JPH0423134B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inwardly expanding brake that effectively prevents the occurrence of unpleasant squeaking noise during braking, called brake squeal.

As shown in Figure 1, internal expansion type brakes, which are widely used in automobiles and motorcycles, consist of a brake drum 1 that is fixed to the wheel side and rotates as a unit, and a brake drum 1 that is installed opposite to the inner surface of the brake drum 1 on the vehicle body side. and a brake shoe 2. The brake shoe 2 has a semicircular shape, two of which are combined into a circular shape, and an anchor pin 3 and a cam 4 on a brake panel fixed to the vehicle body are sandwiched between the joined ends, and return springs 5, 5 are elastically loaded. A brake lining 7 is attached to a lining base 6 on the outer periphery of the brake shoe 2. A cam 4 rotates by a normal brake operation, and a brake shoe 2 expands outward around an anchor pin 3, bringing a brake lining 7 into contact with a rotating brake drum 1 to generate braking force. 8 indicates the web.

During this braking, vibrations are generated due to the strong friction between the brake drum 1 and the brake lining 7, and the vibrations resonate in various parts of the brake, causing brake squeal. To prevent this, it would be better to dampen the vibration, but since this vibration has an extremely high frequency (2.5-5KHz) and little vibration displacement, effective damping is difficult, and the location of the vibration is Each brake is different and inconsistent, so
I can't figure out the mode of vibration. Vibrations on the drum 1 side can be effectively countered by fitting an elastic ring to the outer circumferential surface, but certain countermeasures can be taken against vibrations on the brake shoe side, which has a complex shape. It's impossible. However, since factors on the brake shoe side make a greater contribution to the occurrence of brake squeal, some means for damping vibrations on the brake shoe side is desired in order to suppress this.

In consideration of the above points, this invention aggregates the vibrations that were randomly occurring in the brake shoe so that they occur in a specific part and mode, and then provides a means to dampen this vibration, thereby reducing brake squeal. To provide an inwardly expanding brake designed to effectively prevent such problems.

In order to achieve the above object, the present invention provides one to several slits in at least one of the lining base portion and the web on the brake shoe, thereby identifying the mode of vibration of the brake shoe. In addition, a weight portion is loosely fitted over both sides of the slit to attenuate the specified vibration.

This vibration, which is specified by providing the slit, absorbs most of the excitation energy during braking and acts to concentrate the vibration of the brake shoe. At the same time, since this vibration has a relatively large amount of displacement and a low frequency, it can be easily damped by loosely fitting the weight member.

In this way, brake squeal can be effectively suppressed, and since the position and size of the slit, the type and size of the damping member, etc., are highly reproducible for brakes of the same model, the vibration characteristics are different from each other, unlike conventional brakes. Unlike those without damping means, they are suitable for mass production and have the effect of achieving high reliability.

Some embodiments of the invention will be described below with reference to the figures.

In FIG. 2, a web 8 extending inside the brake shoe 2 is provided with radial slits 9,9. By providing the slits 9, 9, the amount of displacement in the bending and torsion modes between the two sides a, b increases and the phase shifts. That is, the vibration mode is specified, and therefore the effective position for vibration damping becomes clear.

Figures 3 and 4 illustrate one method of damping the vibration modes described above. Slit 9,9
The bolt heads 10a, 10a and the nuts 11, 11 (or the interposed washers 12) are engaged with both sides a, b, and lightly tightened. A weight member consisting of these bolts 10 and nuts 11 (or washers 12) causes braking between a and b,
Damping is given. In this case bolt 10,
Fixing the two sides a and b with the nut 11 is ineffective. In other words, it is important to press and hold the two sides a and b to the extent that braking resistance is generated between them. Rivets can be used instead of bolts and nuts.
Further, an elastic body such as a spring or rubber may be interposed.

As a result of experiments, the above configuration significantly reduces brake squeal, and relatively rough adjustment of the tightening force of bolts and nuts is effective, making it highly practical.

Another method of vibration mode damping using the slits 9, 9 shown in FIG. 2 is shown in FIGS. 5 and 6. A concave portion 13 is provided on one side of the web 8, and a damper weight 14 is attached to the concave portion 13 to form the slits 9, 9.
It is held by a bolt 10 and a nut 11 (or rivet) inserted through the tip. The damper weight 14, bolt 10, and nut 11 (or rivet) constitute a weight member. In this case as well, the damper weight 14 is not completely fixed, but is lightly pressed against it. During vibration, both sides of the slit can move independently, and due to the frictional resistance with the damper weight 14, it acts as a kind of dynamic damper.
Set appropriate damper weight and shape. An elastic body may be interposed.

By adding damper weight in this way, this brake shoe further reduced brake squeal, resulting in a significant improvement.

Next, FIG. 7 shows a brake shoe 2 with slits 15, 15 formed on both sides of the lining base 6 along with the brake lining 7. Due to the slits 15, 15, the torsional and bending vibrations of the brake shoe 2 have a large displacement amount and a specified vibration mode, that is, a state where damping is easily applied.

Therefore, by sandwiching the damper weight 16 that contacts the back surface of the lining base from both sides of the web 8, as shown in FIGS. 8 and 9, the slit 15,
It is held by a pin 18 inserted from the 15 end in the centripetal direction. Bolts or rivets may be used instead of pins 18. In this case, the important thing is that the damper weight 16 can move freely in three dimensions to some extent.
Moreover, make sure that it is in contact with each part. Also in this case, the damper weight 16 and the pin 18, or the damper weight 16 and the bolt or rivet constitute a weight member.

In this way, a type of dynamic damper is formed by the contact and frictional resistance of the damper weight, and it is possible to damp the specified vibration mode of the brake shoe. By appropriately setting the weight and size of the damper weight and using this brake shoe, brake squeal can be significantly reduced.

Although the damper weights 16 shown in FIGS. 8 and 9 are shown as being arranged on both sides of the web 8, the damper weights 16 may be arranged on one side of the web 8.

As described above, the internally expanding brake according to the present invention specifies the vibration mode of the brake shoe by forming a slit in the brake shoe.
A weight member is loosely fitted to counter this vibration mode. Conventionally, it is difficult to determine the location and mode of vibrations that occur irregularly on the brake shoe, and it is difficult to find damping methods, so this is a countermeasure against brake squeal. However, by intensively identifying vibration modes and making damping easier, it is possible to effectively and uniformly deal with brakes of the same model.
This has the effect of ensuring highly reliable mass production of internal expansion type brakes with less brake squeal.

[Brief explanation of drawings]

Fig. 1 is a front view illustrating an internal expansion type brake, Fig. 2 is a front view of a brake shoe showing one embodiment of the present invention, and Fig. 3 is a front view showing a brake shoe to which one method of damping is applied. 4 is a bottom view of the brake shoe shown in FIG. 3, FIG. 5 is a front view of the brake shoe using another damping method, and FIG. 6 is a bottom view of the brake shoe shown in FIG. 5. 7 is a top view of a brake shoe showing another embodiment of the present invention, and FIG. 8 is a front view showing a brake shoe to which the damping method is applied.
FIG. 9 is a sectional view of a main part of the brake shoe shown in FIG. 8, taken along line A--A in FIG. 7. 1... Brake drum, 2... Brake shoe, 6... Lining base, 7... Brake lining, 8... Web, 9, 15... Slit, 10... Bolt, 11... Nut, 14,1
6...Dumper weight, 18...Pin.

Claims (1)

[Claims] 1. One to several slits are arranged in at least one of the lining base part and the web part, thereby specifying the mode of vibration of the brake shoe, and the weight part is loosely straddled on both sides of the slit. An internal expansion type brake characterized by being interposed in a fitted state.