JPS5856438Y2 - Shu hold down spring for drum brake - Google Patents

Description

[Detailed Description of the Invention] - Technical Field The present invention relates to an improvement of a leaf spring type shoe hold down spring in a drum brake.

・Prior art drum brakes use various types of shoe hold down springs, and the leaf spring type shown in FIG. 1 is a typical example.

In FIG. 1, 1 is a backing plate, and 2 is a shoe web.

The U-shaped leaf spring 3 whose lower surface is in contact with the upper surface of the shoe web 2 has a flat semicircular shape whose width decreases as the edge shape approaches the tip, as shown in FIG. Head 4a
It is fixed by a shoe hold-down pin 4 formed at one end and passing through the lower and upper flats 3a and 3b of the backing plate 1, shoe web 2, and leaf spring 3.

As is clear from FIGS. 1 and 3, a groove 5 with a semicircular cross section is formed in the width direction in the upper flat part 3b of the leaf spring 3, and a circular hole 6 and a pin are formed at the bottom of the groove 5. Head 4a
A longitudinal slit 7 is formed in a direction perpendicular to the groove 5 to allow passage of the groove.

As shown in FIG. 4, the plate spring 3 can be assembled using the pin 4. As shown in FIG. 8
This is carried out as shown in FIG.

That is, by holding the pin 4 vertically by hand and pressing down the inclined upper flat part 3b with the tool 8, the pin head 4a is deformed to the position shown by the two-dot chain line in the figure, and the pin head 4a is slit. 7, the tool 8 is inserted into the notch 8a of the tool 8, and the tool 8 is rotated at approximately 90°.
By rotating it, it is fixed as shown in FIGS. 1 and 3.

This leaf spring 3 has the advantage that it has fewer parts and is less expensive than the coil spring type spring 9 shown in FIG.

However, in this case, the assembly is sometimes done with the leaf spring 3.
It is inevitable to avoid giving the pin head 4a more deformation than necessary (this will ensure that the pin head 4a fits into the notch 8a and rotates afterwards), especially when the amount of deformation is large. In some cases, the elastic limit is exceeded and the leaf spring 3 yields, resulting in some cases where the desired design load is not satisfied.

Furthermore, as is clear from FIG. 5, when the leaf spring 3 is assembled, the pin 4 may not only be inclined in a direction perpendicular or parallel to the longitudinal direction of the slit 7, but also the pin head Since it is rather rare for the longitudinal direction of the portion 4a to coincide with the direction of the slit 7, it is possible to move the pin 4 around the axis to precisely match the longitudinal direction of the pin head 4a with the direction of the slit 7. Considerable skill is required to properly insert the pin head 4a into the notch Ba of the tool 8 after passing the pin head 4a through the slit 7.

- Purpose of the invention The object of the invention is to provide a shoe hold down spring that is inexpensive and easy to assemble, and that can prevent excessive deformation during assembly.

・Construction of the invention In order to be distantly related to the purpose of cutting, the gist of the invention is to have a flat part facing each other and a connecting part connecting one end of the flat part to form a U-shape, The shaft diameter of a shoe hold-down pin, one of which is in contact with one side of the shoe web, and the other of which is protruded from the backing plate through the shoe web and one of the flat parts. A shoe for a drum brake that is engaged with the head of a flat shoe hold-down pin with an edge shape that is wider than the tip and becomes narrower toward the tip, and urges the shoe web toward the backing plate. Hold down suff.

In the nong, in the other widthwise center part of the flat part,
A slit having a width smaller than the width of the flat head of the shoe hold down pin is formed in a direction perpendicular to the width direction of the other flat part, and a longitudinally intermediate portion of the slit is formed. an engaging recess that engages with the head of the shoe hold down pin that has passed through the slit to prevent rotation of the shoe hold down pin about its axis; The two adjacent edges are bent toward the one flat part so that the distance between them becomes wider as they approach the one flat part.

・Effect of the idea With this method, since both edges are bent from the other flat part toward one flat part, the other flat part is not pressed toward one flat part during assembly. In this case, both edges act as stoppers and can be elastically deformed by the amount necessary for assembly, thereby preventing excessive deformation of the shoe hold down spring.

Moreover, when the shoe hold down pin is held up by hand so that its flat head faces toward the slit position, and the other flat part is pressed toward one of the flat parts by a tool, the flat head becomes flat. The heads of the shoe hold-down pins slide into contact with the edges in a direction in which the distance between them narrows, thereby reducing the inclination of the shoe hold-down pin in a direction perpendicular to the longitudinal direction of the slit and the flat head of the shoe hold-down pin. The phase shift (rotation angle around the axis) of the slit in the longitudinal direction is automatically corrected, and the flat head is brought into alignment with the slit, allowing the flat head to pass through the slit extremely easily.

At this time, if the notch of the tool that pressed the other flat part is aligned with the longitudinal direction of the slit, the tool and the flat head can be engaged, so that the tool is approximately 90mm wide.
When rotated around the ° axis, the flat head and the engagement recess provided in the middle part of the slit are engaged,
This ensures that the flat head is prevented from being pulled out of the slot 1.

Note that when the shoe hold down pin is supported by hand during pressing with a tool, it is inevitable that the shoe hold down pin will tilt slightly in the longitudinal direction of the slit.
Although the inclination in this direction is not corrected by the above-mentioned edges, the edge shape of the flat head of the shoe hold-down pin, which is the premise of the present invention, was originally formed so that the width becomes smaller as it approaches the tip. Therefore, when the end of the slit and the edge of the flat head come into contact with each other, the inclination of the shoe hold down pin in the longitudinal direction of the slit is automatically corrected by the inclination of the edge shape.

・Example Hereinafter, an example of the present invention will be described in more detail based on FIGS. 7 to 9.

On the shoe web 30 of the brake shoe (only a portion is shown) there are opposed flats 11,12 and flats 11.
．． A leaf spring (shoe hold down) has a semicircularly bent connecting portion connecting the proximal ends of the shoe webs 12 to form a U-shape. Spring) 10 is the shoe hold down pin (
(hereinafter abbreviated as pin) 20 is disposed in an engaged state.

At the upper end of this pin 20, a flat head 20a is formed which has a semicircular shape with a diameter larger than the shaft diameter and whose width becomes smaller toward the upper edge.

The flat portion 12 of the other flat portion 12 of the leaf spring 10 is located at two curves that become increasingly spaced apart from each other as they move toward the base end of the shoe hold down spring 10 from approximately the center in the width direction of the other flat portion 12 of the leaf spring 10. Edges 13a, 13 on both sides
b is bent inward, leaving a flat portion 12a slightly wider than the shaft diameter of the pin 20.

The bent edges 13a and 13b are approximately parallel in the vicinity of the bent portion, and maintain a spacing slightly wider than the shaft diameter of the pin 20, but as they approach one of the flat portions 11, the mutual spacing gradually becomes wider ( widening at the end).

At this time, the lowest end portions 13a' and 13b' reach near the flat portion 11 below the leaf spring 10.

In addition, near the end of the partial flat portion 12a, a width smaller than the head 20a of the pin 20 is provided to allow the flat pin head 20a and the shaft portion of the pin 20 to pass through. A slit 15 is formed to prevent the head 20a from coming off, which is parallel to the width direction of the pin 20. It is possible to pass 15.

That is, a slit 15 slightly wider than the shaft diameter of the pin 20 is formed in the widthwise center of the tip of the other flat portion 12 in a direction from the base end to the tip of the flat portion 12, and This is because both end portions 13 a and 13 b adjacent to each other on both sides in the width direction of the slit 15 are bent toward one of the flat portions 11 so that the distance between them becomes wider as they approach the flat portion 11 .

A pin head 20 is placed in the center of each long side of the slit 15.
Notches 14a and 14b are formed as engagement recesses that are slightly wider than the thickness of the pin 14a, and the pin head 20a that has passed through the slit 15 is rotated approximately 90 degrees to open the notches 14a. , 14b, rotation of the pin 20 around the axis is prevented, and the longitudinal direction of the head 20a becomes parallel to the slit 15, so that the pin head 20a and the slit 15 are engaged. is reliably prevented from unraveling.

The use of the T-shaped tool 8 shown in FIG. 4 in assembling the shoe hold-down spring 10 configured in this way onto the shoe web 30 using the pin 20 is the same as in the prior art, but in this example, the T-shaped tool 8 shown in FIG. Upper flat part 1
The ends 13a and 13b of the two ends are approximately parallel to each other in the vicinity of the bent portion and are spaced apart from each other slightly wider than the shaft diameter of the pin 20, and the width becomes wider toward the bottom (
The inner surfaces of both edges 13a and 13b serve as guide surfaces for the pin head 20H.

That is, the pin 20 is supported by hand so that the pin head 20a faces the slit 15 of the partial flat portion 12a, and the direction of the pin 20 almost coincides with the slit 15 of the partial flat portion 12a. Stand it up almost perpendicular to the backing plate with it penetrated.

Subsequently, as the flat part 12 is pressed downward by the tool 8, both sides of the pin head 20a are pressed against both edges 13a.
and 13b (in the direction where the mutual distance becomes smaller), and when the flat part 12 is pressed to the position where the top of the pin head 20a reaches the slit 15, the pin 20 The deviation of the pin head 20a in the direction perpendicular to the slit 15 due to the rotation is corrected, and the phase (rotational position) of the pin head 20a is automatically matched with the long direction of the slit 15, so that the head The portion 20a can be passed through this slit 15 very easily.

It should be noted that the deviation of the pin head 20a in the longitudinal direction of the slit 15 is caused by the above-mentioned both edges 13a.

13b, but since the pin head 20a is originally formed into a flat semicircular edge shape whose width becomes narrower as it approaches the upper end, the edge of the head 20 is formed into the slit 15. When it comes into contact with the edge of the blade, it is automatically corrected by the effect of the sloped shape of the edge.

At this time, the lower ends 13 and 13b' of both edges 13a and 13b approach the lower flat part 11 at the same time, so the position of the notch 8a' of the tool 8 is moved in the direction of the slit 15. In correspondence, both edges 13a and 1
By simply pushing down the flat part 12 until the lower ends 13a' and 13b' of the pin 3b come into contact with the flat part 11 (the entire pin head 20a is exposed on the flat part 12), the slit 1
The pin head 20a that has passed through 5 is inserted into the notch a of the tool 8.
It can be reliably accommodated within a/.

After the pin head 20a was accommodated in the notch 8a' of the tool 8, the tool 8 was rotated approximately 90 degrees around the cylindrical portion 8a to form the pin head 20a on the long side of the slit 15. Assembly of the leaf spring 10 is completed by accommodating it in the notches 14a and 14b.

Since the shoe hold down spring 10 of this example is as described in detail above, the flat pin head 20a is provided with a pin 2 for aligning the longitudinal direction of the pin with the direction of the slit 15.
Rotational positioning around the axis of 0, and pin head 20H
It becomes unnecessary to position the slit 15 in a direction perpendicular to the longitudinal direction.

This makes it possible to assemble the leaf spring 1o much more easily and quickly than in the conventional example, in which positioning of the pin 20 in the inclination direction as well as positioning of the pin 20 around the axis is essential.

Further, during assembly, both edges 13a and 13b act as stoppers, and the flat part 12 can be deformed by the minimum amount required for assembly to assemble the leaf spring 10, so it is possible to assemble the leaf spring 10 in the same manner as in the past. At the same time, the problem of excessive deformation exceeding the elasticity of the spring, which sometimes occurs when the spring comes loose, is also resolved.

Furthermore, both edge portions 13 a and 13 b are obtained by bending the end portion of the upper flat portion 12 along two curved lines whose distance becomes wider at an accelerating rate from the end toward the base end. Since the area of both edges occupies a not so large proportion of the entire upper flat part 12, the strength characteristics of the leaf spring 10 are not excessively impaired.

Moreover, this leaf spring 10 is obtained by simply bending a leaf spring obtained by taking materials in the same manner as in the prior art, so there is almost no problem in terms of cost.

Note that the embodiment of the present invention is not limited to the above example, and it is sufficient that both edges of the upper flat part are bent upward to widen in the vicinity of the end where the slit is formed. As shown in the figure and FIG. 11, leave an isosceles triangular partial flat portion 22a at the end of the upper flat portion 22, bend both edges 23a and 23b into a shape that widens toward the end, and attach a pin to the partial flat portion 22a. Even if a slit 15' is formed to allow the passage of the slit 20', substantially the same effect as in the above example can be obtained, and in this case, the bending process of both edges is greatly simplified.

Here, in FIGS. 10 and 11, the slit 15'
An engaging recess that is formed in the longitudinally intermediate portion of the shoe hold down pin and engages with the pin head to prevent the shoe hold down pin from rotating around its axis after passing through the slit is omitted.

In addition, if each edge cannot act as a stopper by simply bending both edges due to the width of the leaf spring and the curvature of the curved part, the width near the end of the upper flat part should be adjusted when taking the material. If it is made wider, the lower ends of both bent edges will be located near the lower flat part.

[Brief explanation of drawings]

Fig. 1 is a front view showing an example of a state in which a conventional shoe hold down spring is assembled, Fig. 2 is a perspective view showing an example of the head shape of the shoe hold down spring, and Fig. 3 is a III-III in the first shoe hold down spring. An enlarged view, FIG. 4 is a perspective view showing an example of a conventional spring installation tool, FIG. 5 is an explanatory diagram for explaining a conventional spring installation method, and FIG. 6 shows another conventional example. 7 is a front view corresponding to FIG. 1 showing an embodiment of the present invention, FIG. 8 is a Vllll-Vllll view in FIG. 7, and FIG. 9 is an IX-IX view in FIG. 7. 10 is a plan view corresponding to FIG. 8 showing another embodiment of the present invention, and FIG. 11 is an xt-xt view in FIG. 10. 1: Packing plate, 2, 30: Shoe web, 3
．． 9.10: Shoe hold down spring, 4.
20.20': Shoe hold down pin, 7°15
, 15' Nislit, 8: Installation tool, 11.12.1
2 a. 22, 22 a: flat part, 13a, 13b, 23
a, 23b: Edge, 14a, 14b: Notch (engaging recess).

Claims (1)

[Scope of utility model registration request] It has a U-shape with opposing flat parts and a connecting part connecting one end of the flat part, one of the flat parts is brought into contact with one side of the shoe web, and the other of the flat parts is brought into contact with one side of the shoe web. ,
A flat shoe hold with an edge shape that is wider than the shaft diameter of the shoe hold down pin that protrudes from the backing plate through one of the shoe web and the flat part, and the width decreases as it approaches the tip. In a drum brake shoe hold down spring that is engaged with the head of a down pin and urges the shoe web toward the backing plate, the shoe hold down pin is disposed at the center of the other flat part in the width direction. A slit with a width dimension smaller than the width of the flat head of the other flat part is formed in a direction perpendicular to the width direction of the other flat part, and a slit is formed in a longitudinally intermediate portion of the slit. an engaging recess that engages with the head of the shoe hold down pin to prevent rotation of the shoe hold down pin about its axis, and both edges adjacent to the slit in the width direction of the other flat part; A shoe hold-down spring for a drum brake, characterized in that the spring is bent toward one flat part so that the distance between them increases as the distance approaches the one flat part.