JP3942663B2 - Brake band - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brake band used in a transmission for a vehicle such as an automobile, an agricultural machine, or a construction machine.
[0002]
[Prior art]
In an automatic transmission, a multi-plate clutch, a brake band, and the like are used to shift gears by fixing and releasing input elements such as gears. Among them, the brake band is widely used because it has a characteristic that the braking force is different even when the same operating force is applied depending on the braking direction of the drum and has a preferable characteristic of smoothing upshift.
[0003]
In order to facilitate understanding of the present invention, FIG. 2 shows a basic configuration of the brake band. The brake band 12 is constituted by a strap 3 which is a curved belt-shaped steel plate, and brackets 4 and 5 are respectively coupled to both end portions of the strap 3. A porous paper-like friction material (lining) 2 is bonded to the inner peripheral surface of the curved strap 3 with an adhesive.
[0004]
In the hand brake having such a configuration, the oil groove 10 is provided in the lining 2 and the oil is discharged to the oil groove 10 in order to improve the oil discharge characteristic between the drum and the lining 2 in the hand brake engaging process. The hole 11 may be provided.
[0005]
The operation of the brake band 12 will be briefly described with reference to FIG. 3. The brake band 12 surrounds the drum 1, the bracket 5 serves as the apply bracket on the hydraulic operation side (apply side), and the bracket 4 receives the acting force. Use the anchor bracket on the anchor side. When operating the brake, hydraulic pressure is applied to the apply bracket 5 and the berake band 12 is fastened to the drum 1. The brake band 12 is in close contact with the drum 1 and operates so that the apply side end portion 15 approaches the anchor side end portions 14 on both sides of the cut 13 of the brake band 12. Although the rotation direction of the drum varies depending on the case, it is usually used in a direction (indicated by an arrow R in the figure, called the leading direction) that rotates from the apply side to the anchor side.
[0006]
FIG. 4 is an enlarged view of the structure of the anchor side of a conventional brake band. 1 is a drum, 2 is a lining, 3 is a strap, 6 is a strut that supports the anchor bracket 4, and 8 is an anchor bracket on the strap 3. 4 is a caulking pin for caulking 4, and a caulking portion 9 is formed by the caulking pin 8.
[0007]
A plurality of crimping portions 9 are provided in the axial direction at each coupling portion to form one row. Since FIG. 4 is a cross-sectional view, only one crimping portion 9 is shown at each coupling point, but since a plurality of crimping portions 9 are provided in the axial direction, the caulking portion 9 is seen from the anchor side end portion 14 of the brake band. A plurality of rightmost crimping portions 9 are arranged in the axial direction to form a first row coupling portion, and the leftmost crimping portion 9 in the drawing is the last row coupling portion. Although it is shown as three columns in the figure, it goes without saying that it is an arbitrary number as required.
[0008]
Therefore, as shown in FIG. 4, the bulging of the caulking pin 8 causes a convex bulging 19 in the lining 2 around the caulking portion 9, so that the friction torque of the brake band 12 increases due to the influence of the bulging.
[0009]
If the torque curve at the time of band fastening is shown in FIG. 5 with the friction torque T on the vertical axis and the time t on the horizontal axis, the torque curve in the conventional brake band is as shown by a two-dot chain line B. As the lubrication state, the α region in the initial meshing state can be divided into the fluid lubrication region, the β region in the middle meshing phase can be divided into the mixed lubrication region, and the γ region in the final meshing phase can be divided into the boundary lubrication region.
[0010]
In this meshing region, particularly in the friction characteristics of the α region and the β region, the influence of the convex bulge of the lining tip is large. (Note that the solid line Α indicates that a constant torque curve is obtained by the present invention as will be described later.)
[0011]
[Problems to be solved by the invention]
The increase in friction torque as described above becomes particularly remarkable when the rotation of the drum is in the leading direction. This is because when the drum rotates in the leading direction, the anchor side torque and surface pressure are about three times higher than the apply side. At the initial stage of brake engagement, the surface pressure is extremely concentrated on the convex part and the torque capacity is low. However, when the lining gradually becomes familiar with the drum due to wear of the convex part, the entire surface comes into contact and the torque capacity increases. Therefore, the torque curve changed.
[0012]
In order to prevent the lining from rising, it was considered to connect the strap and the bracket by spot welding instead of caulking. However, when the brake is engaged, the strap and lining strongly suppress the drum rotation, and the reaction force is applied to the anchor bracket. Therefore, a strong shearing force acts on the joint between the strap and the bracket, pulling the strap and the bracket apart. I will try.
[0013]
Further, a moment due to a reaction force acting on the bracket is applied to the bracket, and a strong pulling force between the bracket and the strap is applied to the connecting portion in the last row in FIG.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides the same shape or different shape brackets coupled to both end portions of a belt-like strap that is curved in an annular shape and has a paper-like friction material bonded to the inner peripheral surface thereof. A plurality of coupling portions are arranged side by side in the axial direction at the coupling location, and the coupling location which is a sequence of the coupling portions is a brake band provided in a plurality of rows at predetermined intervals in the circumferential direction. ,
A brake band characterized in that the anchor bracket and the strap are joined by caulking joints at the last row when viewed from the anchor side end of the brake band, and by spot welding at the other joints. Is obtained.
[0015]
【Example】
FIG. 1 shows an embodiment of a brake band of the present invention. 1 is a brake drum, 2 is a lining, 3 is a strap, 4 is an anchor bracket, 5 is an apply bracket, 6 is a strut that supports the bracket 4, and 7 is a strap 3 The first row spot welds for joining the bracket 4 and 8 are the last row caulking pins for caulking the strap 3 and the bracket 4, and 9 is the last row caulking portion. In the drawing, only the joint portion by spot welding in the first row is shown, but as described above, the strap 3 and the anchor bracket 4 are joined by joint portions by spot welding in a plurality of rows not shown. . Only the connecting portion in the last row as viewed from the anchor-side end portion 14 of the break 13 of the brake band is formed as a caulking joint 9.
[0016]
In the brake band of the present invention, most of the joint portions are spot welded and there is no bulging of the lining, so there is no extreme local concentration in the surface pressure distribution of the brake drum 1 and the lining 2, so the torque is almost constant. It becomes. The anchor bracket has the lowest surface pressure distribution, and the joints in the last row that receive concentrated loads from the strap 3 are made of high-strength caulking joints, minimizing the effects of strength reduction caused by spot welding. However, the torque capacity can be stabilized and the heat resistance can be improved.
[0017]
FIG. 5 shows a torque curve at the time of band fastening. A solid line A shows a brake band according to the present invention, and a two-dot chain line B shows a conventional brake band as described above. According to the present invention, it can be seen that the friction torque is substantially constant from the α region at the initial stage of engagement to the γ region at the end of engagement.
[0018]
FIG. 6 is a diagram showing changes in brake band usage time and friction coefficient over time. A is a brake band of the present invention, and B is a conventional brake band. It can be seen that the friction coefficient of the present invention is almost constant and hardly changed from the beginning of use.
[0019]
【The invention's effect】
The brake band of the present invention is a skillful combination of the advantages of spot welding and the strength of caulking joints, combined with the strap and anchor bracket. Most of the joints are spot welded to prevent the lining from rising, and the lining surface By smoothing the surface, there is no local concentration of surface pressure, and the load distribution is ideal.Furthermore, the surface pressure distribution is the lowest, and only the connection point in the last row that receives the detachment load of the strap and bracket is concentrated as a caulking connection. As a result, the decrease in strength is minimized, and the torque capacity is stabilized and the heat resistance is improved.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of the present invention. FIG. 2 is a view showing a configuration of a brake band. FIG. 3 is an explanatory view of the operation of the brake band. ] Figure showing torque curve when band is fastened [Figure 6] Figure showing friction coefficient over time [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Brake drum 2 Lining 3 Strap 4 Anchor bracket 5 Apply bracket 6 Strut 7 Spot welding 8 Caulking pin 9 Caulking part 10 Oil groove 11 Oil discharge hole 12 Brake band 13 Cut 14 Anchor side end 15 Apply side end 19 Swell

Claims (1)

The same or different shape brackets are joined to both ends of the belt-like strap that is curved in an annular shape and has a paper-like friction material bonded to its inner peripheral surface. In the brake band provided in a plurality of rows at a predetermined interval in the circumferential direction, the connecting portion which is a row of the connecting portions is formed in a row.
A brake band characterized in that the anchor bracket and the strap are joined by caulking joints at the last row when viewed from the anchor side end of the brake band, and by spot welding at the other joints.

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