly contacts a shoulder surface 262 of the stepped hole 258. Have been allowed. That is, the second portion 24
4 and the motor housing 42 are airtight
This is realized by the joint of the shoulder surface 262 and the zero. Also, the second portion 224 has a flange portion 256 thereof.
, The flange portion 252 of the first portion 242 is brought into contact with the flange portion 252, whereby the accuracy of the mounting position of the second portion 224 on the motor housing 42 is improved.
Airtightness between the portion 224 and the motor housing 42 is ensured. Further, the second portion 244 is connected to the motor housing 42.
From the vehicle to the floor panel of the vehicle,
It is placed in an environment where oil and dust can adhere. Also,
Both the first part 242 and the second part 244 are placed in an environment that is vibrated when the vehicle is running.

As is clear from the above description, in the present embodiment, the motor housing 4 of the seal member 240
The rigid attachment and the airtight attachment to 2 are realized by two parts having different mechanical properties from each other.
Therefore, the seal member 240 is more firmly and more airtightly attached to the motor housing 42 as compared with the case where the seal member 240 is integrally formed of an elastic material. As a result, waterproofness, oil resistance, dust resistance, and vibration resistance are achieved. Etc. are improved.

Although some of the embodiments of the present invention have been described in detail with reference to the drawings, other various modifications may be made based on the knowledge of those skilled in the art without departing from the scope of the claims. It is possible to implement the present invention in an improved form.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an electric brake device including an electric brake according to a first embodiment of the present invention.

FIG. 2 is a partial sectional side view showing the electric brake.

FIG. 3 is a front sectional view showing a selector in FIG. 2 taken out and enlarged.

FIG. 4 is a flowchart illustrating a brake control routine executed by a computer in FIG. 1;

FIG. 5 is a flowchart showing a solenoid control routine executed by the computer.

FIG. 6 is a partial sectional side view showing an electric brake according to a second embodiment of the present invention.

FIG. 7 is a front sectional view showing the selector in FIG. 6;

FIG. 8 is a solenoid control routine executed by a computer of a controller of the electric brake device including the electric brake according to the second embodiment.

FIG. 9 is a partial sectional side view showing an electric brake according to a third embodiment of the present invention.

FIG. 10 is a partial sectional side view showing a force transmission device in an electric brake according to a fourth embodiment of the present invention.

FIG. 11 is a front sectional view showing a main part of the force transmission device.

FIG. 12 is a front sectional view showing a wire take-out portion of a motor in an electric brake according to a fifth embodiment of the present invention.

[Explanation of symbols]

 10,178,198 Electric brake 12 Disc 20 Friction pad 40 Motor 64 Pressure shaft 80 Planetary roller screw 82 Nut 88 Screw shaft 96 Ball screw 98 Nut 100 Screw shaft 110,180,200 Selector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J058 AA43 AA48 AA53 AA63 AA69 AA73 AA78 AA87 BA16 CC13 CC15 CC22 CC63 CC77 DA03 DA38 DB23 FA01 FA11 FA21

Claims (8)

[Claims] A rotating body that rotates together with a wheel; a friction material pressed against the rotating body to suppress rotation of the wheel; a motor; and the rotation of the motor transfers the friction material to the rotating body. A friction material driving device for moving toward and away from the friction material; and selectively moving the friction material in a pressing force decreasing direction in which a pressing force of the friction material pressed against the rotating body is reduced without rotation of the motor. An electric brake including a selective permitting device that permits. 2. A linear motion in which the friction material driving device is (a) rotated by the motor and (b) linearly moved to move the friction material closer to or away from the rotating body. Member, and (c) a motion conversion mechanism that converts the rotation of the rotating member into a linear motion of the linear motion member, and wherein the selective permitting device is provided between the linear motion member and the friction material. 2. The force transmission device according to claim 1, further comprising a force transmission device for transmitting a force, wherein the force transmission device switches between a state in which the relative movement of the linear motion member and the friction member in the direction of decreasing the pressing force is prevented and an allowable state. Electric brake. 3. The force transmitting device: (a) transmits force between the linear motion member and the friction material;
A force transmission member that is rotatably engaged with any of the linear motion member and the friction material, and is rotated in one direction by a force acting from the friction material,
(B) a state switching device that switches between a state in which rotation of the force transmitting member is permitted and a state in which the rotation of the force transmitting member is blocked, without being moved together with the friction material without linear movement of the linear movement member; The electric brake according to claim 2. 4. A plane perpendicular to an axis of at least one of the force transmission member and the linear motion member, wherein the force transmission device is a slope formed on at least one of the force transmission member and the linear motion member. 4. The electric brake according to claim 3, wherein the electric brake is configured to convert the one-way rotation of the force transmitting member into a movement of the force transmitting member in the direction of decreasing the pressing force by the slope. 5. The electric brake according to claim 3, wherein the force transmitting device includes a first screw mechanism in which the linear motion member and the force transmitting member are screwed. 6. The motion conversion mechanism includes a second screw mechanism in which the rotating member and the linear motion member are screwed together, wherein the second screw mechanism has a lower screw reverse efficiency than the first screw mechanism. The electric brake according to 1. 7. The electric brake according to claim 5, wherein the first screw mechanism is configured such that the force transmitting member is coaxially screwed into a hollow portion formed in the linear motion member. 8. The state switching device comprising: (a) a moving member that is moved to a rotation permitting position for permitting rotation of the force transmitting member and a rotation preventing position for blocking the force transmitting member; and (b) an electromagnetic force. The electric brake according to any one of claims 3 to 7, further comprising a moving member driving device that drives the moving member to be selectively moved to a rotation permitting position and a rotation preventing position.