JP5289182B2 - Electric disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a small structure obtaining large braking force and securing sufficient durability. <P>SOLUTION: A thrust generation mechanism 8a incorporated in a caliper 5a is composed of both first/second boosting mechanisms 19, 20 provided mutually in series with regard to a thrust transmission direction for pressing both inner/outer pads 2a, 3a to both side surfaces of a rotor. The first boosting mechanism 19 on the front-stage side which is the electric motor 9a side is a ball-lamp type boosting mechanism, and the rear-stage side second boosting mechanism 20a is a lever-type boosting mechanism. Thrust load applied on the first boosting mechanism 19 can be reduced by an amount equivalent to a boosting ratio of the second boosting mechanism 20a. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an improvement in an electric disc brake that brakes an automobile using an electric motor as a drive source. Specifically, it is intended to realize a structure that is small and can obtain a large braking force and can secure sufficient durability.

  Electric disc brakes that use an electric motor as a drive source eliminate the need for piping compared to the hydraulic disc brakes that have been widely used in the past, making manufacturing easier and lowering costs. There are many advantages such as reduced brake load and less environmental load, and improved response due to the absence of brake fluid movement. In such an electric disc brake, it is necessary to convert the rotary motion of the electric motor into linear motion while increasing the force, and to strongly press the pair of pads against both side surfaces of the rotor. In view of such circumstances, conventionally, there have been various electric disk brakes that combine a gear-type reduction gear and a ball / lamp type boosting mechanism, for example, as described in Patent Documents 1 to 6. Proposed.

  FIG. 8 shows an example of a conventional structure described in Patent Document 6 among them. In this electric disc brake, as with a general hydraulic disc brake, an inner pad 2 and an outer pad 3 are installed so as to be able to displace in the axial direction of the rotor 1 with a rotor 1 rotating together with a wheel. Yes. For this purpose, the support 4 (see FIG. 1 showing an example of the embodiment of the present invention) is supported on the vehicle body (fixed to the knuckle constituting the suspension device) in a state adjacent to the rotor 1. The inner and outer pads 2, 3 are in a state where the rotor 1 is sandwiched from both sides in the axial direction, and the axial direction (the outer side is the outside in the width direction of the vehicle body when assembled to the vehicle body, and the inner side is Similarly, the center side is also referred to, and the axial direction refers to the axial direction of the rotor 1 unless otherwise specified, both of which are the same throughout the present specification and claims). The support 4 is supported.

  Further, a caliper 5 is assembled to the support 4 so as to be capable of axial displacement. The caliper 5 is provided with a caliper claw 6 at an outer side end portion and a cylinder space 7 inside an inner side portion. The caliper pawl 6 is opposed to the outer side surface of the outer pad 3 and the inner pad 2 is pressed toward the inner side surface of the rotor 1 by a thrust generating mechanism 8 provided in the cylinder space 7. ing. At the time of braking, when the inner pad 2 is pressed against the inner side surface of the rotor 1 by the thrust generating mechanism 8, the caliper 5 is displaced toward the inner side, and the caliper claw 6 moves the outer pad 3 to the outer side surface of the rotor 1. Press. As a result, the rotor 1 is strongly clamped from both sides in the axial direction, and braking is performed. The above configuration and operation are the same as those of a widely used hydraulic disc brake.

  In the case of an electric disc brake, in order to press the inner pad 2 against the inner side surface of the rotor 1 using the electric motor 9 as a drive source, the output shaft 10 of the electric motor 9 and the inner side surface of the inner pad 2 A gear type reduction gear 11, the thrust generating mechanism 8, and a piston member 12 are provided between the two. The rotational force decelerated by the reducer 11 and increased in torque is transmitted to the drive-side rotor 14 constituting the ball / ramp-type force-increasing mechanism via the feed screw engaging portion 13, and this drive-side rotor. 14 is rotated. Note that the drive-side rotor 14 is structured such that the outer side of the inner and outer pads 2 and 3 and the side surface of the rotor 1 are closed by the function of the feed screw engaging portion 13 until the clearance between the side and the rotor 1 is eliminated. Translate side to side. On the other hand, after the gap is eliminated and the function of the feed screw engaging portion 13 is stopped, it rotates. Then, a plurality of drive side ramp grooves 15, 15 provided on the outer side surface of the drive side rotor 14 and a plurality of driven side ramps provided on the inner side surface of the driven side stator 16 attached to the inner side surface of the piston member 12. Based on the engagement (rolling contact) between the driving side ramp grooves 17 and 17 and a plurality of balls 18 sandwiched between the ramp grooves 15 and 17, the driving side rotor 14 and the driven side stator are arranged. Increase the distance to 16 with great force. As a result, the outer side surface of the piston member 12 is strongly pressed against the inner side surface of the inner pad 2.

  The electric disc brake provided with the ball / lamp type thrust generating mechanism 8 as described above is highly efficient in converting the rotational force into the thrust that is the axial force. Easy to obtain braking force. However, since the contact state of the rolling contact portion between the rolling surface of each ball 18 and both the ramp grooves 15 and 17 is close to point contact (the area of the contact ellipse existing in the rolling contact portion is small), the rolling contact. The surface pressure of the part increases. Therefore, if the thrust generated by the thrust generating mechanism 8 (pressing the inner pad 2) is increased in order to obtain a large braking force, the rolling contact portions, particularly the bottoms of the ramp grooves 15, 17 are formed. A large stress is generated. As a result, the rolling fatigue life of each of the lamp grooves 15 and 17 is reduced or, if it is remarkable, damage such as indentation occurs at the bottom of each of the lamp grooves 15 and 17.

  In order to prevent such a decrease in life and occurrence of damage, the cross-sectional shape of each of the ramp grooves 15 and 17 and the diameter of each of the balls may be increased. However, in order to obtain a sufficient effect, The cross-sectional shape and diameter of the electric disc brake must be considerably increased, and it is inevitable that the electric disc brake is considerably increased in size. In particular, the diameter of the thrust generating mechanism 8 is considerably increased. Since the inner diameter of the cylinder space 7 that houses the thrust generation mechanism 8 is limited, the increase in the diameter of the thrust generation mechanism 8 is a very big problem from the viewpoint of putting the electric disk brake into practical use. Become.

JP 2000-291702 A JP 2001-173691 A Japanese Patent Laid-Open No. 2001-311443 JP 2003-14015 A JP 2003-65366 A JP 2004-169729 A

  The present invention has been invented in order to realize a structure of an electric disc brake that is small in size and can obtain a large braking force and can ensure sufficient durability.

The electric disc brake of the present invention includes a rotor, a support, both outer and inner pads, and a caliper, for example, as described above, as in the conventional electric disc brake.
Of these, the rotor rotates with the wheels.
The support is supported on the vehicle body in a state adjacent to the rotor.
The two pads are supported by the support so as to be axially displaceable with the rotor sandwiched from both axial sides.
The caliper is provided with a caliper claw facing the outer side surface of the outer pad at the outer side end, a cylinder space inside the inner side portion, and a side facing the inner pad being opened. And in this cylinder space, the thrust generation mechanism for pressing this inner pad toward the inner side surface of the said rotor is provided. Further, the caliper is supported so as to be capable of axial displacement with respect to the support.
Further, the thrust generating mechanism converts the rotational driving force of the electric motor into axial thrust and transmits it to the inner pad.

In particular, in the electric disc brake of the present invention, the thrust generating mechanism includes a back part of the cylinder space and a piston member fitted into the opening side part of the cylinder space so as to be axially displaceable. The first and second boosting mechanisms are provided in series with each other in the thrust transmission direction.
Of these, the first booster mechanism provided on the inner side of the cylinder space is of the ball / lamp type, and the second booster mechanism provided on the opening side of the cylinder space is an insulator type or reaction disk. Of the formula .

When implementing such an electric disc brake of the present invention, more specifically, as in the invention described in claim 2 or claim 3, the thrust generating mechanism includes an adjuster case, an adjuster plug, It is assumed that a piston member and both first and second boosting mechanisms are provided.
Of these, the adjuster case is provided with a female screw portion on the inner peripheral surface, and is fitted and fixed to the inner portion of the cylinder space.
Further, the adjuster plug has a male threaded portion formed on the outer peripheral surface. By screwing the male threaded part and the female threaded part, the adjuster plug is moved to the inner diameter side of the adjuster case and rotated in the axial direction of the adjuster case. Install so as to displace.
The piston member is fitted into the opening side portion of the cylinder space so as to be capable of axial displacement.
Further, the first and second boosting mechanisms are provided in series with each other in the thrust transmission direction between the adjuster plug and the piston member.

Among these, the first force increasing mechanism provided on the adjuster plug side is of a ball / ramp type, and includes a driving side rotor, a driven side stator, and a plurality of balls.
A plurality of driving side ramp grooves whose depth in the axial direction gradually changes in the same direction with respect to the circumferential direction are formed on the driving side surface of the driving side rotor facing the piston member. Such a drive-side rotor is capable of supporting a thrust load directed toward the inner side, and is installed inside the adjuster plug so as to be able to rotate with respect to the adjuster plug. And it can be freely rotated by the electric motor.
The driven side surface of the driven side stator is axially opposed to the driving side surface, and a depth in the axial direction gradually changes in a direction opposite to the driving side ramp groove in the circumferential direction. A driven side lamp groove is formed. Such a driven-side stator can be displaced in the axial direction with respect to the adjuster plug, and cannot be relatively rotated with respect to the adjuster plug.
Further, each of the balls is sandwiched between each of the driving side lamp grooves and each of the driven side lamp grooves so as to be able to roll along the lamp grooves.

On the other hand, the second force increasing mechanism provided on the piston member side is a lever type in the case of the invention described in claim 2, and a reaction disk type in the case of the invention described in claim 3. .
Of these, the lever-type second force-increasing mechanism includes a sleeve and a plurality of distribution levers.
Of these, the sleeve is provided at the outer side end of the adjuster plug so as to be able to rotate in synchronization with the adjuster plug and to be displaced in the axial direction with respect to the adjuster plug.
Each distribution lever is provided between the outer side surface of the sleeve and the driven side stator and the inner side surface of the piston member.
Further, the inner diameter side portion of the inner side surface of each distribution lever is the outer side surface of the driven side stator, the outer diameter side portion of the inner side surface is the outer side surface of the sleeve, and the radial intermediate portion of the outer side surface is the same. The piston member abuts against the inner side surface of the piston member so as to be swingable.

On the other hand, the reaction disk type second boosting mechanism includes a sleeve and a reaction disk.
Of these, the sleeve is provided at the outer side end of the adjuster plug so as to be able to rotate in synchronization with the adjuster plug and to be displaced in the axial direction with respect to the adjuster plug, as in the case of the lever-type second boosting mechanism. .
The reaction disk is made of an elastic material such as an elastomer such as rubber or vinyl, or a liquid sealed in a bag made of such an elastic material, and the outer end surface of the sleeve and the driven side stator , And sandwiched between the back end face of the piston member.
Then, the outer side surface of the driven-side stator is abutted against the center portion of the inner side surface of the reaction disk.
Further, when using any of the second boosting mechanisms of the lever type and the reaction disk type, the axial distance between the driving side rotor and the driven side stator is set between the driving side rotor and the adjuster plug. A spring is provided to rotate the drive-side rotor in the direction in which the balls roll to shrink.

When carrying out the invention described in claims 2 to 3 as described above, preferably, as in the invention described in claim 4, the outer side surface of the inwardly extending portion formed at the inner side end of the adjuster plug. And a thrust rolling bearing is provided between the inner side surface of the drive side rotor.
Alternatively, as in the invention described in claim 5, an inner peripheral surface of a drive cylinder that is rotatably supported in the inner part of the cylinder space and is rotationally driven by the electric motor via a speed reduction mechanism, and the drive side A driven shaft provided on the inner side portion of the rotor is combined with a torque transmission and a relative displacement in the axial direction.

According to the present invention configured as described above, it is possible to realize an electric disc brake that is small in size and that can obtain a large braking force and that can ensure sufficient durability.
That is, according to the structure of the present invention, the rotational driving force of the electric motor is linearly increased while increasing the power in two stages, that is, a ball / ramp type first boosting mechanism and a lever type or reaction disk type second boosting mechanism. Convert to motion. For this reason, even when a small electric motor is used, the force (total thrust) for pressing the inner pad against the inner side surface of the rotor can be sufficiently increased. The boost ratio (output / input) of the thrust generating mechanism as a whole is the product of the boost ratios of the first and second boost mechanisms. Accordingly, the respective boost ratios of the first and second boost mechanisms can sufficiently ensure the boost ratio as a whole of the thrust generating mechanism without particularly increasing the value. For this reason, it is not necessary to enlarge both said 1st and 2nd booster mechanisms in particular, and these both booster mechanisms can be installed in the cylinder space of a caliper with a limited internal diameter.
Furthermore, the thrust generated by the ball-and-ramp first booster provided on the front side (input side from the electric motor), in other words, the thrust load applied to the first booster is greater than the total thrust. , It becomes smaller by the boost ratio of the second boost mechanism ("total thrust / boost ratio of the second boost mechanism"). For this reason, it is possible to ensure the rolling fatigue life of each lamp groove and prevent the occurrence of damage without particularly increasing the cross-sectional shape and the ball diameter of each of the driving side and driven side ramp grooves constituting the first boosting mechanism. Can be planned.

According to the structure of the invention described in claims 2 to 3, before the inner pad is pressed against the inner side surface of the rotor, that is, in order to eliminate the gap between the inner pad and the inner side surface of the rotor, Until the inner pad is brought close to the inner side surface, both the first and second boosting mechanisms need not be operated. For this reason, instead of increasing the boosting ratio of these two boosting mechanisms, even if the strokes of these two boosting mechanisms are reduced, the inner pad can be reliably pressed against the inner side surface of the rotor with a sufficiently large force. .
Further, according to the invention described in claim 4, the rotational resistance of the drive-side rotor can be suppressed to improve the efficiency, and according to the invention described in claim 5, regardless of the axial displacement of the adjuster plug. Rotational driving of the drive side rotor by the electric motor can be performed stably.

Sectional drawing which shows the 1st example of embodiment of this invention. Sectional drawing which takes out and shows a thrust generation | occurrence | production mechanism. AA sectional drawing of FIG. BB sectional drawing. CC sectional drawing. The fragmentary sectional view equivalent to the D section of Drawing 1 showing the 2nd example of an embodiment of the invention. Sectional drawing similar to FIG. 1 which shows the modification. Sectional drawing which shows an example of a conventional structure.

[First example of embodiment]
1 to 5 show a first example of an embodiment of the present invention corresponding to claims 1, 2, 4, and 5. FIG. The inner and outer pads 2a and 3a and the caliper 5a are supported so as to be able to be displaced in the axial direction on a support 4 that is supported with respect to a portion other than the thrust generating mechanism 8a, that is, a vehicle body (a knuckle constituting the suspension device). Since the structure of the portion is the same as that of a conventionally known hydraulic disc brake, detailed illustration and description thereof will be omitted, and the structure of the thrust generating mechanism 8a portion, which is the feature of this example, and The operation will be mainly described.

  The thrust generating mechanism 8a is housed in a cylinder space 7a provided in the inner side portion of the caliper 5a. For this purpose, the caliper 5a is provided with a caliper claw 6a at the outer side end portion, and the cylinder space 7a is provided inside the inner side portion with the outer side facing the inner pad 2a being opened. . The inner pad 2a can be pressed toward the inner side surface of the rotor 1 (see FIG. 8) by the thrust generating mechanism 8a provided in the cylinder space 7a.

  The thrust generating mechanism 8a converts the rotational driving force of the electric motor 9a supported and fixed to the caliper 5a into axial thrust and transmits it to the inner pad 2a. For this purpose, in order from the output shaft side of the electric motor 9a, a gear-type speed reducer 11a, a ball / lamp type first boosting mechanism 19, a lever-type second boosting mechanism 20, and a piston member 12a Are provided in series with each other with respect to the direction of force transmission. A base end portion (inner side end portion) of a hollow cylindrical drive cylinder 22 is connected and fixed to a central outer side of a reduction gear 21 provided at the final stage of the speed reducer 11a by a connecting pin 23, and the electric motor 9a enables the drive cylinder 22 to be rotationally driven. This drive cylinder 22 becomes an input member of the thrust generating mechanism 8a. The base end portion of the drive cylinder 22 is rotatably supported by a rolling bearing 25 on a base end portion (inner side end portion) of an adjuster case 24 described below.

  The adjuster case 24 as a whole has a stepped cylindrical shape with a small diameter at the base end side and a large diameter at the intermediate portion or the distal end side (outer side), and is fitted in the inner half of the cylinder space 7a. It is fixed. Therefore, the adjuster case 24 does not rotate in the cylinder space 7a. An internal thread portion 26 is provided at the middle or tip of the inner peripheral surface of the adjuster case 24. An adjuster plug 27 is assembled inside the adjuster case 24. The adjuster plug 27 has a male threaded portion 28 formed on the inner side portion of the outer peripheral surface. By screwing the male threaded portion 28 and the female threaded portion 26, the adjuster plug 27 is brought into rotation on the inner diameter side of the adjuster case 24. The lever adjuster 24 is installed so as to be displaced in the axial direction. The piston member 12a is fitted into the opening side (outer side) portion of the cylinder space 7a so as to be capable of axial displacement. The first and second force-increasing mechanisms 19 and 20 are provided in series with respect to the thrust transmission direction between the adjuster plug 27 and the piston member 12a.

  Of these, the ball / lamp type first boosting mechanism 19 provided on the side of the adjuster plug 27 is composed of a drive-side rotor 14a, a driven-side stator 16a, and a plurality of balls 18a.

  Among these, the drive-side rotor 14a, which is an input member of the first force-increasing mechanism 19, is combined with the drive cylinder 22 so that torque transmission and relative displacement in the axial direction are possible. Therefore, in the case of this example, as shown in FIGS. 1 and 3, both end portions of the torque transmission pin 30 provided at the inner side end portion of the driven shaft 29 provided at the inner side portion of the driving side rotor 14a. The torque transmission grooves 31 and 31 formed in the axial direction are engaged at two positions opposite to the diameter direction on the inner peripheral surface of the drive cylinder 22 so as to be capable of sliding displacement in the axial direction. The cross-sectional shapes of both the torque transmission grooves 31 and 31 are arc-shaped, and both end portions of the torque transmission pin 30 are hemispherical. An inward flange 32 is formed at the inner end of the adjuster plug 27, and a thrust rolling bearing 33 is provided between the outer side surface of the inward flange 32 and the inner side surface of the drive rotor 14a. Yes. With this configuration, the drive side rotor 14a is rotationally driven by the drive cylinder 22, and the drive side rotor 14a is allowed to be displaced in the axial direction as the adjuster plug 27 rotates. The driving cylinder 22 and the driven shaft 29 may be combined by general spline engagement.

  A plurality (generally 3 to 4) of driving side ramp grooves 15a and 15a are formed on the driving side surface (outer side surface) of the driving side rotor 14a facing the piston member 12a. Each of the drive-side ramp grooves 15a, 15a is a partial arc shape that exists on a single arc centered on the center of the piston member 12a as viewed from the axial direction. It is a shape. The depth in the axial direction gradually changes in the same direction with respect to the circumferential direction. Such a driving-side rotor 14a is combined with a driven-side stator 16a and a ball 18a, which will be described below, to constitute the first force-increasing mechanism 19.

  The driven-side stator 16a is assembled in a state in which relative rotation with the adjuster plug 27 is prevented (so as to rotate together with the adjuster plug 27), and axial displacement with respect to the adjuster plug 27 is possible. Yes. Therefore, in the case of this example, the driven side stator 16 a is assembled to the adjuster plug 27 via the sleeve 34. For this purpose, a plurality of circumferential positions of the leading edge (outer side edge) of the adjuster plug 27 and a plurality of circumferential positions of the base edge (inner side edge) of the sleeve 34 are shown in FIG. As shown, a concave / convex engaging portion is formed by the engaging concave portion 35 and the engaging concave portion 36 so that the adjuster plug 27 and the sleeve 34 rotate synchronously. Further, as shown in FIG. 5, engaging grooves 37 formed at a plurality of circumferential positions on the inner peripheral surface of the sleeve 34 and a plurality of circumferential positions on the outer peripheral edge of the driven side stator 16a are provided. The driven-side stator 16 a is rotated in synchronism with the sleeve 34 by engaging with the engaging protrusion 38. The axial length of each engaging groove 37 is larger than the axial thickness of each engaging protrusion 38 so that the driven-side stator 16 a can be displaced in the axial direction with respect to the sleeve 34. Like.

  In this way, each drive-side ramp groove 15a is formed on a driven side surface that is an inner side end surface of the driven-side stator 16a, which is assembled to the adjuster plug 27 so that relative rotation is impossible and axial displacement is possible. , 15a, and the same number of driven side lamp grooves 17a, 17a as opposed to the driving side lamp grooves 15a, 15a in the axial direction. Each of the driven-side lamp grooves 17a and 17a has a partial arc shape when viewed from the axial direction, and has a partial arc shape in cross section. The depth in the axial direction gradually changes between the driven lamp grooves 17a and 17a in the same direction with respect to the circumferential direction and in the opposite direction to the driving lamp grooves 15a and 15a. Such a driven-side stator 16a constitutes the first boosting mechanism 19 in combination with the driving-side rotor 14a and the plurality of balls 18a, 18a. That is, one ball 18a, 18a is provided between each driving-side lamp groove 15a, 15a and each driven-side lamp groove 17a, 17a facing each other along the lamp grooves 15a, 17a. Hold it so that it can roll.

  With the above configuration, the balls 18a and 18a roll along the ramp grooves 15a and 17a along with the relative rotation between the drive-side rotor 14a and the driven-side stator 16a. The first force-increasing mechanism 19 is configured to expand and contract the axial distance from the driven-side stator 16a. A torsion coil spring 39 is provided between the drive side rotor 14a and the adjuster plug 27, and elastic force in the rotational direction is applied to the drive side rotor 14a. The direction of the elasticity of the torsion coil spring 39 causes the balls 18a to move in order to reduce the axial distance between the driving-side rotor 14a and the driven-side stator 16 (the thrust generated by the first force-increasing mechanism 19 is lost). The direction to roll.

  The lever-type second force increasing mechanism 20 includes the sleeve 34 and a plurality (for example, 3 to 4) of distribution levers 40 and 40. Each of the distributing levers 40, 40 is provided between the sleeve 34 and the distal end surface (outer side surface) of the driven side stator 16a and the inner back end surface (inner side surface) of the piston member 12a. Of the inner side surfaces of the distribution levers 40, 40, both inner and outer end portions in the radial direction of the sleeve 34 and the driven side stator 16a, and of the outer side surfaces of the distribution levers 40, 40, the piston member 12a. Each of the intermediate portions in the radial direction is a partially cylindrical convex curved surface. Then, the inner diameter side portion of the inner side surface of each of the distribution levers 40, 40 is moved to the front end surface of the driven side stator 16a, and the outer diameter side portion of the inner side surface is also moved to the front end surface of the sleeve 34. It strikes as possible. Further, the radially intermediate portion of the outer side surface of each of the distribution levers 40, 40 can be oscillated and displaced on the inner side surface of an annular plug member 41 fitted into the inner end of the piston member 12a. I'm hitting it. In particular, with respect to the inner side surface of the plug member 41, concave portions 42, 42 each having a circular arc shape and a linear shape when viewed in the axial direction are formed, and the concave portions 42, 42 and the distribution levers 40, The radial intermediate portion of the outer side surface of 40 is brought into contact with a sufficient area. Note that the shape of each of the distribution levers 40, 40 viewed in the axial direction is not a circular arc but a linear shape so that the swinging displacement of each of the distribution levers 40, 40 is performed smoothly and stably. It is said. Further, a compression coil spring 43 is provided between the sleeve 34 and the driven side stator 16a, and the driven side stator 16a is elastically pressed toward the driving side rotor 14a. The ramp grooves 15a and 17a and the balls 18a are always in rolling contact with each other in an appropriate state.

The electric disc brake of this example configured as described above exhibits a braking force as follows.
At the time of braking, the drive side rotor 14a is rotationally driven by the electric motor 9a via the drive cylinder 22. In an initial stage immediately after the start of braking, there is a gap between the inner and outer pads 2a, 3a and both side surfaces of the rotor 1, and the pads 2a, 3a are moved toward the rotor 1. The power required for this is small. For this reason, at the initial stage, the adjuster plug 27 as well as the sleeve 34 and the driven-side stator 16 a are rotated based on the elasticity of the torsion coil spring 39 as the driving-side rotor 14 a rotates. It rotates in synchronization with the drive side rotor 14a. Based on the engagement between the male screw portion 28 and the female screw portion 26, the adjuster plug 27 is displaced toward the outer side toward the rotor 1, and both the pads 2 a and 3 a and both side surfaces of the rotor 1 are Clear the gap between. At this time, two radial positions on the inner side surface of each of the distribution levers 40 and 40 are in sliding contact with the driven-side stator 16a and the tip end surface of the sleeve 34. Since the pressure is small, there is no particular problem. The rotation of the drive cylinder 22 and the drive-side rotor 14a can be stably performed with a light force based on the presence of the rolling bearing 25 and the thrust rolling bearing 33.

  When the gap between the two pads 2a and 3a and both side surfaces of the rotor 1 is eliminated in this way, the force required to move the adjuster plug 27 toward the rotor 1 (the adjuster plug 27 (Rotational resistance) becomes larger than the elasticity given to the adjuster plug 27 by the torsion coil spring 39. As a result, the adjuster plug 27 does not rotate any more (depending on the elasticity), and the adjuster plug 27 stops. At the same time, the rotation of the sleeve 34 and the driven side stator 16a is also stopped. When the driving side rotor 14a is further rotated against the elastic force of the torsion coil spring 39 from this state, the balls 18a are moved to the driving side ramp grooves 15a, 15a and the driven side ramp grooves 17a. , Roll toward the shallow side of 17a. As a result, the distance between the drive-side rotor 14a and the driven-side stator 16a increases, and the driven-side stator 16a is displaced toward the rotor 1 toward the outer side.

  Based on such displacement of the driven-side stator 16a, each of the distribution levers 40, 40 uses the contact portion with the tip end surface of the driven-side stator 16a as a power point, and the contact portion with the sleeve 34 becomes the force point. As a fulcrum, it swings and displaces with the contact part with the plug member 41 as an action point. With respect to the radial direction of the plug member 41, this action point exists between the force point and the fulcrum, so that the force for displacing the driven-side stator 16a is increased (about three times in the illustrated example). The plug member 41 is pressed, and the piston member 12a in which the plug member 41 is fitted and fixed is directed toward the rotor 1 with a large force. As a result, the two pads 2a and 3a are strongly pressed against both side surfaces of the rotor 1 to perform braking. In the case of this example, in the process of eliminating the gap, the first and second boosting mechanisms 19 and 20 do not need to operate, and the strokes of both the boosting mechanisms 19 and 20 are consumed to eliminate the gap. There is nothing to do. Therefore, both the force-increasing mechanisms 19 and 20 can employ a structure having a large force-increasing ratio instead of a short stroke, and the force for pressing the piston member 12a toward the rotor 1 can be particularly increased.

  When releasing the brake, the electric motor 9a is rotated in the reverse direction, and the piston member 12a is retracted from the rotor 1 in the same manner as the conventionally proposed electric disc brake. At this time, after the moment when both the pads 2a and 3a are separated from the both side surfaces of the rotor 1, the electric motor 9a is continuously rotated in the opposite direction by a predetermined angle so that the pads 2a and 3a and the rotor 1 Secure a gap of appropriate thickness between both sides. In the case of this example, by providing the adjuster plug 27, the gap can always be kept at an appropriate thickness regardless of the wear of the pads 2a and 3a. When the electric motor 9 is rotated in the reverse direction, the deepest portions of the ramp grooves 15a and 17a are engaged with the balls 18a. Therefore, from the driving roller 14a to the adjuster plug 27, Sufficient torque can be transmitted.

  As described above, the electric disc brake of this example increases the rotational driving force of the electric motor 9a in two stages, that is, the ball ramp type first boosting mechanism 19 and the lever type second boosting mechanism 20. Therefore, the increase ratio of the thrust generating mechanism 8a as a whole can be increased. For this reason, even when a small motor is used as the electric motor 9a, a sufficiently large braking force can be obtained by sufficiently increasing the force (total thrust) for pressing the inner pad 2a against the inner side surface of the rotor 1. . Further, the overall boosting ratio (output / input) of the thrust generating mechanism 8a is the product of the respective boosting ratios of the first and second boosting mechanisms 19 and 20. Therefore, even if the boosting ratios of the first and second boosting mechanisms 19 and 20 are not particularly large, the boosting ratio of the thrust generating mechanism 8a as a whole can be sufficiently secured. For this reason, it is not necessary to enlarge both the first and second boosting mechanisms 19 and 20, and both the boosting mechanisms 19 and 20 can be installed in the cylinder space 7a of the caliper 5a having a limited inner diameter. .

  Further, the thrust generated by the ball-and-ramp type first booster mechanism 19 provided on the front side near the electric motor 9a and the thrust load applied to the first booster mechanism 19 is the total thrust. Is smaller than the boost ratio of the second boost mechanism 20. For this reason, each of the ramp grooves 15a, 17a, 17a constituting the first booster mechanism 19 can be provided without particularly increasing the sectional shape of the ramp grooves 15a, 17a on the driven side and the diameter of the balls 18a. The rolling fatigue life of 17a can be secured and the occurrence of damage can be prevented.

[Second Example of Embodiment]
FIG. 6 shows a second example of an embodiment of the present invention corresponding to claims 1 and 3 to 5. In the case of this example, a reaction disk type is adopted as the second force increasing mechanism 20a. For this purpose, the second force increasing mechanism 20a is provided with a reaction disk 44 in addition to the sleeve 34 similar to the case of the first example described above. The plug member 41a provided at the inner end of the piston member 12a has a disk shape with a flat inner side surface. The reaction disk 44 is made of an elastic material such as an elastomer such as rubber or vinyl, or a liquid sealed in a hollow bag made of such an elastic material, and the outer side surface of the sleeve 34 and the driven side stator 16a. And the inner side surface of the plug member 41a. The outer side surface of the driven-side stator 16 a is abutted against the inner side surface central portion of the reaction disk 44.

During braking, the driven-side stator 16a is displaced to the outer side by the same action as in the first example of the above-described embodiment, and the outer side surface of the driven-side stator 16a is located at the center of the inner side surface of the reaction disk 44. Press strongly. As a result, the reaction disk 44 is elastically deformed. The reaction disk 44 presses the opposite surface surrounding the reaction disk 44 by a behavior like a kind of incompressible fluid. The pressure per unit area at which the reaction disk 44 presses the mating surface is the same as the pressure per unit area of the pressing portion by the outer side surface of the driven-side stator 16a. When the contact area between the reaction disk 44 and the mating surface is viewed in the axial direction, the contact area S ₁ with the plug member 41a is larger than the contact area S ₂ with the outer side surface of the driven-side stator 16a. Wide enough (S ₁ >> S ₂ ). Therefore, the piston member 12a, in which the plug member 41a is fitted and fixed, is increased by a ratio (S ₁ / S ₂ ) of the contact area with respect to the thrust applied to the driven-side stator 16a, so that the rotor 1 (see FIG. 8).
Since the configuration and operation of other parts are the same as those in the first example of the above-described embodiment, overlapping illustrations and descriptions are omitted.

  When the reaction disk 44 is used as in this example, the plug member 41a is omitted from the structure shown in FIG. 6, and the outer side surface of the reaction disk 44 is connected to the rear end face of the piston member 12b as shown in FIG. (Inner side) can be directly hit. In the case of the structure shown in FIG. 7, the piston member 12b is configured by combining a pair of piston elements 45a and 45b.

DESCRIPTION OF SYMBOLS 1 Rotor 2, 2a Inner pad 3, 3a Outer pad 4 Support 5, 5a Caliper 6, 6a Caliper claw 7, 7a Cylinder space 8, 8a Thrust generating mechanism 9, 9a Electric motor 10 Output shaft 11, 11a Reduction gears 12, 12a, 12b Piston member 13 Feed screw engaging portion 14, 14a Drive side rotor 15, 15a Drive side ramp groove 16, 16a Driven side stator 17, 17a Driven side ramp groove 18, 18a Ball 19 First force increasing mechanism 20, 20a First Double-intensifying mechanism 21 Deceleration large gear 22 Drive cylinder 23 Connecting pin 24 Adjuster case 25 Rolling bearing 26 Female thread part 27 Adjuster plug 28 Male thread part 29 Driven shaft 30 Torque transmission pin 31 Torque transmission groove 32 Inward flange part 33 Thrust rolling bearing 34 Sleeve 35 Engagement recess 36 Engagement Part 37 engaging grooves 38 engage protruding pieces 39 torsion coil spring 40 dispensing lever 41,41a plug member 42 recess 43 compression coil spring 44 reaction disk 45a, 45b piston element

Claims (5)

A rotor that rotates with the wheels, a support that is supported by the vehicle body in a state adjacent to the rotor, and an outer and an inner that are supported by the support so that the rotor can be displaced in the axial direction while sandwiching the rotor from both sides in the axial direction. Both inner pads and a caliper claw facing the outer side surface of the outer pad at the outer side end, and the inner space inside the cylinder space provided with the side facing the inner pad opened. A thrust generation mechanism for pressing the pad toward the inner side surface of the rotor is provided, and a caliper supported so as to be capable of axial displacement with respect to the support is provided. The thrust generation mechanism is configured to rotate an electric motor. In the electric disc brake that converts the driving force into axial thrust and transmits it to the inner pad,
The thrust generation mechanism is provided in series with respect to the transmission direction of the thrust between the inner part of the cylinder space and the piston member fitted in the opening side portion of the cylinder space so as to be axially displaceable. With both first and second booster mechanism,
Of these, the first booster mechanism provided on the inner side of the cylinder space is of the ball / lamp type, and the second booster mechanism provided on the opening side of the cylinder space is an insulator type or reaction disk. electric disc brake, characterized in that it is those of the formula.

The thrust generating mechanism includes an adjuster case that is internally fitted and fixed in the inner part of the cylinder space, and that has an internal thread portion on the inner peripheral surface, and an external thread portion and an internal thread portion formed on the outer peripheral surface on the inner diameter side of the adjuster case. An adjuster plug that can be displaced in the axial direction of the adjuster case as it rotates, and a piston member that is fitted in the opening side portion of the cylinder space so as to be axially displaceable. The first and second boosting mechanisms provided between the adjuster plug and the piston member,
Of these, the ball ramp type first force increasing mechanism provided on the adjuster plug side has the axial depth gradually changing in the same direction with respect to the circumferential direction on the drive side surface facing the piston member. A drive-side rotor that forms a plurality of drive-side ramp grooves and is capable of supporting a thrust load toward the inner side and is installed inside the adjuster plug, and is driven to rotate by the electric motor, and a shaft with respect to the drive side surface A plurality of driven side lamp grooves whose depth in the axial direction gradually changes in the opposite direction to the driving side lamp groove in the circumferential direction are formed on the driven side surface facing the direction, and the axial direction relative to the adjuster plug The driven-side stator, the drive-side ramp grooves, and the driven-units provided so as to be capable of displacement of the adjuster plug and not to rotate relative to the adjuster plug. Are those in which a plurality of balls rollably interposed between the side lamp groove,
The second force increasing mechanism provided on the piston member side is of an insulator type, and can be rotated and displaced in the axial direction with respect to the adjuster plug at the outer side end of the adjuster plug. And a plurality of distribution levers provided between the sleeve and the outer side surface of the driven-side stator and the inner side surface of the piston member, and the inner diameter of the inner side surface of each of the distribution levers The outer side of the driven stator is the outer side, the outer side of the inner side is the outer side of the sleeve, and the radially intermediate part of the outer side is the inner side of the piston member. Is possible and
A spring is provided between the drive side rotor and the adjuster plug to rotate the drive side rotor in a direction in which the balls roll to reduce the axial distance between the drive side rotor and the driven side stator. The electric disc brake according to claim 1. The thrust generating mechanism includes an adjuster case that is internally fitted and fixed in the inner part of the cylinder space, and that has an internal thread portion on the inner peripheral surface, and an external thread portion and an internal thread portion formed on the outer peripheral surface on the inner diameter side of the adjuster case. An adjuster plug that can be displaced in the axial direction of the adjuster case as it rotates, and a piston member that is fitted in the opening side portion of the cylinder space so as to be axially displaceable. The first and second boosting mechanisms provided between the adjuster plug and the piston member,
Of these, the ball ramp type first force increasing mechanism provided on the adjuster plug side has the axial depth gradually changing in the same direction with respect to the circumferential direction on the drive side surface facing the piston member. A drive-side rotor that forms a plurality of drive-side ramp grooves and is capable of supporting a thrust load toward the inner side and is installed inside the adjuster plug, and is driven to rotate by the electric motor, and a shaft with respect to the drive side surface A plurality of driven side lamp grooves whose depth in the axial direction gradually changes in the opposite direction to the driving side lamp groove in the circumferential direction are formed on the driven side surface facing the direction, and the axial direction relative to the adjuster plug The driven-side stator, the drive-side ramp grooves, and the driven-units provided so as to be capable of displacement of the adjuster plug and not to rotate relative to the adjuster plug. Are those in which a plurality of balls rollably interposed between the side lamp groove,
The second force increasing mechanism provided on the piston member side is of a reaction disk type, and the outer side end of the adjuster plug is subjected to rotation synchronized with the adjuster plug and axial displacement with respect to the adjuster plug. A liquid is sealed in a sleeve made of an elastic material or an elastic material, which is sandwiched between an outer end surface of the sleeve and the outer end surface of the driven-side stator and the back end surface of the piston member. A reaction disk, and the outer side surface of the driven-side stator is abutted against the center of the inner side surface of the reaction disk,
A spring is provided between the drive side rotor and the adjuster plug to rotate the drive side rotor in a direction in which the balls roll to reduce the axial distance between the drive side rotor and the driven side stator. The electric disc brake according to claim 1.   The thrust rolling bearing is provided between the outer side surface of the inward flange portion formed at the inner side end portion of the adjuster plug and the inner side surface of the driving side rotor. The electric disc brake described in item 1.   An inner peripheral surface of a drive cylinder that is rotatably supported in the inner part of the cylinder space and is rotationally driven by the electric motor via a speed reduction mechanism, and a driven shaft provided on an inner side portion of the drive side rotor. The electric disc brake according to any one of claims 2 to 4, wherein torque transmission and relative displacement in the axial direction are combined in a possible manner.

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