JPS5817136Y2 - Inner drum brake - Google Patents

Description

[Detailed description of the invention] The invention is characterized in that when the drum rotates in one direction, both of the two brake shoes act as leading shoes, while when the drum rotates in the other direction, both of these two brake shoes act as leading shoes. The brake shoes are configured to act as ring shoes, each of the brake shoes being actuated and pressed against the drum by each of the first and second single-ended hydraulic wheel cylinders and abutting each closed end of the
and an automatic adjustment device for limiting inward movement of the brake shoes to maintain a substantially constant gap between the brake shoes and the drum when the brake is released. Regarding shoe drum brakes.

Generally, drum brakes of the type described above, ie of the two-leading type, are provided with a separate automatic adjustment device for each brake shoe.

Although these automatic adjustment devices can take various forms, a typical configuration thereof is shown in Japanese Patent Publication No. 19044/1983.

This arrangement of providing a separate automatic adjustment device for each brake shoe is expensive and difficult to incorporate into a split-type brake system where two wheel cylinders are connected to separate hydraulic systems. There are drawbacks to it.

That is, when one hydraulic system is damaged, the brake shoes operated by the wheel cylinders of the other, undamaged hydraulic system are pressed against the drum with a stronger force than normal.
Drum distortion occurs.

Since the automatic adjustment device functions normally even in such a situation, the brake shoe, which was pressed against the drum, retreats only a short distance from the drum when the brake pedal pressure is released. It is.

Therefore, the inner surface of the drum and the brake shoes are not completely separated,
A drag phenomenon may occur and overheating of the brake and wheel hub may occur.

The present invention provides an inexpensive and effective automatic adjustment device that can be incorporated into split-type braking systems.

The purpose of this invention is to provide a two-leading type internal shoe drum brake.

That is, according to the present invention, when the drum rotates in one direction, both of the two brake shoes act as leading shoes, while when the drum rotates in the other direction, both of these two brake shoes act as trailing shoes. each of the brake shoes is actuated and urged against the drum by each of the first and second single-ended hydraulic wheel cylinders; abutting the closed end and for limiting inward movement of the brake shoes to maintain a substantially constant gap between the brake shoes and the drum when the brake is released; A type of inner shoe drum brake is provided with an automatic adjustment device.

Reaching trailing type brakes with a single wheel cylinder have a straight line connected at one end to one brake shoe and the other end connected to the other brake shoe via a one-way locking device. It is well known to provide strut members that extend in a shape.

However, in order to provide sufficient clearance between the strut member and the wheel hub, the strut member is inserted in a straight line between both brake shoes through a position close to the wheel cylinder and quite far from the axis of the drum. It extends to

Therefore, when such a bracing member is installed in a sea-leading type brake, it is necessary to install the bracing member in two positions adjacent to each wheel cylinder in order to maintain a uniform gap between each brake shoe and the drum. It will no longer be possible to maintain it.

In view of the above points, the present invention connects both ends of the bracing member to approximately the center position between both ends of each brake shoe in the longitudinal direction, so that it is possible to connect both brake shoes and the drum by simply providing a single bracing member. This allows the gap between the two to be maintained evenly.

In order to make this possible, the central portion of the tension member is curved in an arched shape.

An embodiment of the invention and variants of the friction locking device that can be implemented separately from the device included in the general description of this embodiment will now be described with reference to the drawings.

Referring to FIG. 1, this brake consists of two shoes 1
0.11 both act as a leading shoe in one direction of rotation of the drum (counterclockwise in the figure), and act as a trailing shoe in the other direction of rotation of the drum.

This shoe 10.11 is actuated by two single-ended hydraulic wheel cylinders 12.13 to bias the shoe against the drum.

The closed end 14 of each wheel cylinder abuts a shoe operated by a piston, /15.16, in the other wheel cylinder.

These brake shoes are of conventional type and have an arcuate rim section 17 with a friction lining 18 and a flat web 19 with a surface perpendicular to the brake axis.

The wheel cylinders 12,13 are attached to the back plate 21.

Shoes 10.11 are located at the cylinder end in a known manner at the diametrical slot of the cylinder end and at the piston, and are held with the web 19 of the shoe parallel to the plane of the back plate 21 by a conventional fixing pin 22. has been done.

A strut member in the form of a rigid bar 23 of square cross-section has end portions 24 and 25 parallel to each other and substantially in line with each other, the central portion 26 of the strut member being arcuately shaped so that the two ends The sections are each brought into contact with the web of one shoe at the center along the length of this shoe, and the central section 26
is a wheel hub with a back plate 21 attached or (not shown)
It passes around similar support members.

Each end portion 24,25 of the bar 23 has a shoe 10 or 11
The shoe web 19 is in contact with one side of the web 19, and is located between the shoe web 19 and an elongated plate 27 fixed to the shoe web 19, and is spaced apart from the one side.

The elongated plate 27 is secured to the shoe web by a stabilizer 28 welded to a hole in the shoe web and having an enlarged portion 29, as shown in FIG.

The enlarged portion is located between the shoe web and the elongated plate 27 to maintain the spacing.

The elongated plate is clamped to the shoulder formed by the end of the enlarged section 29 by a nut screwed into the stabilizer.

The end portion 24 of the bar 23 is provided with a transverse projection 32.

This projection extends into a hole 33 provided in the web 19 of the brake shoe 10.

The protrusion and hole are wedge-shaped, as shown in FIG. 1, and have side surfaces that converge radially outward from the center of the brake.

As best seen in FIG. 3, the hole 33 is slightly longer in the wedge axis direction than the projection, so that the bar 23 has limited free movement relative to the shoe along its length.

A pivot locking member 34 is pivotally attached to the shoe 11.

This pivot is conveniently provided by one of the stabilizers 28.

The locking member 34 has an arcuate surface 3 eccentric to its pivot.
5, the end portion 25 of the bar 23 has an arcuate surface 35 and a plate 2
7 and the other stabilizer 28 that fixes the shoe to the shoe.

The arrangement of the arcuate surface 35 is such that clockwise rotation of the locking member moves the arcuate surface away from the bar, and counterclockwise rotation moves the arcuate surface toward the bar.

The locking member is always urged counterclockwise by the blade spring 36.

This blade spring has an ear 37 and a tail 38, the ear has an opening into which the stabilizer 28 to which the locking member 34 is pivoted is received, and the tail is the rim of the shoe 11. 17 engages with the inner surface.

The locking member thus frictionally grips the end portion 25 of the bar to prevent the bar from moving outwardly relative to the shoe 11 while allowing it to move inwardly.

The surface 35 may be smooth or have serrations, and if the surface has serrations, the locking member 34 will be in the form of a plurality of plates stacked on top of each other and fixed together, as shown by reference numeral 39 in FIG. .

Since the serrations formed on each plate are staggered, if the pitch of the serrations on each plate is constant, the effective serration pitch of the locking member as a whole will be considerably reduced.

The brake shoes are separated from the surrounding drum (not shown) by a tension spring 41.

When the brake shoes 10.11 are applied to the drum, the center points of the shoes move apart from each other.

The initial outward movement creates a gap between the protrusion 32 on the bar 23 and the shoe 10.

If it is necessary to move the shoe further outward into full engagement with the drum, the bar 23 slides through the locking member 34.

When the brake is released and the shoe is pulled inwardly by the tension spring 41, the locking member 34 remains in its new position relative to the bar 23 and the shoe is retracted by the amount created by the clearance of the protrusion 32 in the hole 33. .

If the above-mentioned brake is incorporated into a split-type operating system so that the wheel cylinders 12 and 13 are operated by separate hydraulic systems, damage may occur to one of the hydraulic systems and, for example, the wheel cylinder 13 may become damaged. When deactivated, only one shoe 10 is pressed against the drum by the normally active wheel cylinder 12.

Further, at this time, the other shoe 11 is pulled in substantially the same direction as the shoe 10 by the tension spring 41.

Therefore, when the shoe 11 is pulled in the above direction, there is no relative movement between the end 25 of the tension member 23 and the surface 35 of the lock member 34, and the tension member is maintained in a compressed state, so that the shoe 11 is pulled in the above direction. There is no automatic adjustment of the gap between the drum and the drum.

Next, a description will be given with reference to FIGS. 4 and 5.

This brake has a brake shoe 10.11 and a cylinder 12.13 corresponding to that shown in FIG. 1, and a bar 23 similar to that shown in FIG. 1 extends between the central positions of the two shoes. , elongated plates 27 secured to the shoe web at intervals, as described in FIGS. 1 and 2.
It has straight end portions 24 and 25 which are slidably guided between the shoe web 19 and the shoe web 19.

As shown in FIG. 1, this bar also has an arched shape at a point 26ρ to form a space at the center of the brake.

The end portion 24 of the bar 23 has a transverse projection 32 forming a notch 33 in the web 19 of the shoe 10 as previously described.

The locking member in the arrangement shown in FIGS. 4 and 5 is
Short arm pivoted around one of the stabilizers 4
2, these stabilizers fix the plate 27 to the web 19 of the brake shoe 11 and extend beside the bar 23 towards the brake shaft.

A flat side 43 of the arm 42 is tangent to the circle around the arm pivot and is located closer to the center of the brake than the pivot of the arm 42, providing a surface for engagement with the bar.

This surface may be smooth or serrated.

When this surface has serrations, the arm is formed from a plurality of stacked plates, as shown in FIG.

These plates have staggered serrations as previously described.

A vane spring 44 similar to that previously described presses the surface 43 against the end portion 25 of the bar 23.

A screwdriver or other tool may be inserted between the bar 23 and the arm by providing an inner end of the arm 42 and a finger 45 spaced apart from and partially engaging the surface of the bar to replace the worn lining. Depending on the situation, the reissue with the locking member released may be moved considerably inward.

The air movement that forms the shoe gap is the shoe 10 of the bar 23.
Connections can also be made at points other than the point of connection to the bar, for example at the pivot point of the locking member or between relatively movable parts of the bar itself.

[Brief explanation of the drawing]

Fig. 1 is a front view of a two-leaping type inner drum brake according to an embodiment of the present invention, Fig. 2 is a sectional view taken along line II-II of Fig. 1, which is an enlarged view of Fig. 1, and Fig. 3 is an enlarged sectional view taken along line III-III in Figure 1;
5 is a front view similar to FIG. 1 showing a modification of the friction locking device, and FIG. 5 is a sectional view similar to FIG. 2 taken along line 5--5 of FIG. 4. In the symbols shown in each figure, 10.11 is a shoe, 12.13 is a wheel cylinder, 14 is a closed end of the cylinder, 15.
16 is a piston, 17 is a rim, 18 is a lining, 19
21 is a back plate, 22 is a pin, 23 is a bar (stretching member), 24.25 is an end of the bar, 27 is an elongated plate, 2
8 is a stud, 32 is a protrusion, 33 is a hole, 34 is a locking member, 35 is an arcuate surface, 36, 44 is a blade spring, 37 is an ear portion, 38 is a tail, 41 is a tension spring, and 42 is an arm.

Claims (1)

[Scope of utility model registration request] both of the two brake shoes act as leading shoes when the drum rotates in one direction, while both of these two brake shoes act as trailing shoes when the drum rotates in the other direction; Each of the brake shoes is actuated by a respective one of the first and second single-ended hydraulic wheel cylinders against the drum and abuts a respective closed end of the second and first wheel cylinders. and an automatic adjustment device for limiting inward movement of the brake shoes to maintain a substantially constant gap between the brake shoes and the drum when the brake is released. In an internal shoe drum brake of the type comprising, the self-adjusting device has a strut member arched in the center to provide a clearance around the wheel hub, the strut member comprising: The end of one brake shoe in the longitudinal direction is connected to the center position, and the other brake shoe is connected to the center position between the ends of the other brake shoe in the longitudinal direction via a one-way locking device. Features an inner shoe drum brake.