JP2015152126A - Parking brake mechanism and electric parking brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a parking brake mechanism capable of easily laying out a backing plate drawing-out portion of a tension member.SOLUTION: A parking brake mechanism includes a backing plate 15, a first pressing member 17 and a second pressing member 19 respectively kept into contact with adjacent ends at one end side along circular arcs of first and second webs 37, 39 in first and second brake shoes 27, 29 at first claw portion 61 and a second claw portion 87, and a parking lever 13 disposed between the second web 39 and the backing plate 15 at a lever input portion 79 extended from a rotation base portion 73 rotatably supported by the first pressing member 17, and pressing a pressed portion 89 of the second pressing member 19 by a pressing portion 83 projected from the rotation base portion 73 by adding tensile force to a parking cable 59 connected to the lever input portion 79, and rotating the rotation base portion 73.

Description

  The present invention relates to a parking brake mechanism and an electric parking brake.

A parking brake mechanism including a lever expanding mechanism that generates a braking force by expanding a pair of brake shoes of a drum brake for parking brake is known (see, for example, Patent Document 1).
As shown in FIG. 7, the parking brake mechanism provided with this kind of lever expanding mechanism 523 has a parking cable (tensile member) 503 hooked to the cable hooking portion 501 as an operating member (operating lever) in the vehicle interior. ), The parking lever 505 is rotated counterclockwise to the left of the lever pin 507. As a result, the first brake shoe 509 is pushed outward (to the right in FIG. 7). In the first brake shoe 509, the inner peripheral side of the back plate 511 is fixed to the web 513, and the lining 515 is provided on the outer peripheral side of the back plate 511. The first brake shoe 509 pushed outward generates a braking force by pressing the lining 515 against the inner peripheral surface of a brake drum (not shown). In addition, the lever pin 507 is moved to the left in FIG. Then, the bracket 519 is also moved leftward. As a result, the second brake shoe 521 is pushed outward, and the lining 515 of the second brake shoe 521 is pressed against the inner peripheral surface of the brake drum to generate a braking force.

JP 2013-228011 A

  However, in the above-described parking brake mechanism that generates the braking force by expanding the first brake shoe 509 and the second brake shoe 521 of the drum brake for the parking brake, the first brake shoe 509 and the second brake shoe 521 A lever expanding mechanism 523 was installed in the space between the webs 513. For this reason, the cable latching part 501 which is a lever input part for expanding the lever expanding mechanism 523 is installed on the center part side (at least inside the webs 513 on both sides) of the backing plate 500. As a result, the backing plate lead-out portion 502 serving as a pull-out position of the parking cable 503 connected to the cable hooking portion 501 is a wheel cylinder inlet portion disposed on the center side of the backing plate 500 or a vehicle brake mounting portion (hub). ), And the layout is restricted. This makes it difficult to secure a place for installing the drive mechanism for electrifying the parking brake mechanism, which is an obstacle to electrification of the parking brake.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a parking brake mechanism and an electric parking brake in which a backing plate drawer portion of a tension member can be easily laid out.

The above object of the present invention is achieved by the following configuration.
(1) A backing plate that is supported and fixed to the vehicle body in a posture that is substantially perpendicular to the rotational axis of the wheel, and is formed in a substantially arc shape, facing each other across the rotational axis and parallel to the backing plate. A pair of brake shoes arranged to be spreadable on the surface, and a first pressing member and a second pressing member whose outer ends are in contact with adjacent ends on one end side along the arc of the web of the pair of brake shoes, respectively. A rotating base is rotatably supported by a member and either the first pressing member or the second pressing member, and a lever input portion extending from the rotating base is disposed between the web and the backing plate. When the tension member is connected to the lever input portion and a tensile force is applied to rotate the rotation base, the pressing portion protruding from the rotation base is the first pressing member. A parking brake mechanism comprising: a lever that presses the other inner end of the second pressing member.

  According to the parking brake mechanism having the above configuration (1), since the lever input portion is disposed in the space between the web of the brake shoe and the backing plate, the lever does not interfere with the inner edge of the web. Avoided. Therefore, the lever from which the interference with the inner edge portion is avoided can move outward in the radial direction from the rotation axis side of the wheel. Therefore, the backing plate drawer portion, which is the pulling position of the tension member connected to the lever input portion of the lever, can also be moved radially outward from the rotational axis side of the wheel, so the backing plate drawer portion is laid out. It becomes easy. As a result, the pulling member pulled out from the backing plate pull-out portion is less likely to interfere with other members, and the drive mechanism such as an electric actuator connected to the pulling member is also radially outward from the rotational axis side of the wheel. Movement is possible, and interference with other members is less likely to occur. In other words, a drive mechanism that has been difficult to install due to interference with other members in the conventional drum brake device can be more easily installed than in the past. This configuration is particularly effective at a small drum size.

(2) The parking brake mechanism according to (1), wherein each of the first pressing member, the second pressing member, and the web contact point of the pair of webs, the pressing portion, and the inward end, Is located on the same line with respect to a virtual line connecting adjacent ends of the pair of webs or closer to the backing plate than the virtual line. Parking brake mechanism.

  According to the parking brake mechanism having the configuration of (2) above, for example, the link where the pressing portion and the inner end are in contact with the respective web contact points of the first pressing member and the second pressing member and the pair of webs. Compared to the case where the part expansion force generation point is located on the opposite side of the backing plate across the web, the parking brake mechanism of this configuration moves the first pressing member and the second pressing member to the opposite side of the backing plate. Generation of the moment is suppressed. As a result, the parking brake mechanism configured as described above does not generate a lifting force at the link portion between the first pressing member and the second pressing member and each web when the web is expanded, and a stable parking operation is possible.

(3) An electric parking brake including the parking brake mechanism configured as described in (1) or (2) above, wherein the back side surface of the backing plate on the opposite side of the lever input portion across the backing plate An electric parking brake, wherein a drive mechanism for pulling and driving a tension member connected to a lever input portion is provided.

  According to the electric parking brake having the configuration (3), the parking brake can be easily electrified by attaching the drive mechanism to the back side surface of the backing plate.

  According to the parking brake mechanism of the present invention, it is easy to lay out the backing plate drawer portion of the tension member, and an electric parking brake can be easily realized.

  The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through a mode for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings. .

It is a top view of a drum brake device provided with a parking brake mechanism concerning one embodiment of the present invention. It is AA sectional drawing of FIG. FIG. 2 is an enlarged perspective view of the brake shoe, lever expanding mechanism, and switching strut shown in FIG. 1 as viewed from above. FIG. 2 is an enlarged perspective view of the brake shoe, the lever expanding mechanism, and the switching strut shown in FIG. 1 as viewed from below. FIG. 4 is an exploded perspective view of the brake shoe, lever expanding mechanism, and switching strut shown in FIG. 3. FIG. 4 is a plan view of the brake shoe, lever expanding mechanism, and switching strut shown in FIG. It is a side view which shows the conventional lever expansion mechanism, (a) shows the state where the pulling force by a parking cable is not acting, (b) shows the state where the pulling force acted.

Embodiments according to the present invention will be described below with reference to the drawings.
The drum brake device 11 having a parking brake mechanism according to an embodiment of the present invention operates as a leading / trailing (LT) type drum brake device when the hydraulic cylinder device is operated, and is parked by operating the parking lever 13. It has a dual mode structure that operates as a duo-servo (DS) drum brake device during braking.
1 to 6, the drum brake device 11 according to the present embodiment has a posture in which the backing plate 15 is substantially perpendicular to a rotation axis 35 of a wheel (not shown). ). A first brake shoe 27 and a second brake shoe 29, which are a pair of brake shoes each having a substantially arc shape, are opposed to the backing plate 15 with the rotation axis 35 interposed therebetween, and substantially follow the left and right outer peripheral edges. Arranged vertically. The first brake shoe 27 and the second brake shoe 29 are held by the first and second shoe hold-down devices 41 and 43 so as to be expandable.

  As shown in FIGS. 1 and 2, the backing plate 15 is formed with a predetermined strength by raising an outer peripheral edge of a circular substrate 21 made of a thick metal plate as a peripheral wall 23. A first brake shoe 27 and a second brake shoe 29 for constituting the parking brake mechanism of the present embodiment and a later-described lever expanding mechanism are provided on one side of the backing plate 15 (the standing side of the peripheral wall 23). 57 is provided. Further, on the other surface side of the backing plate 15, an electric actuator 25 (described later) for electrically driving the parking brake is provided.

  The first brake shoe 27 and the second brake shoe 29 disposed on the backing plate 15 are fixed to the first web 37 and the second web 39 on the inner peripheral side of the back plate 31 and are lined on the outer peripheral side of the back plate 31. 33 is provided. The first web 37 and the second web 39 are opposed to each other with a diameter of a virtual circle (not shown) centered on the rotation axis 35 perpendicular to the backing plate 15, and are arcuate on a plane parallel to the backing plate 15. Is formed.

  The first brake shoe 27 and the second brake shoe 29 of this embodiment are elastically supported by the first shoe hold-down device 41 and the second shoe hold-down device 43 so that the first web 37 and the second web 39 can move. Can be expanded. Further, the first brake shoe 27 and the second brake shoe 29 are elastically biased in a direction approaching each other by the first shoe return spring 45 and the second shoe return spring 47.

  A wheel cylinder 49 as a fluid actuator is interposed between the adjacent ends of one of the first brake shoe 27 and the second brake shoe 29 (upper side in FIG. 1). The wheel cylinder 49 is attached to the backing plate 15, and the first brake shoe 27 and the second brake shoe 29 are expanded by pushing the space between the adjacent ends of the first piston 51 and the second piston 53 away from each other. Let The other adjacent ends of the first brake shoe 27 and the second brake shoe 29 in the lower part of FIG. 1 are brought into contact with anchor portions 55 attached and fixed to the backing plate 15, respectively.

  The drum brake device 11 of the present embodiment is configured so that the first brake shoe and the second piston 53 protrude from both ends of the wheel cylinder 49 by pressurizing the wheel cylinder 49 during service braking by depressing the foot brake pedal. 27 and the second brake shoe 29 are expanded and rotated around the contact point with the anchor portion 55 from the position shown in FIG. As a result, the first brake shoe 27 and the second brake shoe 29 are frictionally engaged with an inner peripheral surface of a brake drum (not shown) to brake it. At this time, one of the first brake shoe 27 and the second brake shoe 29 is a leading shoe with respect to the rotation direction of the brake drum and has self-servo properties, and the other is a trailing shoe with respect to the rotation direction of the brake drum. Therefore, the drum brake device 11 acts as a leading / trailing drum brake.

Further, between the adjacent ends of the first brake shoe 27 and the second brake shoe 29 in the vicinity of the wheel cylinder 49, a lever expanding mechanism 57 constituting the parking brake mechanism of the present embodiment is interposed.
As shown in FIGS. 2 to 6, the lever expanding mechanism 57 includes a first pressing member 17 and a second pressing member 19, and a parking lever (lever) 13. The lever expanding mechanism 57 is disposed across one adjacent end of the first brake shoe 27 and the second brake shoe 29, and the parking lever 13 is in one direction (counterclockwise direction in FIG. 2). The pair of first brake shoes 27 and second brake shoes 29 are mechanically separated by being rotated. A parking cable 59, which is a tension member, is connected to the parking lever 13, and the parking cable 59 moves the parking lever 13 counterclockwise in FIG. 2, which is the one direction described above, in accordance with the pulling force of the electric actuator 25, which is a driving mechanism. Rotate to

As for the 1st press member 17 and the 2nd press member 19, an outer end contact | abuts to the adjacent ends of the one end side along the circular arc of a pair of 1st web 37 and the 2nd web 39, respectively.
The first pressing member 17 includes a first claw portion 61 that is an outer end of the first pressing member 17 and a pressing rod 63. The first claw portion 61 is screwed to the pressing rod 63 by an adjusting portion 65. The first pressing member 17 is adjustable in screwing length by the relative rotation of the first claw portion 61 and the pressing rod 63 by the adjusting portion 65. Then, the relative rotation of the first claw portion 61 and the pressing rod 63 after adjustment is regulated by the double nut 67.

  As shown in FIGS. 3 to 5, a side plate portion 69 and a rectangular frame portion 71 are connected to the opposite side of the pressing bar 63 to which the first claw portion 61 is screwed. A rotation base 73 of the parking lever 13 is attached to the side plate 69 so as to be rotatable about a support shaft 75. That is, the parking lever 13 has a rotation base portion centered on a support shaft 75 orthogonal to the rotation axis 35 on either the first pressing member 17 or the second pressing member 19 (the first pressing member 17 in this embodiment). 73 is rotatably supported. In the present embodiment, the parking lever 13 is disposed inside the rectangular frame portion 71 of the pressing rod 63 as shown in FIG.

  As shown in FIG. 5, the support shaft 75 that supports the parking lever 13 on the pressing rod 63 passes through the pressing rod 63 and the through holes 64 and 74 of the parking lever 13, and the penetrating tip is prevented from coming off by the E ring 77. . One side of the parking lever 13 is a lever input portion 79 extending from the rotation base portion 73 with the support shaft 75 interposed therebetween. As shown in FIG. 2, the lever input portion 79 is disposed between the second web 39 and the backing plate 15. The lever input portion 79 is formed in a pair of hooks, and a cable engaging body 81 to which the parking cable 59 is fixed is engaged with the hook-shaped portions. A pressing portion 83 projects from the rotation base 73 of the parking lever 13 on the opposite side of the lever input portion 79 across the support shaft 75. As shown in FIGS. 2 and 5, the pressing portion 83 is formed having a J-shaped recess 85.

  On the other hand, the second pressing member 19 is formed in a single plate shape. The second pressing member 19 has a second claw portion 87 that is an outer end locked to the second web 39 at the other end, and an inner end that contacts the J-shaped recess 85 of the pressing portion 83 at one end. A pressed part 89 is formed.

  The parking lever 13 is configured such that a tensile force is applied to the parking cable 59 connected to the lever input unit 79 and the rotation base 73 is rotated, so that the pressing portion 83 protruding from the rotation base 73 becomes the first pressing member. 17 or the second pressing member 19 is pressed on the other inner end (in this embodiment, the pressed portion 89 of the second pressing member 19).

  In the drum brake device 11 of this embodiment, the first brake shoe 27 that is one of the brake shoes includes a switching lever 91 that constitutes the parking brake mechanism according to this embodiment, and is rotatable about the switching lever shaft 93. Is provided. The switching lever 91 is rotated by an action force (expansion force) greater than a predetermined value of the lever expansion mechanism 57. More specifically, the switching lever 91 is pressed by the first claw portion 61 of the first pressing member 17 and rotated counterclockwise in FIG.

  The switching lever 91 is in contact with the switching pressing body 95 on the opposite side of the switching lever shaft 93. The switching pressing body 95 is rotatably supported on the first web 37 by a switching pressing body shaft 97. The switching pressing body shaft 97 that supports the switching pressing body 95 on the first web 37 is prevented from coming off by an E ring 77. When the switching lever 91 is rotated counterclockwise in FIG. 6, the switching pressing body 95 is pressed by the switching lever 91 and rotated clockwise in FIG.

  A switching strut 99 that constitutes the parking brake mechanism of the present embodiment is provided between adjacent ends of the first brake shoe 27 and the second brake shoe 29 on the anchor portion 55 side. The switching strut 99 expands against the urging force of the second shoe return spring 47 at the adjacent end of the first brake shoe 27 and the second brake shoe 29 on the anchor portion 55 side following the rotation of the switching pressing body 95. Let

  With such a configuration, the drum brake device 11 including the parking brake mechanism of the present embodiment operates as a leading / trailing (LT) type drum brake device when the wheel cylinder 49 is operated, and the parking lever 13 At the time of parking brake by the operation of, a dual mode structure that operates as a duo servo (DS) type drum brake device is provided.

  In the configuration of the present embodiment, as shown in FIG. 2, the web contact point 101 between the first pressing member 17 and the first web 37, and the web contact point 101 between the second pressing member 19 and the second web 39. And the imaginary line 105 that connects the adjacent ends of the pair of first and second webs 37 and 39 with respect to the link portion expanding force generation point 103 where the pressing portion 83 and the pressed portion 89 are in contact with each other. It is arranged on the same line or on the backing plate side of the virtual line 105 (in the present embodiment, on the same line with respect to the virtual line 105).

  The backing plate 15 has an electric actuator 25 shown in FIG. 2 on the surface opposite to the surface on which the first brake shoe 27 and the second brake shoe 29 and the lever expanding mechanism 57 are provided (the lower side in FIG. 2). Is attached. The electric actuator 25 is a drive mechanism having an electric motor 107 and a gear unit 109. The other end of the parking cable 59 whose one end is fixed to the cable engaging body 81 is fixed to the gear unit 109. When the electric motor 107 is driven, the electric actuator 25 drives the gear unit 109 to apply tension to the parking cable 59 and pull the lever input portion 79 of the parking lever 13. Accordingly, the parking lever 13 is configured to rotate counterclockwise in FIG.

Next, the operation of the parking brake mechanism having the above configuration will be described.
In the parking brake mechanism according to the present embodiment, since the lever input portion 79 of the parking lever 13 is disposed in the space between the second web 39 of the second brake shoe 29 and the backing plate 15, the parking lever 13 is Interference with the inner edge of the two webs 39 is avoided. Therefore, the parking lever 13 from which the interference with the inner edge of the second web 39 is avoided can move outward in the radial direction from the rotation axis 35 side of the wheel.

Accordingly, the backing plate drawer portion 16 serving as the drawer position of the parking cable 59 connected to the lever input portion 79 of the parking lever 13 can also be moved to the rotation axis 35 side (left side in FIG. 2) of the wheel. The backing plate lead-out portion 16 can be easily laid out.
As a result, the parking cable 59 pulled out from the backing plate lead-out portion 16 is less likely to interfere with other members such as the wheel cylinder inlet portion and the vehicle brake mounting portion (hub), and is electrically connected to the parking cable 59. The actuator 25 can also move radially outward from the wheel rotation axis 35 side, and interference with other members is less likely to occur.

  In other words, the electric actuator 25 that is difficult to install because of interference with other members in the conventional drum brake device can be more easily installed than in the past. This configuration is particularly effective for a small-diameter drum size, and the installation space for the electric actuator 25 can be easily secured.

  In the parking brake mechanism according to the present embodiment, the web contact point 101 between the first claw portion 61 of the first pressing member 17 and the first web 37, the second claw portion 87 of the second pressing member 19, The positional relationship between the web contact point 101 with the two webs 39, the link portion expanding force generation point 103 where the pressing portion 83 of the parking lever 13 and the pressed portion 89 of the second pressing member 19 contact each other is a pair of first The first and second webs 37 and 39 are disposed on the same line as the virtual line 105 that connects the adjacent ends of the first and second webs 37 and 39.

  Thereby, the web contact point 101 between the first claw portion 61 and the first web 37 of the first pressing member 17 and the web contact point between the second claw portion 87 and the second web 39 of the second pressing member 19 are obtained. 101, for example, a link portion expanding force generation point 103 where the pressing portion 83 of the parking lever 13 and the pressed portion 89 of the second pressing member 19 are in contact with the backing plate 15 on the opposite side of the second web 39. Compared to the case where the parking brake mechanism of the present embodiment is disposed, the generation of a moment in which the first pressing member 17 and the second pressing member 19 are moved to the side opposite to the backing plate 15 is suppressed. As a result, the parking brake mechanism of the present embodiment does not generate a lifting force at the link portion between the first pressing member 17 and the second pressing member 19 and the first and second webs 37 and 39 when the web is expanded. Stable parking operation is possible.

Here, the features of the above-described embodiments of the parking brake mechanism and the electric parking brake according to the present invention will be briefly summarized below.
[1] The backing plate 15 that is supported and fixed to the vehicle body in a posture that is substantially perpendicular to the rotational axis 35 of the wheel, and is opposed to the backing plate that is formed in a substantially arc shape and sandwiches the rotational axis 35. 15 and a pair of brake shoes (first and second brake shoes) 27 and 29 which are arranged so as to be able to expand on a plane parallel to 15, and the pair of brake shoes (first and second brake shoes) 27 and 29 The first pressing member 17 and the second pressing member 19 whose outer ends are in contact with the adjacent ends on the one end side along the arcs of the webs (first and second webs) 37 and 39, respectively, and the first pressing member 17 Alternatively, the rotation base 73 is rotatably supported by one of the second pressing members 19 and the lever input portion 79 extending from the rotation base 73 is the web (second web) 39. And the backing plate 15, and a tensile force is applied to a tension member (parking cable) 59 connected to the lever input portion 79 so that the rotation base 73 is rotated, so that the rotation base 73 protrudes. The provided pressing portion 83 includes a lever (parking lever) 13 that presses the other inner end (pressed portion) 89 of the first pressing member 17 or the second pressing member 19. Parking brake mechanism.
[2] The parking brake mechanism of [1] above,
Web contact points 101 and 101 of the first pressing member 17 and the second pressing member 19 and the pair of webs (first and second webs) 37 and 39, the pressing portion 83 and the inward side, respectively. The positional relationship with the link portion expansion force generation point 103 that is in contact with the end (pressed portion) 89 is relative to a virtual line that connects the adjacent ends of the pair of webs (first and second webs) 37 and 39. A parking brake mechanism that is disposed on the same line or closer to the backing plate 15 than the virtual line.
[3] An electric parking brake including the parking brake mechanism having the configuration according to the above [1] or [2],
A driving mechanism (electrically driven) that pulls and drives a pulling member (parking cable) 59 connected to the lever input unit 79 on the back side surface of the backing plate 15 opposite to the lever input unit 79 across the backing plate 15. An electric parking brake, wherein an actuator) 25 is provided.

Therefore, according to the parking brake mechanism according to the present embodiment, it is easy to lay out the backing plate lead-out portion 16 of the parking cable 59, and an electric parking brake can be easily realized. That is, by attaching the electric actuator 25 to the back side surface of the backing plate 15 opposite to the lever input portion 79 with the backing plate 15 interposed therebetween, the parking brake can be easily electrified.
In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimensions, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

13. Parking lever (lever)
DESCRIPTION OF SYMBOLS 15 ... Backing plate 17 ... 1st press member 19 ... 2nd press member 25 ... Electric actuator (drive mechanism)
27 ... 1st brake shoe (brake shoe)
29 ... Second brake shoe (brake shoe)
35 ... Rotational axis 37 ... First web (web)
39 ... Second web (web)
59. Parking cable (tensile member)
61 ... 1st nail | claw part (outward end)
73 ... Rotating base 75 ... support shaft 79 ... lever input part 83 ... pressing part 87 ... second claw part (outward end)
89 ... Pressed part (inward end)
101 ... Web contact point 103 ... Link portion expansion force generation point 105 ... Virtual line

Claims (3)

A backing plate supported and fixed to the vehicle body in a posture substantially perpendicular to the rotational axis of the wheel;
A pair of brake shoes, each of which is formed in a substantially arc shape and is opposed to the rotation axis, and is arranged to be spreadable on a surface parallel to the backing plate;
A first pressing member and a second pressing member whose outer ends are in contact with adjacent ends on one end side along the arc of the web in the pair of brake shoes,
A rotating base is rotatably supported by either the first pressing member or the second pressing member, and a lever input portion extending from the rotating base is disposed between the web and the backing plate, When the external force is applied to the lever input portion and the rotation base is rotated, the pressing portion protruding from the rotation base presses the inner end of the other one of the first pressing member and the second pressing member. Lever to
A parking brake mechanism comprising: The drum brake structure according to claim 1,
The positional relationship between each web contact point of the first pressing member and the second pressing member and the pair of webs, and the link portion expansion force generation point at which the pressing portion and the inner end are in contact with each other, A parking brake mechanism, wherein the parking brake mechanism is disposed on the same line or closer to a backing plate than the virtual line with respect to a virtual line connecting adjacent ends of the pair of webs. An electric parking brake comprising the parking brake mechanism according to claim 1 or 2,
A drive mechanism for pulling and driving a tension member connected to the lever input portion is disposed on the back side surface of the backing plate opposite to the lever input portion with the backing plate interposed therebetween. Electric parking brake.

Images