JPH02229926A - Drum brake with parking brake mechanism - Google Patents

Abstract

PURPOSE:To reduce an installing space by enlarging the first and second brake shoes by means of the first and second pistons with pressure oil supply at the time of stopping run, and pressing the second brake shoe by means of the second piston by the turning movement of a lever at the time of parking. CONSTITUTION:For stopping a running vehicle, pressure oil is supplied to the inside of a cylinder body 13, so that pistons 10, 11 and a rod 12 protrude in the body 13 respectively. The piston 11 presses the web 6 of a brake shoe 3 outwards to move the piston 10 and the rod 12 to the outside of the body 13 respectively. A brake shoe 2 is also pressed outwards with the same force as the shoe 3. As a result, the shoes 2, 3 are pressed and expanded and linings 8, 8 are pressed against a drum for braking. For operating a parking brake, a parking lever 17 is pulled to the left, so that the lever 17 makes forming movement clockwise to press the rod 12 in the body 13 and press the piston 11 to the left. As a result, the lining 8 is pressed against the drum, and the lever 17 presses the lining 8 against the drum as the effect of reaction.

Description

[Detailed Description of the Invention] (Field of Application in Industry A) The tram brake with parking brake mechanism according to the present invention can be used to stop a moving vehicle, or to prevent a stopped vehicle from starting to move unnecessarily. Use it to make sure it doesn't happen.

(Prior Art) Various types of drum brakes have been used to brake automobiles.

In all types of drum brakes used for braking automobiles, a pair of brake shoes are placed inside a drum that rotates with the wheels, and during braking, the wheels are placed between the pair of brake shoes. By supplying pressure oil to the cylinder, the outer peripheral surface of both brake shoes is pressed against the inner peripheral surface of the drum, and braking is performed based on the friction between the inner peripheral surface of the drum and the outer peripheral surface of the brake shoe. It has been done. In addition, the parking brake mechanism, which is used to keep the car in a stopped state when parking, etc., uses the movement of the parking lever, which is rotated by the control lever installed on the driver's seat, to control the above-mentioned operation regardless of the supply of pressure oil to the wheel cylinders. By increasing the distance between the pair of brake shoes, the inner circumferential surface of the drum and the outer circumferential surface of each brake shoe are brought into strong contact.

(Problem to be Solved by the Invention) However, in the case of conventional drum brakes with a parking brake mechanism, both a wheel cylinder that increases the distance between a pair of brake shoes as pressure oil is supplied, and a parking lever that rotates. The parking brake mechanism, which increases the distance between the pair of brake shoes as the machine is used, was constructed independently of each other, requiring a large installation space.
The degree of freedom when designing drum brakes was limited.

The drum brake with parking brake mechanism of the present invention is
This is intended to eliminate such inconvenience.

(Means for Solving the Problems) The drum brake with parking brake mechanism of the present invention includes a mounting board supported by a suspension system of a vehicle, and a first and second drum brake movably supported on the mounting board. It consists of a brake shoe and a first and second piston fitted into a cylinder body fixed on a mounting board, and the movement of the first and second pistons widens the gap as pressure oil is supplied. , a wheel cylinder that presses the ends of the second and second brake shoes outward, and supply of pressure oil to the wheel cylinder as the first brake shoe rotates about a pivot provided on the first brake shoe. Irrespective of this, the parking lever consists of a parking lever that widens the distance between the first and second brake shoes, and a drum that surrounds the first and second brake shoes and rotates together with the wheel.

A through hole extending in the axial direction is formed in the first piston, and the outer end surface of the rod inserted into the through hole so as to be freely displaceable in the axial direction is connected to the end of the parking lever, and the inner end surface of the rod is inserted into the through hole so as to be freely displaceable in the axial direction. are brought into contact with the inner end surface of the second piston, and the portion fixed to the first piston is brought into contact with the end of the first brake shoe.

(Function) The drum brake with parking brake mechanism of the present invention constructed as described above functions as described below. First, when stopping a running automobile, the first and second pistons fitted in the cylinder body are caused to protrude from the cylinder body by supplying pressure oil into the cylinder body.

As a result, as each piston moves, the first and second brake shoes are pushed apart, and the outer circumferential surface of the brake shoe is strongly pressed against the inner circumferential surface of the drum, thereby performing braking.

In addition, in order to prevent a stopped car from moving inadvertently, by rotating the parking lever provided on the first brake shoe, the rod is pushed into the cylinder body, and the inner end surface of this rod Push the second piston out of the cylinder body.

As a result, the second piston presses the outer peripheral surface of the second brake shoe against the inner peripheral surface of the drum, and at the same time, as a reaction, the parking lever pressing the rod pushes the first brake shoe against the drum. The parking brake is activated.

(Example) Next, the present invention will be described in more detail based on the illustrated example.

1 to 3 show a first embodiment of the present invention, FIG. 1 is a sectional view of the wheel cylinder part, and FIG.
-A sectional view and FIG. 3 are front views showing a state in which this wheel cylinder is assembled to a duo-servo type drum brake.

Reference numeral 1 denotes a circular mounting board supported by a suspension system of an automobile, and a first and a second brake shoe 2 are mounted on this mounting board 1.
, 3 are supported so as to be slightly movable.

These first and second brake shoes 2, 3 are constructed by providing linings 8, 8 on the outer circumferential surfaces of approximately crescent-shaped webs 6, 6 via back metals 7, 7, respectively. One ends of the webs 6, 6 (lower ends in FIG. 3) constituting both the first and second brake shoes 2, 3 are connected to each other by a length-adjustable connecting rod 4 and a tension spring 5. The other ends of the webs 6, 6 are connected directly to the end surfaces of first and second pistons 10, 11, respectively, constituting a wheel cylinder 9, which will be described below, or by connecting them to a bar 20, which will be described later. Through, it is confronted.

The wheel cylinder 9 has first and second pistons 10, 11 attached to a cylinder body 13 fixed on the mounting board 1; the cylinder body 13 is oil-tight by means of lug seals 14, 15 provided on the outer peripheral surfaces of the respective pistons 10, 11. The above-mentioned first and second piston 10
511 is configured to widen the interval between them.

A pivot shaft 16 is provided at the end of the first brake shoe 2, and the base end of the parking lever 17 (
3). One end of the Bowden wire is connected to the tip of the parking lever 17 (lower end in Figure 3), and the other end of the Bowden wire is connected to an operating lever provided on the driver's seat. Based on the operation, the parking lever 17 can be rotated clockwise in FIG. 3 about the pivot shaft 16. Also, at the base end of this parking lever 17, the pivot 16
The inner edge of the part slightly closer to the center than the rod 1
The rod 12 is pushed into the cylinder body 13 based on the rotation of the parking lever 17 caused by extending the Bowden wire by one bow.

Although not shown, the first and second brake shoes 2
, 3 is provided with a drum that rotates together with the wheel so as to surround both brake shoes 2 and 3, and when the first and second pistons 10 and 11 constituting the wheel cylinder 9 are made to protrude, The outer peripheral surfaces of the linings 8, 8 constituting each brake shoe 2, 3 and the inner peripheral surface of the drum are made to rub against each other.

Further, in the center of the first piston 10 constituting the wheel cylinder 9, there is a
A through hole 18 is formed extending in the left-right direction in the figure, and the rod 12 described above is inserted into the through hole 18 so as to be freely displaceable only in the axial direction.

That is, a recess 19 extending in the diametrical direction of the rod 12 is formed on the outer end surface of the rod 12.
A rod member 20 (which may be integrated with the first piston 10 or may be a separate member and later combined) is engaged with the first piston 10. The rods 20 are fixed to the outer end openings of the through holes 18 in the diametrical direction thereof, and the edge of the web 6 constituting the first brake shoe 2 is in contact with the rods 20. The edge of the parking lever 17 is in contact with the outer end surface of the rod 12.
It is in contact with the part that is separated from the

As described above, the inner end surface of the rod 12 (see FIG. The left end surface) is brought into contact with the inner end surface of the second piston 11 (the right end surface in FIG. 1).

In Fig. 3, 21 and 21 indicate the position where the first and second brake shoes 2 and 3 are returned to their original positions (the outer circumferential surfaces of the linings 8 and 8 do not rub against the inner circumferential surface of the drum) after the brake is released. position)
The return spring 22 in FIG. 1 is a compression spring provided between the cup seal 14 attached to the first piston 10 and the inner end surface of the second piston 11.
This compression spring 22 has sufficiently weaker elasticity than the return spring 21 described above. Further, 33 is an O-ring for maintaining oil tightness between the inner circumferential surface of the first piston 10 and the outer circumferential surface of the rod 12.

When stopping a running vehicle using the drum brake with parking brake mechanism of the present invention configured as described above, pressure oil is supplied into the cylinder body 13 through an oil filler port (not shown).

As a result of supplying pressure oil into the cylinder body 13, the first and second pistons 10 are fitted in the cylinder body 13 in an oil-tight manner.
, 11 and rod 12 move in the direction of protruding from inside the cylinder body 13, respectively.

In this case, the second piston 11 located on the left side of FIG. Push 6 outward (to the left in Figure 1).

On the other hand, a first piston 10 located on the right side of FIG.
The rod 12 that penetrates the center of the piston 10 is
They have mutually independent pressure receiving surfaces, and each moves toward the outside of the cylinder body 13 (to the right in FIG. 1) as pressurized oil is supplied into the cylinder body 13. However, due to the collision between the rod 20 fixed to the first piston 10 and the inner surface of the recess 19 formed at the outer end of the rod 12, not only the hydraulic pressure applied to the first piston 10 but also the rod 12 is Since the applied hydraulic pressure is also transmitted to the bar 20, the first brake shoe 2, which has the end edge of the web 6 in contact with the bar 20, is also pushed outward by the same force as the second brake shoe 3. (to the right in Figure 1).

As a result, the first and second brake shoes 2, 3 are pushed apart, and the outer peripheral surfaces of the linings 8, 8 that constitute the brake shoes 2, 3 are strongly pressed against the inner peripheral surface of the drum that rotates together with the wheels. Then, braking is performed.

Next, when operating the parking brake mechanism in order to prevent the stopped car from moving inadvertently, the tip of the parking lever 17 is activated using the control lever installed on the driver's seat via a Bowden wire (not shown). Part 3
Pull it to the left of the diagram.

As a result, the parking lever 17 rotates clockwise in the figure around the pivot shaft 16 provided on the first brake shoe 2, and the inner edge of the base portion of the parking lever 17 touches the rod 12 and the cylinder body 13. Push it in one notch. The inner end surface of this rod 12 pushes the second piston 11 toward the outside of the cylinder body 13 and to the left in FIGS. 1 and 3.

For this reason, the second piston 11 presses the outer circumferential surface of the lining 8 constituting the second brake shoe 3 against the inner circumferential surface of the drum. At the same time, as a reaction to this, the parking lever 17 that presses the rod 12 and presses the rod 12 functions like a lever with the abutment between the inner peripheral edge of its base end and the rod 12 as a fulcrum, and plaguish
Press the lining 8 of No. 2 toward the inner peripheral surface of the drum,
Activate the parking brake.

Although the above-mentioned embodiments have been described with reference to the case where the present invention is applied to a duo-servo type drum brake, the present invention is applicable to other types of drum brakes, such as a leading-trailing type as shown in Fig. 4. It can also be applied to drum brakes.

In the case of the leading-trailing type drum brake shown in FIG. The arrangement with 11 is opposite to that of the duo servo type drum brake shown in Fig. 3, and the parking brake mechanism is activated by pulling the tip of the parking lever 17 outward. I'm doing it like that.

Next, FIGS. 5 and 6 show a third embodiment of the present invention,
FIG. 5 is a sectional view of the wheel cylinder portion, and FIG. 6 is a front view showing the wheel cylinder assembled into a leading-trailing type drum brake.

In the case of this embodiment, a threaded portion 23 with a coarse pitch is formed at the inner end of the rod 12 that is inserted through a through hole 18 formed in the center of the first piston 10, and a nut 24 is attached to this threaded portion 23. They are screwed together. A conical convex surface 25, which is a first engagement surface, is formed on the left end surface (left and right according to the drawing) of this nut 24, and a first convex surface 25 is formed on the threaded portion between the threaded portion 23 and the nut 24. , a backlash corresponding to an appropriate gap between the outer peripheral surfaces of the linings 8, 8 constituting the second brake shoes 2, 3 and the inner peripheral surface of the drum is provided.

On the other hand, the inner threaded portion of the second piston 11 is provided with the threaded portion 2.
A concave hole 26 is formed into which the nut 3 can be loosely inserted, and a conical concave surface 27, which is a second engagement surface, is formed in the middle of this concave hole 26, and the nut is inserted only when both surfaces 25 and 27 are separated. 2
It constitutes a clutch mechanism that allows 4 rotations.

Further, at the inner end of the second piston 11, an elastic member 29 and a thrust bearing 3 are disposed between the stop ring 28 fixed to the inner peripheral surface of the opening of the recessed hole 26 and the right end surface of the nut 24.
0 is provided to impart elasticity to the nut 24 in the direction of bringing the conical convex surface 25 and the conical concave surface 27 into close contact with each other.

In the case of this embodiment configured as described above, the lining 8 that constitutes both the first and second brake shoes 2 and 3 is attached to the side of the automatic gap adjuster provided between the rod 12 and the second piston l1. , 8 and the inner circumferential surface of the drum are always maintained within an appropriate range.

That is, in the case of this embodiment, the amount of wear of the linings 8, 8 is small, and the size of the gap that exists between the outer peripheral surface of the linings 8, 8 and the inner peripheral surface of the drum during non-braking is
If it is within the appropriate range, as pressure oil is fed into the cylinder body 13, the first and second pistons 10
, 11 are separated from each other by the distance between the screw part 23 and the nut 24.
The first and second pistons 10 and 11 do not exceed the amount of backlash existing in the threaded portion between the threaded portion 23 and the nut 24 in the axial direction due to the presence of the backlash. The vehicle is braked and brake-released by moving near and far within the range of displacement.

Therefore, during this time, the circular female convex surface 25 of the nut 24 and the conical concave surface 27 on the second piston 11 side are not separated, and there is a gap between the outer circumferential surface of the linings 8 and the inner circumferential surface of the drum. No adjustment work is done.

Lining 8 that constitutes each brake shoe 10, 11,
If the gap between the outer peripheral surface of the linings 8, 8 and the inner peripheral surface of the drum expands beyond the appropriate range due to wear of the linings 8, , the distance that the first and second pistons 10 and 11 are separated from each other exceeds the amount of backlash that exists in the threaded part between the threaded part 23 and the nut 24, and as a result of braking work, the nut 2
4 conical convex surface 25 and conical concave surface 2 on the second piston 11 side
7 and (both pistons 10 and 1 beyond the backlash)
1 tends to be separated by the amount separated from each other).

As a result, the nut 24 is pushed by the elastic member 29 and rotates to the left in FIG.
and the conical concave surface 27 on the second piston 11 side come into close contact.

After the two surfaces 25 and 27 are brought into close contact with each other, the nut 24 will no longer rotate, and the nut 24 and the threaded portion 2
3 means that the members 23 and 24 can be freely displaced in the axial direction by the amount of backlash that exists in the threaded portion of the members 23 and 24.

When the brake is released in this state, the first and second brake shoes 2, 3 are pushed inward by an amount corresponding to the backlash, and the outer circumferential surfaces of the linings 8, 8 and the inner circumferential surface of the drum are The gap between the two is within the appropriate range. In other words, the gap is adjusted.

Other configurations and operations are the same as those of the first and second embodiments described above, and therefore equivalent parts are given the same reference numerals and redundant explanations will be omitted.

Incidentally, instead of being formed on the rod 12, the threaded portion 23 for adjusting the gap is provided on the second piston 11, as shown in FIG. It can also be formed.

(Effect of the invention) The drum brake with parking brake mechanism of the present invention has the following features:
As mentioned above, since the structure differs, there is no need to configure the normal braking mechanism and parking brake mechanism independently of each other, and since independent installation space is not required for each mechanism, the drum with parking brake mechanism The degree of freedom in designing the brake increases, and it becomes possible to construct a brake device with better performance.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, FIG. 1 is a sectional view of the wheel cylinder part, and FIG.
-A sectional view, Figure 3 is a front view showing the state in which this wheel cylinder is assembled to a duo servo type drum brake,
FIG. 4 is a front view showing the above-mentioned wheel cylinder assembled to a leading-trailing type drum brake, and FIGS. 5 and 6 show a third embodiment of the present invention.
The figure is a sectional view of the wheel cylinder part, Figure 6 is a front view showing this wheel cylinder assembled into a leading trailing type drum brake, and Figure S7 is a half sectional view of the wheel cylinder, showing the fourth embodiment. It is. 1: Mounting board, 2: First brake shoe, 5 = Second brake shoe, 4 = Connecting rod, 5: Tension spring,
6: Web, 7: Back metal, 8: Lining, 9: Wheel cylinder, 10: First piston, 11; Second piston, 12: Rod, 13: Cylinder body, 14, 15:
Cup seal, 16: Pivot, 17: Parking lever
18 Consistent hole, 19: Recess, 20: Bar, 21: Return spring, 22: Compression spring, 23: Thread, 24:
Nut, 25: conical convex surface, 26: concave hole, 27: conical concave surface, 28: stop ring, 29: elastic material, 30: thrust bearing, 31: space, 32: anchor, 33: 0 ring.

Claims (1)

[Claims] (1) A mounting board supported by the suspension system of the vehicle, first and second brake shoes movably supported on the mounting board, and first and second brake shoes mounted on the cylinder body fixed on the mounting board. The end portions of the first and second brake shoes are pushed outward by the movement of the first and second pistons, which widen the gap as pressurized oil is supplied. A parking lever that widens the distance between the first and second brake shoes, regardless of the supply of pressure oil to the wheel cylinders, as the wheel cylinder rotates around a pivot provided on the first brake shoe. In a drum brake with a parking brake mechanism, which includes a drum that surrounds the first and second brake shoes and rotates together with the wheel, the first piston has a through hole that extends in the axial direction. The outer end surface of a rod inserted into this through hole so as to be freely displaceable in the axial direction is brought into contact with the end of the parking lever, and the inner end surface of this rod is brought into contact with the inner end surface of the second piston. A drum brake with a parking brake mechanism, characterized in that a portion fixed to the first piston is brought into contact with an end of the first brake shoe.