JP2010181001A - Electric brake device and lock mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved lock mechanism in an electric brake device that is used for both a service brake and a parking brake. <P>SOLUTION: When the service brake is requested to operate, a drive member is moved in an axial direction, and a ball 114 is relatively moved in a service brake groove 124PR (b). When the parking brake is requested to operate, an electric motor is controlled in accordance with a predetermined pattern, whereby the drive member is moved in a P-direction and thereafter moved in a Q-direction. The ball 114 is removed from the service brake groove 124PR and accommodated in a parking lock groove 124PR via a refuge groove 124Q (f). Even if an acting force in the Q-direction is applied to the drive member in this state, the drive member is prevented from moving in the Q-direction, therefore, a parking brake force is retained even if a current is not supplied to the electric motor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lock mechanism.

Patent Documents 1 and 2 disclose a lock mechanism in which a cylindrical roller or ball is brought into a locked state by being moved to a narrow portion of a wedge-shaped space and is brought into an unlocked state by being moved to a wide portion. Is described.
Among them, Patent Document 1 discloses that (a) a brake that is actuated by a tensile force of a cable connected to a drive member, (b) an electric motor, and (c) an output shaft of the electric motor that rotates with rotation. An electric parking brake device including a motion conversion mechanism that converts rotation of the rotation shaft to linear motion of the drive member, and (d) a lock mechanism provided between the output shaft and the rotation shaft of the electric motor is described. ing. The lock mechanism includes (e) a cam surface provided on the outer peripheral surface of the rotating shaft, and (f) a cylindrical roller held in a wedge-shaped space formed between the cam surface and the housing.
When the output shaft is rotated by the drive of the electric motor, the rotation shaft is rotated accordingly, the rotation of the rotation shaft is converted into the linear motion of the drive member by the motion conversion mechanism, the cable is pulled, and the brake ( The parking brake is activated. In this state, when the force to loosen the cable acts on the drive member and the rotating shaft is rotated slightly in the opposite direction, the roller moves in the circumferential direction until it reaches the narrow part of the wedge-shaped space. To be locked. In this locked state, the rotation of the rotating shaft is prevented from being transmitted to the output shaft of the electric motor, and the parking brake force is maintained even if no current is supplied to the electric motor.
Further, in Patent Document 2, (i) a tapered surface provided between the inner peripheral surface of the housing and the outer peripheral surface of the drive member, (i) formed on the inner peripheral surface of the housing, and inclined in the axial direction; A lock mechanism including a ball disposed between the tapered surface and the outer peripheral surface of the drive member is described. In this lock mechanism, the ball is moved between the lock position and the unlock position by the operation of the lever by the operator.

JP 2004-144124 A Japanese Patent Laid-Open No. 2006-97887

  An object of the present invention is to improve a lock mechanism, in particular, a lock mechanism included in an electric brake device.

Means and effects for solving the problem

An electric brake device according to a first aspect of the present invention includes: (a) a brake that is actuated by an axial movement of a drive member; (b) an electric motor; and a rotation of the electric motor that is converted into a linear motion. An electric actuator including a motion conversion mechanism for transmitting; (c) a motor control device that controls the electric motor according to a predetermined pattern when a parking brake operation is requested; and (d) the drive member and its drive A locking mechanism provided between a housing that holds the member so as to be relatively movable in the axial direction, and (i) a movable groove formed in the drive member; and (ii) a fixed formed in the housing. A groove, and (iii) one or more pieces held so as to be relatively movable between the movable groove and the fixed groove, and the movable groove and the fixed groove do not have a portion parallel to each other. Formed in state And the relative movement from the unlocked state to the locked position, which is a predetermined relative position between the movable groove and the fixed groove, according to the control according to the pattern by the motor control device. And a lock mechanism that can be switched to a locked state that prevents the drive member from moving in a direction in which the acting force of the brake is reduced even when no electric current is supplied to the electric motor. The
The piece is moved relative to the housing in the axial direction with respect to the housing of the drive member. When the piece is moved relative to the lock position, the piece is locked.
The movable groove and the fixed groove are formed so as not to have portions that are parallel to each other. This is because the relative positions of the pieces with respect to the drive member and the housing are not determined in the parallel parts, and the relative positions of the pieces cannot be determined. In other words, the movable groove and the fixed groove appear to intersect each other when viewed from the side of the housing, regardless of the relative position of the drive member with respect to the housing (in fact, they do not intersect) ).
The lock position is a position at which the movement of the driving member in the direction in which the braking force of the driving member is reduced is prevented by the piece. For example, when the fixed groove has an annular shape and the movable groove includes a portion extending in the axial direction, the fixed groove and the portion of the movable groove that extends in the axial direction are opposite to the direction in which the braking force is reduced. The position can be determined by the end.
As described above, the structure of the lock mechanism included in the electric brake device according to claim 1 of the present application is different from the structure of the lock mechanism described in Patent Documents 1 and 2.
Note that the piece moves when the drive member is moved relative to the housing in the axial direction, and when the piece does not actually move, but the relative position of the piece with respect to the movable groove changes (apparent movement). There is. Hereinafter, in this specification, both the actual movement and the apparent movement may be referred to as “relative movement of the pieces”. Moreover, it may be used as a term including both.
In addition, the piece can be a sphere, but it is not essential. For example, it may be a disk or cylinder.

Patentable invention

  In the following, the invention that is claimed to be claimable in the present application (hereinafter referred to as “claimable invention”. The claimable invention is at least the “present invention” to the invention described in the claims. Some aspects of the present invention, including subordinate concept inventions of the present invention, superordinate concepts of the present invention, or inventions of different concepts) will be illustrated and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the set of components constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

(1) a brake actuated by axial movement of the drive member;
An electric actuator comprising: an electric motor; and a motion conversion mechanism that converts the rotation of the electric motor into a linear motion and transmits the linear motion to the drive member;
A motor control device that controls the electric motor so as to obtain a required braking force when a service brake is requested, and controls the electric motor according to a predetermined pattern when a parking brake is requested, and the pattern by the motor control device According to the control in accordance with the control, the unlocked state is switched to the locked state in which the driving member is prevented from moving in the direction in which the acting force of the brake is reduced even when no electric current is supplied to the electric motor. An electric brake device including a lock mechanism.
In the electric brake device, the brake is operated by an electric actuator, and is operated as both a service brake and a parking brake.
The electric motor is controlled so as to obtain a required braking force when a service brake is requested, and is controlled according to a predetermined pattern when a parking brake is requested. The lock mechanism is switched from the unlocked state to the locked state in accordance with the control according to the predetermined pattern of the electric motor. In the locked state, even if no electric current is supplied to the electric motor, the drive member is prevented from moving in a direction in which the braking force is reduced, and the braking force is maintained.
Thus, the electric actuator for operating the service brake and the electric actuator for operating the parking brake are the same (common). Therefore, it is possible to reduce the number of parts and reduce the cost of the electric brake device as compared with the case where a dedicated one is provided.
Hereinafter, in this specification, “the operation of the brake” is used as a term including either one or both of the operation for bringing the brake into an applied state and the operation for releasing the brake.
(2) The brake is provided on a wheel of the vehicle, (a) a brake rotating body rotated together with the wheel, (b) a friction member held on the non-rotating body of the vehicle, and (c) the friction member The electric brake device according to item (1), further including a pressing device that presses the brake against the brake rotating body.
The pressing device can include, for example, an electric actuator and a driving member. The brake may be a drum brake or a disc brake.
(3) When the motor control device requests the operation of the parking brake, the motor control device moves the supply current to the electric motor until the drive member reaches a predetermined first position in a direction in which the braking force increases. In addition, the electric brake device according to (1) or (2), further including a parking brake operation time control unit that performs control with a pattern that moves to a predetermined second position in a direction in which the brake operation force decreases.
When the electric motor is controlled according to the pattern (pattern at the time of parking lock), the driving member is moved to the first position in the direction in which the braking action force is increased, and is moved to the second position in the direction in which the braking action force is reduced. . Thereby, the lock mechanism is switched from the unlocked state to the locked state.
The fact that the drive member has reached the first position or the second position is that (i) a stroke sensor for detecting the amount of movement (stroke) from the reference relative position of the drive member to the housing is provided, and based on the detection value by the stroke sensor (Ii) An action force sensor (or a pressing force sensor that detects the pressing force of the friction member against the brake rotating body) is provided and acquired based on the detection value of the action force sensor. You can do it. Since the stroke of the drive member with respect to the housing corresponds to the braking force and the friction material pressing force, the stroke (relative position) can be acquired based on the braking force and the friction material pressing force. (Iii) Drive based on the relative position of the drive member to the housing at the time of parking brake action request (position other than the non-actuated position when the service brake is applied), the rotational speed of the electric motor, etc. The target operation time required for the member to reach the first position can be obtained, and can be acquired by the elapsed time from the start of the operation of the electric motor reaching the target operation time. Further, the time from the first position to the second position is a predetermined set time when the rotation speed of the electric motor is constant. The target operating time can be a fixed value.
(4) Items (1) to (3), wherein the lock mechanism is switched from the locked state to the unlocked state by control of the electric motor according to a predetermined pattern by the motor control device. The electric brake device according to any one of the items.
For example, the control pattern of the electric motor (the parking lock release pattern) is moved until the driving member reaches the third position in the direction in which the braking action force increases and reaches the fourth position in the direction in which the braking action force decreases. It can be a moving pattern.
The third position can be the same position as the first position, but is not essential.
The fourth position is a position where the parking lock is released, for example, the position of the drive member in the non-operating state of the brake, the return spring provided in the brake, etc., without depending on the control of the electric motor, The driving member can be set to a position where the driving member can be returned to the position in the non-operating state, or can be set to a position where bidirectional movement of the driving member is allowed. The fourth position may be a different position depending on whether or not the service brake is requested when releasing the parking lock.
The control pattern of the electric motor for changing the brake from the non-operating state to the locked state and the control pattern of the electric motor for changing the brake state to the non-operating state of the brake are the same.
Further, the unlocked state can be any state that is not in the locked state, or a state in which the service brake can be operated. The state where the service brake can be operated includes a non-operating state of the brake. When all states that are not in the locked state are considered to be in the unlocked state, the state during the operation for parking lock and the state during the operation for unlocking also correspond to the unlocked state.
(5) a brake actuated by axial movement of the drive member;
An electric actuator comprising: an electric motor; and a motion conversion mechanism that converts the rotation of the electric motor into a linear motion and transmits the linear motion to the drive member;
A motor control device for controlling the electric motor in accordance with a predetermined pattern when a parking brake operation is requested;
A locking mechanism provided between the drive member and a housing that holds the drive member so as to be relatively movable in the axial direction, and (a) a movable groove formed in the drive member; and (b) A fixed groove formed in the housing; and (c) one or more pieces held so as to be relatively movable between the movable groove and the fixed groove, the movable groove and the fixed groove being mutually The piece is formed in a state having no parallel part, and the piece is determined in advance by the movable groove and the fixed groove in accordance with the control according to the pattern by the motor control device from the unlocked state. The lock prevents the drive member from moving in the direction in which the acting force of the brake is reduced even when no electric current is supplied to the electric motor by being moved relative to the lock position, which is a relative position. Status Electric brake device which comprises a lock is switched mechanism.
The technical features described in any one of items (1) to (4) can be employed in the electric brake device described in this item.
(6) The drive member has a generally cylindrical shape, and a drive member housing space extending in the axial direction having a circular cross-sectional shape is formed in the housing, and the drive member housing space includes the drive member housing space. A driving member is provided, the movable groove is formed in a circumferentially continuous state on the outer peripheral surface of the driving member, and the fixed groove is formed in a circumferentially continuous state on the inner peripheral surface of the housing. The electric brake device according to item (5).
A lock mechanism is formed between the inner peripheral surface of the housing and the outer peripheral surface of the drive member, the fixed groove is formed in the circumferential direction on the inner peripheral surface of the housing, and the movable groove is the outer periphery of the drive member. It is formed in a continuous state on the surface in the circumferential direction. Either one of the movable groove and the fixed groove may have an annular shape.
It is not indispensable to form the movable groove and the fixed groove in a continuous state in the circumferential direction. However, if the movable groove and the fixed groove are formed in a continuous state in the circumferential direction, the piece also has a relative relationship within the region determined by the movable groove and the fixed groove. It is possible to go around. In addition, when the movable groove and the fixed groove are formed in a state where they are not continuous in the circumferential direction, the piece is reciprocated within an area determined by the movable groove and the fixed groove.
(7) One of the movable groove and the fixed groove is (a) formed in a state of being continuous in the circumferential direction, and a portion having axial components opposite to each other and circumferential components in the same direction. Zigzag grooves formed alternately, and (b) formed in a state in which the zigzag grooves communicate with the zigzag grooves at positions shifted to the same side in the circumferential direction from the bottom of the valleys of the walls constituting the zigzag grooves. The electric brake device according to (5) or (6), including a plurality of extending axial grooves.
The zigzag groove is composed of a plurality of portions that are inclined with respect to the axial direction (hereinafter referred to as inclined portions). The plurality of inclined portions all have circumferential components in the same direction, but some of the plurality of portions have an axial component extending in one of the axial directions, and the rest have an axial component extending in the other. Have. And the inclination part A which belongs to the part and the inclination part B which belongs to the remainder are arrange | positioned alternately. As a result, the zigzag shape is continuous in the circumferential direction.
When one of the movable groove and the fixed groove includes the zigzag groove described above and the other includes an annular groove formed in an annular shape, the piece is annulus as the drive member moves relative to the housing in the axial direction. It is actually moved along the inclined part of the groove and the zigzag groove (the piece is moved in the circumferential direction, not in the direction inclined with respect to the axial direction). In the zigzag groove, the inclined portions A and B having axial components opposite to each other are alternately arranged. Therefore, the drive member is moved relative to the housing in one direction and then moved in the other direction. In the case of relative movement, the piece is moved along the inclined portion A and then moved along the inclined portion B, but is moved in the same circumferential direction of the annular groove ( The traveling direction of the pieces is the same).
The axial groove is formed in a state communicating with the zigzag groove at a position shifted from the bottom of the valley of the wall of the zigzag groove to the same side in the circumferential direction. As a result, the piece can be brought into contact with the wall of the groove to be relatively moved from now on, and can be relatively moved in a desired direction by the relative movement of the fixed groove and the movable groove. The wall of the axial groove and the wall of the zigzag groove serve as a guide wall (guide portion).
In addition, since all the axial grooves are provided at positions shifted from the bottom of the valley of the wall of the zigzag groove to the same side in the circumferential direction, the pieces are moved in the circumferential direction in the direction in which the axial grooves are shifted. Will be. The direction in which the axial groove is displaced with respect to the bottom of the valley of the wall of the zigzag groove is the traveling direction in the circumferential direction of the piece.
(8) Of the plurality of axial grooves, a groove formed on one side of the zigzag groove in the axial direction is a retraction groove, and among grooves formed on the other side, adjacent grooves The electric brake device according to item (7), wherein one is a parking lock groove and the other is a service brake groove longer than the parking lock groove.
The retracting groove is provided to temporarily retract the piece when the direction of relative movement of the driving member in the axial direction is changed when the parking brake is requested to operate. After the piece is relatively moved along the inclined portion A, the piece is accommodated in the retracting groove, and is then relatively moved along the inclined portion B. In this sense, the retracting groove can be referred to as a direction switching groove.
The parking lock groove is a groove having a shape that can prevent the drive member from moving in a direction in which the braking force is reduced when a piece is positioned in the parking lock groove.
The service brake groove is a groove in which the piece is positioned when the brake is not operated and when the service brake is operated, and is longer in the axial direction than the parking lock groove and the retracting groove. As the drive member is moved relative to the housing in the axial direction within a range where the piece is positioned in the service brake groove, the acting force of the service brake is increased or decreased. The length of the service brake groove is the entire stroke of the drive member when the service brake is applied.
When the piece is located between the axial groove and the annular groove, the piece usually does not move in the axial direction or in the circumferential direction. This is because the drive member is usually held so as to be movable relative to the housing in the axial direction and non-rotatable. In this case, the piece apparently moves with respect to the axial groove as the drive member moves relative to the housing in the axial direction.
In addition, the piece is positioned in the service brake groove when the service brake is operated, and can be prevented from being detached from the service brake groove. When the parking brake is operated, the zigzag groove, the parking lock groove, the piece evacuation are performed. It is located in one of the grooves and can be prevented from entering the service brake groove. In this way, it is possible to divide the area where the piece exists between when the service brake is activated (during operation) and when the parking brake is activated. The service brake area and the parking brake area can also be determined by the range of relative movement of the drive member in the axial direction.
The state where the piece is present in the service brake groove can be set to the unlocked state.
(9) One of the movable groove and the fixed groove is provided between the service brake groove and the parking lock groove, with one retraction groove and the zigzag groove having opposite axial directions. The electric brake device according to item (8), wherein the electric brake device is provided in a state in which a pair of portions having an axial component is positioned.
One retracting groove and inclined portions A and B are formed between the service brake groove and the parking lock groove. Therefore, the drive member reciprocates in the axial direction with respect to the housing both when the piece is relatively moved from the service brake groove to the parking lock groove and when the piece is relatively moved from the parking lock groove to the service brake groove. Moved. Thereby, the piece is relatively moved between the service brake groove and the parking lock groove. The lock mechanism is switched between an unlocked state and a locked state.
(10) The width and depth of the gap between the movable groove and the fixed groove are the same in the region where the piece is positioned, as described in any one of (5) to (9) Electric brake device.
The piece is held between the movable groove and the fixed groove. The size of the gap between the movable groove and the fixed groove, that is, the width and the depth are basically the same in all the relative movement ranges of the pieces. The width of the gap is determined by the width of the opening of the movable groove and the fixed groove, and these are usually the same as each other. The depth of the gap is the sum of the depths of the movable groove and the fixed groove.
For example, the depth and width are the same between the gap between the movable groove and the fixed groove at the lock position and the gap at the portion other than the lock position. Further, the depth and width of the gap are both equal to or larger than the corresponding dimensions of the piece.
Conversely, the width and depth of the gap at the lock position can be made larger than the width and depth of the gap at a portion other than the lock position. This is because the lock position is determined by the shapes of the fixed groove and the movable groove.
Further, the width and depth of the gap at the lock position can be made smaller than the width and depth of the gap at portions other than the lock position. It is also possible to make the space of the parking lock groove into a wedge shape.
(11) One of the movable groove and the fixed groove is (a) formed in a state of being continuous in the circumferential direction, and a portion having axial components opposite to each other and circumferential components in the same direction. Zigzag grooves arranged alternately, (b) a plurality of axial grooves formed in communication with the zigzag grooves and extending in the axial direction, and (c) at least of the axial grooves and the zigzag grooves. The electric brake device according to any one of (5) to (10), including a guide wall provided on one side and guiding the piece.
The guide wall is a wall that guides the pieces and determines the direction of relative movement of the pieces. The guide wall is formed around the connecting portion between the axial groove and the zigzag groove, and can be a wall constituting the axial groove and a wall constituting the zigzag groove. For example, when the piece is relatively moved from the zigzag groove to the axial groove, the wall of the axial groove is used as a guide wall, and when the piece is relatively moved from the axial groove to the zigzag groove, the wall of the inclined portion of the zigzag groove is It is a guide wall.
Although guide walls can be provided in both the zigzag groove and the axial groove, this is not essential.
(12) A plurality of the pieces are disposed between the movable groove and the fixed groove, and the lock mechanism includes a piece holding portion that holds the plurality of pieces connected to each other. The electric brake device according to any one of items (11) to (11).
When the piece is held between the movable groove and the fixed groove, the piece may be moved by gravity. On the other hand, if a plurality of pieces are arranged at equal intervals in the circumferential direction and connected to each other, it is possible to cancel the action of gravity in the piece association (including the plurality of pieces and the piece holding portion). .
(13) Item (5) to Item (12), wherein the motor control device includes a service brake action request control unit that controls the electric motor so that a required brake action force is obtained when a service brake action is requested. The electric brake device according to any one of the above.
(14) A lock mechanism provided between the housing and a drive member held in the housing so as to be relatively movable in the axial direction, and for preventing the drive member from moving in a predetermined axial direction. And
A movable groove formed in the drive member;
A fixing groove formed in the housing;
Including one or more pieces that are held between the movable groove and the fixed groove so as to be relatively movable, and the movable groove and the fixed groove are formed in a state in which they do not have a portion parallel to each other. The lock mechanism is switched from the unlocked state to the locked state by being moved relative to the lock position which is a predetermined relative position between the movable groove and the fixed groove.
The technical features described in any one of the items (1) to (13) can be adopted for the lock mechanism described in this item.
(15) The movable groove is formed in a circumferentially continuous state on the outer peripheral surface of the drive member, and the fixed groove is formed in a circumferentially continuous state on the inner peripheral surface of the housing, and fixed to the movable groove. Any one of the grooves comprises (a) a zigzag groove in which portions having axial components opposite to each other and a circumferential component in the same direction are arranged alternately, and (b) constitutes the zigzag groove. A plurality of axial grooves formed in a state of communicating with the zigzag groove at a position shifted from the valley of the wall to the same side in the circumferential direction, and extending in the axial direction, and among the plurality of axial grooves, A groove formed on one side of the zigzag groove in the axial direction is a retracting groove, and one of adjacent grooves among the grooves formed on the other side is a locking groove, and the other is the locking groove. The lock according to (14), which is longer than the groove for unlocking. Structure.

It is a front view of the brake contained in the electric brake device which is one Example of this invention. It is a figure (partial cross section figure) which shows the electric actuator periphery contained in the said electric brake device. It is a part of expanded view which shows the movable groove which is the principal part of the lock mechanism contained in the said electric brake device. It is AA sectional drawing of FIG. It is an action | operation figure of the said locking mechanism. It is a flowchart showing the motor control program memorize | stored in the memory | storage part of the motor control apparatus contained in the said electric brake device. It is a figure which shows the relationship between the stroke of a drive member, and pressing force (action force) in the said electric brake device. It is a figure which shows the principal part of another lock mechanism of the said electric brake device. (a) It is AA sectional drawing of FIG. (b) It is BB sectional drawing of a figure.

  Hereinafter, an electric brake device according to an embodiment of the present invention will be described in detail with reference to the drawings. The electric brake device includes a lock mechanism that is an embodiment of the present invention. The electric brake device is common to the service brake and the parking brake.

As shown in FIGS. 1 and 2, the electric brake device includes a drum brake 10 provided on a wheel, an electric actuator 12 that operates the drum brake 10, and a motor control device that controls an electric motor 14 included in the electric actuator 12. As a brake ECU 16.
The drum brake 10 is of a leading trailing type as shown in FIG. The drum brake 10 is fixed to a non-rotating body of the vehicle, and has a substantially disc-shaped backing plate 20 and a pair of brake shoes 22a that are rotatably held by the backing plate 20 and have a generally arcuate shape. b, and a drum 26 having a friction surface 24 on its inner peripheral surface and rotating together with the wheel.

The pair of brake shoes 22a and 22b are prevented from rotating together with the drum 26 by being engaged with anchors 28 fixed to the backing plate 20 at one end portions facing each other. Further, return springs 34 a and 34 b are provided between each of the one end portions and the backing plate 20.
The other ends of the pair of brake shoes 22a and 22b are connected by a strut 30. The strut 30 transmits a force acting on the brake shoe 22b to the brake shoe 22a. A return spring 32 is also provided between the other ends.
Note that the pair of brake shoes 22a and 22b can be moved along the surface of the backing plate 20 by shoe hold-down devices 35a and 35b.

Brake linings 36a and 36b as friction engagement members are held on the outer peripheral surfaces of the brake shoes 22a and 22b, respectively. When the pair of brake linings 36a and 36b are pressed against the inner peripheral surface 24 of the drum 26, the brake linings 36a and 36b and the drum 26 are frictionally engaged, and a frictional force is generated therebetween. Although this frictional force is a braking force, when the friction coefficient between the brake linings 36a, 36b and the inner peripheral surface 24 of the drum 26 is constant, the frictional force becomes a magnitude corresponding to the pressing force.
In the present embodiment, the strut 30 is provided with an adjusting mechanism, and the gap between the brake linings 36a, 36b and the inner peripheral surface 24 of the drum 26 is adjusted according to wear of the brake linings 36a, 36b. To do.

One end of the lever 50 is rotatably provided via a pin 52 at the other end of the one brake shoe 22b. Notches are provided in portions of the lever 50 and the brake shoe 22b facing each other, and the struts 30 are provided between these notches and the notches provided in the other brake shoe 22a. .
The electric actuator 12 is connected to the other end of the lever 50. The electric actuator 12 is operated regardless of whether a brake operation member (for example, a brake pedal) 60 for service brake is operated or a brake operation member (for example, a parking brake switch) 62 for parking brake is operated. The brake 10 is activated. The electric actuator 12 can be actuated even when it is necessary to automatically activate the service brake.

As shown in FIG. 2, the electric actuator 12 includes a drive transmission mechanism 68, a motion conversion mechanism 70, a lock mechanism 72 and the like in addition to the electric motor 14. In this embodiment, the motion conversion mechanism 70 and the lock mechanism 72 are held on the surface of the backing plate 20 on the side where the pair of brake shoes 22a and 22b are held, and the electric motor 14 and the drive transmission mechanism 68 are connected to the backing plate 20. Is held on the back surface (the surface on which the brake shoes 22a and 22b are not held).
The motion conversion mechanism 70 converts the rotation of the output shaft of the electric motor 14 into a linear movement of the drive member 74 and has a screw mechanism. A screw portion 76 is formed at the intermediate portion of the drive member 74, and a nut member 78 is screwed into the screw portion 76. The nut member 78 is relatively rotatable with respect to the housing 80 via a pair of bearings 82 and 84 and is held so as not to be relatively movable in the axial direction (direction parallel to the axis M in FIG. 2). The drive member 74 is held in the housing 80 in a posture parallel to the axis M via the relative rotation prevention device 86, and is relatively unrotatable about the axis M and is relatively movable in a direction parallel to the axis M. Retained.

The drive transmission mechanism 68 transmits the driving force of the electric motor 14 to the driving member 74 (motion conversion mechanism 70). The motor side gear 90, the motor side gear 90, and the nut are fixed to the output shaft of the electric motor 14. An intermediate gear 92 provided between the member 78 and the member 78 is included. The rotation of the electric motor 14 is transmitted to the nut member 78 through the motor side gear 90 and the intermediate gear 92. The nut member 78 is rotated, and the drive member 74 is moved in the axial direction.
In the non-operating state of the drum brake 10, the drive member 74 is located at the moving end in the Q direction. When the electric motor 14 is rotated, the drive member 74 is moved in the P direction. The lever 50 is rotated and the pair of brake shoes 22a and 22b are expanded, whereby the brake linings 36a and 36b are pressed against the inner peripheral surface 24 of the drum 26. When the amount of movement of the drive member 74 in the P direction is large, the pressing force becomes larger and the brake acting force becomes larger than when the movement amount is small.
When the electric motor 14 is rotated in the reverse direction, the drive member 74 is moved in the Q direction. Thereby, the pressing force is reduced, and the braking force is reduced. When releasing the action of the drum brake 10, the drive member 74 is normally returned to the moving end position in the Q direction by the control of the electric motor 14, but the drive member 74 is moved in the Q direction by the control of the electric motor 14. In the drum brake 10, the pair of brake shoes 22a and 22b are reduced in diameter by the elastic force of the return springs 32, 34a, and b (returned to the non-operating position) without returning to the moving end position. 74 may be returned to the moving end position in the Q direction.

One end of the drive member 74 is linked to the lever connecting member 98 via a spring 96. The other end of the lever 50 is connected to the lever connecting member 98.
The spring 96 is provided between the lever connecting member 98 and the drive member 74, and has a relatively large set load and a relatively small spring constant. While the force in the direction of arrow P applied to the drive member 74 is small, the spring 96 is not elastically deformed. As the drive member 74 moves in the direction of arrow P, the lever connecting member 98 is moved in the direction of arrow P, and the braking force is increased accordingly.
When the force in the direction of arrow P applied to the drive member 74 increases and the set load of the spring 96 is exceeded, the spring 96 is compressed, and the elastic force of the spring 96 is applied to the lever connecting member 98. Since the spring constant of the spring 96 is relatively small, it is possible to suppress the increase gradient of the braking action force and to avoid the braking action force from becoming excessive.

A lock mechanism 72 is provided between the outer peripheral surface of the other end of the drive member 74 and the inner peripheral surface of the housing 80.
The drive member 74 is generally cylindrical. The housing 80 is formed with a space 100 having a circular cross section and extending in parallel with the axis M, and the other end 102 of the drive member 74 is accommodated in the space 100. The lock mechanism 72 is provided between the inner peripheral surface of the portion (outer cylinder) where the space 100 of the housing 80 is formed and the outer peripheral surface (inner cylinder) of the other end portion 102 of the drive member 74.
3 and 4, the lock mechanism 72 is formed on the outer peripheral surface of the annular fixing groove 110 formed on the inner peripheral surface of the housing 80 (outer cylinder) and the drive member 74 (inner cylinder). A movable groove 112 that is continuous in the circumferential direction and a plurality of balls (spheres) 114 that are fitted between the fixed groove 110 and the movable groove 112 are included. In FIG. 3, a part of the movable groove 112 is described by assuming that the outer peripheral surface of the driving member 74 is a single plane. Since both the fixed groove 110 and the movable groove 112 are continuously formed in the circumferential direction, the ball 114 can be turned. In this embodiment, the ball 114 revolves instead of reciprocating in the circumferential direction.

Each of the fixed groove (outer peripheral groove) 110 and the movable groove (inner peripheral groove) 112 has a semicircular cross section, and the fixed groove 110 and the movable groove 112 face each other so that the cross section is circular. A gap is formed. The ball 114 is always held in the gap between the fixed groove 110 and the movable groove 112, and the size of this gap is basically the same. Strictly speaking, there is a portion where the size of the gap is different due to the shape of the movable groove 112, but in any portion, the width and depth of the gap between the fixed groove 110 and the movable groove 112 are: The diameter is not less than the diameter of the ball 114 and not a wedge shape.
Further, the fixed groove 110 and the movable groove 112 are formed in a state in which there are no portions that are parallel to each other. The fixed groove 110 and the movable groove 112 intersect with each other regardless of the relative positional relationship of the drive member 74 with respect to the housing 80, for example, when viewed from the side of the portion where the space 100 of the housing 80 is formed. (Not actually crossing). As a result, the position of the hole 114 is determined by the relative movement between the fixed groove 110 and the movable groove 112.

The movable groove 112 includes a zigzag groove 122 including a plurality of inclined portions 120 inclined with respect to the axis M, and a plurality of axial grooves 124 formed in communication with the zigzag groove 122 and extending in parallel with the axis M. .
The zigzag groove 122 includes a total of 16 inclined portions 120. The circumferential components of all sixteen inclined portions 120 are in the same direction, but the eight inclined portions 120a and the remaining eight inclined portions 120b have the axial components opposite to each other, and the axial components are mutually opposite. Inclined portions 120a and 120b having opposite sides are alternately arranged. Thereby, a zigzag shape continuous in the circumferential direction is formed.
The zigzag groove 122 includes an axial P-side zigzag wall 125P and a Q-side zigzag wall 125Q. The zigzag wall 125P has eight valley bottoms 126P that are concave in the P direction, and the zigzag wall 125Q has eight valley bottoms 126Q that are concave in the Q direction. Note that the bottom portions 126P and Q of the valleys are located at the connecting portions of the adjacent inclined portions 120a and 120b.
An axial groove 124 is formed at a position spaced in the circumferential direction R from the bottom 126P, Q of each valley. As shown in FIG. 3, the axial groove 124 is formed at a position where the center in the width direction of the axial groove 124 is separated from the bottom 126P, Q of the valley by a distance S in the R direction. Specifically, the wall 127 on the bottom side of the valley among the pair of axial walls 127 and 128 constituting the axial groove 124 is δ in the R direction from the bottom 126P, Q of the valley of the zigzag wall 125P, Q in the R direction. The zigzag groove 122 is formed in a posture extending to a separated position, and the zigzag wall 125P of the drive member 74, and the bottom 126P of the valley of the Q, the periphery of the Q is formed in a shape cut out.

The axial groove 124P provided in the vicinity of the valley bottom 126P of the zigzag wall 125P extends in the P direction, and the axial groove 124Q provided in the vicinity of the valley bottom 126Q of the zigzag wall 125Q is Q. The posture is extended in the direction. The axial groove 124Q is a retracting groove, and one of the axial grooves 124P adjacent to each other is a parking lock groove 124PR, and the other is a service brake groove 124PB.
As shown in FIG. 4, the parking lock grooves 124PR and the service brake grooves 124PB are alternately provided, and one retraction groove 124Q and a pair of grooves are provided between the service brake groove 124PB and the parking lock groove 124PR. Inclined portions 120a and 120b are located. Between the adjacent service grooves 124PB, one parking lock groove 124PR, two retraction grooves 124Q, and two pairs of inclined portions 120a and 120b are located.

In this embodiment, a set including one service brake groove 124PB, one parking lock groove 124PR, two retraction grooves 124Q, and two inclined portions 120a and 120b in the circumferential direction of the drive member 74 is provided. A set is provided. In other words, one set of these is formed between the central angles π / 2 of the outer peripheral surface of the drive member 74, and one ball 114 is arranged at equal intervals in each set. In this way, by providing a plurality of balls 114 in the lock mechanism 72, the load applied to one ball 114 can be made smaller than in the case of one, and durability can be improved.
The service brake groove 124PB is longer in the axial direction than the parking lock groove 124PR, and the length of the service brake groove 124PB is the entire stroke of the drive member 74 when the service brake is operated.

In this specification, zigzag walls 125P and bottoms 126P and Q of zigzag walls 125P and Q, axial grooves 124P and Q, and axial walls 127P, Q, 128P and Q constituting the zigzag groove 122 are “P, Q” It means that it is formed on the P side and that formed on the Q side. Further, when “P, Q” is attached to the bottom 126 of the valley, the axial groove 124, the axial walls 127, 128, or these, there are cases where each is shown individually or the whole.
On the other hand, when each of the axial grooves 124 is shown separately, they are referred to as a service brake groove 124PB, a parking lock groove 124PR, and a retracting groove 124Q. Further, in the case where the inclined portions 120a and 120b constituting the valley bottom 126, the axial groove 124, and the zigzag groove 122 are shown separately, for example, a number such as “−1” is added. Distinguish.

As described above, the axial grooves 124 </ b> P and Q are provided at positions shifted in the same direction R from the zigzag walls 125 </ b> P and the bottom portions 126 </ b> P and Q of the valleys of the Q that constitute the zigzag groove 122. For this reason, there is a groove wall in which the ball 114 is to be relatively moved next in the traveling direction of the ball 114, and the ball 114 is in contact with and guided by the wall.
Further, the axial groove 124 is provided in a posture in which the axial wall 127 extends at a position δ away from the bottom portion 126 of the valley, and therefore, the axial groove 124 has a shaft shape as compared with the case where the wall 127 is provided in a posture extending from the bottom portion 126 of the valley. The offset amount of the direction groove 124 can be increased, and the ball 114 can be brought into contact with the wall of the groove to be relatively moved from now on more reliably.
For example, when the ball 114 is positioned in the service brake groove 124PB, if the drive member 74 is moved relative to the housing 80 in the P direction, the ball 114 moves in the direction indicated by the arrow X in FIG. 3 (Q direction). Next, it is moved relative to the service brake groove 124PB. The ball 114 exits from the service brake groove 124PB and comes into contact with the zigzag wall 125Q of the inclined portion 120a-1 of the zigzag groove 122. The ball 114 is pushed by the zigzag wall 125Q of the inclined portion 120a-1 and the wall 129 of the fixing groove 110 along the inclined portion 120a-1 as the drive member 74 moves relative to the housing 80 in the P direction. It is moved relative to the arrow Y. Thereafter, the ball 114 abuts against the axial wall 128Q of the retracting groove 124Q. As the driving member 74 moves in the P direction with respect to the housing 80, the ball 114 is relatively moved in the Q direction along the retracting groove 124Q. In this way, the ball 114 can be relatively moved in a desired direction.
In this case, a guide wall is constituted by the zigzag wall 125Q, the axial wall 128Q, and the like.

In the state where the ball 114 exists in the gap between the fixed groove 110 and the axial groove 124, the ball 114 is not moved in the axial direction even if the driving member 74 is relatively moved in the axial direction. . It only moves apparently relative to the drive member 74, that is, relative to the axial groove 124. Further, since the drive member 74 is held in the housing 80 so as not to be relatively rotatable, the drive member 74 does not move in the circumferential direction.
Further, the ball 114 is actually moved in the R direction along the fixed groove 110 in accordance with the relative movement between the zigzag groove 122 and the fixed groove 110, and is moved along the inclined portion 120. However, it does not move in a direction inclined with respect to the axis M.
As described above, in this embodiment, the case where the ball 114 actually moves or the case where it apparently moves may be referred to as relative movement without distinction.

Hereinafter, the operation of the lock mechanism 72 will be described with reference to FIG.
In the non-operating state of the drum brake 10, the driving member 74 is at a moving end position in the Q direction (for example, a position where movement in the Q direction is blocked by a stopper (not shown)). As shown in FIG. 5A, the ball 114 is located at the end of the service brake groove 124PB in the P direction.
When there is a service brake action request, the electric motor 14 is rotated and the drive member 74 is moved relative to the housing 80 in the P direction. Accordingly, the ball 114 is relatively moved in the Q direction along the service brake groove 124PB as shown in FIG. 5 (b).
When the actual acting force reaches the target acting force, no current is supplied to the electric motor 14, the rotation of the electric motor 14 is stopped, and the driving member 74 is stopped.
If the target acting force decreases, the drive member 74 is relatively moved in the Q direction, and if the target acting force is increased, the driving member 74 is relatively moved in the P direction. While the ball 114 is positioned in the service brake groove 124PR, As shown in the HH sectional view, the bidirectional relative movement of the drive member 74 in the axial direction is allowed.
This state is an unlocked state of the lock mechanism 72. In this sense, the service brake groove 124PB can also be referred to as an unlock groove.
The length of the service brake groove 124PB corresponds to the entire stroke of the drive member 74 when the service brake action is requested, and the range of the acting force that can be controlled in the service brake is determined by the length of the service brake groove 124PB. A range in which the ball 114 relatively moves when the service brake is applied can be referred to as a service brake region.

When the parking brake is requested to operate, the electric motor 14 is controlled according to a predetermined parking lock pattern, and the drive member 74 is relatively moved accordingly. In the present embodiment, the supply current to the electric motor 14 is controlled in a pattern in which the driving member 74 is relatively moved in the P direction until reaching the first relative position and is relatively moved in the Q direction until reaching the second relative position. The The first relative position is a position where the ball 114 reaches the end of the retracting groove 124Q, and the second relative position is a position where the ball 114 reaches the end of the parking lock groove 124PR. The fact that the driving member 74 has reached the first relative position and the second relative position can be detected by the fact that the acting force has reached a predetermined set value. This is because the relative position of the drive member 74 with respect to the housing 80 can be considered to correspond to the acting force.
As shown in FIG. 5C, when the drive member 74 is relatively moved in the P direction by the electric motor 14, the ball 114 is relatively moved in the Q direction. The service brake groove 124PB comes out and comes into contact with the zigzag wall 125Q of the inclined portion 120a-1 of the zigzag groove 122. When the drive member 74 is further moved in the P direction, the ball 114 is pushed by the fixed groove 110 and the inclined portion 120a-1 of the zigzag groove 122 and is relatively moved in the R direction, and the inclined portion 120a-1 is moved. Is in contact with the axial wall 128Q of the retreating groove 124Q-1 (adjacent to the R direction of the service brake groove 124PB). As the drive member 74 moves in the P direction, as shown in FIG. 5D, the ball 114 is relatively moved in the Q direction to the end of the retreating groove 124Q-1.

Next, when the electric motor 14 is rotated in the reverse direction, the drive member 74 is relatively moved in the Q direction, and the ball 114 is relatively moved in the P direction. As shown in FIG. 5 (e), the ball 114 comes out of the retracting groove 124Q-1 and abuts on the zigzag wall 125P of the inclined portion 120b-1. The ball 114 is pushed by the inclined portion 120b-1 and the fixed groove 110 and is relatively moved in the R direction, and comes into contact with the axial wall 128PR of the parking lock groove 124PR, as shown in FIG. It is relatively moved to the end of the parking lock groove 124PR.
In this state, as shown in the KK cross section, since the ball 114 is brought into contact with the end portion in the P direction of the parking lock groove 124PR provided in the driving member 74, the ball 114 causes the driving member 74 to move in the Q direction. Relative movement to is prevented. Even if no current is supplied to the electric motor 14 and a force in the direction of arrow Q (direction in which the braking force is reduced) is applied to the driving member 74, the ball 114 is held at that position. The ball 114 is held in a state in which the drive member 74 is prevented from moving in the arrow Q direction, and the parking brake force is held. This state is the lock state of the lock mechanism 72.

When there is a parking brake release request, the electric motor 14 is controlled in accordance with a predetermined parking lock release pattern, and the drive member 74 is relatively moved accordingly.
In the present embodiment, the supply current to the electric motor 14 is controlled in a pattern in which the driving member 74 is relatively moved in the P direction until reaching the first relative position and is relatively moved in the Q direction until reaching the second relative position. The The first relative position is a position where the ball 114 reaches the end of the retracting groove 124, and the second relative position is a position where the ball 114 reaches the service brake groove 124PB.
From the state of FIG. 5 (f), the drive member 74 is moved in the P direction by the control of the electric motor 14. The ball 114 is relatively moved in the Q direction, and comes out of the parking lock groove 124PR and comes into contact with the zigzag wall 125Q of the inclined portion 120a-2. The ball 114 is relatively moved in the circumferential direction R and comes into contact with the wall 128Q of the retracting groove 124Q-2 adjacent to the parking lock groove 124PR in the R direction (closest to the R direction), as shown in FIG. Thus, it reaches the end of the retreating groove 120Q-2.

Next, the electric motor 14 is rotated in the reverse direction, and the drive member 74 is moved in the Q direction. The ball 114 is relatively moved in the P direction, comes out of the retreating groove 124Q-2, contacts the zigzag wall 125P of the inclined portion 120b-2, and is relatively moved along the inclined portion 120b-2. As shown in FIG. 5 (h), it abuts against the wall 128PB of the service brake groove 124PB and is relatively moved to a predetermined position inside the service brake groove 124PB.
If there is a service brake operation request when the parking brake is requested to be released, then the relative position in the axial direction M of the drive member 74 is determined so that the target operating force of the service brake can be obtained. It is controlled by the control of the electric motor 14.
When there is no service brake action request, the drive member 74 can be further moved relative to the Q direction under the control of the electric motor 14 and returned to the position shown in FIG. On the other hand, when the brake shoes 22a, 22b are reduced in diameter by the return springs 32, 34a, b of the drum brake 10 and the drive member 74 can be returned to the moving end in the Q direction, the drive member 74 is driven by the electric motor 14. It is not necessary to return 74 to the position of FIG.

In addition, since the ball 114 is moved in the zigzag groove 122, the retraction groove 124Q, and the parking lock groove 124PR when the parking brake is operated, an area in which these balls 114 are movable can be referred to as a parking brake area.
In the present embodiment, the service brake region in which the ball 114 is relatively movable and the parking brake region are provided with no overlapping portion. However, the relative movement range in the axial direction of the drive member 74 is also the same as that in the service brake region. It is provided in a state where it does not overlap with the brake region.

  As shown in FIG. 2, the brake ECU 16 mainly includes a computer including an execution unit, a storage unit, and an input / output unit, and a brake pedal 60 for service brake is in an operating state in the input / output unit. A service brake switch 150 for detecting whether or not, an operation amount sensor 152 for detecting an operation amount and an operation force of the brake pedal 60, a parking brake switch 62, an action force sensor 154 for detecting a brake action force, and the like are connected. At the same time, the electric motor 14 is connected via a drive circuit (not shown). The acting force sensor 154 is provided at a portion that contacts each of the brake shoes 22a and 22b of the anchor 28. In addition, the storage unit stores an electric motor control program represented by the flowchart of FIG.

The electric motor control program is executed at predetermined time intervals.
In step 1 (hereinafter abbreviated as S1. The same applies to other steps), it is determined whether or not the service brake switch 150 is in an ON state and whether or not the parking brake switch 154 is operated in S2. The If neither of these is the case, the electric motor 14 is not operated.
When the service brake switch 150 is in the ON state, the determination in S1 is YES, and in S3, the target acting force is determined based on the detected value of the operation amount etc. sensor 152, and in S4, the acting force sensor 154 The electric motor 14 is controlled so that the actual acting force determined based on the detected value approaches the target acting force.
It should be noted that the electric motor 14 can be operated even when the service brake pedal 60 is not operated even when there is a request to automatically activate the service brake.

If the parking brake switch 62 is operated, the determination in S2 is YES, and in S5, it is determined whether or not a lock operation has been performed. When the lock operation is performed, the electric motor 14 is controlled according to the parking lock pattern in S6 as described above, and when the lock release operation is performed, the control is performed according to the parking lock release pattern in S7.
The parking brake can be locked and released according to the operation of the shift operation member. In this case, when the shift operation member is operated according to a predetermined pattern, the electric motor 14 is controlled according to the parking lock pattern or the parking lock release pattern.
When the parking switch 62 is locked, the drive member 74 is moved in the P direction. In this case, the drive member 74 is moved beyond the service brake region. In other words, a force larger than the force applied during the service brake action is applied to the driving member 74 in the P direction, and the pressing force greater than the maximum pressing force applied in the service brake is applied to the drum brake 10. It is done. In this case, when the acting force in the P direction applied to the drive member 74 exceeds the set load of the spring 96, the spring 96 is elastically deformed. As a result, as shown in FIG. 7, the acting force applied to the lever connecting member 98 is reduced, the increase gradient of the acting force in the P direction with respect to the stroke of the drive member 74 is suppressed, and the acting force of the drum brake 10 is excessive. Can be avoided.
Since the drive member 74 is moved in the P direction and then returned in the Q direction to the parking lock position, the acting force of the parking brake becomes smaller than the outputted acting force. A stroke in which the drive member 74 is moved in the P direction and returned in the Q direction is referred to as a loss stroke. The parking lock position is set to a position where a parking brake force capable of maintaining the vehicle in a stopped state is output.

As described above, in this embodiment, when the service brake is operated, the ball 114 is positioned in the service brake groove 124PB, and the free movement of the drive member 74 in both the P and Q directions is allowed. In addition, the target acting force can be approached.
Further, since the ball 114 is held in the parking lock groove 124PR when the parking brake is applied, even if a force in a direction in which the acting force decreases is applied to the drive member 74 in a state where no current is supplied to the electric motor 14. Thereby, the driving member 74 is not moved in the Q direction, and the acting force (parking brake force) of the drum brake 10 can be maintained.
Thus, by providing the mechanical lock mechanism 72, the service brake and the parking brake can satisfy the respective requirements satisfactorily while using the drum brake 10 and the electric actuator 12 in common. Therefore, the cost of the electric brake device can be reduced as compared with the case where a dedicated device is provided.
The drum brake 10 includes a lever 50, and the brake shoes 22a and 22b are expanded by the rotation of the lever 50. Therefore, compared with the case where the brake shoes 22a and 22b are directly rotated, the output of the electric actuator 12 can be reduced and the size can be reduced.
In this embodiment, a guide wall is constituted by the zigzag walls 125P and Q and the axial wall 128.

The structure of the lock mechanism is not limited to that in the above embodiment. For example, the lock mechanism 198 may include a ball holding portion 200 that connects the plurality of balls 114 to each other in addition to the fixed groove 110, the movable groove 112, and the plurality of balls 114, as in the above embodiment.
The ball holding part (piece holding part) 200 has a generally annular shape, and is provided on the inner peripheral side, and has a ball accommodating part 203 having four concave portions 202 formed at intervals of 90 °, and an outer peripheral side. The connecting portion 204 is provided and has an annular shape and a flat plate shape. The cross section of the ball accommodating portion 203 has a semicircular shape. On the other hand, an annular groove 214 having a quadrangular cross section protruding outward is formed at the bottom of the annular fixing groove 110 formed on the inner peripheral surface of the housing 80.
The ball holding portion 200 is allowed to rotate relative to the housing 80 around the axis M in a state where the ball housing portion 203 is fitted in the fixed groove 110 and the connecting portion 204 is fitted in the annular groove 214. In this state, the relative movement in the axial direction M is prevented. The connecting portion 204 also has a function of preventing the ball holding portion 200 from rotating.
In addition, the balls 114 are accommodated in the four concave portions 202 of the ball accommodating portion 203 in a state where the balls 114 can rotate but are prevented from moving relative to the ball holding portion 200. The four balls 114 and the ball holding unit 200 are collectively referred to as a ball alliance 210.

For example, when the electric actuator 12 is attached to the backing plate 20 in a posture where the axis M is horizontal while the vehicle is stopped on a horizontal road surface, the driving member 74 is generally in a posture extending in the horizontal direction. Is held by the housing 80. In that case, the ball 114 may be moved along the fixed groove 110 by its own weight.
Specifically, in the state shown in FIGS. 5A, 5 </ b> B, and 5 </ b> F, the ball 114 is positioned in the axial groove 124, and the drive member 74 cannot rotate relative to the housing 80. Since the ball 114 is held in a state, the ball 114 is not moved in the circumferential direction.
However, in the intermediate state shown in FIGS. 5C and 5D, the direction opposite to the R direction is formed along the gap formed by the ball 114 by the gravity and the fixed groove 110 and the zigzag groove 122. May be moved relative to
On the other hand, in the ball union 210, as shown in FIG. 8 (a), the four balls 114 are arranged at equal intervals (at 90 ° intervals). The force Ga acting on the left portion of FIG. 8A is balanced with the force Gb acting on the right portion, and the influence of gravity is canceled in the entire ball assembly 210. As a result, the ball assembly 210 can be relatively rotated in a desired direction (R direction).

Further, the housing 80 may be constituted by an outer cylinder part 230 and an inner cylinder part 232 that can be divided. For example, as shown in FIG. 8 (b), the outer cylindrical portion 230 is configured to constitute a wall on the Q direction side of the fixing groove 110 and the annular groove 214 and a bottom portion of the annular groove 214. Are to constitute the walls on the P direction side of the fixed groove 110 and the annular groove 214.
Then, by disposing the ball 114 and the ball holding portion 200 on the outer cylindrical portion 230 and then assembling the inner cylindrical portion 232, the ball holding portion 200 can be relatively rotated with respect to the housing 80 and cannot be relatively moved in the axial direction. Can be fitted.

In the above embodiment, the fixed groove 110 is an annular groove and the movable groove 112 includes the zigzag groove 122 and the axial groove 124. However, the movable groove is an annular groove. The fixed groove may include a zigzag groove and an axial groove.
In the above-described embodiment, the gap between the movable groove 112 and the fixed groove 110 is not wedge-shaped in the parking lock groove 124PR. However, it can be wedge-shaped.
Furthermore, in the said Example, although the movable groove 112 was made into the shape where the same pattern was repeated 4 times in the circumferential direction, the frequency | count of repetition may be 2 times or 3 times, or may be 5 times or more. it can.
Further, the number of balls arranged is not limited. For example, it is normal to arrange the same number of balls as the number of repetitions of the same pattern (set) of the movable groove 112, but the present invention is not limited thereto.
Further, the lock mechanism 72 may be provided at any portion in the longitudinal direction of the drive member 74, or may be provided at an intermediate portion of the drive member 74.
Moreover, in the said Example, although the piece was made into the spherical body (ball), it can also be made into a cylindrical body.
Furthermore, in the above-described embodiment, one parking lock groove 124PR is included in one set, but a plurality of parking lock grooves 124PR having different axial lengths may be provided. In this case, the ball can be moved relative to the parking brake groove having a length determined by the required acting force of the parking brake. In this case, the acting force of the parking brake can be controlled in a plurality of stages.
Further, it is not essential to provide the spring 96.
Furthermore, the structure of the electric actuator 12 and the structure of the drum brake 10 do not matter. For example, a duo-servo type drum brake or a two-leading type drum brake may be used. In the case of a duo-servo type brake, the lever 50 is not necessary, and the brake shoe can be directly expanded by the electric actuator 12. It can also be applied to disc brakes.
The lock mechanisms 72 and 198 are not limited to vehicle brake devices, and can be widely applied to machine tools. For example, the present invention is not limited to the above-described embodiments, and various modifications can be made based on the knowledge of those skilled in the art. It can be implemented in an improved manner.

  10: drum brake 12: electric actuator 14: electric motor 16: brake ECU 26: drum 50: lever 60: brake pedal for service brake 62: parking brake switch 70: motion conversion mechanism 72: lock mechanism 74: drive member 80: housing 110: Fixed groove 112: Movable groove 114: Ball 122: Zigzag groove 124: Axial groove 125: Wall 126: Bottom of valley 198: Lock mechanism 200: Ball holding portion 202: Housing recess 204: Connecting portion

Claims (6)

A brake actuated by axial movement of the drive member;
An electric actuator comprising: an electric motor; and a motion conversion mechanism that converts the rotation of the electric motor into a linear motion and transmits the linear motion to the drive member;
A motor control device for controlling the electric motor in accordance with a predetermined pattern when a parking brake operation is requested;
A locking mechanism provided between the drive member and a housing that holds the drive member so as to be relatively movable in the axial direction, and (a) a movable groove formed in the drive member; and (b) A fixed groove formed in the housing; and (c) one or more pieces held so as to be relatively movable between the movable groove and the fixed groove, the movable groove and the fixed groove being mutually The piece is formed in a state having no parallel part, and the piece is determined in advance by the movable groove and the fixed groove in accordance with the control according to the pattern by the motor control device from the unlocked state. The lock prevents the drive member from moving in the direction in which the acting force of the brake is reduced even when no electric current is supplied to the electric motor by being moved relative to the lock position, which is a relative position. Status Electric brake device which comprises a lock is switched mechanism.   Either one of the movable groove and the fixed groove is (a) formed continuously in the circumferential direction, and portions having axial components opposite to each other and circumferential components in the same direction are alternately arranged. (B) a plurality of zigzag grooves formed in a state communicating with the zigzag grooves at positions shifted to the same side in the circumferential direction from the bottoms of the valleys of the walls constituting the zigzag grooves. Of the plurality of axial grooves, a groove formed on one side of the zigzag groove in the axial direction is a retraction groove, and a groove formed on the other side 2. The electric brake device according to claim 1, wherein one of adjacent grooves is a parking lock groove, and the other is a service brake groove longer than the parking lock groove.   Either one of the movable groove and the fixed groove is (a) formed continuously in the circumferential direction, and portions having axial components opposite to each other and circumferential components in the same direction are alternately arranged. (B) a plurality of axial grooves formed in communication with the zigzag grooves and extending in the axial direction; and (c) provided in at least one of the axial grooves and the zigzag grooves. The electric brake device according to claim 1, further comprising a guide wall that guides the piece.   4. The device according to claim 1, wherein a plurality of the pieces are disposed between the fixed groove and the movable groove, and the lock mechanism includes a piece holding portion that holds the plurality of pieces connected to each other. The electric brake device as described in any one.   The said motor control apparatus contains the service brake action request | requirement time control part which controls the said electric motor so that a request | requirement brake action force may be obtained at the time of the action | operation request | requirement of a service brake. Electric brake device. A lock mechanism provided between the housing and a drive member held in the housing so as to be relatively movable in the axial direction, and preventing the drive member from moving in a predetermined axial direction;
A movable groove formed in a circumferentially continuous state on the outer peripheral surface of the drive member;
A fixing groove formed in a circumferentially continuous state on the inner peripheral surface of the housing;
One or more pieces that are held so as to be relatively movable between the movable groove and the fixed groove, and either one of the movable groove and the fixed groove is (a) an axial component opposite to each other. And zigzag grooves formed by alternately arranging portions having circumferential components in the same direction, and (b) formed at positions shifted to the same side in the circumferential direction from the bottom of the valleys of the walls constituting the zigzag grooves. A plurality of axial grooves extending in the axial direction, and among the plurality of axial grooves, a groove formed on one side in the axial direction of the zigzag groove is used as a retraction groove, When one of the grooves adjacent to each other is a locking groove, the other is an unlocking groove longer than the locking groove, and the piece is positioned in the locking groove, The drive member is prevented from moving in the one direction. Lock mechanism.

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