JPH0142676Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a device for preventing squeals produced during braking of a band brake used for a bicycle or the like.

(Prior Art) Band brakes used for bicycles have traditionally had the problem of generating unpleasant squeals during braking. In order to prevent this noise, it is necessary to change the material and shape of the lining, add dampers to the parts to attenuate vibrations, and change the natural frequency of each part so that the parts do not resonate. There are ways to do this. However, since it is important to reduce the weight and cost of brake devices for bicycles and other devices, it is currently not possible to expect significant effects from preventive measures that meet these requirements.

The mechanism behind band brake squeal is that frictional vibration is generated by frictional sliding between the lining and drum, and this vibration is transmitted to the brake device band, bell crank, case, car body, etc., and as a result, one of these is the source of the sound. This causes an unpleasant squeal. In order to prevent this squeal, measures must be taken using the methods described above, but in the case of bicycle band brakes, each part is made of thin plates that easily transmit vibrations, and there are restrictions in terms of weight and cost. Therefore, countermeasures become difficult.

Conventional general band brakes 10th to 13th
To explain with the drawings, 1 is a brake drum, 2 is a soft lining, 3 is a steel band, and the lining 2 is fixed to the band 3 with rivets 4. An end 3b of the band 3 is attached to the vehicle body by a pin 5, and the other end 3a of the band 3 is attached to a bell crank 6. And the bell crank 6 is the first
By pulling in the direction of arrow A in Figure 0, the lining 2 comes into pressure contact with the drum 1 to generate braking force.

When this band brake generates braking force,
As shown in FIG. 12, frictional vibrations occur on the sliding surface B. At the same time, vibrations occur on the back surface C of the lining 2 in the same way as on the braking surface B, causing frictional vibrations on both surfaces. Since the drum 1 and the band 3 are generally made of substantially the same material, their coefficient of friction with the lining 2 is also substantially the same. Therefore, even if the lining 2 and band 3 are fixed with rivets 4,
The frictional vibrations on both sides of the lining 2 are approximately the same, and the entire lining 2 vibrates greatly due to the frictional vibrations. On the other hand, since the band 3 fixed to the lining 2 is also a thin plate with a small mass and a simple shape, it is affected by the vibration of the lining 2 and the first
As shown in FIG. 2, the lining 2 and band 3 begin to vibrate in the same way, which becomes a large vibration as shown in FIG. 13 and is transmitted to other parts.

FIG. 14 shows a band brake device disclosed in Japanese Utility Model Application No. 59-10528, in which the same reference numerals as those mentioned above indicate equivalent parts. In this method, a plurality of notches 2a are added to the sliding surface of the lining 2 as a measure against the squeal of the band brake, but this method still has problems and is incomplete as a measure to prevent squeal. In other words, if a notch is made on the sliding surface of the lining over the entire width of the lining, the lining 2 will naturally be more likely to crack and disintegrate from the vicinity of the notch, and the servo characteristics that are characteristic of band brakes will be affected. A major problem arises in that the braking force is reduced because it is separated at the notch.

(Purpose and structure of the invention) The present invention was made to solve the problems of the conventional device described above. By providing the concave portion so that it does not touch the outer edge of the lining, the purpose is to attenuate the vibrations generated on the sliding surface of the drum and prevent unpleasant squealing, as well as to prevent the servo characteristics of the brake from decreasing. It is something.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 9. In the figure, the same reference numerals as the above-mentioned reference numerals indicate equivalent parts. Also in the device of the present invention, the relationship among the drum 1, lining 2, band 3, and bell crank 6 is the same as in the conventional band brake. However, a plurality of (four in this embodiment) recesses 7 are provided over the front half range (range D in FIG. 1) on the input side of the lining surface in contact with the band 3 so as not to cover the outer edge of the lining. .

2 and 3 show an embodiment in which the concave portion 7 is circular, and FIG. 4 shows an embodiment in which the concave portion 7 is circular.
This is the case when the planar shape of is oval. In either case, the width x of the concave portion 7 is approximately 1/of the width X of the lining 2.
The depth y of the recessed portion 7 is preferably about 1/2 of the thickness Y of the lining 2. Note that 8 in the figure
is a rivet hole provided in the lining 2.

(Operation and Effect) Next, the operation of the device of the present invention configured as described above will be explained. The frictional vibrations generated during braking of the band brake according to the present invention are the same as those of the prior art in the range E of FIG. 1, but are different in the range D. The vibration states shown in FIGS. 5 and 6 are within the FF cross section shown in FIG. 2.
In other words, when the lining 2 is pressed against the drum 1 to generate braking force, frictional vibrations occur on the sliding surface H between the drum 1 and the lining 2, and vibrations also occur on the back surface I of the lining 2, resulting in noise. However, in the case of the device of the present invention, the surface pressure and frictional vibration of each part are no longer single due to the influence of the recessed part 7 provided in the lining 2, and the vibrations of each part cancel each other out and are attenuated. FIG. 6 shows the state of the vibration.

Further, the vibration state within the GG cross section in FIG. 2 is as shown in FIGS. 7 and 8. In this case, the manner in which frictional vibrations are generated is similar to the F-F plane described above, but this G-G plane has a recess 7 that does not penetrate to the joint surface J side of the lining 2 that contacts the band 3. Therefore, the part corresponding to this concave part 7 on the K side, which is the sliding surface of the lining 2 with the drum 1, is
Surface pressure and frictional vibration are the most likely to change, and the influence on vibration in this area is also large. moreover,
Since this concave portion 7 expands and contracts by pressing the lining 2 against the drum 1, this action also damps vibrations.

As described above, in the present invention, since the non-sliding surface of the lining 2 is provided with the recessed portion 7 that does not penetrate, the vibrations of the front and back of the lining 2 and the band 3 affected by the recessed portion 7 interfere with each other and change. Furthermore, the vibrations shown in Figures 6 and 8 are vibrations for one section of the lining 2 and band 3, but if we consider this as vibration across the entire width of the lining band, the vibrations shown in Figures 6 and 8 are further interfere with each other and are further attenuated as shown in FIG. Also, the vibration state of the entire circumference of band 3 is as follows.
Since the vibrations at portion D and the vibration at portion E in FIG. 1 produce different vibrations within one vibration system, they interfere with each other, and the vibrations are further damped. Therefore, according to the present invention, brake squeal, which has been a problem in the past, can be effectively prevented simply and at low cost.

In addition, the lining 2 of the present invention includes the drum 1.
Since the recess 7 that does not touch the outer edge of the lining 2 is provided on the non-sliding surface of the drum 1, the bottom of the recess 7 does not come into direct contact with the drum 1. Therefore, there is no possibility that the lining 2 will crack or crumble as in the device shown in FIG. 14. Further, since no cutouts are made on the sliding surface of the lining 2 of the present invention, servo characteristics as shown by the shaded area L in FIG. 15 can be obtained. On the other hand, the servo characteristics of the device shown in Fig. 14 are the shaded area M in Fig. 16.
This results in a stepped shape as shown in , which impairs the servo characteristics.

Therefore, the device of the present invention has the effect that the servo characteristics of the brake are not impaired and the braking force is not reduced.

[Brief explanation of drawings]

Figure 1 is a front view of a band brake equipped with the device of the present invention, Figure 2 is a developed plan view of its lining,
Fig. 3 is a partially enlarged sectional view showing the state of connection between the lining and the band, Fig. 4 is a modification of Fig. 2, and Fig. 5 is an explanatory diagram of the frictional vibration state on the F-F plane of Fig. 2. , Figure 6 is the vibration waveform diagram, and Figure 7 is the vibration waveform diagram.
The figure is an explanatory diagram of the frictional vibration state on the G-G plane in Figure 2, Figure 8 is the vibration waveform diagram, Figure 9 is the vibration waveform diagram of the entire brake, and Figure 10 is the conventional general band. A front view of the brake, Fig. 11 is an enlarged sectional view of the band and lining, Fig. 12 is an explanatory diagram of the frictional vibration state of the band brake, Fig. 13 is its vibration waveform diagram, and Fig. 14 is the conventional A front view of a band brake showing an example of anti-squeal measures, and FIGS. 15 and 16 are explanatory diagrams showing servo characteristics of the band brake. 1... Drum, 2... Lining, 3... Band, 4... Rivet, 5... Pin, 6... Bell crank, 7... Recessed portion, 8... Rivet hole.

Claims (1)

[Scope of utility model registration request] A steel band 3 is attached to the flange of the brake drum 1.
In a band brake having a structure in which braking force is obtained by pressing the soft lining 2 through the band brake, a plurality of circular or oval recesses are provided over a range D of the front half of the input side of the surface of the lining 2 that contacts the band 3. A squeal prevention device for a band brake, characterized in that 7 is provided so as not to cover the outer edge of the lining 2.