JP2017089871A - Disc brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an electric disc brake device capable of obtaining a large brake force while achieving downsizing and ensuring sufficient durability.SOLUTION: A thrust generating mechanism 8a for pushing out a piston 12a from a cylinder space 7a by converting a turning force of an electric motor to a thrust in an axial direction is made up of a feed screw mechanism 13a and a boosting mechanism 14a. A disc brake device employs such a structure that as the boosting mechanism 14a of these mechanisms, a spherical roller 47 for a lamp, whose outer peripheral surface is a spherical shape, is used instead of a conventional ball-lamp type boosting mechanism using a ball.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an improvement in a disc brake device provided with a service brake that decelerates or stops a traveling vehicle or a parking brake that is a brake during parking.

  For example, a disc brake with an electric parking mechanism that uses a service brake hydraulically and a parking brake electricly eliminates the need for cables and reduces costs, as well as switch ON / OFF operations. In recent years, it has begun to spread because it has advantages such as braking and releasing it to improve operability and facilitating control for automatically releasing when starting. In such a disc brake device, it is necessary to convert the rotational motion of the electric motor, which is a drive source, into a 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, various electric disc brake devices combining a gear-type reduction device and a ball / lamp type boosting mechanism have been proposed, for example, as described in Patent Documents 1 to 4. Has been.

  FIG. 8 shows an example of a conventional structure described in Patent Document 1 among them. In this electric disc brake device, as with a general hydraulic disc brake, an inner pad 2 and an outer pad 3 are installed so as to be capable of displacement in the axial direction of the rotor 1 with the rotor 1 rotating together with the wheels interposed therebetween. ing. For this purpose, the support 4 is supported on the vehicle body (fixed to the knuckle constituting the suspension device) adjacent to the rotor 1. The inner and outer pads 2, 3 are in a state in which the rotor 1 is sandwiched from both sides in the axial direction, and the axial direction (the outer side is the outer side 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.

  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 the outer side end portion and a cylinder space 7 inside the inner side portion. The caliper claw 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 based on the pressure, and the caliper pawl 6 causes the outer pad 3 to move to the rotor. Press against the outer side of 1. 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 the electric disc brake device, the electric motor 9 is used as a drive source to press the inner pad 2 against the inner side surface of the rotor 1, and the output shaft 10 of the electric motor 9 and the inner side surface of the inner pad 2. Are provided with a gear-type speed reducer 11, the thrust generating mechanism 8, and a piston 12. The rotational force decelerated by the speed reducer 11 and increased in torque is transmitted to the ball / ramp type power increasing mechanism 14 via the feed screw mechanism 13 to rotate the lamp rotor 15 constituting the power increasing mechanism 14. Let The ramp rotor 15 is parallel to the outer side by the function of the feed screw mechanism 13 until the clearance between the inner and outer pads 2 and 3 and the side surface of the rotor 1 is eliminated. Moving. On the other hand, after the gap is eliminated and the function of the feed screw mechanism 13 is stopped, it rotates. Then, a plurality of lamp lamp grooves 16, 16 provided on the outer side surface of the lamp rotor 15 and a plurality of driven side lamp grooves 18 provided on the inner side surface of the lamp stator 17 attached to the inner side surface of the piston 12. , 18 and a plurality of balls 19 sandwiched between the lamp grooves 16 and 18 (rolling contact), the distance between the lamp rotor 15 and the lamp stator 17 is increased. Expand with. As a result, the outer side surface of the piston 12 is strongly pressed against the inner side surface of the inner pad 2.

In the case of the electric disc brake device provided with the ball-and-lamp type boosting mechanism 14 as described above, the number of balls 19 that can be used is limited (generally, three) due to restrictions on dimensions and the like, Since the contact state of the rolling contact portion between the rolling surface of each ball 19 and both the ramp grooves 16 and 18 is close to point contact (the area of the contact ellipse existing in the rolling contact portion is small), Surface pressure increases (Hertz stress increases). For this reason, in order to obtain a large braking force, when the thrust generated by the force-increasing mechanism 14 (pressing the inner pad 2) is increased by, for example, loosening the inclination angle of the ramp grooves 16, 18. A particularly large stress is generated at the bottom of each of the ramp grooves 16 and 18 in each of the rolling contact portions. As a result, the rolling fatigue life of each of the lamp grooves 16 and 18 may be reduced or, if remarkable, damage such as indentation may occur at the bottom of each of the lamp grooves 16 and 18.
Further, in order to obtain a large braking force, when the thrust generated by the force-increasing mechanism 14 (pressing the inner pad 2) is increased, the stress at the contact portion is allowed (the Hertz stress at the contact portion is reduced). In order to prevent the occurrence of damage such as indentation as described above, it is conceivable to increase the diameter of each ball 19. However, if such a configuration is adopted, the force-increasing mechanism 14 and, consequently, the electric disc brake device are increased in size.
As described above, in the case of the electric disc brake device provided with the ball / lamp type boosting mechanism 14 of the conventional structure, a large braking force is obtained and a reduction in size is achieved while ensuring sufficient durability. It becomes difficult to balance things.

JP 2004-169729 A JP 2010-265971 A JP 2000-291702 A JP 2012-77809 A

  The present invention has been invented in order to realize an electric disk brake device capable of obtaining a large braking force while achieving downsizing and ensuring sufficient durability in view of the circumstances as described above.

The disc brake device of the present invention includes a piston, a pad, and a ramp mechanism.
Among these, the piston is arranged in a state of facing the axial side surface of the rotor that rotates together with the wheel.
The pad is disposed closer to the rotor than the piston.
The ramp mechanism is driven by an input from a driving source to displace the piston toward the rotor, thereby pressing the pad against the axial side surface of the rotor.

In particular, in the case of the disc brake device of the present invention, the ramp mechanism includes a ramp rotor, a ramp stator, and a plurality of spherical rollers for lamp.
Among these, the ramp rotor has a plurality of drive side ramp tracks whose height in the axial direction gradually changes in the same direction with respect to the circumferential direction on the side surface on the rotor side.
The lamp stator has a plurality of driven side lamp tracks whose height in the axial direction gradually changes in the opposite direction to the driving side lamp tracks in the circumferential direction on the side surface opposite to the rotor.
Each of the lamp spherical rollers has a spherical outer peripheral surface, and is sandwiched between the drive side lamp raceways and the driven side lamp raceways so as to be able to roll.

When the disk brake device of the present invention as described above is implemented, for example, as in the invention described in claim 2, the radius of curvature of the generatrix of the spherical roller for lamp is set to _Ra , and the spherical roller for lamp is used. When the outer diameter (the outer diameter of the maximum diameter portion) is D _a , _a configuration satisfying the relationship of D _a ≦ R _a ≦ 5D _a can be employed.

  When the disc brake device of the present invention as described above is implemented, for example, as in the invention described in claim 3, the disc rotor device is rotated by an input from the drive source so that the lamp rotor is rotated. It is possible to adopt a configuration including a screw that directly or indirectly rotationally drives. When such a configuration is adopted, a configuration in which a thrust roller bearing is provided between a back end surface of a cylinder space in which the screw is disposed and a flange portion provided in an intermediate portion in the axial direction of the screw. Can be adopted. And the rolling element which comprises the said thrust roller bearing is used as the spherical roller for bearings whose outer peripheral surface is spherical.

When carrying out the invention described in claim 3 as described above, for example, as in the invention described in claim 4, the radius of curvature of the generatrix of the spherical roller for bearing is R _b, and the spherical surface for bearing is used. the outer diameter of the roller (outer diameter of the maximum diameter portion) in the case of the D _b, can adopt a configuration which satisfies the relation _{R b ≦ D b ≦ 5R b} .

  When implementing the disc brake device of the present invention as described above, for example, a configuration in which the drive source is an electric motor as in the invention described in claim 5 can be adopted.

According to the present invention configured as described above, it is possible to realize an electric disc brake device capable of obtaining a large braking force while achieving downsizing and ensuring sufficient durability.
That is, in the case of the present invention, a force-increasing mechanism using a spherical roller is adopted as a force-increasing mechanism constituting the thrust generating mechanism, instead of the conventional ball-and-ramp-type force-increasing mechanism using a ball. For this reason, the contact state of the rolling contact portion between the rolling surface of the spherical roller and the driving and driven lamp raceways can be changed from point contact to line contact, and the surface pressure is increased by increasing the area of the rolling contact portion. (Hertz stress) can be kept low. Therefore, in order to obtain a large braking force, for example, when the thrust generated by the force-increasing mechanism is increased by, for example, loosening the inclination angle of each of the driving side and driven side ramp tracks, a large stress is applied to each ramp track. Can be effectively prevented.
In addition, when the spherical roller with the same diameter as the ball constituting the ball / lamp type boosting mechanism is adopted as in the conventional structure described above, the area of the rolling contact portion is made larger than in the conventional structure. The surface pressure (Hertz stress) can be kept low. Therefore, even when the thrust generated by the booster mechanism is increased, the booster mechanism can be downsized.
As described above, according to the structure of the present invention, it is possible to realize an electric disc brake device that can obtain a large braking force while achieving downsizing and ensuring sufficient durability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an example of an electric disc brake device according to an embodiment of the present invention as seen from the outer side and radially outward. The orthographic view shown in the state similarly seen from the inner side. The orthographic view shown in the state similarly seen from radial direction outward. Similarly, the orthographic projection shown in the state seen from the left of FIG. Similarly, sectional drawing of the part corresponded to the A section of FIG. Similarly, the disassembled perspective view which shows the state which took out the piston and the components arrange | positioned inside this piston. Similarly, the figure which takes out and shows only the spherical roller which comprises a thrust bearing and a booster mechanism. Sectional drawing which shows an example of a conventional structure.

[Example of Embodiment]
An example of an embodiment of the present invention will be described with reference to FIGS. The feature of this example is that the structure of the thrust generating mechanism 8a including the force-increasing mechanism 14a is devised in order to realize a structure capable of obtaining a large braking force while achieving downsizing and ensuring sufficient durability. is there. Since the configuration and operation of the other parts are almost the same as those of the conventional structure shown in FIG. 8, the explanation about the equivalent parts will be omitted or simplified, and the characteristic part of this example and the explanation will be described below. The explanation will focus on the missing part.

  The electric disc brake device of this example is a floating caliper type, and a pair of guide pins on a support 4 provided in a state of straddling a portion near the outer diameter of a rotor 1 (see FIG. 8) that rotates together with wheels (not shown). 20 and 20 support the caliper 5a so that the displacement of the rotor 1 in the axial direction is possible. Further, both ends of the inner pad 2 and the outer pad 3 are supported on the support 4 so as to be displaceable in the axial direction of the rotor 1, and the caliper 5 a is straddled across the inner and outer pads 2, 3. Is arranged.

  The electric actuator incorporated in the electric disc brake device of this example includes an electric motor 9a corresponding to the drive source described in the claims, a gear-type reduction gear (not shown), and the thrust generating mechanism 8a. Is provided. Then, the electric motor 9 a causes the piston 12 a fitted in the cylinder space 7 a provided in the inner side portion of the caliper 5 a to move toward the rotor 1 through the speed reducer and the thrust generating mechanism 8 a. The braking force is generated by pushing the inner and outer pads 2 and 3 strongly against both axial side surfaces of the rotor 1.

  The piston 12a has a bottomed cylindrical shape, and has a distal end side (side closer to the rotor 1) closed with a bottom portion 21 and a proximal end side opened. A concave conical receiving surface 22 is formed on the inner surface of the bottom portion 21 near the outer diameter. Further, at two positions on the opposite side in the diameter direction of the cylindrical side wall portion 23 of the piston 12a, slits 24, 24 that are long in the axial direction are opened at the inner side end edges on the base end side of the piston 12a. Is forming. Further, in a state where such a piston 12a is fitted in the cylinder space 7a, a boot (illustrated) is formed between the outer peripheral surface of the front end portion of the piston 12a and the inner peripheral surface of the outer edge of the cylinder space 7a. (Omitted).

  The electric motor 9a rotationally drives the output shaft in both directions based on energization. The gear-type speed reducer is formed by meshing a plurality of gears, and includes an output shaft of the electric motor 9a and an inner side end portion of an adjustment screw 26 constituting a feed screw mechanism 13a described later. It is provided between. In the case of this example, the electric motor 9a and the speed reducer are housed in a casing 25 fixed to the inner side end of the caliper 5a with a plurality of bolts.

  The thrust generating mechanism 8a is for converting the rotational driving force of the electric motor 9a transmitted through the speed reducer into axial thrust, and for pushing out the piston 12a from the cylinder space 7a. The feed screw mechanism 13a and the force increasing mechanism 14a are provided in series with respect to the force transmission direction.

  Of these, the feed screw mechanism 13 a is composed of an adjustment task screw 26 corresponding to the screw described in the claims and a ramp rotor 27. The adjuster screw 26 is provided with a male screw portion 28 in the outer half of the outer peripheral surface, and an outward flange-like thrust receiving portion 29 that functions as one raceway of a thrust bearing 39, which will be described later, in the middle portion. Is provided. Further, in the adjustment task screw 26, the inner side end portion protruding from the cylinder space 7a toward the inner side is relatively located inside the final gear (not shown) constituting the speed reducer housed in the casing 25. It is engaged so that it cannot rotate. Accordingly, the adjustment task screw 26 can be rotationally driven by the electric motor 9a, and the adjustment task screw 26 is used as an input member of the thrust generating mechanism 8a.

  The lamp rotor 27 includes a small-diameter cylindrical portion 31 having an internal thread portion 30 on an inner peripheral surface provided in the inner-side half portion, and an outer-side half portion having an outer diameter outside the small-diameter cylindrical portion 31. It consists of a large-diameter cylindrical portion 32 that is larger than the diameter. Of these, three drive side ramp tracks 34 are formed on the drive side surface (outer side surface) of the large diameter cylindrical portion 32 facing the piston 12a. A spring locking hole 33 penetrating the large-diameter cylindrical portion 32 in the axial direction is formed at a position in the circumferential direction near the radially outer end of the large-diameter cylindrical portion 32. Such a lamp rotor 27 is arranged around the outer half of the adjustment task screw 26. The ramp rotor 27 can be displaced in the axial direction with the rotation of the adjustment screw 26 by screwing the female screw portion 30 into the male screw portion 28 of the adjustment screw 26.

  In the case of this example, an adjuster case 35 is provided at the back end of the cylinder space 7a in a state of covering the intermediate portion of the adjustment task screw 26 (the inner side portion from the thrust receiving portion 29). The adjuster case 35 has a bottomed cylindrical shape having a bottom portion 36 at an inner side end portion. Further, a through hole 37 is formed in the center of the bottom portion 36 of the adjuster case 35 so as to penetrate the bottom portion 36 in the axial direction and allow a portion near the inner side end of the adjuster screw 26 to be inserted therethrough. ing. Such an adjuster case 35 is fitted and fixed to the inner portion (inner side end portion) of the cylinder space 7a of the caliper 5a. A thrust bearing 39 and an axial load are measured between the adjuster case 35 and the thrust receiving portion 29 of the adjustment task screw 26 in this order from the side closer to the thrust receiving portion 29 (outer side). An axial force sensor unit 40 is arranged.

The thrust bearing 39 is constituted by the thrust receiving portion 29, a thrust plate 41, a plurality of bearing spherical rollers 42 and 42, and a cage 43. The thrust bearing 39 corresponds to the thrust roller bearing described in the claims.
Outer side thrust track surface 44 is formed on the inner side surface of thrust receiving portion 29 of the thrust receiving portion 29. The outer side thrust track surface 44 has a concave arc shape in cross section with respect to a virtual plane including the central axis of the adjustment task screw 26. . In the case of this example, the thrust receiving portion 29 corresponds to the flange portion described in the claims.

  The thrust plate 41 is an annular member, and is externally fitted on the inner side portion of the adjustment task screw 26 with respect to the thrust receiving portion 29 so as to be capable of axial displacement with respect to the adjustment task screw 26. . On the outer side surface of the thrust plate 41, an inner side thrust raceway surface 45 having a concave arc shape in cross section with respect to a virtual plane including the central axis of the adjuster screw 26 is formed over the entire circumference.

As shown in FIG. 7, each of the bearing spherical rollers 42 and 42 is made of a hard metal material such as a high carbon chrome bearing steel, for example, having a symmetric shape in which the maximum diameter portion is at the center in the axial direction. . In this example, the D ₄₂ of the outer diameter of the curvature radius of the generatrix of the spherical rollers 42 for each bearing and R _42, the maximum diameter of 42, 42 of the spherical roller for each bearing (axial center) In this case, the relationship of R ₄₂ ≦ D ₄₂ ≦ 5R ₄₂ is satisfied. Each of the bearing spherical rollers 42 and 42 is arranged between the outer side thrust raceway surface 44 and the inner side thrust raceway surface 45 so as to be freely rollable. The retainer 43 prevents the bearing spherical rollers 42 and 42 from being separated.

The force-increasing mechanism 14 a includes the lamp rotor 27, a lamp stator 46, three lamp spherical rollers 47, and a cage 48.
Among these, the ramp rotor 27 serving as an input member of the force-increasing mechanism 14 a is a member common to the feed screw mechanism 13 a described above, and is disposed around the outer half of the adjuster screw 26. Such a lamp rotor 27 can be displaced in the axial direction with the rotation of the adjustment screw 26 by screwing the female screw portion 30 into the male screw portion 28 of the adjustment screw 26. Further, as described above, the three drive-side ramp tracks 34 and 34 are formed on the drive side surface (outer side surface) of the large-diameter cylindrical portion 32 constituting the ramp rotor 27 facing the piston 12a. Each of the drive-side ramp tracks 34, 34 has an arc shape as viewed from the axial direction, and has an arc shape that exists on a single arc centered on the center of the piston 12a, and the cross-sectional shape (bus shape) is also an arc shape. is there. The height in the axial direction gradually changes in the same direction with respect to the circumferential direction.

  Further, a resistance is applied to the lamp rotor 27 so that the lamp rotor 27 as described above does not rotate in the rotating direction of the adjustment task screw 26 during braking operation. Therefore, in this example, a compression coil spring 49 is provided between the ramp rotor 27 and the piston 12a. Specifically, one end (outer side end) of the compression coil spring 49 is locked in the spring locking hole 33 of the lamp rotor 27. The other end portion (inner side end portion) of the compression coil spring 49 is one of the pair of guide protrusions 51, 51 provided on the opposite side in the diameter direction of the substantially annular guide member 50. The projection 51 is locked in a mounting hole 52. Such a guide member 50 allows the guide protrusions 51 and 51 to enter the insides of the slits 24 and 24 of the piston 12a so that the guide member 50 cannot rotate relative to the inside of the portion near the base end of the piston 12a. Moreover, it is arranged so as to be capable of axial displacement. In the case of this example, the compression coil spring 49 is arranged in this manner, so that the lamp rotor 27 is rotated in a direction opposite to the rotation direction of the adjustment task screw 26 during braking operation (with the lamp rotor 27 and In order to reduce the axial distance from the lamp stator 46, a resistance (elasticity) in the direction in which the spherical roller 47, 47 rolls is provided. The magnitude of the resistance is determined by the male screw portion 28 of the adjustment task screw 26 and the ramp rotor 27 when the both sides of the rotor 1 and the pads 2 and 3 are separated from each other in the non-braking state. The screw between the male screw portion 30 and the female screw portion 30 when both side surfaces of the rotor 1 and the pads 2 and 3 are in contact with each other is larger than the resistance of the screwed portion with the female screw portion 30. It is set smaller than the joint resistance. In the case of this example, in order to restrict the displacement of the guide member 50 toward the inner side, a locking groove 53 is formed over the entire circumference on the inner peripheral surface of the base end portion of the piston 12a. A notched annular retaining ring 54 is locked inside the groove 53.

  The lamp stator 46 is a cylindrical member, and a stator flange portion 55 is formed on the outer peripheral surface of the inner side end portion so as to protrude radially outward over the entire circumference. Further, at the radially opposite position (two positions in the circumferential direction) of the outer side end portion of the outer peripheral surface of the stator flange portion 55, rotation prevention convex portions 56 and 56 are formed in a state of projecting radially outward. Has been. Further, on the driven side surface, which is the inner side surface of the stator flange portion 55 (the lamp stator 46), the same number (three) of driven side lamp tracks 57, 57 as the driving side lamp tracks 34, 34 are provided. Each drive side lamp track 34 is formed so as to be opposed in the axial direction. Each of the driven side lamp tracks 57 and 57 has an arc shape when viewed from the axial direction, and a cross-sectional shape (bus shape) also has an arc shape. Then, the height in the axial direction gradually changes in the same direction with respect to the circumferential direction between the driven lamp tracks 57 and 57 and in the opposite direction to the driving ramp tracks 34 and 34. The outer side surface (tip surface) of the lamp stator 46 is a spherical convex surface. Such a ramp stator 46 has the non-rotating projections 56, 56 inserted into the inner sides of the slits 24, 24 of the piston 12a, and at the inner side of the piston 12a near the outer side end. 12a is provided such that it cannot be rotated relative to the shaft 12a and can be displaced in the axial direction. In this state, the outer side surface (tip surface) of the lamp stator 46 is in contact with the receiving surface 22 provided on the bottom portion 21 of the piston 12a. In this manner, the piston 12a can be slightly swung.

As shown in FIG. 7, each of the lamp spherical rollers 47 has a symmetrical shape in which the respective maximum diameter portions are in the central portion in the axial direction, and is made of a hard metal material such as high carbon chromium bearing steel. Further, when the radius of curvature of the bus bar of each of the lamp spherical rollers 47 is R ₄₇ and the outer diameter of the largest diameter portion (axial center position) of the lamp spherical rollers 47 is D ₄₇ , R ₄₇ ≦ The relationship of D ₄₇ ≦ 5R ₄₇ is satisfied. In the case of this example, the three spherical rollers 47 for lamps are arranged at equal intervals (120 degree intervals) in the circumferential direction, and the drive side lamp tracks 34 and 34 and the driven sides are arranged. Between the ramp tracks 57, 57, the respective central axes are sandwiched in the diametrical direction. In this state, the spherical roller 47 for each lamp is rotatably held in pockets 58 and 58 formed at three locations in the circumferential direction of the substantially annular retainer 48.

The electric disc brake device of this example configured as described above operates as follows, and presses the inner and outer pads 2 and 3 against both side surfaces of the rotor 1 to perform braking.
During non-braking, there is a gap between the inner and outer pads 2 and 3 and both side surfaces of the rotor 1. From this state, in order to perform braking, the electric motor 9a is energized, and the adjustment screw 26 constituting the feed screw mechanism 13a is rotationally driven via the speed reducer. In this state, the resistance (elasticity) applied to the lamp rotor 27 by the compression coil spring 49 is caused by the resistance generated at the threaded portion of the male screw portion 28 of the adjustment task screw 26 and the female screw portion 30 of the ramp rotor 27. Smaller than). Therefore, the lamp rotor 27 does not rotate but is displaced (translated) toward the outer side toward the rotor 1. Then, the piston 12a is pushed out of the cylinder space 7a through the spherical roller 47 for each lamp and the lamp stator 46. As a result, the inner pad 2 is pressed against the inner side surface of the rotor 1 by the piston 12a, and the caliper 5a is displaced toward the inner side, and the caliper claw 6 causes the outer pad 3 to be moved to the outer side surface of the rotor 1. Press on. In this way, the force-increasing mechanism 14a does not function particularly while the gap between the pads 2 and 3 and the both side surfaces of the rotor 1 is eliminated.

  When the gap between the pads 2 and 3 and both side surfaces of the rotor 1 is eliminated, the resistance generated at the threaded portion between the male screw portion 28 and the female screw portion 30 due to the generation of axial force. And the function of the feed screw mechanism 13a stops (the ramp rotor 27 does not rotate relative to the adjustment task screw 26), the elasticity (resistance) of the compression coil spring 49 causes the ramp rotor 27 to move. Rotate against As a result, each of the lamp spherical rollers 47 rolls toward the higher side in the axial direction of each of the drive side lamp tracks 34, 34 and each of the driven side lamp tracks 57, 57. Based on the engagement (rolling contact) between the driving-side lamp tracks 34 and 34 and the driven-side lamp tracks 57 and 57 and the lamp spherical rollers 47, the lamp rotor 27 and the lamp The space with the stator 46 is increased with a large force. As a result, the outer side surface of the piston 12 a is strongly pressed against the inner side surface of the inner pad 2. As a result, the inner and outer pads 2 and 3 are strongly pressed against both side surfaces in the axial direction of the rotor 1 to generate a braking force.

  When braking is released, the output shaft of the electric motor 9a is rotated in the direction opposite to that during braking based on the energization of the electric motor 9a. Then, each part is displaced in the direction opposite to that at the time of braking described above, and the piston 12a is retracted into the cylinder space 7a. As a result, a gap exists between the inner and outer pads 2 and 3 and both side surfaces of the rotor 1.

According to the electric disc brake device of the present example having the above-described configuration and operating as described above, a large braking force can be obtained while reducing the size and ensuring sufficient durability.
That is, in the case of this example, as the force-increasing mechanism 14a that constitutes the thrust generating mechanism 8a, in place of the conventional ball-and-ramp-type force-increasing mechanism that uses balls, the force-increasing power that uses the spherical roller 47 for each lamp is used. The mechanism is adopted. For this reason, the contact state of the rolling contact portion between the rolling surface of each of the lamp spherical rollers 47 and each of the driving side and driven side lamp raceways 34 and 57 can be changed from point contact to line contact. The surface pressure (hertz stress) of the part can be kept low. Therefore, in order to obtain a large braking force, for example, the driving force and the driven side lamp tracks 34, 57 are loosened, and the driving force generated by the force-increasing mechanism 14a is increased. It is possible to effectively prevent large stresses from being generated on the lamp tracks 34 and 57 on the side and driven side.
In addition, when the spherical roller with the same diameter as the ball constituting the ball / lamp type boosting mechanism is adopted as in the conventional structure described above, the area of the rolling contact portion is made larger than in the conventional structure. The surface pressure (Hertz stress) can be kept low. Therefore, even when the thrust generated by the force-increasing mechanism 14a is increased, the force-increasing mechanism 14a can be downsized.
As described above, according to the structure of this example, it is possible to realize an electric disk brake device that can obtain a large braking force while achieving downsizing and ensuring sufficient durability.

  Further, in the case of the electric disc brake device of this example, the spherical rollers 42 and 42 for the bearings are employed as the rolling elements constituting the thrust bearing 39. For this reason, at the time of braking, the contact state of the rolling contact portion between the rolling surface of each of the bearing spherical rollers 42, 42 and the outer side thrust raceway surface 44 and the inner side thrust raceway surface 45 is indicated by a point contact line. It can be changed to contact, and the surface pressure (Hertz stress) of the rolling contact portion can be kept low. As a result, the thrust bearing 39 can be smoothly operated while improving the durability of the thrust bearing 39.

[Industrial applicability]
The present invention can be applied to an electric parking disc brake and an electric service brake.
The present invention can also be applied to a hydraulic disc brake device.
Moreover, the structure of the part which operates the thrust generation mechanism 8a is not limited to the structure of an example of the above-described embodiment.
Furthermore, the present invention can be applied not only to a floating caliper type disc brake but also to an opposed piston type disc brake.

DESCRIPTION OF SYMBOLS 1 Rotor 2 Inner pad 3 Outer pad 4 Support 5, 5a Caliper 6 Caliper claw 7, 7a Cylinder space 8, 8a Thrust generating mechanism 9, 9a Electric motor 10 Output shaft 11, 11a Reducer 12, 12a Piston 13, 13a Feed screw mechanism 14, 14a Booster mechanism 15 Lamp rotor 16 Driven side lamp groove 17 Lamp stator 18 Driven side lamp groove 19 Ball 20 Guide pin 21 Bottom part 22 Reception surface 23 Side wall part 24 Slit 25 Casing 26 Adjusting task screw 27 Lamp rotor 28 Male thread part 29 Thrust receiving portion 30 Female thread portion 31 Small diameter cylindrical portion 32 Large diameter cylindrical portion 33 Spring locking hole 34 Drive side ramp track 35 Adjuster case 36 Bottom portion 37 Through hole 38 Back end wall 39 Thrust bearing 40 Axial force sensor unit 41 Thrust stop 42 Bearing spherical roller 43 Cage 44 Outer side thrust raceway surface 45 Inner side thrust raceway surface 46 Lamp stator 47 Lamp spherical roller 48 Cage 49 Compression coil spring 50 Guide member 51 Guide projection 52 Mounting hole 53 Locking Groove 54 Retaining ring 55 Stator flange 56 Non-rotating convex part 57 Drive-side ramp orbit 58 Pocket

Claims (5)

A piston disposed in a state of being opposed to the axial side surface of the rotor rotating together with the wheel, a pad disposed on the rotor side from the piston, and a ramp mechanism,
A disc brake device that presses the pad against an axial side surface of the rotor by driving the ramp mechanism by an input from a drive source and displacing the piston toward the rotor;
The ramp mechanism includes a ramp rotor in which a plurality of drive-side ramp tracks whose height in the axial direction gradually changes in the same direction with respect to the circumferential direction are formed on a side surface on the rotor side, and a side surface on the side opposite to the rotor. A lamp stator having a plurality of driven lamp tracks whose height in the axial direction gradually changes in a direction opposite to the driving ramp track in the circumferential direction, each driving lamp track and each driven A disc brake device including a plurality of spherical rollers for a lamp that are sandwiched between the side ramp raceways and have a spherical outer peripheral surface. The radius of curvature of the bus bar of the lamp spherical roller is R _a ,
The outer diameter of the spherical rollers for the lamp when the D _a,
The disc brake device according to claim 1, wherein a relationship of D _a ≦ R _a ≦ 5D _a is satisfied. A screw that rotates the lamp rotor directly or indirectly by rotating by input from the drive source,
A thrust roller bearing is provided between a back end surface of the cylinder space in which the screw is disposed and a flange portion provided in an axially intermediate portion of the screw,
The disc brake device according to any one of claims 1 to 2, wherein the rolling element constituting the thrust roller bearing is a spherical roller for a bearing having a spherical outer peripheral surface. When the radius of curvature of the bus bar of the spherical roller for bearing is R _b and the outer diameter of the spherical roller for bearing is D _b ,
The disc brake device according to claim 3, wherein the relationship of R _b ≦ D _b ≦ 5R _b is satisfied. The disc brake device according to any one of claims 1 to 4, wherein the drive source is an electric motor.

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