JP6180199B2 - Drum brake for vehicles - Google Patents

Description

  The present invention relates to a vehicular drum brake, and more specifically, a lining attached to an outer periphery of a brake shoe by changing a return position of both brake shoes to an outer peripheral side between a pair of brake shoes arranged opposite to a back plate. The present invention relates to a vehicular drum brake provided with an automatic brake gap adjusting device that automatically adjusts a brake gap formed between the brake drum and the brake drum.

  2. Description of the Related Art Conventionally, an automatic brake gap adjusting device for a drum brake for a vehicle includes a connecting rod and an adjusting lever, and the connecting rod is connected to a first strut member connected to one brake shoe and the other brake shoe. The adjustment lever, which is formed by connecting the second strut member with an adjustment bolt having an adjustment gear and pivotally supported by the brake shoe, the feed claw rotates the adjustment gear in the extension direction of the strut. It was urged by an adjustment spring. The adjustment spring is formed of a coil spring, and one end is locked to the adjustment lever and the other end is locked to the anchor-side web of the brake shoe (see, for example, Patent Document 1). In addition, there is a type in which the tip of an elastic arm provided integrally with the adjusting lever is pressed against the inner peripheral surface of the rim of the brake shoe and the feeding lever of the adjusting lever is urged in the rotating direction of the adjusting gear (for example, , See Patent Document 2).

JP 2012-36959 A JP2012-1410112A

  However, in the above-mentioned Patent Document 1, the adjustment spring may interfere with other parts, the degree of freedom of layout is reduced, and the adjustment spring is easily caught by other parts. There was a risk of lowering.

  In Patent Document 2, the adjustment spring can be omitted and layout and assembly can be improved. However, if the brake shoe has a different diameter, the shape of the elastic arm also changes. Since the adjusting bar must be formed according to the diameter of the adjusting lever, the versatility of the adjusting lever has been reduced.

  Accordingly, the present invention provides a vehicle drum brake that omits an adjustment spring, reduces the number of parts, improves the assembly, improves the versatility of the adjustment lever, and reduces the cost. It is an object.

  In order to achieve the above object, a vehicle drum brake according to the present invention includes a pair of brake shoes disposed opposite to a back plate, an anchor that abuts one end side of both brake shoes, and the other end of both brake shoes. An expansion device that expands the side, a return spring that urges both the brake shoes in the diameter-reducing direction, and an automatic brake clearance adjusting device disposed between the brake shoes, the automatic brake clearance adjusting device Comprises a connecting rod whose both ends are in contact with the expanded sides of the brake shoes, and an adjusting lever for rotating an adjusting gear of the connecting rod, and the brake rods are extended by extending the connecting rod. The vehicle's return position is changed to the outer periphery of the back plate to automatically adjust the braking gap. In the ram brake, the adjustment lever elastically contacts the connecting rod, an attachment portion that is rotatably attached to the web of the brake shoe by a support shaft, a feed arm that engages with the adjustment gear, and the connecting rod. An elastic arm that urges the feeding claw in the rotation direction of the adjustment gear is integrally formed.

According to a first aspect of the present invention, the adjusting arm extends in the adjusting gear direction via a rising piece that rises from the mounting portion to the anti-web side, and the elastic arm is the anti-expanding device side of the adjusting arm. side back bend curved in S-shape strips extending in the connecting rod side is extended in the counter-connecting rod side from, by elastic contact with the distal end side of the arm curved outer peripheral surface of the connecting rod The connecting rod is biased in the rotation direction of the adjusting gear at a position away from the support shaft.

Further, according to a second aspect of the invention, the adjustment arm extends in the adjustment gear direction via a rising piece that rises from the mounting portion to the anti-web side, and the elastic arm extends from the rising piece in the adjustment gear direction. An elastic loop portion formed by bending a protruding elongated piece back into an arc shape on the connecting rod side, and extending from the bent return end of the elastic loop portion in the anti-adjustment gear direction along the connecting rod, with the tip side on the connecting rod e Bei an elastic piece elastically contacts the rod, co next-coating rod at both ends, the connecting portion formed between expanding device side provided with a split groove, which is connected to the brake shoe and the counter-expanding device side in a plane And the elastic piece extends along the flat portion on the anti-expansion device side of the connecting portion, and on the flat portion on the anti-expansion device side on the tip side. It is characterized in that it comprises a contact projection.

  Further, it is preferable that the support shaft is formed by pressing a part of the attachment portion of the adjustment lever into a cylindrical shape.

  According to the vehicle drum brake of the present invention, the adjustment lever includes an attachment portion that is rotatably attached to the brake shoe web by a support shaft, an adjustment arm having a feed claw that meshes with the adjustment gear, and a connecting rod. Since the elastic arm for elastically contacting the feed claw and urging the feed claw in the rotation direction of the adjustment gear is integrally provided, the conventionally used adjustment spring can be omitted, and the number of parts can be reduced. At the same time, cost reduction and weight reduction of the drum brake can be achieved. Furthermore, since the space at the center of the drum brake is widened, the degree of freedom in layout of other parts is improved, and the ease of assembly of the parts is also improved. In addition, since the elastic arm has a structure that generates elastic force by abutting the connecting rod, it can be applied to a plurality of types of drum brakes having different brake shoe diameters, thereby improving versatility. And cost reduction can be achieved.

The adjustment arm extends in the direction of the adjustment gear through a rising piece that rises from the mounting portion to the anti-web side, and the elastic arm has an elongated piece that extends from the side surface of the adjustment arm on the anti-expansion device side. After extending to the connecting rod side, it is bent back to the connecting rod side, and the tip end side is elastically contacted with the outer peripheral surface of the connecting rod, so that the connecting rod is urged in the rotational direction at a position away from the support shaft of the adjusting lever. Therefore, even with a small urging force, a high rotational force can be generated on the connecting rod.

  Furthermore, the adjusting arm extends in the adjusting gear direction through a rising piece that rises from the mounting portion to the anti-web side. The elastic arm is provided with an elastic loop portion formed back and an elastic piece extending in the anti-adjustment gear direction along the connecting rod from the bending return end of the elastic loop portion, and the tip side elastically contacts the connecting rod. The elastic loop portion can provide a high biasing force with respect to the rotating direction of the connecting rod. Further, since the adjustment lever has few portions protruding toward the center side of the drum brake, a wide space can be secured in the center of the drum brake. Furthermore, the connecting rod is provided with a connecting portion provided with a split groove connected to the brake shoe at both ends, and the elastic piece is provided with a protrusion that abuts against the flat portion of the connecting portion, thereby connecting the elastic piece. It can be made to contact with the flat part of the part in a stable state, and a higher urging force can be obtained. Furthermore, the support shaft can be easily formed by forming a part of the mounting portion of the adjustment lever by pressing it into a cylindrical shape.

It is a principal part front view of the drum brake for vehicles which shows the 1st form example of this invention. It is II-II sectional drawing of FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 1. It is a principal part perspective view of the drum brake for vehicles which shows the 1st form example of this invention. It is VV sectional drawing of FIG. It is a front view of the drum brake for vehicles which shows the 1st example of the present invention. It is a principal part front view of the drum brake for vehicles which shows the 2nd form example of this invention. It is VIII-VIII sectional drawing of FIG. It is IX-IX sectional drawing of FIG. It is a principal part perspective view of the drum brake for vehicles which shows the 2nd form example of this invention.

1 to 6 are views showing a first embodiment of the vehicle drum brake of the present invention. Drum brake 1 of this are, on the inner surface of the back plate 2 which is fixed to the vehicle body, disposed between the first brake shoe 3 of the pair formed in the arcuate and the second brake shoe 4, two brake shoes 3, One end of 4 is in contact with the piston of the wheel cylinder 5 (expansion device of the present invention) and the other end is in contact with the anchor 6.

  In the drum brake 1, the first brake shoe 3 and the second brake shoe 4 are expanded outward in the radial direction of the back plate 2, and the outer linings 3a and 4a are slid on a brake drum (not shown). This is a leading / trailing type that performs a braking action. One end of a parking lever 7 is pivotally supported on the first brake shoe 3 by a support shaft, and the parking lever 7 is pulled to the other end of the parking lever 7. The brake cable 8 is connected.

  The first brake shoe 3 and the second brake shoe 4 include webs 3b and 4b arranged in parallel with the back plate 2, rims 3c and 4c fixed perpendicularly to the webs 3b and 4b, and the rims, respectively. The linings 3a and 4a are attached to the outer peripheral surfaces of 3c and 4c. In the first brake shoe 3 and the second brake shoe 4, substantially intermediate portions of the webs 3 b and 4 b are respectively held by the back plate 2 by shoe hold pins 9 and shoe hold springs 10. Further, between the webs 3b and 4b, a shoe return spring 11 and a connecting spring 12 are stretched between the inside of the wheel cylinder 5 and the outside of the anchor 6, so that both brake shoes 3 and 4 are always contracted. Further, an automatic braking gap adjusting device 13 is arranged on the center side of the back plate of the shoe return spring 11 on the wheel cylinder side.

  The brake clearance automatic adjusting device 13 includes a cylindrical connecting rod 14 and an adjusting lever 15, and the connecting rod 14 includes a first strut member 14 a connected to the first brake shoe 3 and a second brake shoe 4. The second strut member 14b connected to the stub is connected by an adjusting bolt 16 having an adjusting gear 16a. The first strut member 14a and the second strut member 14b are respectively provided with connecting portions 14e and 14f having split grooves 14c and 14d on the outer end side, and the first strut member 14a has the first split groove 14c. The second strut member 14b abuts against the web 3b of the brake shoe 3 and the parking lever 7, and the split groove 14d abuts against the web 4b of the second brake shoe 4 to regulate the reduced diameter positions of the brake shoes 3 and 4. ing. A rotation restricting piece insertion groove 14g is formed on the opening side of the dividing groove 14d of the second strut member 14b, and an adjusting lever 15 is provided between the rotation restricting piece insertion groove 14g and the dividing groove 14d. A step portion 14h that restricts the rotation is formed. Moreover, as for the connection parts 14e and 14f, the wheel cylinder side and the anti-foil cylinder side are formed in planar shape.

  As shown in FIG. 5, the adjusting bolt 16 has a male screw 16b formed on the outer periphery of the long shaft portion protruding from one side of the adjusting gear 16a, and the male screw 16b is screwed into the female screw hole 14i of the first strut member 14a. The short shaft portion 16c protruding from the other side of the adjustment gear 16a is rotatably fitted in a fitting hole 14j formed in the second strut member 14b.

  The adjusting lever 15 is integrally formed with a mounting portion 15a attached to the web 4b of the second brake shoe 4, an adjusting arm 15c provided with a feed claw 15b, and an elastic arm 15d elastically contacting the second strut member 14b. Yes. The attachment portion 15a is formed with a support shaft 15e that is pressed into a cylindrical shape at the center, and the support shaft 15e is rotatably inserted into an attachment hole 4d formed in the web 4b. The adjustment arm 15c extends toward the adjustment gear 16a via a first rising piece 15f (the rising piece of the present invention) that rises on the opposite side of the web on the end surface of the mounting portion 15a on the center side of the back plate. The feed claw 15b that meshes with the adjustment gear 16a is formed at the tip of the arm 15c. Further, a rotation restricting piece 15g extending to the wheel cylinder side is provided on an end surface of the attachment portion 15a on the wheel cylinder side, and a second rising piece rising on the side opposite to the web is provided at the tip of the turn restricting piece 15g. 15h is formed.

  The elastic arm 15d is bent and bent back in an S shape on the second strut member 14b side after an elongated piece extending from the side of the adjustment arm 15c on the side opposite to the wheel cylinder is extended to the side opposite the wheel cylinder. A strut contact portion 15i that is convexly curved toward the wheel cylinder side is formed on the tip side.

  The adjustment lever 15 thus formed inserts the support shaft 15e into the mounting hole 4d, inserts the rotation restricting piece 15g into the rotation restricting piece insertion groove 14g, and meshes the feed claw 15b with the adjustment gear 16a. The strut contact portion 15i of the elastic arm 15d is brought into contact with the second strut member 14b. At this time, the elastic force of the elastic arm 15d generates a rotational force that urges the feed claw 15b in the rotation direction of the adjustment gear 16a, but the adjustment lever 15g and the step portion 14h contact each other to adjust the lever. Fifteen rotations are restricted.

  In the above-described embodiment, when hydraulic pressure is supplied to the wheel cylinder 5 by a braking operation, the piston of the wheel cylinder 5 is pushed, and the shoe return spring is moved around the first brake shoe 3 and the second brake shoe 4 around the anchor 6. The linings 3a and 4a are brought into sliding contact with the inner peripheral surface of the brake drum to perform a braking action. When the braking is released, the first brake shoe 3 and the second brake shoe 4 return to the initial state by the elastic force of the shoe return spring 11.

  When the first brake shoe 3 and the second brake shoe 4 are expanded at the time of braking, the connecting rod 14 is separated from the state in contact with the first brake shoe 3 and the second brake shoe 4 to become a free state, and the elastic arm Due to the elastic force of 15d, the feed claw 15b at the tip of the adjusting arm 15c rotates the adjusting gear 16a in the rotating direction. Therefore, the brake gap is automatically adjusted only with the adjusting lever 15 having the elastic arm 15d, without the need to span the adjusting spring between the adjusting lever and the web on the anchor side of the brake shoe as in the prior art. Can do. As a result, the number of parts can be reduced, the cost can be reduced, and the weight of the drum brake 1 can be reduced. Furthermore, since the central space of the drum brake 1 is widened, the degree of freedom in layout of other parts is improved, and the ease of assembly of the parts is also improved. The elastic arm 15d has a structure in which the elastic force is generated by coming into contact with the second strut member 14b. Therefore, the elastic arm 15d can be applied to a plurality of types of drum brakes having different diameters of the brake shoes 3 and 4. The cost can be reduced. Further, the adjusting lever 15 inserts the support shaft 15e pressed into a cylindrical shape into the attachment hole 4d of the web 4b, and inserts the rotation restricting piece 15g into the rotation restricting piece insertion groove 14g. It can be easily assembled by engaging with the adjustment gear 16a and bringing the strut contact portion 15i of the elastic arm 15d into contact with the second strut member 14b.

  FIGS. 7 to 10 show a second embodiment of the present invention. Components that are the same as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. .

  The adjustment lever 17 of this embodiment is different from the adjustment lever 15 of the first embodiment in the shape of the elastic arm 15d, and the elastic arm 17a of this embodiment is the end of the first rising piece 15f on the second strut member 14b side. An elastic loop portion 17b formed by bending an elongated piece protruding from the portion in the direction of the adjustment gear 16a into an arc shape on the second strut member 14b side, and a bent return end of the elastic loop portion 17b to the second strut member 14b. And an elastic piece 17d extending in the anti-adjustment gear direction. The elastic piece 17d extends in the anti-adjustment gear direction along the flat portion 14k on the anti-foil cylinder side formed in the connecting portion 14e of the second strut member 14b, and the protrusion 17c formed on the tip side is formed as a flat portion. 14k.

  By forming the present embodiment as described above, the elastic arm 17a can be provided with a high urging force with respect to the rotation direction of the connecting rod 14 by the elastic loop portion 17b. Further, since the adjustment lever 17 has few portions protruding toward the center side of the drum brake 1, a wide space can be secured in the center of the drum brake 1. Moreover, since the elastic piece 17d can make the protrusion 17c contact | abut to the plane part 14k of the connection part 14e in the stable state, it can obtain higher urging | biasing force.

  Note that the present invention is not limited to the case where the support shaft of the adjustment lever is formed by press working as in the above-described embodiment, and may be attached to the web using a separate support shaft. Further, the connecting rod may be of any type as long as it has an adjusting gear that meshes with the feed pawl and a rotation restricting portion that restricts the rotation of the adjusting lever.

  DESCRIPTION OF SYMBOLS 1 ... Drum brake, 2 ... Back plate, 3 ... 1st brake shoe, 3a ... Lining, 3b ... Web, 3c ... Rim, 4 ... 2nd brake shoe, 4a ... Lining, 4b ... Web, 4c ... Rim, 4d ... Mounting hole, 5 ... Wheel cylinder, 6 ... Anchor, 7 ... Parking lever, 8 ... Brake cable, 9 ... Shoe hold pin, 10 ... Shoe hold spring, 11 ... Shoe return spring, 12 ... Connection spring, 13 ... Automatic brake clearance Adjusting device, 14 ... connecting rod, 14a ... first strut member, 14b ... second strut member, 14c, 14d ... split groove, 14e, 14f ... connection part, 14g ... rotation restricting piece insertion groove, 14h ... step part, 14i ... Female screw hole, 14j ... Fitting hole, 14k ... Flat surface part, 15 ... Adjust lever, 15a ... Mounting part, 15b ... Feeding claw, 5c ... adjusting arm, 15d ... elastic arm, 15e ... support shaft, 15f ... first rising piece, 15g ... rotation restricting piece, 15h ... second rising piece, 15i ... strut contact part, 16 ... adjusting bolt, 16a ... Adjust gear, 16b ... male screw, 16c ... short shaft part, 17 ... adjust lever, 17a ... elastic arm, 17b ... elastic loop part, 17c ... projecting part, 17d ... elastic piece

Claims (3)

A pair of brake shoes opposed to the back plate, an anchor that contacts one end of both brake shoes, an expansion device that expands the other end of both brake shoes, and the brake shoes A return spring for urging in the radial direction, and a braking gap automatic adjusting device disposed between the two brake shoes,
The automatic brake clearance adjusting device includes a connecting rod whose both ends are in contact with the expansion sides of both brake shoes, and an adjusting lever for rotating an adjusting gear of the connecting rod, and extends the connecting rod. In the vehicle drum brake that automatically adjusts the braking gap by changing the return positions of both brake shoes to the outer peripheral side of the back plate,
The adjusting lever includes a mounting portion that is rotatably attached to a web of the brake shoe by a support shaft, an adjusting arm that includes a feeding claw that meshes with the adjusting gear, and elastically contacts the connecting rod, and the feeding claw And an elastic arm that urges the adjusting gear in the rotation direction of the adjustment gear ,
The adjusting arm extends in a direction of the adjusting gear via a rising piece that rises from the mounting portion to the anti-web side, and the elastic arm extends from a side surface of the adjusting arm on the anti-expansion device side. Is extended to the anti-connecting rod side, bent in an S-shape to the connecting rod side, bent back, the arm curved surface on the tip side is elastically contacted with the outer peripheral surface of the connecting rod, and the position away from the support shaft The vehicle drum brake according to claim 1, wherein the connecting rod is urged in the rotating direction of the adjusting gear . A pair of brake shoes opposed to the back plate, an anchor that contacts one end of both brake shoes, an expansion device that expands the other end of both brake shoes, and the brake shoes A return spring for urging in the radial direction, and a braking gap automatic adjusting device disposed between the two brake shoes,
The automatic brake clearance adjusting device includes a connecting rod whose both ends are in contact with the expansion sides of both brake shoes, and an adjusting lever for rotating an adjusting gear of the connecting rod, and extends the connecting rod. In the vehicle drum brake that automatically adjusts the braking gap by changing the return positions of both brake shoes to the outer peripheral side of the back plate,
The adjusting lever includes a mounting portion that is rotatably attached to a web of the brake shoe by a support shaft, an adjusting arm that includes a feeding claw that meshes with the adjusting gear, and elastically contacts the connecting rod, and the feeding claw And an elastic arm that urges the adjusting gear in the rotation direction of the adjustment gear,
The adjusting arm extends in a direction of the adjusting gear via a rising piece that rises from the mounting portion to the anti-web side, and the elastic arm has an elongated piece that protrudes from the rising piece in the adjusting gear direction as a connecting rod. An elastic loop portion formed by bending back in a circular arc shape on the side, and an elastic piece extending in the anti-adjustment gear direction along the connecting rod from the bent return end of the elastic loop portion, and the tip side elastically contacting the connecting rod Prepared,
The connecting rod has split grooves connected to the brake shoes at both ends, and provided with connecting portions formed in a planar shape on the expanding device side and the anti-expanding device side, and the elastic piece is connected to the connecting piece. along the plane of the anti-expansion device side parts with extending, distally, it characterized <br/> said the plane portion of the anti-expansion device side is provided with abutting projections car dual drum brakes. The vehicular drum brake according to claim 1 or 2 , wherein the support shaft is formed by pressing a part of a mounting portion of the adjustment lever into a cylindrical shape .

Images