JP2003156087A - Brake cylinder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake cylinder device with a simple structure and an easy assembling work, capable of sustaining smooth sliding of a piston for a long time and providing a stable shoe gap. SOLUTION: This brake cylinder device is provided with a fluid type operation mechanism expanding a brake shoe, a mechanical wedge actuation mechanism, and a shoe clearance automatic adjustment mechanism. An adjust nut 40 constituting the shoe clearance automatic adjustment mechanism is rotatably supported in a bottomed hole 20b of a main piston 20 with intervention of a thrust bearing 90.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake cylinder device for a drum brake, which has, as a brake shoe expanding mechanism, a fluid type operating mechanism and a mechanical wedge operating mechanism, and an automatic shoe clearance adjusting mechanism. Is.

[0002]

2. Description of the Related Art Conventionally, a brake cylinder device having both a hydraulic actuating mechanism and a mechanical wedge actuating mechanism as a brake shoe expanding mechanism has been disclosed, for example, in Japanese Utility Model Publication 2-18.
It is disclosed in Japanese Patent No. 835. In outlining its configuration based on FIGS.
The automatic shoe clearance adjusting mechanism disclosed in Japanese Patent No. 9 will be attached and described.

As shown in the longitudinal sectional view of the brake cylinder device of FIG. 5, a cylinder body 10 having a substantially T-shape is slidably and closely fitted to the main cylinder hole 11 with a gap in the axial direction. A pair of main pistons 20, 20 and both main pistons 2
A sub piston 21 which is provided in a central portion between 0 and 20 in a direction intersecting with the axis of the main cylinder hole 11 and which is slidably tightly fitted in a sub cylinder hole 12 separated from the main cylinder hole 11. Defines a fluid chamber 13 and is used as a pressurizing chamber when the service brake is activated. And
The return positions of the main pistons 20, 20 arranged in series when the brakes are not operated are restricted by the stoppers 14 having the opposed rear end surfaces 20a, 20a formed on the cylinder body 10.

Since the structure of the shoe clearance automatic adjusting mechanism and the like attached to the front side of the main pistons 20, 20 is the same on the left and right of FIG. 5, only the left side of the main piston 20 will be described.

An adjust nut 40 is rotatably fitted and supported in a bottomed hole 20b formed from the front end side of the axial center of the main piston 20, and the adjust nut 40 has:
A reversible screw 40a is screwed on the outer peripheral portion protruding from the main piston 20, and an irreversible screw 40b is screwed on the inner peripheral portion. The term "reversible screw" as used herein means a "screw" that causes relative rotation between two members when an axial thrust is applied to one of the members that are screwed together.
The “irreversible screw” means a “screw” in which relative rotation does not occur between both members even when an axial thrust is applied to one of the members that are screw-coupled. A drive ring 50 is screwed onto the reversible screw 40a, and the drive ring 5
The respective conical surfaces (the reference numeral indicates only the conical surface of the drive ring 50 as 50a) formed on the outer peripheral surface of 0 and the opening end of the main cylinder hole 11 are engaged with the clutch. Also, an irreversible screw 40b of the adjusting nut 40 is screwed with an adjusting bolt 60 for supporting one end portion of a brake shoe (not shown), and the adjusting nut 40 is adjusted between the spring cage 41 and the drive ring 50 fixed to the front end portion of the adjusting nut 40. The spring 42 is contracted.

Reference numeral 43 is for preventing the drive ring 50 from coming out to the right in the figure in a state where the drive ring 50, the spring cage 41 and the adjust spring 42 are assembled to the adjust nut 40. Reference numeral 61 is a circlip, which is an anti-rotation clip for restricting the rotation of the adjustment bolt 60 during the operation of automatically adjusting the shoe clearance. A brake shoe (not shown) is fitted in the groove 61a at the front end of the anti-rotation clip 61 to regulate the rotation of the adjustment bolt 60. However, when the adjusting tooth 60a engraved on the outer circumference of the head of the adjusting bolt 60 is manually rotated from outside the brake, the adjusting bolt 60 is rotatable with respect to the anti-rotation clip 61.

On the other hand, the push actuating wedge actuating mechanism 30 of this embodiment used as a parking brake is disposed in the fluid chamber 13 and is composed of a wedge body 31, rollers 34, 34, a roller cage 35 and the like. ing. The wedge body 31 includes a wedge portion 32 and a rod portion 33.
And the tip portion of the wedge portion 32 is fitted into the notches 20c, 20c provided in the rear end surfaces 20a, 20a of the two main pistons 20, 20 facing each other, and the rod portion 3
The lower end of 3 is swingably and operatively engaged with the sub piston 21. Tapered surface 3 of the wedge portion 32
2a, 32a and notches (concave grooves) 20 in both main pistons 20, 20 corresponding to the tapered surfaces 32a, 32a.
c, 20c the roller 3 between the bottom inclined surface 20d, 20d
4 and 34 are rotatably interposed. The roller cage 35 made of a substantially U-shaped leaf spring has a base portion 35a that is slidably fitted to the rod portion 33 under the wedge portion 32,
A pair of opposed pieces 35b extending from both ends of the base portion 35a along the tapered surfaces 32a, 32a of the wedge portion 32,
35b, and rollers 34, 34 rotatably supported at the tips of the opposing pieces 35b, 35b, and rollers 34, 3
4 and the restriction portions 35c, 35c for restricting rotation of the wedge main body 31 with respect to the axis.
In addition, under the neck of the wedge portion 32 and the base portion 3 of the roller cage 35.
Between 5a, the wedge portion 32 when the brake is not operated
A weak spring 36 for positioning the rollers 34, 34 with respect to is contracted. It should be noted that the rotation preventing guide 32b formed on the tip of the wedge portion 32 with respect to the axis of the wedge body 31 is provided on the inclined surfaces 20d, 2
It is integrally molded so as to extend in the 0d direction.

A socket 15 is fixedly press-fitted in the vicinity of the side of the main cylinder hole 11 of the sub cylinder hole 12, and between the socket 15 and a spring seat 16 fixed near the lower end of the rod portion 33. Strong spring 17 for positioning the wedge operating mechanism 30 when the brake is not operating
Has been reduced. The return position of the sub piston 21 is regulated by a nut 18 screwed to the opening end of the sub cylinder hole 12. Incidentally, reference numerals 80, 80 and 81 respectively denote the main pistons 20, 20 in order to keep the fluid chamber 13 dense.
And a piston cup fitted to the sub piston 21,
Reference numerals 82 and 82 denote dust boots that seal the open end of the main cylinder hole 11.

Next, the brake operation in the above-mentioned structure will be described. First, when the fluid chamber 13 is pressurized during service braking, the main pistons 20, 20 and the like spread laterally to frictionally engage a pair of brake shoes (not shown) with the brake drum to brake the brake drum. When the wedge main body 31 is pushed by the well-known air chamber or the like via the sub piston 21 during the parking brake, the rollers 34, 34 roll up and move upward to move the main pistons 20, 20 left and right. The pair of brake shoes (not shown) are expanded and frictionally engaged with the brake drum to maintain the brake drum in a stationary state.

Next, the operation of automatically adjusting the shoe clearance in the above-described structure will be described based on the structure on the left side of FIG. When the lining of the brake shoe (not shown) is worn, the brake is activated and the stroke of the adjust nut 40 that advances together with the main piston 20 is the drive ring 50.
When the backlash of the threaded portion of the drive ring 50 is exceeded, the clutch engagement of the conical surface 50a of the drive ring 50 is released, and thereafter, the drive ring 50 rotates while sliding by the biasing force of the adjust spring 42. Then, when the brake is released, the adjusting nut 40, the main piston 20, etc. are integrally retracted by an amount corresponding to the backlash by the returning force of a shoe return spring (not shown), and the conical surface 50a of the drive ring 50 is mainly moved. The conical surface of the cylinder hole 11 is engaged with the clutch so that it cannot rotate. Therefore, the main piston 20 and the like thereafter are the same as the rear end surface 2 of the main piston 20.
0a is retracted until it abuts on the stopper 14 of the cylinder body 10, and at this time the adjusting nut 40 is rotated, so that the adjusting bolt 60 advances and the shoe gap is automatically kept substantially constant.

At the time of this automatic shoe clearance adjustment operation, the bottomed hole 2 of the main piston 20 that supports the adjustment nut 40.
Since a relatively large frictional force in the rotational direction is generated on the bottom surface of 0b, the guide means as shown in FIG. 8 is provided to guide the main piston 20 so as not to rotate together with the adjust nut 40. That is, the small-diameter shaft portion 70a on the tip side of the stepped bolt 70 screwed to the cylinder body 10 is slidably fitted into the long groove 20e slightly wider than the small-diameter shaft portion 70a formed on the main piston 20, Main piston 20 with stepped bolt 7
By 0, it was guided so as to be movable in the axial direction and non-rotatable with respect to the shaft center.

[0012]

However, the provision of the guide means for the main piston described above has the following problems.

<A> Tightening work of the stepped bolt is troublesome. In addition, if muddy water enters the main cylinder hole through the fastening part, it may cause galling or sticking of the main piston.Therefore, some waterproofing means such as application of a sealant or fastening with a copper washer is required, resulting in high cost. Invite. <B> In order to smoothly guide the main piston with the stepped bolt, the diameter of the small-diameter shaft part of the stepped bolt, the mounting position and angle of the female screw threaded on the cylinder body, the width of the long groove of the main piston, and this Since the dimensional accuracy with respect to the machining position and angle is extremely high, precise machining is required, resulting in high cost. Incidentally, if the smooth sliding of the main piston is obstructed by the stepped bolt, not only the brake shoe will not return properly, but the shoe clearance that requires fine adjustment will not be stable, and the braking effectiveness will be delayed. .
If the play of the main piston in the rotation direction is large, the groove position of the main piston with respect to the small-diameter shaft portion of the stepped bolt becomes unstable, and the shoe gap is not stable in this case as well.

The present invention has been made in view of the above problems, and has a simple structure, facilitates assembly work, and maintains a smooth sliding movement of the main piston for a long period of time, and a stable shoe gap can be obtained. An object is to provide a brake cylinder device.

[0015]

In order to achieve the above object, in the brake cylinder device of the present invention, an adjust nut constituting an automatic shoe clearance adjusting mechanism is provided with a thrust bearing interposed in a bottomed hole of a main piston. It is rotatably supported.

As the thrust bearing described above, either a rolling bearing or a sliding bearing can be adopted.

The above-mentioned plain bearing may be one having a solid lubricating coating formed thereon or one having a surface layer portion of carbide and nitride formed thereon, and the shape thereof may be a flat plate shape or a cup shape.

Further, the brake cylinder device described above is
Two main pistons are arranged opposite to each other in a cylinder hole of the cylinder body to define a fluid chamber between the pair of main pistons, and a wedge operating mechanism is disposed in the fluid chamber, or a cylinder. Three pistons are arranged in series in the cylinder hole of the body to define a fluid chamber between the intermediate piston and one main piston, and a wedge operation mechanism is arranged between the intermediate piston and the other main piston. It may be of the form

According to the brake cylinder device configured as described above, due to the property of the thrust bearing, only the adjusting nut rotates with a weak thrust when the shoe clearance is automatically adjusted, so that the shoe clearance is stable for a long period of time.
As a result, the guide means (stepped bolt) for preventing co-rotation of the main piston can be abolished, resulting in a significant cost reduction and complete elimination of concerns about brake shoe return failure and brake delay. it can.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An example of a brake cylinder device according to the present invention will be described in detail below. In the description, the basic structure in that it has both a fluid actuating mechanism and a mechanical wedge actuating mechanism, and in addition that it has an automatic shoe clearance adjusting mechanism, is the same as the brake cylinder device of the prior art described above. Therefore, parts and portions having the same function will be denoted by the same reference numerals and the description thereof will be omitted, and the description will focus on the differences between the brake operation and the shoe clearance automatic adjusting operation. In the brake cylinder device of FIG. 1, for simplification of the drawing, the configuration of the first embodiment is shown on the left main piston 20 side, and the right main piston 2 is shown.
The configuration of Examples 2 and 3 to be described later is also shown on the 0 side.

First, a first embodiment of the present invention will be described with reference to FIGS. In this example, as shown on the left side of the main piston 20 in FIG. 1, the rear end surface of the adjust nut 40 can be rotated with the well-known thrust rolling bearing 90 interposed at the bottom of the bottomed hole 20b of the main piston 20. In support of.

According to the above-mentioned structure, when the brake is actuated and released, the main piston 20 can slide without any obstruction of its rectilinear movement, so that the braking effect can be surely and quickly raised, and the brake can be activated. It is possible to reliably eliminate drag due to poor return of the shoe.

Further, the adjusting nut 40 at the time of the automatic adjustment of the shoe clearance is provided with the reversible screw 4 which rotates with a weak thrust.
0a part fully demonstrates its unique function, and the main piston 2
0 does not rotate together with the adjusting nut 40 due to the sealing force of the piston cup 80 and the abutting force of the roller 34, etc., so that the shoe clearance is always stable and the wedge operating mechanism 30 is not adversely affected.

Next, a second embodiment of the present invention will be described with reference to the right main piston 20 side in FIG. The present example is different only in that a flat plate-shaped thrust sliding bearing 91 is adopted instead of the thrust rolling bearing 90 of the first embodiment.

An example of the thrust slide bearing 91 described above is one in which a solid lubricating coating is formed on the surface of a flat plate. This solid lubricating coating may be prepared by dispersing one or several solid lubricating agents such as molybdenum disulfide, graphite and fluororesin in a binder to form a paint, and baking and curing the coating. Further, as the solid lubricant, there are tungsten disulfide, metal oxides and the like other than the above, and as the binder,
Generally, organic resins such as epoxy resin and polyimide resin are used. The material to be coated is iron,
It is possible to apply non-ferrous metals, plastics, etc., and by selecting and adopting these appropriately, a flat plate-shaped film with many features such as low friction coefficient, large load bearing capacity, wide application temperature range, etc. The thrust slide bearing 91 can be easily manufactured, and the same operational effects as those of the above-described first embodiment can be obtained. The flat slide bearing 91 of the present embodiment is a ring to avoid interference with the adjusting bolt 60 when the outer diameter of the brake shoe (not shown) is sufficiently reduced to improve the detachability of the brake drum and the like. Although it is an example in which it is formed into a shape, the central hole may be omitted.

Next, a third embodiment of the present invention will be described. In this example, a surface layer portion having a low friction coefficient is formed on a flat plate by, for example, a nitriding treatment by a molten salt bath method instead of the solid lubricating coating treatment in the above-described Example 2, and It has almost the same function and effect. That is, the flat plate in this example is made of a steel material, and is immersed in a molten salt bath for nitriding at a temperature of 570 to 580 degrees far below the transformation point of the steel to form a hardened layer of carbide and nitride on the surface layer of the steel. is doing.

Next, a fourth embodiment of the present invention will be described with reference to the sectional view of the principal part of FIG. In this example, the plate-shaped thrust slide bearing 91 of Embodiments 2 and 3 described above is replaced by a cup-shaped thrust slide bearing 92, which is provided with a bottomed hole 20b of the main piston 20 and an adjustment nut 40.
It is inserted between and. According to this example, since the outer peripheral portion of the adjust nut 40 also slides against the cup-shaped thrust slide bearing 92, even if the main piston 20 or the adjust nut 40 is twisted during brake operation,
The adjusting nut 40 rotates more smoothly.

Next, referring to FIG. 4, a fifth embodiment of the present invention will be described.
The following describes the related art and the first to the first embodiments.
The parts having the same functions as those of No. 4 are designated by the same reference numerals, and the description thereof will be omitted. This example is a known brake cylinder device of a different type from the above-described brake cylinder device, and here, the thrust rolling bearing 90 and the flat plate-shaped thrust sliding bearing 91 of Examples 1 to 3 described above are shown. The cup-shaped thrust slide bearing 92 of Example 4 can also be adopted, and substantially the same action and effect can be obtained. That is, this brake cylinder device has three pistons, which are two main pistons 20 and 20 and one intermediate piston 22, arranged in series in the main cylinder hole 11, and the intermediate piston 22 and one of the main pistons (see the figure). Left main piston) 2
The fluid chamber 13 is defined between 0 and the intermediate piston 22
A pulling operation type wedge operation mechanism 30 is arranged between the other main piston (the main piston on the right side in the drawing) 20.

In the conventional brake cylinder device,
Guide means for the two main pistons 20, 20 relative to the cylinder body 10 described in the above-mentioned prior art (stepped bolt 7
0), one of the main pistons 20 and the intermediate piston 22
A guide means is appropriately attached to a portion where the rear shaft portion of one of the main pistons 20 is fitted in the bottomed hole 22b of the intermediate piston 22 in a concave-convex manner so as to be connected so as to be relatively movable in the axial direction and non-rotatable relative to However, as clearly shown in FIG.
In the present invention, the thrust rolling bearing 90 and the flat thrust sliding bearing 9 described in the first to fourth embodiments are described.
By interposing the 1 or cup-shaped thrust slide bearing 92 between the bottom of the bottomed hole 20b of the main piston 20 and the adjust nut 40, the above-mentioned guide means can be eliminated.

The present invention is not limited to the above-mentioned embodiments, but may be, for example, a plate-shaped thrust slide bearing 9.
1 and the cup-shaped thrust slide bearing 92 may be used in combination, and the brake cylinder device of each of the above-described embodiments has been described as a double-ended open type having a pair of main pistons. Of course, it can be applied to a known single-ended open type having a main piston on only one side of the mechanism.

[0031]

Since the present invention has been described above, the following effects can be obtained.

<A> In the brake cylinder device of the present invention, the adjust nut which constitutes the automatic shoe clearance adjusting mechanism is rotatably supported by interposing the thrust bearing in the bottomed hole of the main piston. With this configuration, the reversible thread part of the adjust nut originally has a unique function, in other words, the function that the adjust nut smoothly rotates with a weak thrust is fully exerted. Without letting
The shoe clearance is always stable.

<B> As described above, since only the adjusting nut can be rotated with a weak thrust, the guide means for the main piston by the stepped bolt and the waterproof means associated therewith which have been adopted in the prior art can be eliminated. This eliminates the need for troublesome tightening work of stepped bolts and eliminates the need for machining the female threads of the cylinder body and the long groove of the main piston, which requires extremely high dimensional accuracy, thus achieving a significant cost reduction. . Moreover, in the brake cylinder device having the main piston and the intermediate piston, the guide means that can relatively move in the axial direction between the one main piston and the intermediate piston can be eliminated, and the structure can be further simplified and the cost can be reduced.

<C> Further, by eliminating the stepped bolt, the factor that hinders the smooth sliding of the main piston can be eliminated, so that the brake shoe may not return properly and the brake effectiveness may be reduced. There is no fear of causing delays.

<D> Further, since it is only necessary to interpose the thrust bearing between the main piston and the adjust nut, the structure can be made simple and the assembling work of the brake cylinder device is easy.

<E> Furthermore, the brake cylinder device is
It is applicable as long as it has both a fluid type operating mechanism and a mechanical wedge operating mechanism and an automatic shoe gap adjusting mechanism.The wedge operating mechanism built in is not limited to the push type, but a pulling type. It can be a mold. Further, the present invention can be applied not only to the double-ended open type brake cylinder device but also to the single-ended open type brake cylinder device, and its application range is wide.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a brake cylinder device according to first to third embodiments of the present invention, in which a left main piston side is a first embodiment.
The right side main piston side shows Examples 2 and 3.

FIG. 2 is an enlarged explanatory view of a thrust bearing arrangement portion according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a main part according to a fourth embodiment of the present invention.

FIG. 4 is a vertical sectional view of a brake cylinder device according to a fifth embodiment of the present invention.

FIG. 5 is a vertical sectional view of a conventional brake cylinder device.

6 is a right side view of FIG.

FIG. 7 is a front view showing a main part of the brake cylinder device of FIG.

8 is a sectional view taken along line VIII-VIII in FIG.

[Explanation of symbols]

10 cylinder body 11 Main cylinder hole 13 Fluid chamber 20 Main piston 20b bottomed hole 21 Secondary piston 22 Intermediate piston 30 Wedge actuation mechanism 40 Adjust Nut 42 Adjust spring 50 drive ring 60 Adjust bolt 90 Thrust Roller Bearing 91 Flat plate thrust slide bearing 92 Cup-shaped thrust slide bearing

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Terada             5-14-5 Toyota, Minami-ku, Nagoya-shi, Aichi             Nisshinbo Corporation Nagoya factory F term (reference) 3J058 AA07 AA13 AA17 AA24 AA28                       AA37 BA57 BA62 DA03 DA13                       DA24 EA36

Claims (9)

[Claims] 1. A shoe expanding mechanism for expanding a brake shoe by pushing a main piston, comprising a fluid type operating mechanism and a mechanical wedge operating mechanism provided in a cylinder body, and the main piston Adjusting nut that is rotatably fitted in and supported by the bottomed hole of the adjust nut, a drive ring that reversibly engages with a male screw threaded on the outer peripheral portion of the adjust nut, and an inner peripheral portion of the adjust nut. An adjusting bolt that irreversibly engages with the mounting screw to support one end of the brake shoe, and an adjusting spring that biases the outer peripheral portion of the drive ring in a direction to engage the opening of the cylinder body with the clutch. In the brake cylinder device including an automatic shoe clearance adjusting mechanism, the adjusting nut is provided in a bottomed hole of the main piston. Characterized in that supported with intervening brake cylinder device. 2. The brake cylinder device according to claim 1, wherein the thrust bearing is a rolling bearing. 3. The brake cylinder device according to claim 1, wherein the thrust bearing is a slide bearing. 4. The brake cylinder device according to claim 3, wherein the plain bearing has a solid lubricating coating formed thereon. 5. The brake cylinder device according to claim 3, wherein the slide bearing has a surface layer of carbide and nitride. 6. The brake cylinder device according to claim 3, wherein the slide bearing has a flat plate shape. 7. The brake cylinder device according to claim 3, wherein the slide bearing is cup-shaped. 8. The cylinder body according to claim 1, wherein two main pistons are arranged opposite to each other in a cylinder hole of the cylinder body to define a fluid chamber between the pair of main pistons. A brake cylinder device, wherein a wedge actuating mechanism is provided in the fluid chamber. 9. The piston according to claim 1, wherein three pistons are arranged in series in a cylinder hole of the cylinder body, and a fluid chamber is defined between the intermediate piston and one main piston. The brake cylinder device is characterized in that a wedge actuating mechanism is arranged between the intermediate piston and the other main piston.