Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
  • F16D51/16—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis
  • F16D51/18—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D65/00—Parts or details
  • F16D65/02—Braking members; Mounting thereof
  • F16D65/04—Bands, shoes or pads; Pivots or supporting members therefor
  • F16D65/08—Bands, shoes or pads; Pivots or supporting members therefor for internally-engaging brakes
  • F16D65/09—Pivots or supporting members therefor

Definitions

• the present invention relates to drum brakes used for braking vehicles.
• the brake shoes of the vehicle drum brake described in Patent Document 1 have webs arranged parallel to the back plate, and the webs are elastically supported on the back plate via shoe-hold mechanisms, such as shoe-hold pins and shoe-hold springs.
• one of the objectives of the present invention is to provide a drum brake equipped with a shoe hold mechanism that improves the followability of the brake shoe movement.
• the drum brake of the present invention comprises a back plate fixed to a vehicle, a brake shoe placed on the back plate, a shoe-hold spring arranged on the surface of the shoe web of the brake shoe opposite the back plate side, and a shoe-hold pin that holds the shoe-hold spring so as to be swingable so as to urge the brake shoe towards the back plate, the shoe-hold pin having a base that is engaged with the back plate, a shaft portion that is provided continuously from the base and that is inserted into insertion holes formed in the back plate, the shoe web, and the shoe-hold spring, respectively, and a tip head portion that is provided continuously from the axial end of the shaft portion and to which a hook portion provided on the shoe-hold spring is hooked, and an abutment portion against which the hook portion abuts is provided at a position spaced from the tip head toward the shaft portion.
• the drum brake according to one embodiment of the present invention can improve the ability of the shoe-hold mechanism to follow the movement of the brake shoe.
• FIG. 2 is a front view of the drum brake according to the embodiment.
• FIG. 2 is a front view of a shoe-hold mechanism used in the drum brake according to the embodiment.
• FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, showing only the essential parts.
• 4A is a cross-sectional view of a retainer of a shoe-hold mechanism employed in the drum brake according to this embodiment
• FIG. 4B is a view taken in the direction of an arrow B in FIG.
• FIG. 4 is a side view of a shoe-hold pin of the shoe-hold mechanism used in the drum brake according to the embodiment.
• FIG. 2 is a perspective view of the vicinity of the tip head of a shoe-hold pin of a shoe-hold mechanism employed in the drum brake according to the embodiment.
• FIG. 1 is a diagram showing a shoe-hold mechanism employed in the drum brake according to this embodiment, illustrating a state in which the hook portions of the retainer are hooked onto the respective protrusions of the shoe-hold pin.
• 8 is a diagram showing the state in which the retainer swings relative to the shoe hold pin from the state shown in FIG. 7;
• a pair of bow-shaped first and second brake shoes 3, 4 are disposed on the inner surface of a back plate 2 fixed to a non-rotating portion of an axle of a vehicle.
• One end of the first and second brake shoes 3, 4 abuts against a piston of a wheel cylinder 7, and the other end abuts against a piston of a spreader device 8.
• the drum brake 1 according to this embodiment is of a leading/trailing type.
• the drum brake 1 when the drum brake 1 according to this embodiment functions as a normal hydraulic brake, the wheel cylinder 7 is actuated to spread the first and second brake shoes 3, 4 radially outward from the back plate 2, and the first and second linings 27, 28 on the outer periphery slide against a brake drum (not shown) to apply braking.
• the first and second brake shoes 3, 4 when acting as a parking brake, which is an example of an action for maintaining the vehicle in a stopped state, the first and second brake shoes 3, 4 are spread radially outward from the back plate 2 by operation of an electric actuator including the spreader device 8, and the first and second linings 27, 28 on the outer periphery are slid against a brake drum (not shown) to apply braking.
• first and second shoe return springs 10, 11 are respectively tensioned on the inside of the wheel cylinder 7 and the inside of the spreader device 8.
• the first and second shoe return springs 10, 11 constantly urge the first and second brake shoes 3, 4 in the direction of contraction.
• An automatic brake gap adjustment device 14 is disposed on the center side of the back plate 2 of the first shoe return spring 10 on the wheel cylinder 7 side, which regulates the contraction position of the first and second brake shoes 3, 4 and automatically adjusts the brake gap.
• An axle insertion hole 17 is formed in the approximate center of the back plate 2.
• the back plate 2 is formed with an insertion hole 19 (see FIG. 3) through which the shoe hold pin 33 of each shoe hold mechanism 30 described later, more specifically the shaft portion 64 of the shoe hold pin 33, is inserted.
• the insertion hole 19 is formed in a circular shape.
• first and second brake shoes 3, 4 are formed in the same shape and are used by inverting them.
• the first and second brake shoes 3, 4 each include a first and second shoe web 21, 22 arranged parallel to the back plate 2, arc-shaped first and second rims 24, 25 arranged on the outer edges of the first and second shoe webs 21, 22 in a direction perpendicular to the first and second shoe webs 21, 22, and first and second linings 27, 28 attached to the outer peripheral surfaces of the first and second rims 24, 25.
• the first and second shoe webs 21, 22 are formed with insertion holes 29 through which shoe hold pins 33 of each shoe hold mechanism 30 described below, more specifically the shaft portions 64 of the shoe hold pins 33, are inserted.
• the insertion holes 29 are formed in a circular shape.
• the portions of the first and second shoe webs 21, 22 between the first and second shoe return springs 10, 11 are elastically supported on the back plate 2 by a plurality of shoe hold mechanisms 30. In this embodiment, two shoe hold mechanisms 30 are provided for each of the first and second shoe webs 21, 22.
• each shoe-hold mechanism 30 elastically supports the first and second shoe webs 21, 22, respectively, relative to the back plate 2, and has the same structure for the first and second shoe webs 21, 22. Therefore, only the structure of the shoe-hold mechanism 30, in particular the structure that elastically supports the first shoe web 21 relative to the back plate 2, will be described below.
• the shoe-hold mechanism 30 includes a shoe-hold spring 32 arranged on the surface of the first shoe web 21 of the first brake shoe 3 opposite the back plate 2 side, and a shoe-hold pin 33 that holds the shoe-hold spring 32 so as to be swingable so as to bias the first brake shoe 3 toward the back plate 2 side.
• the shoe-hold spring 32 includes a compression coil spring 36 arranged to surround the shaft portion 64 of the shoe-hold pin 33, and a retainer 37 that abuts against one axial end of the compression coil spring 36 and has a hook portion 48 that is hooked to the tip head portion 65 of the shoe-hold pin 33.
• the other axial end of the compression coil spring 36 abuts against the surface opposite the back plate 2 side around the insertion hole 29 of the first shoe web 21 via a spring hold member 40.
• the spring hold member 40 holds the other axial end of the compression coil spring 36.
• the spring holding member 40 includes an annular plate portion 43 that abuts against the surface of the first shoe web 21 on the side opposite to the back plate 2, a small diameter cylindrical portion 44 that protrudes from the inner periphery of the annular plate portion 43 toward the insertion hole 29 of the first shoe web 21 and fits into the insertion hole 29, and a large diameter cylindrical portion 45 that protrudes from the outer periphery of the annular plate portion 43 on the side opposite to the back plate 2.
• the other axial end of the compression coil spring 36 is held in the large diameter cylindrical portion 45 of the spring holding member 40.
• the compression coil spring 36 corresponds to the spring portion.
• the inner diameter of the pair of arc-shaped opening wall surfaces 58, 58 is substantially equal to the outer diameter of the shaft portion 64 of the shoe hold pin 33 described later.
• the width of the opposing openings on the short sides of the vertically elongated opening 53 is set to be slightly larger than the thickness (the distance between a pair of flat surfaces 73, 73) of the arrowhead-shaped tip head 65 of the shoe-hold pin 33 described below, smaller than the maximum width (the maximum distance between a pair of curved surfaces 72, 72) of the arrowhead-shaped tip head 65, and smaller than the outer diameter of the shaft 64 of the shoe-hold pin 33.
• the opposing opening width on the long side of the vertical opening 53 is set to be slightly larger than the maximum width of the arrowhead-shaped tip head 65 of the shoe-hold pin 33 described later.
• the width on the short side of the vertical recess 54 is set to be slightly larger than the thickness of the arrowhead-shaped tip head 65 of the shoe-hold pin 33 described later.
• the width on the long side of the vertical recess 54 is set to be slightly larger than the maximum width of the arrowhead-shaped tip head 65 of the shoe-hold pin 33 described later.
• the peripheral wall of the body portion 49 extends radially outward while expanding in diameter.
• the flange portion 50 has a predetermined thickness and is formed in an annular shape.
• a pair of linear cutout portions 60, 60 are provided on the outer peripheral surface of the flange portion 50 so as to face each other.
• the outer diameter of the flange portion 50 is the same as the outer diameter of the compression coil spring 36. And, one axial end of the compression coil spring 36 abuts against the surface of the flange portion 50 on the back plate 2 side.
• the shoe hold pin 33 has a base 63 that engages with the back plate 2, a shaft 64 that extends continuously from the base 63 and is inserted into the insertion hole 19 of the back plate 2, the insertion hole 29 of the first shoe web 21 and the inside of the compression coil spring 36, and an arrowhead-shaped tip head 65 that is provided continuously with the axial end of the shaft 64 and to which the hook portion 48 of the retainer 37 is hooked.
• the internal space of the compression coil spring 36 corresponds to the insertion hole.
• the side of the base 63 opposite the back plate 2 is formed into a circular flat surface 68, and the side that abuts against the back plate 2 is formed into a curved convex surface 69 that protrudes from the circular flat surface 68 toward the back plate 2 and gradually reduces in diameter.
• the curved convex surface 69 of the base 63 of the shoe-hold pin 33 abuts against the opening edge of the insertion hole 19 of the back plate 2, and as a result, the shoe-hold pin 33 is locked to the back plate 2 so as to be able to swing about the base 63.
• the shaft 64 extends from the radial center of the curved convex surface 69 of the base 63. The shaft 64 is inserted into the insertion hole 19 of the back plate 2, the small diameter cylindrical portion 44 of the spring hold member 40 including the insertion hole 29 of the first shoe web 21, and the compression coil spring 36.
• the tip head 65 is formed in a tapered arrowhead shape. More specifically, the tip head 65 is composed of a pair of curved surface portions 72, 72 whose distance from each other gradually decreases toward the tip, and a pair of flat surfaces 73, 73 whose distance from each other is the same along the axial direction. The top surface 75 of the tip head 65 is formed flat. Naturally, the maximum width of the tip head 65 (the maximum distance between the pair of curved surface portions 72, 72) is set to be considerably larger than the thickness of the tip head 65 (the distance between the pair of flat surfaces 73, 73). The thickness of the tip head 65 is set to be smaller than the outer diameter of the shaft portion 64.
• the maximum width of the tip head 65 is set to be smaller than the inner diameter of the small diameter cylindrical portion 44 of the spring hold member 40, which includes the insertion hole 19 of the back plate 2 and the insertion hole 29 of the first shoe web 21, and the inner diameter of the compression coil spring 36. As mentioned above, the maximum width of the tip head 65 is set to be slightly smaller than the width of the longitudinal side of the vertically elongated recess 54 that serves as the hook portion 48 of the retainer 37.
• a pair of curved concave surfaces 78, 78 are formed on the pair of curved surface portions 72, 72 side at the boundary between the tip head 65 and the shaft portion 64.
• a plurality of protrusions 80 are formed on the shaft portion 64 side from the pair of curved concave surfaces 78, 78 protruding radially outward from the outer circumferential surface of the shaft portion 64.
• the protrusions 80 are formed as a step portion between the outer circumferential surface of the shaft portion 64 and the curved concave surface 78.
• the protrusions 80 do not protrude outward from the flat portion 73 of the tip head 65. In short, the protrusions 80 are positioned inside the flat portion 73.
• the protrusions 80 are formed on a curved concave surface 82, and the apex is formed in a rounded, approximately spherical shape.
• the area from the curved concave surface 82 to the apex of the protrusions 80 corresponds to a curved surface.
• the protrusions 80 are formed at two locations on each of the widthwise ends of the single curved surface portion 72 of the tip head 65, for a total of four locations on each pair of curved surface portions 72, 72.
• each protrusion 80 contacts the short-side opening edge of the vertically elongated opening 53, which is the hook portion 48 of the retainer 37, i.e., the curved convex surfaces 56, 56 (drooping surfaces) of the opening edge of the pair of arc-shaped opening wall surfaces 58, 58.
• the shoe-hold pin 33 is rotated about 90° around the axis relative to the retainer 37, and the arrowhead-shaped tip head 65 of the shoe-hold pin 33 is positioned to fit into the vertically long recess 54 of the hook portion 48 of the retainer 37. Then, the compression coil spring 36 is held by the spring hold member 40 between the flange portion 50 of the retainer 37 and the first shoe web 21 with a predetermined set load. Also, referring to FIG.
• the short-side opening edge of the vertically long opening 53 which is the hook portion 48 of the retainer 37, i.e., the curved convex surfaces 56, 56 (drooping surfaces) of the opening edges of the pair of arc-shaped opening wall surfaces 58, 58, respectively abut against the curved concave surface 82 side from the apex of each protrusion 80 of the shoe-hold pin 33. Furthermore, a gap is created between the arrowhead-shaped tip head 65 of the shoe-hold pin 33 and the bottom surface of the vertically long recess 54, which is the hook portion 48 of the retainer 37.
• the shoe-hold mechanism 30 elastically supports the first brake shoe 3 against the back plate 2 so that the first brake shoe 3 can swing toward the back plate 2.
• the short side opening edge of the vertically elongated opening 53 which is the hanging portion 48 of the retainer 37, i.e., the curved convex surfaces 56, 56 (drooping surfaces) of the opening edges of a pair of arc-shaped opening wall surfaces 58, 58 abut from the apex of each protrusion 80 of the shoe hold pin 33 to the curved concave surface 82 side. Therefore, as shown in Figure 8, even if a tilting force is applied to the corresponding shoe hold pin 33 to follow the movement of the first and second brake shoes 3, 4 due to the torque load caused by braking or lining wear, the shoe hold pin 33 and the retainer 37 can easily swing relative to each other.
• each protrusion 80 of the shoe-hold pin 33 moves to the short-side opening edge of the vertically elongated opening 53, which is the hook portion 48 of the retainer 37, i.e., to the rear side (opposite the opening side) of the curved convex surfaces 56, 56 of the opening edge of the pair of arc-shaped opening wall surfaces 58, 58, thereby further suppressing the increase in the biasing force transmitted to the shoe-hold pin 33 via the retainer 37 by the compression coil spring 36, and further improving the ability to follow the movement of the first brake shoe 3.
• the shoe-hold pin 33 of the shoe-hold mechanism 30 has a base 63 that engages with the back plate 2, a shaft 64 that is provided continuously from the base 63 and that is inserted into the insertion hole 19 of the back plate 2, the insertion hole 29 of the first or second shoe web 21 or 22, and the inside of the compression coil spring 36, and a tip head 65 that is provided continuously from the axial end of the shaft 64 and to which a hook 48 (the short-side opening edge of the vertical opening 53) provided on the retainer 37 of the shoe-hold spring 32 is hooked.
• An abutment portion (projection 80) against which the hook 48 (the short-side opening edge of the vertical opening 53) abuts is provided at a position spaced from the tip head 65 toward the shaft 64 and inside the flat portion 73 of the tip head 65.
• the shoe-hold mechanism 30 of the drum brake 1 employs a protrusion 80 that protrudes radially outward from the outer circumferential surface of the shaft portion 64 as the abutment portion, so that the hook portion 48 (the short-side opening edge of the vertically elongated opening 53) provided on the retainer 37 can be easily hooked.
• the abutment portion is formed as a curved concave surface 82 including the approximately spherically rounded apex of each protrusion 80, while the short-side opening edge of the vertically elongated opening 53, which is the hook portion 48 of the retainer 37, i.e., the opening edge of the pair of arc-shaped opening wall surfaces 58, 58, is also formed as a curved convex surface 56, 56 (drooping surface).
• the shoe-hold spring described in Patent Document 1 is made by bending a metal leaf spring into a U-shape.
• a metal leaf spring into a U-shape.
• the shoe-hold spring 32 of the shoe-hold mechanism 30 of the drum brake 1 comprises a compression coil spring 36 arranged to surround the shaft portion 64 of the shoe-hold pin 33, and a retainer 37 that abuts against one axial end of the compression coil spring 36 and has a hook portion 48 that hooks onto the tip head 65 of the shoe-hold pin 33.
• This allows the shoe-hold mechanism 30 to occupy less space than a conventional shoe-hold mechanism that has a shoe-hold spring made of a metal leaf spring bent into a U-shape, and can be used without problems even in small-diameter drum brakes that do not have enough space between the axle and the drum.
• the shoe-hold mechanism 30 provided in the drum brake 1 there is no need to form the insertion hole 19 in the back plate 2 in a vertically elongated shape (a shape used when the base of the shoe-hold pin is arrowhead-shaped and inserted from the brake shoe side), and the insertion hole 19 is formed in a circular shape, which improves waterproofing and eliminates the need for a waterproof structure such as a waterproof cover, and also provides good workability and cost benefits.
• a compression coil spring 36 and a retainer 37 are used as the shoe-hold spring 32, but a metal leaf spring bent into a U-shape can also be used, although this may pose concerns about the space required.
• the drum brake 1 according to this embodiment is of the leading/trailing type
• the shoe-hold mechanism 30 according to this embodiment can also be applied to other types of drum brakes, such as duo-servo or two-leading, and the automatic brake gap adjustment device 14 need not be provided.
• the present invention is not limited to the above-described embodiments, but includes various modified examples.
• the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Braking Arrangements (AREA)

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• 2024
  • 2024-03-12 JP JP2025521815A patent/JPWO2024241668A1/ja active Pending
  • 2024-03-12 CN CN202480017776.6A patent/CN120936819A/zh active Pending
  • 2024-03-12 DE DE112024002195.6T patent/DE112024002195T5/de active Pending
  • 2024-03-12 WO PCT/JP2024/009454 patent/WO2024241668A1/ja not_active Ceased

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