JP2016109281A - Brake device - Google Patents

Abstract

A brake device capable of constantly applying a preload to a load sensor with a simple structure. A brake device includes a cylindrical brake cylinder, a brake piston having an outer periphery surrounded by a brake cylinder, and a rotary motion from an electric motor that is converted into a linear motion to generate a brake piston. And a load sensor 44 provided to receive an axial load directed in the second axial direction X2. The load sensor 44 receives a reaction force from the first pad 6 and detects an axial load that acts on the screw shaft 28 in the second axial direction X2. Between the annular step 15c of the brake cylinder 13 and the flange 41, an elastic body 37 that elastically presses the annular step 15c and the flange 41 apart from each other along the axial direction X is interposed. [Selection] Figure 1

Description

  The present invention relates to a brake device.

In a brake device such as an electric brake device, a transmission mechanism for transmitting a driving force to a brake piston includes a ball screw device including a screw shaft and a ball nut screwed to the screw shaft via a plurality of balls. (See, for example, Patent Document 1 below).
Further, in order to control the braking force of the brake device to a desired magnitude, the brake device may incorporate a load sensor in a portion that receives a reaction force from the pad. In the following Patent Document 2, a load sensor is incorporated between a flange provided on the central axis of an electric linear actuator and a shaft support member that supports the central axis.

JP 2014-145465 A JP 2014-47845 A

By the way, depending on the type of load sensor, there is a type of load sensor that requires an initial preload at the time of measurement. When using such a load sensor, a preload must be constantly applied to the load sensor.
Therefore, when such a load sensor is mounted on a brake device, it is necessary to provide a preload application mechanism for constantly applying a preload to the load sensor. For example, in a brake device including a ball screw device, it is conceivable to provide a preload applying mechanism between a screw shaft (center shaft) and a cylindrical housing. Such a preload application mechanism is desired to have a simple structure.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a brake device that can always apply a preload to a load sensor with a simple structure.

  In order to achieve the above-mentioned object, the invention according to claim 1 provides a braking force by applying a pressing force along the wheel axis direction to the pads (6, 7) to the disk (2) rotating integrally with the wheel. A brake device (1) to be generated, which is a cylindrical housing (13) and a cylindrical brake piston (17) for pressing the pad, and an outer periphery (17a) is surrounded by the housing. And a screw nut (28) extending along the wheel shaft direction, and a ball nut (30) screwed to the screw shaft via a plurality of balls (29), and is housed inside the housing, A ball screw device (22) for converting rotational motion from a rotational drive source (20) into linear motion and transmitting it to the brake piston, wherein the brake piston is integrated with the ball nut. The pressing force is applied to the pad when the brake piston is moved toward one axial direction (X1). The shaft of the housing An annular step (15c) is formed at the other end in the direction, and the brake device receives the reaction force of the pressing force applied to the pad and acts on the screw shaft. A load sensor (44) provided to receive an axial load toward (X2) and detecting the magnitude of the axial load; and a fixedly provided on the outer periphery of the screw shaft, the diameter of the screw shaft A flange (41) extending along the direction (Z), wherein at least an outer peripheral portion (41c) is axially opposed to the annular step portion, and the annular step portion and the flange of the housing. Between It is instrumentation, further comprising annular shoulder portion and the flange elastic body along the axial direction elastically pressed so as to separate from each other and (37), to provide a brake device.

  The invention according to claim 2 further includes a thrust bearing (42) externally fixed to the outer periphery of the screw shaft, and the load sensor is disposed on the other axial side with respect to the thrust bearing, and the flange The brake device according to claim 1, wherein when the thrust bearing is pressed, the axial load is applied to the load sensor via the thrust bearing.

The invention according to claim 3 is the brake device according to claim 1 or 2, wherein the elastic body is supported by the annular step portion of the housing.
The invention according to claim 4 is the brake device according to any one of claims 1 to 3, wherein a sliding bearing (51) is interposed between the elastic body and the flange.
In the above description, numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

  According to the configuration of the first aspect, the flange is always elastically pressed to the other side in the axial direction by the elastic body interposed between the annular step portion of the housing and the flange. Since the flange is fixedly provided on the screw shaft, the elastic pressing force is transmitted to the screw shaft. Thereby, the force which goes to an axial direction other side can always be provided to a screw shaft. Therefore, a preload can be always applied to the load sensor. Thereby, application of the preload to the load sensor can be realized with a simple structure of a combination of a flange and an elastic body. Therefore, it is possible to provide a brake device that can always apply preload to the load sensor with a simple structure.

According to the configuration of the second aspect, the flange serves as a pressing flange that applies an axial load to the load sensor via the thrust bearing and a receiving flange that receives the elastic pressing force from the elastic body. ing. Therefore, as compared with the case where these flanges are provided individually, the structure can be further simplified.
According to the structure of Claim 3, since an elastic body is supported by the annular step part, even if a screw shaft is a rotation state, an elastic body does not rotate. In the rotational state of the screw shaft, the elastic body is in sliding contact with the rotating flange. Thereby, rotation of the flange with respect to the brake cylinder can be satisfactorily secured while constantly pressing the screw shaft via the flange.

  According to the configuration of the fourth aspect, since the sliding bearing is interposed between the elastic body and the flange, the flange can be rotated more favorably with respect to the housing.

It is a schematic sectional drawing of the brake device concerning one embodiment of the present invention, and has shown at the time of non-braking. It is a disassembled perspective view which shows the structure of a ball screw apparatus. It is a general | schematic expanded sectional view of the brake device which concerns on other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of a brake device 1 according to an embodiment of the present invention, showing a non-braking time. The brake device 1 is a device that applies a braking force by friction to a disk 2 that rotates integrally with a wheel of an automobile or the like.
The brake device 1 includes, for example, a floating type caliper 3 that is movably supported by a knuckle (not shown) and the like, and a first backup plate that is disposed with a disc 2 interposed therebetween and supported by the caliper 3 so as to be able to approach / separate from each other. 4 and the second backup plate 5, and a first pad 6 and a second pad 7 fixed to the first backup plate 4 and the second backup plate 5 and capable of pressing the corresponding side surfaces of the disk 2, respectively. .

The caliper 3 includes a first body 8 and a second body 9 that are fixed to each other, and a cover 10 that is fixed to the second body 9. The first body 8 includes a main body portion 11 to which one end of the second body 9 is fixed, and an arm portion 12 connected to the main body portion 11 in an orthogonal shape. The second backup plate 5 is fixed to the arm portion 12.
The second body 9 includes a brake cylinder (housing) 13 fixed to the main body 11 of the first body 8 and an extending plate 14 extending from the brake cylinder 13. A brake piston 17 is accommodated in the brake cylinder 13.

  In the following description, the axial direction of the screw shaft 28 described later is referred to as an axial direction X. The axial direction of the ball nut 30 described later is also the axial direction X. The axial direction of the brake piston 17 and the axial direction of the brake cylinder 13 coincide with the axial direction X. Further, in the axial direction X, the axial direction (left direction in FIG. 1) on the first pad 6 side when viewed from the screw shaft 28 is defined as a first axial direction (one axial direction) X1, and the first axial direction X1 The opposite axial direction (the right direction in FIG. 1) is defined as a second axial direction (the other axial direction) X2.

The circumferential direction of the screw shaft 28 is a circumferential direction Y. The circumferential direction of the ball nut 30 is also the circumferential direction Y. The circumferential direction of the brake piston 17 and the circumferential direction of the brake cylinder 13 coincide with the circumferential direction Y.
Further, the rotational radial direction of the screw shaft 28 is defined as a radial direction Z. The radial direction of the ball nut 30 is also the radial direction Z. The radial direction of the brake piston 17 and the radial direction of the brake cylinder 13 coincide with the radial direction Z.

  The brake cylinder 13 includes a first end portion 151 and a second end portion 152 that are opposed to each other in the axial direction X. The tubular portion 15 with the first end portion 151 opened, and the second end portion of the tubular portion 15. And end face plate 16 connected to 152. A brake piston 17 is accommodated in the brake cylinder 13 so as to be movable in the axial direction X. An annular step portion 15 c that is continuous with the end face plate 16 is formed in the middle portion in the axial direction X of the inner periphery 15 b of the cylindrical portion 15. The annular step portion 15 c has a facing surface 45 that faces the end face plate 16. The facing surface 45 is an annular surface orthogonal to the axial direction X.

One end 171 of the brake piston 17 protrudes toward the disc 2 through an open portion of one end of the brake cylinder 13 (corresponding to the first end 151 of the cylindrical portion 15), and presses the first backup plate 4.
A sealing member 18 is interposed between the outer periphery 17a of the brake piston 17 and the inner periphery of the brake cylinder 13 (corresponding to the inner periphery 15b of the cylindrical portion 15). The sealing member 18 may be an O-ring housed in a housing groove provided on the inner circumference of the brake cylinder 13 (the inner circumference 15b of the cylindrical portion 15).

Both the outer periphery 17a of the piston 17 and the inner periphery of the cylinder 13 (the inner periphery 15b of the cylindrical portion 15) are connected via a key 19 disposed across a key groove provided in both. . The movement of the piston 17 in the axial direction X is guided through the key connection using the key 19 and the rotation of the piston 17 relative to the cylinder 13 is restricted.
Hydraulic pressure for urging the brake piston 17 toward the disc 2 may be supplied into the brake cylinder 13 from a hydraulic path (not shown). In that case, the brake cylinder 13 and the brake piston 17 constitute a hydraulic actuator.

The caliper 3 functions to generate a braking force by pressing the pads 6 and 7 against the disk 2. The caliper 3 transmits an electric motor (rotation drive source) 20, a speed reducer 21 that decelerates the rotation of the electric motor 20, and rotational motion transmitted from the electric motor 20 via the speed reducer 21 to the axial direction of the brake piston 17. And a ball screw device 22 for converting into X linear motion.
The electric motor 20 includes a motor housing 23 fixed to the extending plate 14 of the second body 9 and an output shaft 24.

  The reduction gear 21 includes a drive gear 25 that is attached to one end of an output shaft 24 of the electric motor 20 so as to be integrally rotatable, an idle gear 26 that meshes with the drive gear 25, and a driven gear 27 that meshes with the idle gear 26. . The idle gear 26 is rotatably supported by the second body 9. The cover 10 is fixed to the second body 9 so as to cover the reduction gear 21.

FIG. 2 is an exploded perspective view showing the configuration of the ball screw device 22. In FIG. 2, not only the ball screw device 22 but also the brake piston 17 are shown together.
As shown in FIGS. 1 and 2, the ball screw device 22 includes a screw shaft 28 as an input member, and a ball nut 30 as a rotatable output member screwed to the screw shaft 28 via a plurality of balls 29. The retaining ring 40 and the brake piston 17 are provided. The screw shaft 28 is inserted through the ball nut 30. The screw shaft 28 is supported by the second body 9 so as not to move in the axial direction X and to be rotatable. The ball nut 30 is supported by the second body 9 so as to be movable in the axial direction X and non-rotatable.

  Specifically, the screw shaft 28 is supported rotatably and immovably in the axial direction X by a rolling bearing 32 held on the inner circumference of a support hole 31 provided in the end face plate 16 of the brake cylinder 13. Yes. One end 281 of the screw shaft 28 is connected to a transmission shaft 45 coupled to the driven gear 27 so as to be coaxially rotatable, via a coupling 46 so as to be integrally rotatable. The screw shaft 28 includes an outer periphery 28a in which a male screw groove 34 is formed.

  The screw shaft 28 is provided with a disk-like flange 41 at a predetermined position on the second axial direction X2 side with respect to the position where the male screw groove 34 is formed. The flange 41 extends along the radial direction Z of the screw shaft 28. In this embodiment, as shown in FIG. 1, the flange 41 is provided as a separate member from the screw shaft 28, and is externally fixed to the outer periphery 28 a of the screw shaft 28. Further, the flange 41 may be provided integrally with the screw shaft 28.

The flange 41 is provided with a larger diameter than the inner periphery 15 b of the cylindrical portion 15 of the brake cylinder 13. The flange 41 is arranged so that the outer peripheral portion 41c of the first main surface 41a on the first axial direction X1 side faces the facing surface 45 of the annular step portion 15c in the axial direction X.
An elastic body 37 made of a rubber member is interposed between the facing surface 45 of the annular step portion 15 c and the first main surface 41 a of the flange 41. The rubber member is formed using a rubber material such as nitrile rubber. The elastic body 37 has a rectangular cross section perpendicular to the circumferential direction Y. The elastic body 37 has a first main surface 37a on the first axial direction X1 side and a second main surface 37b on the second axial direction X2 side. The first main surface 37a of the elastic body 37 is fixed (supported) to the annular step portion 15c in a state of being in contact with the facing surface 45 of the annular step portion 15c. The second main surface 37b of the elastic body 37 is in contact with the first main surface 41a of the flange 41 and elastically presses the first main surface 41a toward the second axial direction X2. That is, the elastic body 37 elastically presses the brake cylinder 13 (annular step portion 15c) and the flange 41 so as to be separated from each other along the axial direction X. Since the flange 41 is fixedly provided on the screw shaft 28, a force in the second axial direction X2 is always applied to the screw shaft 28.

  Since the elastic body 37 is supported by the annular step portion 15c, the elastic body 37 does not rotate even if the screw shaft 28 is in a rotating state. In the rotational state of the screw shaft 28, the second main surface 37b of the elastic body 37 is in sliding contact with the first main surface 41a of the rotating flange 41. Thereby, rotation of the flange 41 with respect to the brake cylinder 13 can be favorably secured while always pressing the screw shaft 28 via the flange 41.

  Between the main surface 41b on the second axial direction X2 side of the flange 41 and the end face plate 16 of the brake cylinder 13, a thrust bearing 42, an alignment member 43 and a load sensor 44 are provided from the flange 41 side (second Are arranged in this order (towards the axial direction X2). In other words, the thrust bearing 42 and the load sensor 44 are incorporated between the main surface 41 a of the flange 41 and the facing portion of the end face plate 16.

The thrust bearing 42 is externally fixed to the outer periphery of the screw shaft 28. The thrust bearing 42 is constituted by, for example, a thrust needle bearing or a thrust roller bearing. Further, the thrust bearing 42 may be a thrust ball bearing. An axial load applied to the screw shaft 28 is supported by the thrust bearing 42.
The load sensor 44 is sandwiched between the thrust bearing 42 and the end face plate 16 of the brake cylinder 13 via the alignment member 43. The load sensor 44 has an annular shape. The load sensor 44 is constituted by, for example, a strain detection type load sensor. The load sensor 44 receives an axial load supported by the thrust bearing 42. That is, the load sensor 44 is provided so as to receive an axial load applied to the screw shaft 28 in the second axial direction X2.

The ball nut 30 includes a first end 301 on the disk 2 side and a second end 302 opposite to the first end 301 in the axial direction X. The ball nut 30 includes an outer periphery 30a and an inner periphery 30b in which a female screw groove 33 is formed. A row of balls 29 is interposed between the female screw groove 33 and the male screw groove 34.
The first end 301 of the ball nut 30 is in contact with the positioning step 39 on the inner periphery 17b of the brake piston 17. A retaining ring 40 fitted in an annular groove provided on the inner periphery 17 b of the brake piston 17 is engaged with the end surface 303 of the second end 302 of the ball nut 30. Thereby, the brake piston 17 and the ball nut 30 are connected so as to be movable integrally in the axial direction X.

  When the rotation of the output shaft 24 of the electric motor 20 is transmitted via the speed reducer 21 and the screw shaft 28 is rotated, the ball nut 30 moves in the axial direction X. At this time, the brake piston 17 moves together with the ball nut 30 in the first axial direction X1 by the guidance of the key 19. As a result, the brake piston 17 presses the first pad 6 in the first axial direction X1 (a pressing force is applied), and both the pads 6 and 7 press the disk 2 to generate a braking force.

  At this time, the reaction force of the pressing force is applied to the brake piston 17 from the first pad 6. The reaction force (force in the second axial direction X2) from the first pad 6 is transmitted to the screw shaft 28 via the ball nut 30 and the plurality of balls 29. That is, an axial load in the second axial direction X2 is generated on the screw shaft 28. The magnitude of this axial load is measured by the load sensor 44.

  In a state where the brake piston 17 presses the first pad 6 in the first axial direction X1 and a braking force is generated in the electric brake device 1, the reaction force of the pressing force is applied to the brake piston 17 from the first pad 6. As a result, an axial load is generated on the screw shaft 28 in the second axial direction X2. The magnitude of the axial load at this time, that is, the magnitude of the reaction force of the pressing force is measured by the load sensor 44.

  By the way, the load sensor 44 used in this embodiment is a type of load sensor that requires an initial preload. With this type of load sensor 44, an accurate value may not be measured unless a preload is applied at the start of measurement. As described above, a force in the second axial direction X2 is always applied to the screw shaft 28 by the elastic pressing of the flange 41 by the elastic body 37. Since the force in the second axial direction X2 applied to the screw shaft 28 is applied to the load sensor 44 via the thrust bearing 42, this force always acts on the load sensor 44 as a preload. Thereby, even if it is a case where the type of load sensor which requires initial preload is used, the axial direction load given to screw axis 28 can be detected satisfactorily.

The control unit of the brake device 1 controls the electric motor 20 based on the detection output of the load sensor 44. Thereby, the braking force of the brake device 1 can be controlled to a desired magnitude.
As described above, according to this embodiment, the flange 41 is always elastically pressed to the second axial direction X2 side by the elastic body 37 interposed between the annular step portion 15c and the flange 41. Since the flange 41 is fixedly provided on the screw shaft 28, the elastic pressing force is transmitted to the screw shaft 28. Thereby, the force which goes to the 2nd axial direction X2 can always be provided to the screw shaft 28. FIG. Therefore, a preload can be always applied to the load sensor 44. Thereby, the preload can be applied to the load sensor 44 with a simple structure of the combination of the flange 41 and the elastic body 37. Therefore, it is possible to provide the brake device 1 with a simple structure that can always apply the preload to the load sensor 44.

The flange 41 also serves as a pressing flange that applies an axial load to the load sensor 44 via the thrust bearing 42 and a receiving flange that receives an elastic pressing force from the elastic body 37. Therefore, as compared with the case where these flanges are provided individually, the structure can be further simplified.
Although one embodiment of the present invention has been described above, the present invention can be implemented in other forms.

FIG. 3 is a schematic enlarged cross-sectional view of a brake device according to another embodiment of the present invention.
As shown in FIG. 3, a sliding bearing 51 may be interposed between the elastic body 37 and the flange 41. The slide bearing 51 has an annular plate shape. The main surface 51a on the first axial direction X1 side of the slide bearing 51 is in sliding contact (sliding contact) with the first main surface 41a of the flange 41. In this case, the flange 41 can be rotated more favorably with respect to the brake cylinder 13.

Further, a pressing flange that applies an axial load to the load sensor 44 via the thrust bearing 42 and a receiving flange that receives an elastic pressing force from the elastic body 37 may be provided individually.
Further, although the strain detection type load sensor is exemplified as the load sensor 44, a magnetic type load sensor can be adopted as the load sensor.

The elastic body 37 is not limited to a rubber member, and for example, a plurality of coil springs can be arranged in the circumferential direction Y.
In addition, various modifications can be made within the scope of the claims.

DESCRIPTION OF SYMBOLS 1 ... Brake device, 2 ... Disc, 6 ... 1st pad, 7 ... 2nd pad, 13 ... Brake cylinder (housing), 15b ... Inner periphery, 15c ... Annular step, 17 ... Brake piston, 17a ... Outer periphery, 19 DESCRIPTION OF SYMBOLS ... Key, 20 ... Electric motor (rotation drive source), 22 ... Ball screw device, 28 ... Screw shaft, 29 ... Ball, 30 ... Ball nut, 37 ... Elastic body, 41 ... Flange, 41c ... Outer peripheral part, 42 ... Thrust Bearing, 44 ... Load sensor, 51 ... Slide bearing, X ... Axial direction, X1 ... First axial direction (one axial direction), X2 ... Second axial direction (the other axial direction), Z ... Radial direction

Claims (4)

A brake device that generates a braking force by applying a pressing force along a wheel axis direction to a pad with respect to a disk that rotates integrally with a wheel,
A tubular housing;
A cylindrical brake piston that presses the pad, the outer periphery of the brake piston being surrounded by the housing;
A screw shaft extending along the wheel shaft direction, and a ball nut screwed to the screw shaft via a plurality of balls, and is housed in the housing, and the rotational motion from the rotational drive source is linear motion A ball screw device for converting to and transmitting to the brake piston,
The brake piston is provided so as to be movable in an integral axial direction with respect to the ball nut,
The pressing force is applied to the pad by moving the brake piston toward one axial direction,
An annular step portion is formed at the end portion on the other axial side of the housing,
The brake device is
A load sensor that receives the reaction force of the pressing force applied to the pad and that acts on the screw shaft, receives an axial load toward the other axial direction, and detects the magnitude of the axial load; ,
A flange fixedly provided on an outer periphery of the screw shaft and extending along a radial direction of the screw shaft, wherein at least an outer peripheral portion is opposed to the annular step portion in the axial direction;
The brake device further includes an elastic body that is interposed between the annular step portion of the housing and the flange and elastically presses the annular step portion and the flange away from each other along the axial direction. A thrust bearing that is externally fitted and fixed to the outer periphery of the screw shaft;
The load sensor is disposed on the other axial side with respect to the thrust bearing,
The brake device according to claim 1, wherein the axial load is applied to the load sensor via the thrust bearing by the flange pressing the thrust bearing.   The brake device according to claim 1 or 2, wherein the elastic body is supported by the annular step portion of the housing.   The brake device according to any one of claims 1 to 3, wherein a sliding bearing is interposed between the elastic body and the first main surface of the flange.

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