JPS5923133A - Mechanical drum brake - Google Patents

Abstract

PURPOSE:To obtain nearly equal clearance for both side of brake shoes by equalizing the angles of opening of said both side of brake shoes which are spread out by the rotation of a cam member. CONSTITUTION:If linings 2 and 2' are worn creating a braking gap greater than the set value, only a cam member 5, cam collars 11 and 11', and an adjusting lever 22 rotate, when braking, by the amount of the increased braking gap. Thereby, the resilient claw 22c of the adjusting lever 22 passes over one tooth of an adjusting gear 14 and is mated with the next tooth 14c, while an adjusting bolt 12 is screwed into the cam member 5 and moves leftward. And, the cam collars 11 and 11', pushed by the head 12c of the adjusting bolt 12 toward a backplate 1, spread out shoe-web free ends 2b and 2b' to adjust the braking gap. The amount of projection of the outer cam collar 11 is adjusted to be greater than that of the inner cam collar 11' and the angles of rotation of the both brake shoes 2 and 2' are always constant with theta3=theta4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a mechanical drive mechanism equipped with a cam machine H4 that expands the brake shoe by mechanical means and a braking gap adjustment mechanism.
, regarding brakes.

When operating the Tonowap mechanical drum brake, the player depresses the play V lever or the brake pedal, and the cam rotates via an operating wire or rod 17. A pair of brake shoes which abut on both sides of the cam member 7 and are arranged so as to be expandable as full fulcrums of the anchor bin are pushed apart and the lining is pressed against the inner surface of the drum. When the lining wears due to this control 4 and 11, the distance between the brake and the inner surface of the drum increases, causing problems such as a large increase in the operating speed. The cam collar is designed to protrude in the direction of expansion, so that it protrudes as the lining wears during braking.

The braking interval is automatically adjusted.

The object of the present invention is to provide a structure suitable for application to a mechanical drum brake that is equipped with a braking gap adjustment mechanism in a cam mechanism that expands the brake shoes by such mechanical means,
To provide a mechanical drum brake in which the opening angles of left and right brake shoes that are expanded by the rotation of a cam member are made equal, and approximately equal shoe clearance can be obtained for both left and right brake shoes.

In accordance with the above object, the present invention provides a shoe web free end which is slidably fitted in the axial direction of the cam post phase which expands the shoe web by rotation of the shoe web. The cam υ roller that comes into contact with the front F
An adjustment pole I that pushes the L cam collar, an adjustment gear f that is integrally rotatably engaged with the ``jar'' and bolt, and a stopper that engages with this r adjustment pin T to restrict the rotation of the post phase in the operating direction. Mechanical type consisting of a lever and an adjustment lever which is rotatably provided on the cam post phase and is provided to adjust the engagement position by changing the engagement position in the operating direction of the cam member when the lining wears out beyond a predetermined amount. In the braking gap automatic adjustment device for the brake and brake, the points on the cam collar where the respective cam collars come into contact with the free end of the spring web are Pl and P2, and the center of expansion of the brake shoe is fa=Q, and the cam post position is An embodiment of the present invention is shown in the drawings. The explanation will be based on.

Inside the back plate 1, there is a pair of brake shoes 2.
．． A brake shoe 2.2' is provided with its proximal end 2.2a pivoted to an r hook pin 3.
are always biased toward each other by the shoe return spring 4. The cam member 5 is the brake shoe 2,
2' shoe web free end 2b.

2b' through the back plate 1 through the washer 6, and connects the cam portion 5a to both two web free end portions 2.
Opposed to b and 2 b', a trap shaft portion 5b is rotatably provided on the back 1v-1i. Brake γ-J-7r, Parallel L, -) 1 protruding outside, 9 shaft part 5 c K fixed iLl Brake piece operation 1 gear (rotated by 3K, cam postal Rotate 5.

The cam portion 5a of the cam member 5 has a shoe web free end portion 21.
], a pair of opposing surfaces 5 d , 5 d ′ facing each other
Force is applied to the shoe pushing part of this opposing surface 5 (], 5 d'! - After part 5 a, it is inclined from yBra Z+" to the tip and 7/1 < 14] Cam collar?##9,
9' is formed in the Mf angle direction with respect to the opposing surface 5 (1°5 d') at a symmetrical position on the upper side, sandwiching the adjustment bolt insertion hole 1u.

Then, the expansion center of brake/knee 2, 2' is 0. The inclination angle of the cam collar groove 9 on the side far from the expansion center O8 is set larger than the inclination angle of the cam collar groove 9' on the side closer to the expansion center O8, and a cam collar 11° 11' is slidably provided in each of these cam collar grooves 9. ing.

The cam collars 11, 11' are formed into a plate-like right triangle shape, and the slopes 11a, Ila' of the cam collars 11, 11' are the bottom surfaces 9a! of the cam collar grooves 9, 9'. 9 Abuts on a',
The vertical plane 11 b, i i b' is the free end portion 2b of the shoe web.

2 It is in contact with b'. The inclination angle θ1 of the slope 11a of the cup collar 11 that fits into the outer cam collar groove 9 is equal to the angle θ1 of the cam collar 11' that fits into the inner cam collar groove 9'.
The inclination angle θ2 of the slope 113' is set larger than that of the slope 113'. As a result, when both cam collars 11 and 11' move simultaneously in the cam shaft direction, the vertical surfaces 11b and 1l
A' where b' protrudes in the shoe expansion direction is made so that the outer cam collar 11 becomes larger.

At this time, the amount of protrusion of the cam collars 11 and 1 in the shoe expansion direction is determined by assuming that the points on the cam collars 11 and 11' where the cam collars 11 and 11' come into contact with the shoe web free ends 2b and 2b''e are P and P. , the center of rotation of the cam member 52 is 02, then at each rotational position of the cam member 5, θ3・−Otsuyumi o, o2, and 04=OtsuP20.0
．． and is set to maintain the same relationship.

As a result, the expansion angles of the left and right brake shoes 2, 2' are always equal, so the left and right brake shoes 2, 2'
It is possible to maintain approximately the same shoe clearance with both.

The bottom surface 9a + 93' of the cam collar groove 9.9' has a concave shape with a mountain-like protrusion at the center, and forms an inclined surface 11a when the cam collar 11.11' is fitted.

11a', a space is formed on both sides, and the strength of this part is 1.
In addition to lowering 91k, the sliding side corners of the slopes 11a and 11a' of the cam collars 11 and 11' have a structure that allows smooth sliding even if the braking force kondo may be soaked and deformed. ing. Further, as shown in Fig. 1, the same effect can be obtained by providing a structure in which R or C chamfers are provided at the slide-side corners of the slopes 11a and 11a' of the cam collars 11 and 11'.

The adjustment bolt 12 is attached by inserting the shaft portion 12a into the adjustment bolt insertion hole 10 and screwing the male thread portion 12bt at the end of the shaft portion into the cam member 5, and its head 12c is fitted into the cam collar grooves 9, 9'. It abuts a pair of fitted cam collars 11 and 11' via a washer 13. Then, from the opposite side, the adjustment gear 14 is inserted through the shaft portion 14affi force member 5, and the flat plate portion 14b at the tip of the shaft portion 14a is slotted into the adjustment bolt 12. It engages with l'$126 and moves without rotation to the adjustment pin T14.

A partition wall 15 is provided on the outside of the pack plate 1 so as to cover the mounting portion of the brake arm 7, and the shaft portion 5e of the cam member 5 projects from the partition wall 15 via a seal member 16. Then, the dust cover 11 is attached to the sealing member 1
8, one end fits into the accelerator shaft boss 19, and the other end is tightened and fixed to the partition wall 15 at one point with a screw 20, and the partition wall 1
The -L part of 5 is built.

The stopper lever 21 has a large diameter hole 21a, a small diameter hole 21b, and an elastic claw part 21c, and the large diameter hole 21a is inserted into the shaft part 5e, and the other end f: m is connected to the wall 15 and the dust cover. 11 and the screw 20'f.

small diameter hole 211] and are fixed in line with each other.

The tip of the elastic claw portion 21c restricts the rotation of the adjustment gear 14 when the brake arm 7 is pulled in the operating direction in the direction shown in FIG. They mesh together as if to do so.

The L/bar 22 has a fitting hole 22a in the center, and the upper contact piece 22b of the camshaft 1 formed on the inner peripheral surface of the fitting hole 22a is attached at three locations on the outer periphery of the shaft portion 5e. The axial flat surfaces chamfered at intervals are press-fitted and engaged with the first part 5f. This adjustment lever 2
An elastic claw portion 22c provided on the outer periphery of the r-just gear 14 meshes with the teeth 14c of the r-just gear 14 from the periphery. And r
The gear lever 22 rotates together with the cam member 5 as the brake arm 1 rotates in the operating direction, and meshes with the next tooth 14c of the adjustment gear plate 4 when the lining 2 c +20 is worn down by a predetermined amount. And Bregi Y-mu I
When the brake arm I returns, the adjust key γ14
The elastic claw portion 21b' of the stopper lever 21 rotates integrally with the
It meshes with the next tooth 14c of the Ir near-shift gear 14.

Next, the operation of this embodiment will be explained.

When the brake lever or brake pedal is operated, the brake arm 7 is rotated by the brake operation wire 8 in the direction shown in FIGS. As shown in the figure, the cam portion 5a opens the shoe web free end portions 2b, 2b'ffi, and thereby the brake shoes 2, 2' (rJ-n) expand against the return spring 4. Lining 2 c, 2 c'ff
i It performs braking by coming into pressure contact with the inner circumferential surface of a brake drum (not shown).

At this time, as the brake arm 7 rotates, the cam portion 5, cam collars 11, 11', γ-just gear 14, and adjustment bolt 12 rotate integrally, and the rotation angle is such that the elastic claw portion 22c of the adjustment lever 220 This is the range in which each of the teeth 14c slides on the slope of the same tooth.

If the linings 2c and 2c' are worn out by this braking action and a braking gap larger than the set value occurs, the rotation of the adjustment gear 14 is regulated by the elastic pawl 21c of the stopper lever 21 during braking, so the cam Only the member 5, the cam collars 11, 11' and the adjustment lever 22 are rotated by the increase in their braking clearance. As a result, the elastic claw portion 22c of the adjustment lever 22 moves to the adjustment lever r1.
4, and engages with the next tooth 14c, and the Asha x I-holt 121d: In FIG.
goes up to the head 12 (of the adjustment bolt 12) and is pushed toward the back play 11. From this iLK, the cam collar 1
1.11' is a cap that slides in the axial direction through the collar grooves 9, 9', and the opposing surfaces 5d, 5(]' of the cap 5a.
The free end portion 2 protrudes from the tube in the expansion direction.
Adjust the braking gap by expanding It, i l)'-J
Ru. 1 When the braking operation is released, the brake shoe 7, cam member 5, cam collars 11 and 11', adjustment gear 14 and adjustment bolt 12 are integrally moved to the first position.
It rotates in the B direction in the figure and FIG. At this time,
The adjust gear 14 is reliably rotated together with the cam phase 5 by the adjust lever 22, so that the instep claw portion 21b of the stopper lever 21 passes over one tooth of the r adjust gear 14 and moves to the next tooth. 14C and adjusts. In this way, the elastic claw part 'l of the stopper lever 21
lb and the elastic claw portion 22c of the adjustment lever 22 sequentially mesh with the teeth 14C of the adjustment gear 14, and the cam collar 12.12' protrudes in the shoe expansion direction (so that the braking gap is always constant). Adjust automatically.

In adjusting this braking gap, the cam collar 11°11'
is adjusted by protruding in the shoe expansion direction, but the amount of protrusion of the outer cam collar 11 is smaller than that of the inner cam collar 11.
' is adjusted to be larger than the protrusion 1. As a result, the rotation angle of the pair of left and right pre-kin knees 2゜2' becomes θ3-
It is always constant at 04. Therefore, during braking, the shoe clearances of the left and right brake shoes 2.degree. 2' can be made substantially equal, resulting in more stable braking.

FIGS. 7 to 10 illustrate other embodiments.

Figure 7 (cam collar 11 of the outer shell and inner shell)
, 11 have the same shape and the same amount of adjustment, but the rotation center O of the cam member 5 is shifted by a distance MA toward the expansion center O of the brake shoe, and the cam parts 'A', A51 The distance to the center of rotation 02 is longer than the distance m from the points. Therefore, angle θ3・−angle 0. It is said that

In FIG. 3, the inner cam collar 11'♀ has its slanted awn close to the line L2 that is perpendicular to the line L1 connecting the center of expansion of all the brake shoes at its tip and the rotation center 02 of the cam member 5. . As a result, the distance between point P1 and lines 1 and 2 -〇2 is determined by the distance between point P2 and line L2 -β3. ing.

Figure 7 shows the inner 1i1 cal of the outer cam collar 11.
The width is thicker than that of J Fuller 11', and with this, P point material and pure L
Distance with 2 e4 gold point 1), 21%l L, is longer than distance with 2 L5. 10th [! ;'I r 7th
Contrary to what is shown in the figure), the inner force l, the outer fttl of the collar 11', the entire notch - the tip of the C is made narrow, and the distance between the point PI and the line L2 - e6 the gold point P2 The distance between I and 2 is longer than e.

As described above, according to the present invention, the left and right brake shoes, which are spread apart by the rotation of the cam member, are spread out by the protrusion of the cam collar, and the brake shoes are opened during braking! Since t is automatically adjustable, the opening angle of the pair of brake shoes that are opened by the rotation of the cam member during braking is equal, and this makes it possible to equalize the shoe clearance of both gray tires. The cam mechanism that spreads the brake shoes by mechanical means ensures stable braking.
Suitable for mechanical drum brakes equipped with a tonne adjustment mechanism.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show one embodiment of the present invention, and FIG. 1 is a front view;
Figure 1 is a rear view, Figure 3 is a sectional view of tri-111 in Figure 1, Figure 9 is a plan view, and Figure 5 [! XH・j, cam member,
Figure 7 is an exploded perspective view of the cover, collar, solenoid ear, adjustment bolt, and adjustment gear lever, and is an enlarged view of the main parts. Fig. g, Fig. 9 and Fig. 70 are enlarged views of main parts showing different embodiments, respectively, and Fig. 1/Fig. 1 is a front view showing another embodiment of the cam collar. 2.2' is a brake shoe, 5 is a cam post phase, 9°9' is a cam collar groove, 11, 11' is a cam collar, and 12 is an adjustment bolt. k1 Figure 1 Figure 2 1 〃3 Affiliate 1 Le 4 Figure 4 Procedural Amendments November 51, 1939] Kazuo Ishibori, Commissioner of the Patent Office 1, Display of the case Showa 5 File % Permit Application No. 133392υ2, Name of the invention Mechanical drum brake 3, parties making the amendment (relationship with 'l) Patent applicant 4, agent 5, voluntary submission of amendment order with 11 6, number of inventions increased by amendment 7, clear examination of the benefits of the amendment Ministry No. 19 Negative 1st line "Disassembly perspective" is followed by 1-Le 1,
” is inserted. "2 Procedural Amendments 1982 I C'6% t 51 Kazuo Wakasugi, Commissioner of the Japan Patent Office, 1. Indication of the Case 1972.1 Patent Application No. 133392, 2. Description No. 1 as per the title of the invention attached. In the first line of page 19, after “``Disassembly perspective view'', there is a ``figure''.
Insert. 10

Claims (1)

[Claims] 1. A cam collar that is slidably fitted in the axial direction to a cam member that expands the brake shoes by rotation of the brake arm and comes into contact with the free end of the shoe web, and a cam collar that is screwed in the axial direction to the cam post and presses the cam collar. Adjustment bolt that moves and γ that is integrally rotatable with the adjustment bolt and engaged with J function.
A just gear, a stopper lever that meshes with this rjust gear to restrict the rotation of the cam member in the operating direction, and a stopper lever that is rotatably provided on the cam post phase and rotates in the operating direction of the cam member when the lining wears out more than a predetermined amount. In an automatic braking gap adjustment device for a mechanical drum brake comprising an adjustment lever provided to change and adjust the meshing position, the cam collar points 1p and 1 where each of the cam collars comes into contact with the free end of the shoe web. Toshi, AiJ
When the rotation center of the cam portion is O1, the expansion center metal O1 of the platen knee is

2 The cam collar has angles p, o at each rotational position.
, o2 and angle P20. A mechanical drum brake characterized by maintaining an equal relationship between Iλ and Iλ.