WO2014007256A1 - Parking brake mechanism and electric parking brake - Google Patents

Description

Parking brake mechanism and electric parking brake

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

Drum brake devices are classified into leading trailing, two leading, or duo servo types depending on the fulcrum position at which the brake shoe opens and the anchor structure.

For example, as shown in FIGS. 17A to 17D, the duo-servo type drum brake 501 includes a first brake shoe 503 and a second brake shoe 505 that are disposed opposite to each other in a cylindrical brake drum 509. A pair of brake shoes is provided. In the first brake shoe 503, the forward rotation direction inlet side (upper side in the figure) of the brake drum 509 is an input portion, and the forward rotation direction outlet side (lower side in the figure) of the brake drum 509 is provided via an adjuster 515, for example. The second brake shoe 505 is connected to the inlet side (the lower side in the figure). On the other hand, the outlet side (the upper side in the figure) of the second brake shoe 505 is brought into contact with the anchor portion 507 provided on the backing plate, and the anchor reaction force acting on the first brake shoe 503 and the second brake shoe 505 is engaged. Is received by the anchor portion 507.

Thereby, the first brake shoe 503 and the second brake shoe 505 are expanded and pressed against the inner peripheral surface 511 of the brake drum 509. Then, the anchor reaction force acting on the first brake shoe 503 is input to the inlet side of the second brake shoe 505, and the second brake shoe 505 acts to be pressed against the inner peripheral surface 511 of the brake drum 509. Therefore, both the first brake shoe 503 and the second brake shoe 505 operate as leading shoes, and a braking force with a very high gain can be obtained.

Such a duo-servo type drum brake 501 not only can obtain a very high braking force, but also can be easily reduced in size compared to a leading trailing type or a two leading type drum brake device, and can be incorporated into a disc brake. It may be incorporated as a parking brake mechanism (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2003-28212

By the way, the duo-servo type drum brake 501 as the parking brake mechanism starts from the state before the operation shown in FIG. 17A by the expansion force of the expansion mechanism (not shown) (the white arrow in the figure). When the anchor portion 507 side of the shoe 503 and the second brake shoe 505 is expanded, the expanded first brake shoe 503 and the second brake shoe 505 are anchored to each other at the initial stage of operation shown in FIG. It is separated from the portion 507 and is in pressure contact with the inner peripheral surface 511 of the brake drum 509. At this time, the first brake shoe 503 and the second brake shoe 505 move to the adjuster 515 side by a reaction force (arrow in the figure) from the inner peripheral surface 511.

At the end of the operation shown in FIG. 17C, the first brake shoe 503 and the second brake shoe 505 move along the curvature of the inner peripheral surface 511 of the brake drum 509, and the brake drum on the side opposite to the anchor portion 507. 509 is in pressure contact with the inner peripheral surface 513. Therefore, from the inner peripheral surface 513, an upward reaction force (arrow in the figure) toward the anchor portion 507 acts on the first brake shoe 503 and the second brake shoe 505.

At this time, since the first brake shoe 503 and the second brake shoe 505 do not have a spreading function on the side opposite to the anchor portion 507 (generally, the adjuster 515 side), the first brake shoe 503 and the second brake shoe 505 have close adhesion to the inner peripheral surface 513 of the brake drum 509. There may be a shortage.
As a result, by the time the parking braking force shown in FIG. 17D is generated, the outlet side of the second brake shoe 505 is displaced in the direction in contact with the anchor portion 507, so that the first brake shoe 503 and the second brake shoe 505 are The expansion force of the expansion mechanism decreases due to a slight displacement. Therefore, when the parking braking force is generated, a so-called loosening phenomenon may occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a parking brake mechanism and an electric parking brake that can prevent a loosening phenomenon that occurs when a parking braking force is generated in a duo-servo parking brake. .

The above object of the present invention is achieved by the following configuration.
(1) A first brake shoe disposed along the inner peripheral surface of the brake drum, one end of which is an input side from the expansion mechanism, and an inner peripheral surface of the brake drum facing the first brake shoe. And a second brake shoe, one end of which is an input side from the expansion mechanism, and a backing plate, which are in contact with one end of the first brake shoe and one end of the second brake shoe. And an adjuster that is rotatably supported by the first brake shoe and whose input side end abuts the expansion mechanism and whose output side end is connected to the other end side of the second brake shoe. A parking brake mechanism comprising: a transmission lever that is in contact; and a predetermined gap provided between the other end side of the first brake shoe and the adjuster.

According to the parking brake mechanism having the above configuration (1), when the parking brake is operated, the one end sides of the first brake shoe and the second brake shoe which are spread apart are separated from the anchor portion, and the inner peripheral surface of the brake drum. Pressure contact. At this time, the input from the spreading mechanism to the one end side of the first brake shoe and the input side end of the transmission lever is input to the other end side of the second brake shoe connected to the adjuster via the output side end of the transmission lever. Communicated.
After the parking brake operation is completed, until the parking braking force is generated by the self-boosting effect of the duo-servo drum brake, one end of the first brake shoe or the second brake shoe comes into contact with the anchor portion and the brake drum Close contact with the inner peripheral surface. At this time, although the first brake shoe and the second brake shoe are slightly displaced, the reaction force generated on the adjuster side by the parking braking force is transmitted to the expansion mechanism via the transmission lever, and the first brake shoe A gap provided between the other end side and the adjuster absorbs this minute displacement. Therefore, the expansion force of the expansion mechanism does not decrease, and the loosening that occurs when the parking braking force is generated is prevented. As a result, the safety of the parking brake is improved.

(2) The parking brake mechanism having the configuration of (1), wherein a stepped sleeve is penetrated through the first web of the first brake shoe, and the stepped sleeve is penetrated and supported by the backing plate. The lift of the first brake shoe is regulated by the pressing of a spring seat and a sleeve pressing spring that are penetrated by the pin and sandwiched between the stepped portion on the opposite side of the backing plate across the first web. The transmission lever is sandwiched between the first web and the backing plate through the stepped sleeve so as to be rotatable around the stepped sleeve and partially bent into a U shape. A parking brake mechanism that is held by the first brake shoe with the first web sandwiched by one part.

According to the parking brake mechanism having the above configuration (2), the stepped sleeve regulates the lifting of the first brake shoe through the spring seat and the sleeve pressing spring by the through pin supported by the backing plate. . The transmission lever is disposed between the first web and the backing plate, and is rotatable around a stepped sleeve that is passed therethrough. The transmission lever that is rotatable about the stepped sleeve is held on the first web by the sandwiching piece that sandwiches the first web. Therefore, both the first web and the transmission lever are supported via the stepped sleeve, and the first brake shoe is prevented from being lifted and the transmission lever is rotatably supported.

(3) A first brake shoe disposed along the inner peripheral surface of the brake drum, one end of which is an input side from the expansion mechanism, and an inner peripheral surface of the brake drum facing the first brake shoe. And a second brake shoe, the other end of which is connected to the other end of the first brake shoe via an adjuster, and a backing plate, and one end of the first brake shoe and the second brake An anchor portion that is in contact with one end of the shoe, and is rotatably supported by the first brake shoe, an input side end is in contact with the expansion mechanism, and an output side end is in contact with the adjuster, A parking lever comprising: a switching lever mechanism for expanding the other end side before the one end side of the first brake shoe and the second brake shoe by an input from the expansion mechanism; Over key mechanism.

According to the parking brake mechanism having the above configuration (3), when the parking brake is operated, the other end side (adjuster side) of the first brake shoe and the second brake shoe is moved by the input from the expansion mechanism via the switching lever mechanism. It is expanded before one end side (anchor part side). Therefore, the one end side of the first brake shoe and the second brake shoe is moved to the anchor portion side at the time of expansion, and does not leave the anchor portion. Accordingly, since the first brake shoe and the second brake shoe have an expanding force on both the other end side and the one end side, the adhesion between the first brake shoe and the second brake shoe and the drum sliding surface is improved. In addition, loosening that occurs when parking braking force is generated is prevented. As a result, the safety of the parking brake is improved.

(4) A parking brake mechanism having the above-described configuration (3), wherein the switching lever mechanism is rotatably supported by the first brake shoe by a first fulcrum pin and is an input side; A second switching lever that is rotatably supported by the first brake shoe by a two fulcrum pin and that is an output side that rotates following the first switching lever, and the first switching lever is expanded The expansion mechanism protruding end provided in the mechanism and the first web are sandwiched in the rotational axis direction, and the second switching lever is sandwiched in the rotational axis direction between the adjuster protruding end provided in the adjuster and the first web. Parking brake mechanism.

According to the parking brake mechanism having the configuration (4), the first switching lever is rotatably held on the first brake shoe by the first fulcrum pin, and the second switching lever is attached to the first brake shoe by the second fulcrum pin. It is held freely. Therefore, the position of the first fulcrum pin and the second fulcrum pin, the position of the sliding contact between the expansion mechanism and the first switching lever, the position of the sliding contact between the first switching lever and the second switching lever, By setting the position of the sliding contact between the switching lever and the adjuster, an appropriate transmission ratio of the first and second switching levers can be easily selected. Accordingly, it is easy to obtain optimum adhesion between the first brake shoe and the second brake shoe and the drum sliding surface.
Further, the first switching lever is sandwiched in the rotation axis direction between the expansion mechanism protruding end and the first web, and the second switching lever is sandwiched in the rotation axis direction between the adjuster protruding end and the first web. It is. Therefore, even if the first switching lever and the second switching lever have a flat plate shape, their contact points do not come off, and a simple shape and an inexpensive configuration can be achieved.

(5) An electric parking brake including the parking brake mechanism having any one of the above configurations (1) to (4), wherein a parking cable connected to the spreading mechanism is provided on the back side surface of the backing plate. An electric parking brake provided with a driving mechanism for pulling driving.

According to the electric parking brake configured as described in (5) above, when the parking cable is pulled by the driving mechanism disposed on the back side surface of the backing plate, the expansion mechanism can be operated electrically.

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. .

FIG. 1 is a perspective view of a drum brake constituting the parking brake mechanism according to the first embodiment of the present invention. FIG. 2 is a front view of the drum brake shown in FIG. FIG. 3 is a right side view of the drum brake shown in FIG. FIG. 4 is a rear view of the drum brake shown in FIG. FIG. 5 is a top view of the drum brake shown in FIG. 6 is a VV cross-sectional arrow view of the drum brake shown in FIG. FIG. 7 is a VII-VII cross-sectional enlarged view of the drum brake shown in FIG. FIG. 8 is a sectional view of the drum brake shown in FIG. 2 taken along the line VIII-VIII. 9 (A) to 9 (D) are action explanatory diagrams showing the drum brake before operation (A), the initial operation (B), the operation end (C), and the braking force generation (D) shown in FIG. is there. FIG. 10 is a perspective view of a drum brake constituting the parking brake mechanism of the second embodiment according to the present invention. FIG. 11 is a front view of the drum brake shown in FIG. 12 is a left side view of the drum brake shown in FIG. 13 is a cross-sectional view of the drum brake shown in FIG. 11 taken along the line XIII-XIII. FIG. 14 is a schematic configuration diagram of the drum brake before the first switching lever and the second switching lever shown in FIG. 11 are actuated. FIG. 15 is a schematic configuration diagram of the drum brake after the first switching lever and the second switching lever shown in FIG. 11 are actuated. 16 (A) to 16 (D) are action explanatory diagrams showing the drum brake before operation (A), the initial operation (B), the operation end (C), and the braking force generation (D) shown in FIG. is there. (A) to (D) in FIG. 17 show the pre-operation (A), initial operation (B), operation end (C), and braking force generation (D) of the duo-servo type drum brake constituting the conventional parking brake mechanism. FIG.

Embodiments according to the present invention will be described below with reference to the drawings.
As shown in FIGS. 1 to 5, the drum brake 11 constituting the parking brake mechanism according to the first embodiment is a so-called duo servo drum brake. The drum brake 11 is integrally fixed to the vehicle body in such a posture that the backing plate 13 is substantially perpendicular to the rotational axis of the wheel. A first brake shoe 15 and a second brake shoe 17, which are a pair of brake shoes each having a substantially arc shape, are arranged on the backing plate 13 vertically along the left and right outer peripheral edges.

The first brake shoe 15 is arranged along the inner peripheral surface of a brake drum (not shown), and the drum forward rotation direction inlet side (one end side) is an input side from the toggle type spreading mechanism 19. The second brake shoe 17 is disposed along the inner peripheral surface of the brake drum so as to face the first brake shoe 15, and the drum forward rotation direction outlet side (one end side) is an input side from the expansion mechanism 19.

As shown in FIG. 7, the spreading mechanism 19 includes a lever member 25 and a strut 27 that are connected to each other by a connecting pin 23 so as to be relatively rotatable, and the connecting pin 23 is substantially parallel to the backing plate 13. It is arranged with the posture.
The lever member 25 is made of a metal plate, and is provided with an engaging portion 29 (concave portion) that is engaged with the second brake shoe 17. Further, a cable latching portion 31 is provided at the other end of the lever member 25, and a latching member fixed to the tip of the parking cable 33 is latched.
The strut 27 is formed by bending two metal plates into a substantially U shape. A lever member 25 is disposed inside the strut 27, and the other end opposite to the connecting pin 23 is in close contact with each other. An engagement portion 29 (concave portion) that is bent inward and integrally overlapped with the first brake shoe 15 is provided. The strut 27 is provided with a leaf spring 35 bent into a predetermined shape.

The backing plate 13 is equipped with an anchor part 37. The anchor portion 37 is formed by cutting or forging a metal block and is fixed to the backing plate 13. The anchor portion 37 is in contact with the drum forward rotation direction inlet side (one end side) of the first brake shoe 15 and the drum forward rotation direction outlet side (one end side) of the second brake shoe 17.

The expansion mechanism 19 is supported in contact with a plurality of bolt heads 39 that integrally fix the anchor portion 37 together with the backing plate 13 to a vehicle carrier (not shown). The backing plate 13 is provided with an insertion hole 41 through which the parking cable 33 is inserted. The cable hooking portion 31 is located at a portion that substantially coincides with the insertion hole 41 in a direction substantially perpendicular to the backing plate 13. The parking cable 33 is hooked on the cable hooking portion 31 by being inserted into the insertion hole from the vehicle body side (lower side in FIG. 7). A tension coil spring 43 shown in FIG. 2 is disposed substantially horizontally between one end sides of the first brake shoe 15 and the second brake shoe 17 supported by the anchor portion 37.

The adjuster 21 adjusts the distance between the other ends of the first brake shoe 15 and the second brake shoe 17 in accordance with the progress of wear of the lining 45 of the first brake shoe 15 and the second brake shoe 17. The adjuster 21 moves the distance between the other ends of the first brake shoe 15 and the second brake shoe 17 by the operation of an adjuster lever (not shown) whose tip is brought into contact with the adjustment gear 47 on the adjuster by the adjuster spring 85. Configured to automatically adjust.

The first brake shoe 15 and the second brake shoe 17 are held on the backing plate 13 by the first shoe hold-down device 49 and the second shoe hold-down device 51 so as to be expandable.

Further, a transmission lever 53 shown in FIGS. 1, 2 and 4 is rotatably supported by the first brake shoe 15. As shown in FIGS. 4 and 8, the transmission lever 53 has an input side end in contact with the expansion mechanism 19 and an output side end in contact with the adjuster 21. The shape of the output side end of the transmission lever 53 is set so that a predetermined gap S1 is formed between the other end side of the first brake shoe 15 and the adjuster 21 (see FIG. 8).

In the first embodiment, the transmission lever 53 is rotatably supported by the first web 55 of the first brake shoe 15 by the first shoe hold-down device 49. As shown in FIG. 6, the first shoe holddown device 49 includes a stepped sleeve 57, a penetrating pin 59, a spring seat 61, and a sleeve pressing spring 63. A stepped sleeve 57 is passed through the first web 55 of the first brake shoe 15. The stepped sleeve 57 is penetrated by a penetration pin 59 that is penetrated and supported by the backing plate 13. The stepped sleeve 57 has a first brake 55 pressed by a spring seat 61 and a sleeve pressing spring 63 that are interposed between a through pin 59 and a stepped portion 57a opposite to the backing plate 13 across the first web 55. The lifting of the shoe 15 is restricted. The transmission lever 53 passes through the stepped sleeve 57 between the first web 55 and the backing plate 13 and is rotatable around the sleeve 57. Further, the transmission lever 53 is held by the first brake shoe 15 with the first web 55 sandwiched by a sandwiching piece 65 that is partially bent into a U shape.

In the second shoe hold-down device 51, the stepped sleeve 57 is omitted from the configuration of the first shoe hold-down device 49. Accordingly, the second shoe hold-down device 51 is configured such that the sleeve pressing spring 63 directly presses the second web 67.

In the drum brake 11 that constitutes the parking brake mechanism according to the first embodiment, when the parking brake is activated, the parking cable 33 acts in a direction substantially perpendicular to the backing plate 13 in accordance with the operation of an operation member (such as an operation lever) in the vehicle compartment. (Downward in FIG. 7).

Then, when the lever member 25 is rotated counterclockwise, the second brake shoe 17 is pushed outward (rightward in FIG. 7) and is pressed against the inner peripheral surface of a brake drum (not shown). When the connecting pin 23 is moved in the left direction in FIG. 7 by using the engaging portion 29 with the second brake shoe 17 by the reaction force from the brake drum, the strut 27 is also moved in the left direction.
With this movement, the strut 27 presses one end side of the first brake shoe 15 and the input side end of the transmission lever 53 to the left in FIG. The first brake shoe 15 and the transmission lever 53 pressed by the strut 27 are rotated counterclockwise around the stepped sleeve 57 of the first shoe holddown device 49 of FIG. And the one end side of the 1st brake shoe 15 and the 2nd brake shoe 17 which were expanded is mutually separated from the anchor part 37, and press-contacts to the internal peripheral surface of a brake drum.
At this time, since a predetermined gap S1 is provided between the other end side of the first brake shoe 15 and the adjuster 21, the expansion to the one end side of the first brake shoe 15 and the input side end of the transmission lever 53 is performed. The input from the opening mechanism 19 is transmitted to the other end side of the second brake shoe 17 connected to the adjuster 21 via the output side end of the transmission lever 53.

Next, the operation of the drum brake 11 having the above configuration will be described.
FIGS. 9A to 9D show before the operation of the drum brake 11 constituting the parking brake mechanism according to the first embodiment (A), the initial operation (B), the operation end (C), and the generation of braking force ( It is an operation explanatory view showing D).
In the drum brake 11 constituting the parking brake mechanism according to the first embodiment, the parking cable 33 follows the operation of the operation member (operation lever, etc.) in the vehicle compartment from the state before the operation shown in FIG. When pulled, the anchoring portion 37 side of the first brake shoe 15 and the second brake shoe 17 is expanded by the expansion force of the expansion mechanism 19 (the white arrow in the figure), and the transmission lever 53 is also connected to the first brake. It is moved together with the shoe 15.

Then, at the initial stage of the operation shown in FIG. 9B, the first brake shoe 15 and the second brake shoe 17 that have been expanded are separated from the anchor portion 37 and pressed against the inner peripheral surface 100 of the brake drum. At this time, the first brake shoe 15 and the second brake shoe 17 move to the adjuster 21 side by a reaction force (arrow in the figure) from the inner peripheral surface 100.

At the end of the operation shown in FIG. 9C, the first brake shoe 15 and the second brake shoe 17 move along the curvature of the inner peripheral surface 100 of the brake drum, and the brake drum on the side opposite to the anchor portion 37 moves. Press contact with the inner peripheral surface 101. Accordingly, from the inner peripheral surface 101, an upward reaction force (in the drawing, an arrow) to the anchor portion 37 side acts on the first brake shoe 15 and the second brake shoe 17. A predetermined gap S1 is provided between the other end side of the first brake shoe 15 and the adjuster 21. The reaction force toward the anchor portion 37 side is stepped from the output side end of the transmission lever 53. It is transmitted to the first brake shoe 15 through the attached sleeve 57.

After the operation is completed, one end side of the second brake shoe 17 comes into contact with the anchor portion 37 until the parking braking force shown in FIG. 9D is generated due to the self-boosting effect of the duo servo drum brake. The inner peripheral surfaces 100 and 101 are in close contact. At this time, the first brake shoe 15 and the second brake shoe 17 are slightly displaced, but the reaction force (open arrow in the figure) generated on the adjuster 21 side by the parking braking force is expanded via the transmission lever 53. While being transmitted to the mechanism 19, the gap S1 provided between the other end of the first brake shoe 15 and the adjuster 21 is reduced to the gap S2 to absorb this minute displacement.
Therefore, in the drum brake 11 of the first embodiment, the expansion force of the expansion mechanism 19 does not decrease, and the loosening that occurs when the parking braking force is generated is prevented. As a result, the safety of the parking brake is improved.

In the first embodiment, the stepped sleeve 57 has the stepped portion 57 a lifted up from the first brake shoe 15 via the spring seat 61 and the sleeve pressing spring 63 by the through pin 59 supported by the backing plate 13. regulate. The transmission lever 53 is disposed between the first web 55 and the backing plate 13 and is rotatable about a stepped sleeve 57 that is penetrated by the sleeve through hole 69. The transmission lever 53 that is rotatable around the stepped sleeve 57 is held on the first web 55 by a clamping piece 65 that sandwiches the first web 55 in the thickness direction. Accordingly, both the first web 55 and the transmission lever 53 are supported via the stepped sleeve 57, and the first brake shoe 15 is prevented from being lifted up and the transmission lever 53 is rotatably supported. Become.

Next, a drum brake 71 constituting a parking brake mechanism according to a second embodiment of the present invention will be described.
As shown in FIGS. 10 to 12, the drum brake 71 constituting the parking brake mechanism according to the second embodiment is called a so-called duo-servo drum brake, like the drum brake 11 according to the first embodiment. Is. In addition, the same code | symbol is attached | subjected to the structural member equivalent to the structural member of the drum brake 11 shown in the said 1st Embodiment, and the overlapping description is abbreviate | omitted.

The drum brake 71 of the second embodiment includes a first switching lever 73 and a second switching lever 75 instead of the transmission lever 53 used in the drum brake 11 shown in the first embodiment. The switching lever mechanism 74 is used.
The first switching lever 73 is rotatably supported by the first fulcrum pin 77 suspended from the first web 55 of the first brake shoe 15 at the position in the drum forward rotation direction inlet side (one end side) of the first brake shoe 15. To the input side. The second switching lever 75 is rotatably supported at a substantially intermediate position of the first brake shoe 15 by a second fulcrum pin 79 suspended from the first web 55, and rotates on the output side following the first switching lever 73. It becomes.

As shown in FIG. 13, the first switching lever 73 is sandwiched between the expansion mechanism protruding end portion 81 provided in the expansion mechanism 19 and the first web 55 in the rotation axis direction. The second switching lever 75 is sandwiched between the adjuster protruding end 83 provided on the adjuster 21 and the first web 55 in the rotation axis direction. The adjuster 21 side of the first brake shoe 15 and the second brake shoe 17 is urged in the approaching direction by an adjuster spring 85.

The first switching lever 73 and the second switching lever 75 are arranged on the adjuster 21 side (the other end) rather than the anchor portion 37 side (one end side) of the first brake shoe 15 and the second brake shoe 17 by the input from the spreading mechanism 19. The distance between the fulcrum, the force point, and the action point is set so that the side) expands first.
In the second embodiment, in the non-operating state of the operating member, as shown in FIG. 14, the strut 27 and the first switching lever 73 are in contact with each other at the first sliding contact 87, and the first switching lever 73 and the second switching lever 73 are in contact with each other. The switching lever 75 is in contact with the second sliding contact 89, and the second switching lever 75 and the adjuster 21 are in contact with the third sliding contact 91.
Note that one end sides of the first brake shoe 15 and the second brake shoe 17 supported by the anchor portion 37 are biased in the approaching direction by the tension coil spring 43, but as shown in FIG. The shapes of the first switching lever 73 and the second switching lever 75 are set so that a predetermined gap S is formed between one end side of the shoe 15 and the strut 27 (see FIG. 14).

The first sliding contact 87 and the first fulcrum pin 77 in the direction along the virtual center line 93 that divides the backing plate 13 in which the first brake shoe 15 and the second brake shoe 17 are arranged on the left and right in FIG. The distance is A, the distance between the first fulcrum pin 77 and the second sliding contact 89 in the direction along the virtual center line 93 is B, and the distance between the second sliding contact 89 and the second fulcrum pin 79 in the direction along the virtual center line 93 C, and the distance between the second fulcrum pin 79 and the third sliding contact 91 in the direction along the virtual center line 93 is D. Each distance is set to (A / B) × (C / D)> 1, and a predetermined gap S is provided between one end of the first brake shoe 15 and the strut 27. As shown in FIG. 15, from the anchor portion 37 side (one end side) of the first brake shoe 15 and the second brake shoe 17 by the input from the spreading mechanism 19 via the first switching lever 73 and the second switching lever 75. Also, the adjuster 21 side (the other end side) is expanded first.

Next, the operation of the drum brake 71 having the above configuration will be described.
(A) to (D) of FIG. 16 show the pre-operation (A), initial operation (B), operation end (C), and braking force generation ( It is an operation explanatory view showing D).
In the drum brake 71 constituting the parking brake mechanism according to the second embodiment, the parking cable 33 is operated according to the operation of the operation member (operation lever or the like) in the vehicle compartment from the state before the operation shown in FIG. When pulled, a predetermined gap S is provided between the one end side of the first brake shoe 15 and the strut 27, so that the first expansion force (the white arrow in the drawing) of the expansion mechanism 19 is the first. Before the anchor portion 37 side of the brake shoe 15 and the second brake shoe 17 is expanded, the first switching lever 73 is rotated counterclockwise about the first fulcrum pin 77.

Then, at the initial stage of the operation shown in FIG. 16B, the first switching lever 73 presses the second switching lever 75, and the second switching lever 75 rotates counterclockwise around the second fulcrum pin 79. As a result, the second switching lever 75 presses the adjuster 21 side (the other end side) of the second brake shoe 17 via the adjuster 21. As a result, the first brake shoe 15 and the second brake shoe 17 are opened on the adjuster 21 side and pressed against the inner peripheral surface 101 of the brake drum, and then the reaction force from the inner peripheral surface 101 (arrow in the figure). It moves to the anchor part 37 side. That is, when the second switching lever 75 presses the adjuster 21, the adjuster 21 side (the anti-anchor side) of the first brake shoe 15 and the second brake shoe 17 is first expanded. Therefore, the anchor portion 37 side of the first brake shoe 15 and the second brake shoe 17 is moved to the anchor portion 37 side during the expansion, and does not leave the anchor portion 37.

At the end of the operation shown in FIG. 16C, the first brake shoe 15 and the second brake shoe 17 are placed on the inner peripheral surface 101 of the brake drum on the adjuster 21 side and the inner peripheral surface 100 of the brake drum on the anchor portion 37 side. Press contact. Therefore, an inward reaction force (arrow in the figure) toward the adjuster 21 acts on the first brake shoe 15 and the second brake shoe 17 from the inner peripheral surface 101 of the brake drum on the adjuster 21 side, and the anchor portion A downward reaction force (arrow in the figure) acts from the inner peripheral surface 100 of the brake drum on the 37 side toward the adjuster 21 side.

At this time, the first brake shoe 15 and the second brake shoe 17 are expanded on both the anchor portion 37 and the adjuster 21 side, and the adhesion to the brake drum sliding surface is improved. As a result, until the parking braking force shown in FIG. 16D is generated, the anchor portion 37 (one end side) of the first brake shoe 15 or the second brake shoe 17 is displaced in a direction in contact with the anchor portion 37. The loosening phenomenon that occurs is prevented.

As described above, in the drum brake 71 of the second embodiment, the first brake shoe 15 and the first brake shoe 15 are connected to each other by the input from the expansion mechanism 19 via the switching lever mechanism 74 including the first switching lever 73 and the second switching lever 75. The adjuster 21 side (the other end side) with the two brake shoes 17 is expanded before the anchor portion 37 side rod (one end side). Therefore, the anchor portion 37 side of the first brake shoe 15 and the second brake shoe 17 is moved to the anchor portion 37 side during the expansion, and does not leave the anchor portion 37. Accordingly, since the first brake shoe 15 and the second brake shoe 17 have an expanding force on both the adjuster 21 side and the anchor portion 37 side, the first brake shoe 15 and the second brake shoe 17 and the drum sliding surface. And the looseness that occurs when parking braking force is generated is prevented. As a result, the safety of the parking brake is improved.

In the drum brake 71 of the second embodiment, the first switching lever 73 is rotatably held by the first brake shoe 15 by the first fulcrum pin 77, and the second switching lever 75 is rotated by the second fulcrum pin 79. One brake shoe 15 is rotatably held. Therefore, the positions of the first fulcrum pin 77 and the second fulcrum pin 79, the position of the first sliding contact 87 between the strut 27 and the first switching lever 73, and the positions of the first switching lever 73 and the second switching lever 75. By setting the position of the second sliding contact 89 and the position of the third sliding contact 91 between the second switching lever 75 and the adjuster 21, an appropriate transmission ratio of the first and second switching levers 73 and 75 can be easily selected. can do. Therefore, it becomes easy to obtain the optimum adhesion between the first brake shoe 15 and the second brake shoe 17 and the drum sliding surface.

Further, the first switching lever 73 is sandwiched between the expansion mechanism protruding end portion 81 and the first web 55 in the rotation axis direction, and the second switching lever 75 is interposed between the adjuster protruding end portion 83 and the first web 55. Is sandwiched in the direction of the rotation axis. Therefore, even if the first switching lever 73 and the second switching lever 75 have a flat plate shape, their contact points do not come off, and a simple shape and an inexpensive configuration can be achieved.

The drum brake 11 and the drum brake 71 according to the first and second embodiments are disposed on the backing plate rear side surface 97 of the backing plate 13 and pull the parking cable 33 connected to the spreading mechanism 19 to drive the driving mechanism. By attaching a motor gear unit 95 (see FIG. 13), an electric parking brake can be obtained.
According to the electric parking brake, when the parking cable 33 is pulled by the motor gear unit 95 disposed on the back side surface 97 of the backing plate, the expansion mechanism 19 can be operated electrically.

Therefore, according to the drum brake 11 or the drum brake 71 constituting the parking brake mechanism according to the present embodiment, it is possible to prevent the loosening phenomenon that occurs when the parking braking force is generated in the duo servo parking brake.

In addition, according to the electric parking brake according to the present embodiment, the parking brake can be electrified.

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] A first brake shoe 15 disposed along the inner peripheral surface of the brake drum and having one end side as an input side from the expansion mechanism 19, and an inner side of the brake drum facing the first brake shoe 15 A second brake shoe 17 disposed along the peripheral surface and having one end side as an input side from the expansion mechanism 19 and a backing plate 13 are provided. One end side of the first brake shoe 15 and the second brake shoe are provided. An anchor portion 37 that is in contact with one end of the shoe 17 and the first brake shoe 15 are rotatably supported. An input side end contacts the expansion mechanism 19 and an output side end is the second brake shoe. A transmission lever 53 that contacts the adjuster 21 connected to the other end side of the first brake shoe 17, and a predetermined gap is provided between the other end side of the first brake shoe 15 and the adjuster 21. A parking brake mechanism provided with S1.
[2] The parking brake mechanism of [1] above,
A stepped sleeve 57 is passed through the first web 55 of the first brake shoe 15;
The stepped sleeve 57 is penetrated by a penetration pin 59 that is penetrated and supported by the backing plate 13, and a stepped portion 57 a on the opposite side of the backing plate 13 across the first web 55 is between the penetration pin 59. The lifting of the first brake shoe 15 is restricted by the pressing of the spring seat 61 and the sleeve pressing spring 63 interposed between
The transmission lever 53 is penetrated by the stepped sleeve 57 between the first web 55 and the backing plate 13 and is rotatable about the stepped sleeve 57, and a part thereof is bent in a U shape. A parking brake mechanism that is held by the first brake shoe 15 with the first web 55 sandwiched by the sandwiched piece 65.
[3] An electric parking brake comprising the parking brake mechanism according to [1] or [2],
An electric parking brake in which a driving mechanism (motor gear unit) 95 that pulls and drives the parking cable 33 connected to the expansion mechanism 19 is disposed on the backing plate back side surface 97 of the backing plate 13.
[4] A first brake shoe 15 that is disposed along the inner peripheral surface of the brake drum and that has one end side as an input side from the expansion mechanism 19;
A second brake shoe 17 is disposed along the inner peripheral surface of the brake drum so as to face the first brake shoe 15 and has the other end connected to the other end of the first brake shoe 15 via an adjuster 21. When,
An anchor portion 37 mounted on the backing plate 13 and abutting against one end side of the first brake shoe 15 and the second brake shoe 17;
The first brake shoe 15 is rotatably supported, the input side end is in contact with the expansion mechanism 19 and the output side end is in contact with the adjuster 21, and the input from the expansion mechanism 19 A parking brake mechanism comprising: a first brake shoe 15 and a switching lever mechanism 74 that opens the other end side before one end side of the second brake shoe 17.
[5] The parking brake mechanism of [4] above,
The switching lever mechanism 74 is rotatably supported on the first brake shoe 15 by the first fulcrum pin 77 and is rotated to the first brake shoe 15 by the first switching lever 73 on the input side and the second fulcrum pin 79. A second switching lever 75 that is freely supported and is an output side that rotates following the first switching lever 73;
The first switching lever 73 is sandwiched between the expansion mechanism protruding end portion 81 provided in the expansion mechanism 19 and the first web 55 in the rotation axis direction,
A parking brake mechanism in which the second switching lever 75 is sandwiched between an adjuster protruding end 83 provided on the adjuster 21 and the first web 55 in the rotation axis direction.
[6] An electric parking brake comprising the parking brake mechanism of [4] or [5] above,
An electric parking brake in which a driving mechanism 95 for pulling and driving a parking cable 33 connected to the spreading mechanism 19 is disposed on a backing plate rear side surface 97 of the backing plate 13.

Note that the parking brake mechanism and the electric parking brake of the present invention are not limited to the above-described embodiment, and can be appropriately modified and improved. 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.
This application is based on a Japanese patent application (Japanese Patent Application No. 2012-150638) filed on July 4, 2012, the contents of which are incorporated herein by reference.

According to the parking brake mechanism of the present invention, in the duo servo parking brake, it is possible to prevent a loosening phenomenon that occurs when a parking braking force is generated.
Moreover, according to the electric parking brake according to the present invention, the parking brake can be electrified.

DESCRIPTION OF SYMBOLS 13 ... Backing plate 15 ... 1st brake shoe 17 ... 2nd brake shoe 19 ... Expansion mechanism 21 ... Adjuster 33 ... Parking cable 37 ... Anchor part 53 ... Transmission lever 55 ... 1st web 57 ... Stepped sleeve 59 ... Through pin 61 ... Spring seat 63 ... Sleeve pressing spring 65 ... Nipping piece 73 ... First switching lever 74 ... Switching lever mechanism 75 ... Second switching lever 77 ... First fulcrum pin 79 ... Second fulcrum pin 81 ... Expanding mechanism protruding end 83: Adjuster protruding end 95: Motor gear unit (drive mechanism)
97 ... Back side of backing plate

Claims (6)

A first brake shoe disposed along the inner peripheral surface of the brake drum and having one end side as an input side from the expansion mechanism, and disposed along the inner peripheral surface of the brake drum facing the first brake shoe. A second brake shoe having one end side as an input side from the expansion mechanism, and an anchor mounted on the backing plate and in contact with one end side of the first brake shoe and one end side of the second brake shoe. And a transmission lever that is rotatably supported by the first brake shoe, and that has an input side end in contact with the expansion mechanism and an output side end in contact with an adjuster connected to the other end side of the second brake shoe. A parking brake mechanism in which a predetermined gap is provided between the other end side of the first brake shoe and the adjuster. The parking brake mechanism according to claim 1,
A stepped sleeve is passed through the first web of the first brake shoe,
The stepped sleeve is penetrated by a through pin that is penetrated and supported by the backing plate, and a stepped portion opposite to the backing plate across the first web is interposed between the through pin and a spring seat Restricting the lifting of the first brake shoe by pressing the sleeve pressing spring;
The transmission lever is passed through the stepped sleeve between the first web and the backing plate so as to be rotatable around the stepped sleeve, and a sandwiching piece portion partially bent into a U shape A parking brake mechanism held by the first brake shoe with the first web interposed therebetween. An electric parking brake comprising the parking brake mechanism according to claim 1 or 2,
An electric parking brake, wherein a driving mechanism for pulling and driving a parking cable connected to the spreading mechanism is disposed on the back side of the backing plate. A first brake shoe disposed along the inner peripheral surface of the brake drum, and having one end side as an input side from the spreading mechanism;
A second brake shoe disposed along the inner peripheral surface of the brake drum so as to face the first brake shoe and having the other end connected to the other end of the first brake shoe via an adjuster;
An anchor portion mounted on a backing plate and in contact with one end side of the first brake shoe and the second brake shoe;
The first brake shoe is rotatably supported, the input side end is in contact with the expansion mechanism and the output side end is in contact with the adjuster, and the first brake shoe is input by the input from the expansion mechanism. And a switching lever mechanism for expanding the other end side before the one end side of the second brake shoe. The parking brake mechanism according to claim 4, wherein
The switching lever mechanism is rotatably supported on the first brake shoe by a first fulcrum pin and is input to the first brake shoe, and is rotatably supported by the first brake shoe by a second fulcrum pin. A second switching lever on the output side that rotates following the switching lever,
The first switching lever is sandwiched in the rotation axis direction between the expansion mechanism protruding end provided in the expansion mechanism and the first web;
A parking brake mechanism in which the second switching lever is sandwiched in the rotation axis direction between an adjuster protruding end provided on the adjuster and the first web. An electric parking brake comprising the parking brake mechanism according to claim 4 or 5,
An electric parking brake, wherein a driving mechanism for pulling and driving a parking cable connected to the spreading mechanism is disposed on the back side of the backing plate.

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