JPH0211768B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a drum brake equipped with a built-in automatic shoe gap adjustment device, which adjusts the shoe gap of the drum brake to stop adjusting the gap between the brake drum and the shoe when the brake temperature rises. This invention relates to an adjustment and stop device.

<Prior Art> In drum brakes, there is an automatic shoe gap adjustment device that automatically reduces the gap between the brake drum and the shoe when the gap between the brake drum and the shoe increases due to wear of the shoe.

The shoe gap automatic adjustment device is located, for example, between the left and right shoes a1 and a2, as shown in FIG.

That is, one end of the strut b of the automatic shoe gap adjustment device is connected to the shoe a1 by a spring c.

Furthermore, at the other end of the strut b, a bell crank lever d is movable in the direction of operation of the shoe a2.
It is rotatably supported by a pin p, and the cam d1 at the tip thereof is inserted into the web hole e1 of the shoe a2 with a certain amount of play g.

The bell crank lever d is constructed such that a rack portion d2 engages with teeth b1 formed at the intermediate portion of the strut b, and a spring f stretched between the pin p and the strut b engages them.

When the shoes a1 and a2 are expanded by a wheel cylinder (not shown), if the linings of the shoes a1 and a2 are worn out, the expansion of the shoes a1 and a2 proceeds beyond the setting, and the web e
The play g between the web hole e1 and the cam d1 is eliminated.

Then, the web hole e1 pushes the bell crank lever d in the movable direction of the shoe a2, so that the rack part d2
and the tooth b1 is disengaged.

The bell crank lever d rotates counterclockwise around the pin p, and the new teeth of the rack part d2 engage with the teeth b1 of the strut b, expanding the outer diameter of the shoes a1 and a2, and the shoes a1 and a2. Automatically adjust the gap between brake drums.

The above-mentioned device also prevents the shocks a1 and a2 even when the brake drum expands due to frictional heat during braking.
As in the case of wear, the outer diameters of both shoes a1 and a2 are enlarged.

In this case, when the brake drum cools down, the brake drum and shoes a1 and a2 become extremely close to each other.

In order to prevent such a situation, as shown in FIGS. 6 and 7, a detection part m of bimetal m is installed in the web hole e1.
2 is inserted from the top side of the web e.

The bimetal m is a member whose fixing portion m1 is fixed to the upper surface of the web e, and is deformed when the temperature rises, and the sensing portion m2 at the tip of the bimetal m is removed from the web hole e1.

Therefore, when the temperature rises, the play between the web hole e1 and the cam d1 of the bell crank lever d increases, and the action of the automatic shoe gap adjustment device stops.

<Problems to be Solved by the Present Invention> The shoe gap adjustment and stop device as described above has the following problems.

(a) The detection part m2 at the tip of the bimetal m, which deforms using the fixed part m1 as a fulcrum, draws a circular locus of radius r in the direction approaching the inner wall e2 of the web hole e1, as shown in FIG. Therefore, a certain gap h must be provided between the detection part m2 and the inner wall e2, which is extremely difficult.

(b) In addition, since the above-mentioned gap h becomes a factor of variation in the play between the cam d1 and the detection part m2, which essentially determines the gap between the brake drum and the shoes a1 and a2, the gap between the brake drum and the shoes a1 and a2 varies. becomes larger.

(c) Since there is a gap h between the detection part m2 and the inner wall e2 of the web hole e1, the bimetal m can be used only by pushing the bell crank lever d against the force of the spring f during normal automatic shoe gap adjustment. Rigidity is required.

Therefore, the thickness of the bimetal m must be increased, and its sensitivity decreases.

(d) Since the deformation of the bimetal m is unlimited, there is a risk of interference with other rotating parts such as the brake drum.

<Object of the present invention> The present invention has been made to solve the above-mentioned problems. To provide a shoe gap adjusting and stopping device for a drum brake equipped with a bimetal without fear of interfering with the body.

<Configuration of the Present Invention> An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

(a) Shoe gap adjustment/stop device The shoe gap adjustment/stop device for a drum brake of the present invention is constructed by attaching a stopper 2 to a bimetal 1 whose intermediate portion is bent into a stepped shape.

Each part will be explained below.

(b) Bimetal (Figure 1) Bimetal 1 is a member that deforms due to temperature rise.

The shape is an L-shaped plate consisting of a long side part 11 and a short side part 12. The middle part of the long side part 11 is bent into a stepped shape to form a slope part 13, and the base end of the long side part 11 is formed by bending it into a stepped shape. This is referred to as a fixed part 14.

The bimetal 1 is formed so that the surface of the fixing portion 14 is lower than the surface of the short surface portion 12 with a step formed by the slope portion 13 .

Furthermore, a detection section 15 is provided at the free end of the short surface section 12 in a protruding L-shape toward the fixing section 14 side in the step direction.

The detection part 15 is a part inserted into the web hole U1 of the web U.

And the long surface portion 1 between the slope portion 13 and the short surface portion 12
A stopper 2 is attached to the back side of the first part.

The stopper 2 is a member that extends from the free side of the bimetal 1 in the same direction as the short surface 12, and its tip 2
1 is positioned at a constant distance from the back surface of the web U, and is configured so as to come into contact with the back surface of the web U when the detection section 15 is removed from the web hole U1 due to deformation of the bimetal.

(c) Installation on the web The above bimetal 1 is installed on the web U of the shoe as in the conventional manner.

That is, as shown in FIG. 1, the detection part 15 is inserted into the web hole U1 of the web U, and the fixing part 14 is fixed to the back surface of the curved part U2 of the outer shape of the web U with rivets or the like.

At this time, the detection portion 15 of the bimetal 1 is positioned by lightly abutting against the inner wall U3 of the web hole U1.

Further, the end portion 21 of the stopper 2 of the bimetal 1 is located below the web U.

<Function> Next, the operating state of the drum brake in which the bimetal 1 described above is installed on the web U will be described.

(a) Deformation of the bimetal When the atmospheric temperature inside the drum brake increases due to brake operation, the bimetal 1 begins to deform.

As shown in FIG. 2, the bimetal 1 deforms so as to draw a circular locus with a radius R, with the point of contact with the inner edge of the curved portion U2 of the web U as the fulcrum 1.

Therefore, the detection unit 15 detects the inner wall U3 of the web hole U1.
move away from.

(b) Stopping the automatic shoe gap adjustment When the bimetal 1 comes off from the web hole U1, the play between the cam of the bell crank lever inserted into the web hole U1 and the web hole U1 increases as in the conventional example.

Therefore, even if the gap between the brake drum and the shoe increases due to expansion of the brake drum and the shoe moves more than necessary, the inner wall U3 of the web hole U1 will not push the cam of the bell crank lever.

Therefore, the bell crank lever does not rotate and automatic adjustment of the shoe gap stops.

<Other Embodiments> In addition to the shoe gap adjustment device shown in the above embodiments, the shoe gap adjustment/stop device based on the same principle can be applied to a shoe gap adjustment device as shown in FIG.

The shoe gap adjustment and stop device shown in Figures 3 and 4 consists of loosely fitting the tip of a bolt V, which passes through a web hole U and is frictionally attached to the shoe, into an adjustment hole J1 of a batch J fixed to a back plate B. Configure.

In this device as well, if a bimetal M is installed in the adjustment hole J1 of the batch J as shown in Fig. 3, automatic adjustment of the shoe gap will stop when the gap between the shoe S and the brake drum D increases due to temperature rise. do.

In this embodiment, when the fixing part M2 of the bimetal M is fixed to the lower surface of the thin part of the batch J with rivets, the detection part formed at the free end extending from the fixing part M2 toward the adjustment hole J1 is used. Set M1 by lightly touching the inner surface of the adjustment hole J1.

In addition, the bimetal M has its detection part M1 and fixed part M2 located on the same side of the batch J, and
The detection part M1 is installed so that the tip thereof is located below the fixed part M2.

To explain its adjustment function, when the lining of the shoe S wears out at room temperature, the shoe S moves along with the bolt V toward the brake drum D.

At this time, when the tip of the bolt V comes into contact with the detection part M1 of the bimetal M installed along the inner wall of the adjustment hole J1 of the batch J, the bolt V overcomes the frictional force and moves toward the inner side of the brake of the shoe S. move relative to
When releasing the brake, bring the shoe S closer to the brake drum D side.

Next, the operation during temperature rise will be explained.

As shown in Fig. 4, when the bimetal M tilts toward the back plate B due to temperature rise,
The detection part M1 of the bimetal M comes off from the adjustment hole J1 of the batch J, and the play between the adjustment hole J1 and the tip of the bolt V increases.

The tilting of the bimetal M is regulated by the bending portion forming the detection portion M1 hitting the back plate B.

Then, the spherical part at the tip of bolt V is aligned with adjustment hole J1.
Since it does not come into contact with the inner surface of the shoe, automatic adjustment of the shoe gap stops.

At this time, the movement of the detection part M1 of the bimetal M is also in the direction of movement inside the adjustment hole J1, so the detection part M1 of the bimetal M can be set in contact with the inner wall of the adjustment hole J1.

<Effects of the Invention> Since the present invention has been described above, the following effects can be expected.

(a) The present invention is configured such that the detection portion moves away from the inner wall of the shoe web hole or the batch adjustment hole when the bimetal is deformed.

Therefore, the bimetallic detection section can be set in contact with the inner wall of the web hole or the adjustment hole, thereby simplifying the work.

(b) Since the bimetallic detection part is in contact with the web hole or the inner wall of the adjustment hole, there is no risk of deformation even if force is applied during normal adjustment.

Therefore, it is possible to improve sensitivity by reducing the plate thickness, and to reduce cost and weight.

(c) When the bimetal deforms by a certain amount, the stop comes into contact with the back surface of the web or the back plate and limits further deformation, so there is no risk of interference with other rotating bodies.

[Brief explanation of drawings]

Figure 1: An explanatory diagram of the shoe gap adjustment and stop device of the present invention, Figure 2: An explanatory diagram of the bimetal of the present invention during deformation, Figures 3 and 4: Explanatory diagrams of other embodiments, Figure 5: Shure Explanatory diagram of automatic gap adjustment device, No. 6
Figure: An explanatory diagram of a conventional bimetal. Fig. 7: An explanatory diagram of a conventional bimetal during deformation.

Claims (1)

[Scope of Claims] 1. Equipped with an automatic shoe clearance adjustment device that is linked to the operation of the brake shoe, one member of the linking member of the automatic shoe clearance adjustment device is connected to a hole formed in the other member, and the operation of the brake shoe is connected to the hole formed in the other member. In a drum brake that engages with some play in the direction and automatically adjusts the gap between the brake shoes when the amount of expansion of the brake shoe exceeds the play, the bimetallic part of the drum brake is bent in the middle. A height difference is provided between the base end and the free end, a sensing portion is formed at the free end of the bimetal that protrudes toward the base end, and the sensing portion is connected to the shutter so as to set the play at room temperature. The proximal end of the bimetal is inserted into contact with the inner surface of the hole formed in the linking member of the automatic gap adjustment device, and when the bimetal is deformed by heating, the tip of the detection part comes out of the inner surface of the hole,
A shoe gap adjusting and stopping device for a drum brake, characterized in that the device is fixed at a position where the play is deformed in a direction that narrows the play. 2. The drum brake shoe gap adjustment and stop device according to claim 1, characterized in that a stopper is provided in the middle of the bimetal to restrict deformation of the bimetal to a certain amount.