JPH11257389A - Motor-operated brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the initial responsiveness and the like of a motor-operated brake device by eliminating its axial backlashes with a ball screw mechanism, and reduce the size of the device by rendering its overall outside diameter small. SOLUTION: A caliper 3 is integrally provided on its side of an inner leg 5 with a motor case 4, in which an electric motor 9 is stored with its rotor 11 integrated with a nut cylinder 16 in a ball screw mechanism 14. The ball screw mechanism 14 is constituted of the nut cylinder 16 formed in its internal surface with a tapped hole 16A, a screw shaft 18 formed in its external surface with a spiral groove 18A, and a plurality of balls 17 interposed for rolling motion between the tapped hole 16A of the nut cylinder 16 and the spiral groove 18A of the screw shaft 18 to hold the screw shaft 18 screwed tight with the tapped hole 16A of the nut cylinder 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric brake device preferably used for applying a braking force to a vehicle or the like, and more particularly to an electric brake device for generating a braking force by an electric motor. .

[0002]

2. Description of the Related Art In general, an electric motor is provided in a brake housing, and a rotational output (torque) of the electric motor is converted into a pressing force in an axial direction to control a rotating disk of a vehicle or the like via a friction pad or the like. An electric brake device configured to apply power is known, for example, from WO96 / 03301.

[0003] In this type of conventional electric brake device, a stator of an electric motor is fixedly provided in a brake housing, and a rotor located radially inside the stator is rotatable in the brake housing. At the same time, the rotor is provided with a pressing force generating means such as a precision roller screw.

In a conventional electric brake device, when a driver of a vehicle depresses a brake pedal, the electric motor is rotated at a rotation angle or a rotation torque corresponding to the operation amount at this time. The pressing force generating means converts the rotation of the electric motor into axial displacement of the piston, and applies a braking force to the vehicle via the disc by pressing the friction pad toward the surface of the disc with the piston. I have to.

[0005]

By the way, the prior art described above employs a precision roller screw as the pressing force generating means, and converts the rotation of the electric motor into the axial displacement of the piston by the precision roller screw. Therefore, the precision roller screw tends to increase the overall outer diameter, and there is a problem that it is difficult to reduce the size of the electric brake device.

Further, since the precision roller screw is engaged at a plurality of places, the backlash in the axial direction is liable to be generated, not only the initial response at the time of a brake operation or the like is deteriorated, but also the precision roller of the circulating type. When a screw is used, there is a problem that the operating noise is increased.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can improve initial response and the like by eliminating backlash in the axial direction, and reduce the overall outer diameter to reduce the size. It is an object of the present invention to provide an electric brake device which can be designed.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a brake housing, an electric motor provided in the brake housing, and conversion of rotation of the electric motor into axial displacement of a piston. The present invention is applied to an electric brake device comprising a pressing force generating means for generating an axial pressing force on the piston, and a friction pad which is pressed toward the disk by the piston and applies a braking force to the disk.

The present invention is characterized in that the pressing force generating means includes a nut cylinder rotatably provided in the brake housing and having a threaded hole on an inner peripheral side; And a screw shaft that is screwed into the screw hole through a plurality of balls and is axially displaced together with the piston by rotation of the nut tube. The electric motor is provided in the brake housing. And a rotor positioned radially inward of the stator and integrated with the nut cylinder of the ball screw mechanism.

With the above configuration, when power is supplied to the electric motor at the time of a brake operation or the like and the rotor is driven, the nut cylinder of the ball screw mechanism rotates and the screw shaft is displaced in the axial direction. Axial pressing force can be generated,
The piston can apply a braking force to the disk via the friction pad.

According to the second aspect of the present invention, the ball shaft of the ball screw mechanism is provided with a spherical portion at a contact portion with the piston to allow the piston to tilt with respect to the screw shaft.

Thus, even if the friction pad is tilted by the reaction force from the disk when the friction pad is pressed against the disk, the spherical portion provided on the tip side of the screw shaft allows the piston to tilt, and the piston is tilted. The behavior of the friction pad can be followed. The spherical portion transmits the pressing force from the screw shaft to the piston, and the piston can press the friction pad against the surface of the disc to apply a braking force.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electric brake device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking an example in which the present invention is applied to a floating caliper type disc brake.

FIG. 1 shows a first embodiment of the present invention. In the drawing, reference numeral 1 denotes a carrier as a mounting bracket provided on a non-rotating portion of a vehicle. It has a pair of arms (not shown) fixed to the outer side via bolts or the like and extending toward the outer side. Each arm of the carrier 1 straddles the outer peripheral side of the disk 2 that rotates integrally with the wheel (not shown) of the vehicle, and slides friction pads 22 described later on both axial sides of the disk 2. It has a configuration to support.

Reference numeral 3 denotes a caliper which constitutes a brake housing which is attached to the carrier 1 so as to be displaceable in the axial direction of the disk 2. The caliper 3 is located on one side (inner side) of the disk 2 and has a step. Inner leg 5 in which cylindrical motor case 4 is integrated, and the other side (outer side) of disk 2
And a bridge portion 7 in which the inner leg portion 5 is integrated with the outer side claw portion 6 over the outer peripheral side of the disc 2.
The motor case 4 of the inner leg portion 5 is provided with a lid 8 for detachably closing one end side.

The inner leg 5 has a substantially stepped cylindrical shape, and has a bearing mounting hole 5A for mounting a bearing 15 described later in a fitted state on the inner peripheral side thereof, and a piston 19 described later.
And a piston accommodating hole 5B for accommodating the motor case 4 displaceably, and the other end of the motor case 4 is fitted in the bearing mounting hole 5A. That is, the motor case 4 is fitted into the bearing mounting hole 5A of the inner leg 5 with the stator 10 of the electric motor 9 described later housed therein, and integrated with the inner leg 5 by means such as a bolt. Have been.

Reference numeral 9 denotes an electric motor provided in the motor case 4 of the inner leg portion 5. The electric motor 9 is configured as a direct-acting motor (DD motor) and is fixed to the inner wall side of the motor case 4. The stator 10 includes windings and the like, and a rotor 11 provided radially inside the stator 10. The rotor 11 of the electric motor 9 includes a nut tube 16 described later and a magnet 13 fixed together with a yoke 12 on the outer peripheral side of the nut tube 16. Reference numeral 11 denotes a rotary drive in the motor case 4.

That is, when the driver of the vehicle depresses a brake pedal (not shown), a signal corresponding to the operation amount (for example, brake pedal depression force, brake pedal stroke) at this time is transmitted to a brake control controller (not shown). The controller side outputs the electric motor 9 with a rotation angle or a rotation torque corresponding to the operation amount.
The control signal is output so as to rotate the motor, and power is supplied to the winding side of the stator 10. And the stator 10 of the electric motor 9
Is to rotate the rotor 11 by power supply from the controller and to displace the piston 19 in the axial direction of the disk 2.

Reference numeral 14 denotes the inner leg 5 together with the electric motor 9.
The ball screw mechanism 14 is provided in the (motor case 4) as a pressing force generating means. The ball screw mechanism 14 is rotatably provided in the inner leg portion 5 via a bearing 15, and is spirally formed on the inner peripheral side. A stepped cylindrical nut cylinder 16 having a threaded hole 16A formed therein, and a cylindrical screw screwed into the threaded hole 16A of the nut cylinder 16 via a plurality of balls 17, 17,. And a shaft 18.

Here, the nut cylinder 16 forms a part of the rotor 11, and one end thereof extends in the motor case 4 in the axial direction to a position close to the lid 8. Also, nut tube 1
An annular flange 16B is provided on the other end side of the stator 6 so as to protrude radially outward and has a diameter larger than the inner diameter of the stator 10. An inner leg 5 is provided on the outer peripheral side of the flange 16B. The bearing 15 is disposed between the bearing 15 and the bearing mounting hole 5A. And
A circulation path (not shown) for each ball 17 is formed in the nut cylinder 16.
Passes through the circulation path and the screw hole 16A and the spiral groove 1 described later.
8A.

On the other hand, the outer peripheral surface of the screw shaft 18 has a screw hole 16.
A spiral groove 18A having a certain lead angle corresponding to A
Are formed, and each ball 17 is rotatably accommodated between the spiral groove 18A and the screw hole 16A of the nut cylinder 16 in a state where a pressure is applied. And the ball screw mechanism 1
4 converts the rotation of the nut cylinder 16 into the axial displacement of the screw shaft 18 in a state where the rotation of the nut cylinder 16 is decelerated when the electric motor 9 rotates the nut cylinder 16. 18 generates a large axial driving force.

When the driving force in the axial direction of the screw shaft 18 is to be further increased, the lead angle of the spiral groove 18A or the like may be reduced, whereby the rotational load (torque) of the electric motor 9 is further reduced. It becomes possible.

Reference numeral 19 denotes a piston receiving hole 5B of the inner leg portion 5.
The piston 19 follows the axial displacement of the screw shaft 18, and moves from the piston receiving hole 5 </ b> B of the inner leg 5 to the disk 2.
It is configured to move forward and backward. Then, the piston 19 is driven by the electric motor 9 via the screw shaft 18 of the ball screw mechanism 14, and the friction pad 22 is
Is displaced in the axial direction so as to be pressed.

Also, the piston receiving hole 5B of the inner leg 5
A boot 20 made of an elastic material
The boot 20 is configured to protect the electric motor 9 and the ball screw mechanism 14 in the inner leg 5 from external dust and the like. Further, a detent 21 is provided between the piston 19 and an inner friction pad 22 which will be described later. The detent 21 follows the nut cylinder 16 and restricts the screw shaft 18 from rotating together with the piston 19. Things.

Reference numerals 22 and 22 denote a pair of friction pads provided on both sides of the disk 2, each of which is slidably supported by the carrier 1 via a pad spring (not shown) or the like. Of the friction pads 22, the inner friction pad 22 is pressed by the piston 19 toward one side surface of the disk 2.

The outer friction pad 22 is displaced axially with respect to the carrier 1 by the pressing reaction force at this time, so that the claw 6 of the caliper 3 is displaced.
At the same time, the disk 2 is pressed toward the other side surface. Each friction pad 22 applies a braking force to the rotating disk 2 by strongly holding the disk 2 from both sides.

Reference numerals 23 and 24 denote stoppers mounted on both ends of the screw shaft 18 in the axial direction. The stoppers 23 and 24 are formed of retaining rings or the like, and are located at the maximum stroke positions of the screw shaft 18 in the screw holes 16A of the nut cylinder 16. Is regulated.

Further, reference numeral 25 denotes a rotational position detector provided between the motor case 4 and the nut tube 16 at a position close to the lid 8. The rotational position detector 25 rotates the nut tube 16 with respect to the motor case 4. The position is detected, and the detection signal is output to a brake control controller.

The disk brake according to the present embodiment has the above-described configuration, and its operation will be described below.

First, when the driver of the vehicle depresses the brake pedal, the operation amount of the brake pedal (for example, the brake pedal) is detected by a brake pedal operation amount detection sensor (not shown) provided near the brake pedal. A detection signal corresponding to the pedaling force and the brake pedal stroke is output to the controller. Then, the controller outputs a control signal to the electric motor 9 in accordance with the operation amount, and rotates the rotor 11 of the electric motor 9 with a rotation angle or a rotation torque corresponding to the operation amount.

The nut cylinder 16 of the ball screw mechanism 14, which forms a part of the rotor 11, rotates its rotation to a screw hole 16A.
Is transmitted to a screw shaft 18 via each ball 17 in the nut, and the screw shaft 18 converts the rotational force at this time as an axial driving force while allowing the nut cylinder 16 to rotate along the spiral groove 18A. By doing so, it is displaced with a large driving force in the axial direction toward the disk 2 side.

As a result, the screw shaft 18 can strongly press the piston 19 together with the inner friction pad 22 toward the disk 2, so that a braking force can be reliably applied to, for example, a running vehicle via the disk 2. .

Next, when the depression operation of the brake pedal is released in this state, the rotor 11 of the electric motor 9 is reversely rotated by the signal from the operation amount detection sensor, and the screw shaft 18 is rotated by the reverse rotation of the nut cylinder 16. Is displaced in the opposite direction to that during the brake operation, and the piston 19 is
At the same time, it can be driven in the direction of retreating from the disk 2, and the pressing force of the friction pad 22 on the disk 2 can be automatically released.

The nut cylinder 16 of the ball screw mechanism 14
And the screw shaft 18 are reversibly screwed through each ball 17 in the screw hole 16A and the spiral groove 18A of the screw shaft 18, so that, for example, when the brake operation is released or when the thickness of the disk 2 fluctuates. When a reaction force is generated in the piston 19 due to, for example, the screw shaft 18, the nut cylinder 16 can be forcibly rotated in the reverse direction in accordance with the reaction force from the piston 19 side, whereby the friction pad 22 is quickly retracted from the disk 2. Therefore, it is possible to avoid the occurrence of dragging of the wheels.

Thus, according to the present embodiment, the motor case 4 is integrally provided on the inner leg 5 side of the caliper 3,
While accommodating the electric motor 9 in the motor case 4,
Since the rotor 11 of the electric motor 9 is integrated with the nut cylinder 16 of the ball screw mechanism 14, the electric motor 9 and the ball screw mechanism 14 are placed in the inner leg 5 (motor case 4) of the caliper 3. It can be housed compactly, and the whole device can be downsized.

The rotation of the electric motor 9 is controlled by the piston 19.
The ball screw mechanism 14 that converts the axial displacement of the screw groove 16 into a helical groove 1 with a lead angle corresponding to the screw hole 16A on the outer peripheral surface side and a nut cylinder 16 having a screw hole 16A formed on the inner peripheral side.
The screw shaft 18 having the screw shaft 8A formed therein and the screw shaft 18A of the screw shaft 18 and the screw hole 16A of the nut tube 16 are rotatably mounted between the screw groove 16A and the screw hole 16A of the nut tube 16. A plurality of balls 17, 1 for holding the shaft 18 in a screwed state
.., The following operational effects can be obtained.

That is, each ball 17 inserted between the screw hole 16A of the nut cylinder 16 and the spiral groove 18A of the screw shaft 18
By adjusting the preload, the axial gap between them can be made substantially zero, and the meshing can be made at one point to eliminate the backlash in the axial direction. by this,
The initial responsiveness at the time of a brake operation or the like can be improved, and the generation of operation noise or the like can be reliably reduced.

Further, by employing the ball screw mechanism 14, the outer diameter can be reduced as compared with the prior art using, for example, a precision roller screw, and the electric motor 9 can be used.
Can be efficiently converted to axial displacement of the piston 19, the output of the electric motor 9 can be reduced, and power consumption and the like can be reduced.

The ball screw mechanism 14 is a nut cylinder 1
6. Since it can be manufactured with a simple structure from the three members of each ball 17 and the screw shaft 18, it is possible to reduce the weight as compared with, for example, a precision roller screw or the like, and to reduce the inertial force during operation. Responsiveness can be improved.

Therefore, according to the present embodiment, by providing the ball screw mechanism 14 on the rotor 11 side of the electric motor 9, the initial response can be improved by eliminating the backlash in the axial direction, and the friction pad 22 can be mounted on the disk. 2 can be pressed early, and the friction pad 22 can be returned early even when the brake operation is released, so that responsiveness can be improved and operability and safety can be greatly improved. Then, the outer diameter of the motor case 4 and the like can be reduced, and the size of the entire apparatus can be reduced.

When the brake operation is released or when the disc 2
When a reaction force is generated in the piston 19 due to a change in wall thickness of the piston 19, the screw shaft 18 is quickly retracted in accordance with the reaction force from the piston 19 due to the reversibility of the ball screw mechanism 14, and the nut cylinder 16 is turned in the opposite direction. Forced rotation can be performed, whereby the friction pad 22 is immediately retracted from the disk 2, and the occurrence of dragging of the wheels and the like can be favorably prevented.

Next, FIG. 2 shows a second embodiment of the present invention. The feature of this embodiment is that a sphere is provided between the distal end side of the screw shaft and the piston so that the piston can be mounted on the screw shaft. The piston is allowed to swing or tilt with respect to the piston, and the piston follows the behavior of the friction pad. Note that, in the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 31 denotes a cover covering one end of the motor case 4. The cover 31 is substantially the same as the cover 8 described in the first embodiment. A projecting shaft 31A is integrally provided on the center side of the lid 31. The projecting shaft 31A is spline-engaged with a screw shaft 35 described later, thereby holding the screw shaft 35 in a detented state.

Reference numeral 32 denotes the inner leg 5 together with the electric motor 9.
A ball screw mechanism as a pressing force generating means provided in the (motor case 4). The ball screw mechanism 32 is substantially the same as the ball screw mechanism 14 described in the first embodiment, and the inner leg 5 A stepped cylindrical nut cylinder 33 having a screw hole 33A and a flange 33B formed therein so as to be rotatable via a bearing 15 therein, and a plurality of balls 34, 34 in the screw hole 33A of the nut cylinder 33. ,... And a cylindrical screw shaft 35 formed with a spiral groove 35A.

However, in the ball screw mechanism 32 employed in this embodiment, a spline groove 35B is formed on the inner circumference of one end of the screw shaft 35, and the spline groove 35B is provided with a lid 31.
Is spline-engaged. A recess 35C is formed on the other end side of the screw shaft 35 opposite to a piston 36 described later, and a spherical body 37 described later is rollably accommodated in the recess 35C.

Reference numeral 36 denotes a piston provided on the other end (tip) side of the screw shaft 35 via a sphere 37.
6 is substantially the same as the piston 19 described in the first embodiment, but the piston 36 has a spherical body 37.
Is provided with a concave portion 36A for accommodating the same. The concave portion 36A is formed to have a concave curvature with a curvature slightly larger than the spherical body 37.

Reference numeral 37 denotes a sphere as a spherical portion provided on the side of the screw shaft 35 in contact with the piston 36. The sphere 37 is formed of a steel ball or the like, and the recesses 35C and 35C between the screw shaft 35 and the piston 36 are provided. Rollably mounted in 36A. The sphere 37 transmits the pressing force from the screw shaft 35 to the piston 36, and the piston 36
2 is pressed against the surface of the disk 2.

The sphere 37 has a piston 36 on which the screw shaft 3 is mounted.
5 can be tilted or oscillatingly displaced. For example, even if the friction pad 22 is pressed against the disc 2 and the inner friction pad 22 is tilted by the reaction force from the disc 2, the piston 36 follows the behavior of the friction pad 22.

Thus, in the present embodiment configured as described above, substantially the same operation and effects as those of the first embodiment can be obtained. Even if the friction pad 22 on the inner side is inclined by the reaction force from the disc 2 due to the spherical body 37 provided on the
The piston 36 can follow the behavior of the friction pad 22, and the moment and the like from the friction pad 22
5 can be prevented from being added.

As a result, it is possible to cancel the moment or bending load from the friction pad 22 acting on the ball screw mechanism 32, and it is possible to extend the durability and life of the ball screw mechanism 32. When the screw shaft 35 of the ball screw mechanism 32 is driven in the axial direction by the electric motor 9, the pressing force from the screw shaft 35 can be reliably transmitted to the piston 36 via the sphere 37, and the friction pad 22 can be pressed against the surface of the disk 2 to apply a braking force.

Next, FIG. 3 shows a third embodiment of the present invention. The feature of this embodiment is that the spherical portion is integrally formed on the tip end side of the screw shaft so that the piston can be moved with respect to the screw shaft. This configuration allows the piston to follow the behavior of the friction pad. Note that, in the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 41 denotes a cover covering one end of the motor case 4. The cover 41 has substantially the same structure as the cover 8 described in the first embodiment. At the center side of the lid 41, a cylindrical projection 41A is integrally provided. The cylindrical protrusion 41A is connected to a screw shaft 45 described later.
, The screw shaft 45 is held in a detented state.

Reference numeral 42 denotes the inner leg 5 together with the electric motor 9.
A ball screw mechanism as a pressing force generating means provided in the (motor case 4). The ball screw mechanism 42 is substantially the same as the ball screw mechanism 14 described in the first embodiment, and the inner leg 5 And a stepped cylindrical nut cylinder 43 having a screw hole 43A and a flange 43B formed therein, and a plurality of balls 44, 44 in the screw hole 43A of the nut cylinder 43. , And a cylindrical screw shaft 45 in which a spiral groove 45A is formed.

However, the ball screw mechanism 42 employed in the present embodiment has a spline 4
5B is formed, and the spline 45B is spline-engaged with the cylindrical projection 41A of the lid 41. A hemispherical spherical portion 45C is formed on the other end of the screw shaft 45. The spherical portion 45C is formed in a concave portion 46 of a piston 46 described later.
A, and is configured to allow swing displacement (tilt) of the piston 46.

Reference numeral 46 denotes a piston swingably provided on the other end (tip) side of the screw shaft 45. Although the piston 46 is configured substantially similarly to the piston 19 described in the first embodiment, The piston 46 has a truncated conical recess 46A for accommodating the spherical portion 45C of the screw shaft 45. The piston 46 receives the pressing force from the screw shaft 45 via the spherical portion 45C and the concave portion 46A, thereby pressing the friction pad 22 against the surface of the disk 2.

Further, the spherical portion 45C is swingably inserted into the concave portion 46A of the piston 46, thereby allowing the piston 46 to be inclined with respect to the screw shaft 45 or to be displaced by swinging. For example, even when the friction pad 22 is pressed against the disk 2 and the inner friction pad 22 is tilted by the reaction force from the disk 2, the piston 46 can follow the behavior of the friction pad 22.

Thus, also in the present embodiment configured as described above, it is possible to prevent the moment and the like from the friction pad 22 from being applied to the screw shaft 45, and to obtain substantially the same operation and effect as in the second embodiment. Can be obtained. Further, in the present embodiment, the spherical portion 45C is integrally formed on the tip end side of the screw shaft 45, and the piston 46 is provided with the truncated conical recess 46A, so that the piston 46 is used in the second embodiment. The spherical body 37 can be eliminated, the number of parts can be reduced, and the processing of the recess 46A and the like can be simplified, and the productivity can be increased.

Next, FIG. 4 shows a fourth embodiment of the present invention. The feature of this embodiment is that a rotation position detector for detecting a rotation position of a nut cylinder is disposed at a position close to a piston. It is in the configuration. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals,
The description is omitted.

In the figure, reference numeral 51 denotes a caliper which constitutes a brake housing which is attached to the carrier 1 so as to be displaceable in the axial direction of the disk 2. The caliper 51 is the same as the caliper 3 described in the first embodiment. In substantially the same manner, an inner leg 53 in which a stepped cylindrical motor case 52 is integrated, a claw portion 54 on the outer side, and a bridge portion 55 for integrating the inner leg 53 with the claw portion 54 on the outer side. It is composed of

However, in the present embodiment, the motor case 52, which is a part of the inner leg 53, is formed in a cylindrical shape with a lid, and the motor case 52 is integrally provided with a lid 52A at one end. I have. Then, the motor case 52 is fitted in the bearing mounting hole 53A of the inner leg 53 with the stator 10 of the electric motor 9 housed therein, and is integrated with the inner leg 53 by means such as a bolt. Things. Also,
A detector mounting portion 53C is formed integrally with the inner leg portion 53 on the side of the piston housing hole 53B.

Reference numeral 56 denotes an inner leg 53 together with the electric motor 9.
A ball screw mechanism as a pressing force generating means provided in the (motor case 52). The ball screw mechanism 56 has an inner leg 53 similar to the ball screw mechanism 14 described in the first embodiment. A stepped cylindrical nut cylinder 57 having a screw hole 57A and a flange 57B formed therein so as to be rotatable via a bearing 15 therein; and a screw hole 57 of the nut cylinder 57.
A is screwed through a plurality of balls 58, 58,.
And a cylindrical screw shaft 59 in which a spiral groove 59A is formed.

However, in the ball screw mechanism 56 employed in the present embodiment, a rotational position detector (described later) is positioned between the flange 57B of the nut cylinder 57 and the detector mounting portion 53C of the inner leg 53. 60 are provided.

Reference numeral 60 denotes a position near the piston 19 and a detector mounting portion 53C of the inner leg 53 and a flange 57 of the nut cylinder 57.
B, the rotational position detector 60 detects the rotational position of the nut cylinder 57 with respect to the inner leg 53, and outputs a detection signal to a brake control controller. is there.

Thus, in the present embodiment having the above-described structure, substantially the same operation and effect as those in the first embodiment can be obtained. By integrally forming 52A, it is possible to reduce the number of parts and improve the workability during assembly.

In each of the above embodiments, the case where the stator 10 of the electric motor 9 is constituted by windings and the like and the magnet 13 is provided on the rotor 11 side has been described as an example.
The present invention is not limited to this. For example, a configuration may be adopted in which a magnet is provided on the stator side of the electric motor and a winding is provided on the rotor side. In this case, the ball screw mechanism 14 (32, 4)
A winding may be provided on the side of the nut tube 16 (33, 43, 57) of (2, 56) to constitute a rotor.

In each of the above embodiments, the case where the electric brake device is applied to a floating caliper type disk brake has been described as an example. However, the present invention is not limited to this, and for example, an opposed piston type disk brake may be used. The present invention may be applied to a brake, or may be applied to other electric brake devices.

[0067]

As described in detail above, according to the first aspect of the present invention, a ball screw mechanism is employed as the pressing force generating means, and a plurality of screw holes are provided in the screw holes of the nut cylinder rotatably provided in the brake housing. The screw shaft is screwed through the ball of the nut, the screw shaft is displaced in the axial direction together with the piston by the rotation of the nut cylinder, and the stator of the electric motor is provided in the brake housing, and is disposed radially inside the stator. Since the rotor to be installed is integrated with the nut cylinder of the ball screw mechanism, the outer diameter can be reduced as compared with the conventional technology using, for example, a precision roller screw, and the size of the entire apparatus can be reduced. At the same time, the rotation of the electric motor can be efficiently converted into the axial displacement of the piston, so that the output of the electric motor can be reduced and the power consumption and the like can be reduced. In addition, the weight can be reduced by the ball screw mechanism, the inertial force during operation can be reduced, and the initial response can be improved by eliminating the backlash in the axial direction, improving the operability and safety as a brake device be able to.

Further, in the invention according to the second aspect, since the spherical portion is provided at the contact portion between the screw shaft of the ball screw mechanism and the piston, the friction pad is attached to the screw shaft by a reaction force from the disk or the like. Even when the piston is inclined, the piston can follow the behavior of the friction pad, and the addition of a moment or the like to the screw shaft can be canceled.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a disc brake according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a disc brake according to a second embodiment.

FIG. 3 is a longitudinal sectional view showing a disc brake according to a third embodiment.

FIG. 4 is a longitudinal sectional view showing a disc brake according to a fourth embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Carrier (mounting bracket) 2 Disk 3,51 Caliper (brake housing) 5,53 Inner leg 9 Electric motor 10 Stator 11 Rotor 14,32,42,56 Ball screw mechanism (pressing force generating means) 16,33 , 43, 57 Nut cylinder 16A, 33A, 43A, 57A Screw hole 17, 34, 44, 58 Ball 18, 35, 45, 59 Screw shaft 18A, 35A, 45A, 59A Helical groove 19, 36, 46 Piston 22 Friction Pad 25, 60 Rotational position detector 37 Spherical part (spherical part) 45C Spherical part

Claims (2)

[Claims] 1. A brake housing, an electric motor provided in the brake housing, and pressing force generating means for converting rotation of the electric motor into axial displacement of a piston to generate an axial pressing force on the piston. A friction pad that is pressed toward a disk by the piston to apply a braking force to the disk, wherein the pressing force generating means is rotatably provided in the brake housing and has an inner peripheral side threaded. With a nut tube that became a hole,
A screw shaft which is screwed into a screw hole of the nut cylinder via a plurality of balls, and is displaced in the axial direction together with the piston by rotation of the nut cylinder. An electric brake device comprising: a stator provided inside the stator; and a rotor positioned radially inside the stator and integrated with a nut cylinder of the ball screw mechanism. 2. The electric brake according to claim 1, wherein the screw shaft of the ball screw mechanism is provided with a spherical portion at a contact portion with the piston to allow the piston to tilt with respect to the screw shaft. apparatus.