JP3915068B2 - Electric disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric disk brake with a speed reducing mechanism which can easily obtain a large reduction ratio and can obtain sufficient strength. <P>SOLUTION: Rotational speed of a rotor 17 of an electric motor 9 is reduced by a differential speed reducing mechanism 10 to drive a ball ramp mechanism 12. Braking force is generated by pushing brake pads 5, 6 against a disk rotor 2. In the differential speed reducing mechanism 10, when an eccentric shaft 20 of a rotor 17 eccentrically rotates, an external gear member 21 carries out revolution and rotation by engagement of the input side external teeth 23 of the external gear member 21 with a fixed ring gear 25. At the same time, the output side external teeth 24 carries out revolution and rotation. Accordingly, a ring gear 28 integrated with the rotary disk 27 of the ball ramp mechanism 12 is driven. A large reduction ratio can be easily obtained by this configuration. Further, since the differential speed reducing mechanism 10 is a gear mechanism, it can easily be machined and can have sufficient strength. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial application fields]
The present invention relates to an electric disc brake that generates a braking force by converting a rotary motion of an electric motor into a linear motion and pressing a brake pad against a disc rotor.
[0002]
[Prior art]
Conventionally, the rotational motion of the rotor of the electric motor is converted into the linear motion of the piston using a rotation-linear motion conversion mechanism such as a ball screw mechanism or a ball ramp mechanism, and the brake pad is pressed against the disc rotor by the piston. There is known an electric disk brake device that generates power. The electric disc brake can detect a driver's brake pedal depression force (or displacement amount) with a sensor and a controller can control the rotation of the electric motor based on the detected value to obtain a desired braking force. .
[0003]
By the way, various electric disc brakes have been proposed in which a speed reduction mechanism is provided between the electric motor and the rotation-linear motion conversion mechanism in order to amplify the torque of the motor. For example, Japanese Patent Application Laid-Open No. 2001-263395 describes an electric disc brake including a differential reduction mechanism in which a planetary gear and an Oldham mechanism are combined as a reduction mechanism.
[0004]
In this electric disc brake, the differential reduction mechanism is configured such that an eccentric plate is rotatably attached to an eccentric shaft attached to a rotor of a motor, a fixed pin is inserted into a hole of the eccentric plate, and external teeth of the eccentric plate are inserted into a ball lamp. It is structured to mesh with the internal teeth of the rotating disk of the mechanism. With this structure, when the eccentric shaft is rotated, the eccentric plate revolves without rotating, and the rotating disk of the ball ramp mechanism can be driven at a predetermined reduction ratio.
[0005]
In addition, the above publication describes a differential reduction mechanism that exhibits the same operations and effects as described above by combining a cycloid ball mechanism and an Oldham mechanism using an annular hole and a ball.
[0006]
[Problems to be solved by the invention]
However, the electric disk brake described in the above publication has the following problems. Since the eccentric plate and the pin constituting the Oldham mechanism require high processing accuracy, the manufacturing cost is high. Furthermore, in order to withstand a high load during braking, a high strength is required, but it is difficult to increase the strength because of the structure.
[0007]
In addition, the combination of the cycloid ball mechanism and the Oldham mechanism requires a high machining accuracy as described above, and in particular, the requirement for the dimensional accuracy in the axial direction is severe, which is a problem in practical use.
[0008]
The present invention has been made in view of the above points, and an object of the present invention is to provide an electric disc brake including a speed reduction mechanism capable of obtaining a desired speed reduction ratio and sufficient strength with a simple structure. .
[0009]
[Means for Solving the Problems]
In order to solve the above problems, an invention according to claim 1 includes an electric motor, a speed reduction mechanism that decelerates rotation of a rotor of the electric motor, and a conversion mechanism that converts rotation of the speed reduction mechanism into linear motion. An electric disc brake that generates a braking force by pressing a brake pad against the disc rotor by the conversion mechanism, and the speed reduction mechanism is rotatable to the eccentric shaft and a hollow eccentric shaft connected to the rotor of the motor An external gear member having input-side external teeth and output-side external teeth that rotate integrally with each other, a fixed ring gear having internal teeth that mesh with the input-side external teeth, and meshing with the output-side external teeth, A ring gear for driving the conversion mechanism, and an extension portion of the hollow portion of the eccentric shaft that is eccentric with respect to the shaft of the rotor is integrally provided between the rotor and the eccentric shaft. It is characterized by that.
With this configuration, when the eccentric shaft rotates eccentrically, the input-side external teeth that engage with the fixed ring gear, that is, the external gear member, rotate and revolve, and the rotation and revolution cause the output-side external teeth to drive the ring gear. A differential is generated between the rotor and the ring gear to obtain a predetermined reduction ratio, and the extension portion is eccentric with respect to the axis of the rotor, so that the rotation balance of the rotor can be achieved.
The electric disc brake according to a second aspect of the invention is characterized in that, in the configuration of the first aspect, the number of teeth of the input side external teeth and the number of teeth of the fixed ring gear are equal.
With this configuration, the input side external teeth and the fixed ring gear operate as an Oldham mechanism, and the external gear member revolves without rotating.
The electric disc brake according to a third aspect of the invention is characterized in that, in the configuration of the first aspect, the number of teeth of the input side external teeth is equal to the number of teeth of the output side external gear.
With this configuration, the input side external teeth and the output side external teeth of the external gear member can be simultaneously and integrally processed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 to 5, the electric disc brake 1 has a caliper body 3 disposed on one side (usually inside the vehicle body) of a disc rotor 2 that rotates with wheels (not shown). A claw portion 4 that is formed in a substantially C shape and extends to the opposite side across the disc rotor 2 is integrally coupled to the caliper body 3 by bolts (not shown). Brake pads 5 and 6 are provided on both sides of the disc rotor 2, that is, between the disc rotor 2 and the caliper body 3 and between the tip portions of the claw portions 4, respectively. The brake pads 5 and 6 are supported by the carrier 7 fixed to the vehicle body so as to be movable along the axial direction of the disc rotor 2, and receive the braking torque by the carrier 7. The caliper body 3 Is mounted on the caliper body 3 and is slidably guided along the axial direction of the disk rotor 2 by a slide pin 8 (only the center axis is shown) provided on the carrier 7 so as to be slidable.
[0011]
In the caliper body 3, the electric motor 9, a differential reduction mechanism 10 (deceleration mechanism) that decelerates the rotation of the electric motor 9, and the rotational movement of the electric motor 9 decelerated by the differential reduction mechanism 10 are converted into a linear movement. A ball ramp mechanism 12 (conversion mechanism) that moves the piston 11 that contacts the brake pad 5 forward and backward, and a pad wear compensation mechanism 13 that adjusts the position of the piston 11 according to the wear of the brake pads 5 and 6. It has been.
[0012]
The electric motor 9 includes a stator 14 fixed to the caliper body 3, and a hollow rotor 17 rotatably supported by the caliper body 3 by bearings 15 and 16, and is connected to a controller (see FIG. The rotation position is detected by a resolver 19 attached to the rotor 17 and rotated by a desired angle.
[0013]
Next, the differential reduction mechanism will be described with reference to FIGS.
A hollow eccentric shaft 20 is integrally formed on the rotor 17 of the electric motor 9, and a cylindrical external gear member 21 is rotatably attached to the outer periphery of the eccentric shaft 20 via a bearing 22. Here, the hollow portion of the eccentric shaft 20 has a circular sectional shape that is concentric with the eccentric shaft 20, and the axial depth extends further from the eccentric shaft 20 to the rotor 17 side. The external gear member 21 is formed with input side external teeth 23 and output side external teeth 24 on both sides in the axial direction. A fixed ring gear 25 having internal teeth that mesh with the input side external teeth 23 of the external gear member 21 is fixed to the caliper body 3 by bolts 26. Further, the output side external teeth 24 are meshed with internal teeth of a ring gear 28 formed integrally with the rotary disk 27 of the ball ramp mechanism 12.
[0014]
Here, the number of teeth Z1 of the input side external teeth 23 of the external gear member 21, the number of internal teeth Z2 of the fixed ring gear 25, the number of teeth Z3 of the output side external teeth 24, the number of teeth of the internal teeth Z4 of the ring gear 28, In this embodiment, the number of teeth Z1 of the input side external teeth 23 and the number of teeth Z2 of the fixed ring gear 25 are made equal (Z1 = Z2), and the rotation of the eccentric shaft 20 causes the input side external teeth 23 to rotate without rotating. (In FIG. 7, an example is shown in which the number of teeth Z1 of the input side external teeth 23 and the number of teeth Z2 of the fixed ring gear 25 are different). As a result, the moment of the external gear member 21 can be reduced, and the required torque of the electric motor 9 can be reduced correspondingly, and a small motor can be used.
[0015]
The ball ramp mechanism 12 is opposed to the caliper body 3 by a bearing 29 (axial bearing) rotatably supported by a rotary disk 27 fixed in the axial direction and a linear motion disk 30 supported so as to be movable in the axial direction. In this way, ball grooves 31 and 32 (inclined grooves) are respectively formed, and a ball 33 as a rolling element is inserted between these ball grooves 31 and 32. When the rotating disk 27 rotates, the ball 33 rolls in the inclined ball grooves 31 and 32, so that the linearly moving disk 30 moves in the axial direction according to the rotation angle of the rotating disk 27.
[0016]
The pad wear compensation mechanism 13 is integrally coupled to the rotor 17 of the electric motor 9 and the linear motion disk 30 with a limiter 34 that restricts the relative rotation of the rotor 17 and the linear motion disk 30 to a certain amount, and the cylindrical portion 30a of the limiter 34 and the linear motion disk 30. The spring holder 35 is connected by a coil spring 36 which is elastically coupled. As a result, the rotational force of the rotor 17 is transmitted to the linear motion disk 30, and when the brake pads 5 and 6 are worn and a gap is formed between the piston 11 and the piston 11, the linear motion disk 30 is rotated. The piston 11 is advanced by the adjusting screw 37 between the brake pad 5 and the piston 11 to adjust the wear of the brake pads 5 and 6.
[0017]
Next, the operation of the present embodiment configured as described above will be described.
During braking, the controller detects the brake pedal depression force (or displacement) of the driver with a brake pedal sensor, and based on the detected value, the driver circuit applies a drive voltage to the electric motor 9 of the electric disc brake 1 of each wheel. The rotor 17 is rotated by a predetermined rotation angle with a predetermined torque. The rotation of the rotor 17 is decelerated at a predetermined reduction ratio by the differential reduction mechanism 10 and converted into a linear motion by the ball ramp mechanism 12 to advance the piston 11. One brake pad 5 is pressed against the disk rotor 2 by the piston 11, and the caliper body 3 moves along the slide pin 8 of the carrier 7 by the reaction force, and the claw portion 4 moves the other brake pad 6 to the disk rotor. Press to 2. Accordingly, the driver can adjust the braking force according to the brake pedal depression force. At the time of releasing the brake, the electric motor 9 is rotated in the reverse direction, the piston 11 is moved backward, and the brake pads 5 and 6 are separated from the disc rotor 2 to release the brake.
[0018]
The controller uses various sensors to detect the vehicle state such as the rotational speed of each wheel, vehicle speed, vehicle acceleration, steering angle, vehicle lateral acceleration, etc., and controls the rotation of the electric motor 9 based on these detections. Thus, boost control, anti-lock control, traction control, vehicle stabilization control, and the like can be executed.
[0019]
In the differential reduction mechanism 10, the eccentric shaft 20 rotates the external gear member 21 eccentrically by the rotation of the rotor 17. Since the number of teeth Z1 of the input side external teeth 23 of the external gear member 21 and the number of internal teeth Z2 of the fixed ring gear 25 are equal (Z1 = Z2), these act as an Oldham mechanism, The external gear member 21 revolves without rotating. As a result, the output side external teeth 24 (number of teeth Z3) revolve without rotating, the ring gear 28 (number of teeth Z4) is rotated, and the rotary disk 27 is driven. Here, the hollow portion of the eccentric shaft 20 is extended to the rotor side by a length l, and since this extension portion 17a is eccentric with respect to the shaft of the rotor 17, the diameter φd of the hollow portion of the eccentric shaft 20 is By adjusting, the rotational balance of the rotor 17 can be achieved.
[0020]
At this time, the rotation ratio N1 of the rotating disk 27 to the rotor 17 is N1 = 1−Z3 / Z4.
The reduction ratio α1 of the differential reduction mechanism 10 is α1 = 1 / N1 = 1 / (1-Z3 / Z4). The movement amount X of the linear motion disk 30 with respect to the rotation angle θ of the rotor 17 is X = (L / 360) × (θ / α1), where L is the inclination (lead) of the ball groove of the ball ramp mechanism 12. Become.
[0021]
In this manner, a desired reduction ratio can be obtained depending on the number of teeth of the output side external teeth 24 and the ring gear 28, and a large reduction ratio can be easily obtained. As a result, the electric motor 9 can be reduced in size and power consumption can be reduced, and the electric disc brake 1 can be reduced in size, thereby improving the mountability on the vehicle. The differential reduction mechanism 10 is composed only of a gear mechanism, and does not use the above-described conventional pin, hole, ball, etc., so that the demand for machining accuracy can be eased and the required strength can be achieved. Can be easily obtained. Furthermore, each gear of the differential reduction mechanism 10 can be machined relatively easily by an existing processing machine, so that the manufacturing cost can be reduced. Although Z1 = Z2 is assumed here, the same action and effect can be obtained by configuring so that Z3 = Z4.
[0022]
Next, as a second embodiment of the present invention, in the electric disc brake 1, the number of teeth Z1 of the input side external teeth 23 of the external gear member 21 is made smaller than the number of internal teeth Z2 of the fixed ring gear 25 (Z1 <Z2 The case where the number of teeth Z1 of the input side external teeth 23 and the number of teeth Z3 of the output side external teeth 24 are made equal (Z1 = Z3) and these modules are made equal will be described.
[0023]
In this case, when the eccentric shaft 20 of the rotor 17 rotates eccentrically, the external gear member 21 revolves while rotating. As a result, the output side external teeth 24 (number of teeth Z3) revolve while rotating to rotate the ring gear 28 (number of teeth Z4) and drive the rotary disk 27.
[0024]
At this time, the rotation ratio N2 of the rotating disk 27 to the rotor 17 is N2 = 1− (Z2 / Z1) × (Z3 / Z4) = 1−Z2 / Z4, and the reduction ratio α2 of the differential reduction mechanism 10 is α2 = 1 / N2 = 1 / (1-Z2 / Z4). The movement amount X of the linear motion disk 30 with respect to the rotation angle θ of the rotor 17 is X = (L / 360) × (θ / α2), where L is the inclination (lead) of the ball groove of the ball ramp mechanism 12. Become.
[0025]
Thereby, in addition to the effect of the first embodiment, a larger reduction ratio can be easily obtained. In addition, since the number of teeth and the modules of the input side external teeth 23 and the output side external teeth 24 of the external gear member 21 are equalized, the input side external teeth 23 and the output side external teeth 24 can be simultaneously cut and processed. The manufacturing process can be reduced by simplifying the process.
[0026]
【The invention's effect】
As described above in detail, according to the electric disc brake of the invention of claim 1, the speed reduction mechanism is provided with the eccentric shaft, the external gear member having the input side external teeth and the output side external teeth, the fixed ring gear, and the ring gear. Thus, a differential is generated between the rotor of the motor and the ring gear, and a predetermined reduction ratio can be obtained. As a result, a large reduction ratio can be easily obtained. Further, since the speed reduction mechanism is composed only of a gear mechanism and does not use the pin, hole, ball, or the like of the above-described conventional example, it is possible to ease the demand for processing accuracy and easily obtain the necessary strength. be able to. Furthermore, since each gear of the speed reduction mechanism can be machined relatively easily by an existing processing machine, the manufacturing cost can be reduced. Further, since the extension portion is eccentric with respect to the axis of the rotor, it is possible to balance the rotation of the rotor . According to the electric disc brake of the invention of claim 2, since the number of teeth on the input side external teeth and the number of teeth on the fixed ring gear are equal, the input side external teeth and the fixed ring gear operate as an Oldham mechanism, The gear member revolves without rotating. As a result, the moment of the external gear member can be reduced, and the required torque of the electric motor can be reduced correspondingly, and a small motor can be used. Therefore, the manufacturing cost can be reduced. In addition, since the electric disk brake according to the invention of claim 3 has the same number of teeth on the input side external teeth and the number of external teeth on the output side of the external gear member, it is possible to process these simultaneously and integrally. Thus, the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an electric disc brake according to an embodiment of the present invention.
FIG. 2 is a front view of the electric disk brake shown in FIG.
FIG. 3 is a side view of the electric disc brake shown in FIG.
4 is a plan view of the electric disc brake shown in FIG. 1. FIG.
FIG. 5 is a rear view of the electric disc brake shown in FIG.
6 is an exploded view of a speed reduction mechanism of the electric disk brake shown in FIG. 1. FIG.
7 is a cross-sectional view taken along a plane orthogonal to the input-side external teeth and fixed ring gear axes of the electric disk brake reduction mechanism shown in FIG. 1. FIG.
8 is a cross-sectional view taken along a plane orthogonal to the output-side external teeth and the ring gear axis of the reduction mechanism of the electric disk brake shown in FIG. 1. FIG.
[Explanation of symbols]
1 Electric disc brake
2 Disc rotor
5,6 Brake pads
9 Electric motor
10 Differential reduction mechanism (deceleration mechanism)
12 Ball ramp mechanism (conversion mechanism)
17 Rotor
20 Eccentric shaft
21 External gear member
23 Input side external teeth
24 Output side external teeth
25 Fixed ring gear
28 Ring gear

Claims (4)

An electric motor, a reduction mechanism that decelerates the rotation of the rotor of the electric motor, and a conversion mechanism that converts the rotation of the reduction mechanism into a linear motion, and the braking mechanism presses the brake pad against the disk rotor by the conversion mechanism. In the electric disk brake for generating the motor, the speed reduction mechanism includes a hollow eccentric shaft connected to the rotor of the motor, an input side external tooth and an output side external tooth that are rotatably attached to the eccentric shaft and rotate integrally with each other. An external gear member, a fixed ring gear having internal teeth meshing with the input side external teeth, a ring gear meshing with the output side external teeth and driving the conversion mechanism, the rotor and the eccentric shaft, An electric disc brake characterized in that an extension portion of a hollow portion of the eccentric shaft that is eccentric with respect to the shaft of the rotor is integrally provided therebetween.   2. The electric disc brake according to claim 1, wherein the number of teeth of the input side external teeth is equal to the number of teeth of the fixed ring gear.   2. The electric disc brake according to claim 1, wherein the number of teeth of the input side external teeth is equal to the number of teeth of the output side external gear.   2. The electric disc brake according to claim 1, wherein the number of teeth on the output side external teeth is equal to the number of teeth on the ring gear that drives the conversion mechanism.

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