JPH11311274A - Brake drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently secure circularity of a drum by arranging the step part recessed inward in a cross-sectional V shape in the shoulder parts of the drum and the flange, and setting a thickness of the bending part smaller than a thickness of the drum and the flange. SOLUTION: The inward recessed step part 14 is arranged in the shoulder parts of a drum 12 and the flange 12a. The step part 14 is a cross-sectional dog legged shape, and a thickness T3 of the bending part 15 is set smaller than a thickness T1 of the drum 12 and a thickness T2 of the flange 12a. While the drum 12 side part 16 from the bending part 15 is thinner than the bending part 15 and is straightly formed in the radial direction, the flange 12a side part 17 gradually reduces in a thickness while tiltably extending to the bending part 15. When surface accuracy of a wheel is bad, the flange 12a is deformed after surface accuracy of the wheel by fastening force of a bolt, but since the step part 14 deflects so as to open and close through the bending part 15, deformation of the flange 12a is absorbed, and is hardly transmitted to the drum inside surface. Therefore, circularity of the drum inside surface can be kept well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in a brake drum.

[0002]

2. Description of the Related Art A brake drum is assembled as shown in FIG. Reference numeral 1 denotes a hub that rotates integrally with an axle, and has a flange 1a formed on its outer periphery. The disk 2a of the wheel 2 is provided on one flange surface of the hub 1, and the flange 3 of the drum 3 is provided on the other flange surface.
a are respectively abutted, and they are fastened together by a plurality of bolts 4 arranged on the same circumference around the axle.

Although not shown, a brake mechanism (fixed to the vehicle body) for operating a brake shoe is housed inside the drum 3, and the brake shoe is pressed against the inner surface of the drum via the lining when the brake is operated (braking). Then, a braking force (brake torque) for suppressing the rotation of the wheel 2 is generated by the frictional force acting between them.

When the roundness of the drum 3 is deteriorated, the brake torque fluctuates in accordance with the rotation angle of the drum 3. Therefore, the brake torque is used as a source of vibration. Brake squeal is likely to occur. Therefore, in order to ensure the roundness of the drum 3, the surface accuracy between the flange 3a of the drum 3 and the flange 1a of the hub 1 and the disk 2a of the wheel 2 and the hub 1
It is required to improve the surface accuracy between the first and second flanges 1a.

Although a good surface accuracy can be secured between the flange 3a of the drum 3 and the flange 1a of the hub 1 by controlling the processing accuracy in these production steps, the flange 1a of the hub 1 and the wheel 2 Disk 2a
Since there are various wheels 2 on the market, there is a possibility that when the wheels 2 with poor surface accuracy are assembled, the distortion is transmitted to the drum 3 and the roundness of the inner surface of the drum is deteriorated. Can be

For this reason, a plurality of concave grooves are arranged concentrically on the flange of the drum, and the flexibility of the flange is increased so that the deformation of the wheel mounting surface is prevented from being transmitted to the drum. Known (Japanese Unexamined Patent Publication No. Hei 8-226)
474). It is not a measure to prevent the deformation of the drum, but to prevent brake judder and brake squeal, even if the brake shoe falls down in the width direction of the brake shoe due to deformation of the drum inner surface when the brake is activated, the brake lining should be Also, there is one in which both ends of the lining surface are formed as inclined surfaces so that they contact each other on the center side (Japanese Utility Model Laid-Open No. 5-83485).

[0007]

Among the conventional examples, in the former case, since the flexible portion is formed by a plurality of concave grooves on the outer periphery of the mounting surface with respect to the flange of the hub, the width of the flange of the drum is large. Become. In other words, as shown in FIG. 5, when the hub diameter is large (that is, the difference between the wheel diameter and the hub diameter is small), there may be a problem that it is difficult to secure a sufficient flexible portion on the flange. In the latter case, as the lining wears, the contact position with the drum inner surface is displaced to both ends, and the effect of suppressing brake judder and brake squeal is gradually reduced.

FIG. 6 shows wheels (commercially available) NO1 to NO1.
An analysis result of the measurement is shown for the mounting surface accuracy of 0, and undulation (distortion) around the axis is observed on the mounting surface of the wheel. Among them, the one that most affects the deformation of the brake drum is a second-order undulation having two peaks between 0 ° and 360 °, and FIG. 7 shows a schematic diagram of this undulation. When the mounting surface of the wheel 2 undergoes such secondary deformation, the brake drum will be deformed into an elliptical shape.

It is an object of the present invention to provide a countermeasure for solving the conventional problems based on such an analysis result.

[0010]

According to a first aspect of the present invention, in a brake drum assembled to a hub together with a wheel, a shoulder portion is provided in a shoulder portion between the drum and a flange thereof so as to be inwardly concave in a cross-sectional shape. The thickness of the portion is set smaller than the thickness of the drum and the thickness of the flange.

[0011]

According to the first invention, the wheel (disk)
When the flange of the drum is deformed due to the deformation, the concave portion having a V-shape in cross section is bent based on the deformation, such that the concave portion opens and closes via the thin bent portion. Therefore, the transmission of the deformation of the flange to the drum is absorbed, and the roundness of the inner surface of the drum (the sliding surface with the brake shoe) can be satisfactorily secured.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 and 2, reference numeral 10 denotes a hub which rotates integrally with an axle, and has a flange 10a formed on the outer periphery thereof. The disk 11a of the wheel 11 is abutted against one flange surface of the hub 10 and the flange 12a of the drum 12 is abutted against the other flange surface, and these bolts are located on the same circumference around the axle. (Not shown).

The shoulder 13 between the drum 12 and its flange 12a is provided with a step 14 which is depressed inward as shown in FIG. The step portion 14 is formed in a V shape in cross section, and the bent portion 1 is formed.
The thickness of the wall thickness T ₃ the drum 12 of the 5 T ₁ and the flange 12
It is set smaller than the thickness T ₃ of the _{a (T 3 <T 1,} T 3 <
T ₂ ). In the step portion 14, a portion 16 on the side of the drum 12 from the bent portion 15 having a U-shaped cross section is formed thinner and straight in the radial direction than the bent portion 15, while a portion 17 on the side of the flange 12a is also formed. Are formed such that the wall thickness is gradually reduced while extending obliquely to the bent portion 15.

Although not shown, a brake mechanism (fixed to the vehicle body) for operating a brake shoe is housed inside the drum 12, and when the brake is operated (during braking), the brake shoe is pressed against the inner surface of the drum via the lining. Then, a braking force (brake torque) for suppressing the rotation of the wheel 11 is generated by the frictional force acting between them.

With such a configuration, the flange 12a of the drum 12 sandwiches the flange 10a of the hub 10 between the flange 12a and the disk 11a of the wheel 11, and is fastened to these by a plurality of bolts. If the surface accuracy of the wheel 11 is poor,
The flange 12a of the drum 12 is deformed in accordance with the surface accuracy of the wheel 11 by the tightening force of the bolt, and the stepped portion 14 having a V-shaped cross section opens and closes via the bent portion 15 based on the deformation. Due to the bending, deformation of the flange 12a of the drum 12 is absorbed, and transmission to the drum inner surface is reduced. Therefore, the roundness of the inner surface of the drum (the sliding surface with the brake shoe) can be favorably maintained even for the wheel 2 as shown in FIGS.

In this case, the drum 12 and its flange 12
Since flexibility is given to the shoulder portion 13 with the shoulder portion 13 by the step portion 15,
Application to a layout as shown in FIG. 5 where the difference between the hub diameter and the wheel diameter is relatively small is also possible. Step 14
Is formed as described above, the rigidity of the drum 12 (the rotation direction is increased) can also be secured. Step 1
4 at each corner (see FIG. 3)
A _{1 to} a ₃ , b _{1 to} b ₃ , and c ₁ ), the curved surfaces A _{1 to} A ₃ , B _{1 to} B ₃ , and C ₁ having the predetermined radius R can be smoothly connected. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is an assembly diagram illustrating an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the same.

FIG. 3 is a partially enlarged view of the drum.

FIG. 4 is a partially enlarged view of the drum.

FIG. 5 is an explanatory diagram of a conventional example.

FIG. 6 is a graph showing a deformation state of a mounting surface of a wheel.

FIG. 7 is a schematic diagram illustrating a deformed state of a mounting surface of a wheel.

[Explanation of symbols]

 Reference Signs List 10 Hub 10a Hub flange 11 Wheel 11a Wheel disc 12 Drum 12a Drum flange 13 Shoulder 14 Step 15 Bend 16 Step drum side part 17 Step flange side part

Claims (1)

[Claims] In a brake drum assembled to a hub together with a wheel, a shoulder portion between a drum and a flange thereof is provided with a stepped portion which is depressed in the shape of a cross section inward, and the thickness of the bent portion is adjusted by the thickness of the drum and the flange. A brake drum characterized by being set smaller than the wall thickness.