JP2011085227A - Dust cover structure for spring brake chamber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust cover for a spring brake chamber, hard to crack and superior in durability. <P>SOLUTION: The whole dust cove structure is formed in a hollow cylindrical shape with a small-diameter part 28A on the upper side, a large-diameter cylindrical part 28B on the lower side, and a chevron-shaped protruded part 28C in an intermediate area. On the upper opening of the small-diameter cylindrical part 28A, a first locking protrusion 28a is provided which is fitted to a retaining peripheral groove 27b of a push rod 27. The retaining peripheral groove 27b is set at a position a length L<SB>2</SB>almost half a total length L<SB>1</SB>from a front end P of the push rod 27. The small-diameter cylindrical part 28A has a turn-back portion 28b approximately U-shaped in cross section, formed in a range from the first locking protrusion 28a to one slope 28e of the mountain-shaped protruded part 28C. On the opening of the large-diameter part 28B, a second locking protrusion 28c is formed in a range starting from an outer peripheral face 28d of the second locking protrusion 28c to the other slope 28f of the mountain-shaped protruded part 28C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a structure of a dust cover in a spring brake chamber particularly applied to a compressed air brake device for a vehicle.

Conventionally, the spring chamber A has been employed in a braking control system for large vehicles such as buses, trucks, and trailers. In the prior art, there is the spring chamber A shown in FIG. To explain this, 1 is one case, 2 is the other case, and both cases 1 and 2 are connected by a connecting case 3. The one case 1 has a chamber 1a, and a piston member 6 is disposed in the axial direction in the axial direction. In one case 1, a spring receiving portion 6A of a piston member 6 holding a power spring 5 is accommodated so as to be capable of moving forward and backward in the axial direction. The piston member 6 includes a spring receiving portion 6A, a diaphragm 6B, a push rod 6C, and a spring 6D.

The piston member 6 includes a push plate 6a on the back surface of the diaphragm 6B, and a spring 6D is wound between the push plate 6a and one surface 3a of the connecting case 3 so as to be able to advance and retreat. Reference numerals 7 and 8 denote clamp rings, which fix the one case 1 and the connecting case 3 and the other case 2 and the connecting case 3 with diaphragms 6B and 9 interposed therebetween. The other case 2 or the connecting case 3 has a chamber 2a, and the push rod 10 is disposed in the chamber 2a. The push rod 10 is fixed to a push plate 10a. The diaphragm 9 is moved to the right of the push rod 10 to move the dust cover 11 and the wedge 12 to the right. In the other case 2, a cylindrical base 2b is integrally formed, and a push rod guide 13 is disposed in the cylindrical base 2b. The push rod guide 13 connects the push rod 10 on the one hand and the wedge 12 on the other hand. Further, the tip 12 a of the wedge 12 protruding from the cylindrical base 2 b of the other case 2 intervenes in the expander 14. The expander 14 is connected to a brake shoe 15 from above and below, and when compressed air is fed, the tip 12a of the wedge 12 enters in the direction of arrow B. The sleeves 14 a, 14 a of the expander 14 are pushed and extended through the rollers 16, 16 arranged above and below to expand the brake shoe 15.

By the way, the spring chamber A operates as follows. That is, when the brake pedal as the service brake is depressed, the command air pressure is operated from the dual brake valve, and the compressed air flows from the service brake port 17 of the spring chamber A. Therefore, air pressure is applied to the front surface of the diaphragm 9 in the pressure chamber of the connection case 3, and the diaphragm 9 moves rightward. Then, the push plate 10a of the push rod 10 is moved rightward. The leading end 12a of the wedge 12 projects and moves in the right direction. This is transmitted to the wheel brake attached to the axle. Then, the sleeves 14 a, 14 a of the expander 14 in the brake shoe 15 are spread in the direction of arrow C, and the braking operation is performed by the action of the brake shoe 15.

On the other hand, when the parking brake lever is operated to the parking position, the compressed air in the spring brake port 18 of the spring chamber A is discharged from the chamber 1a. The power spring 5 in the one case 1 is extended to move the spring receiving portion 6A, the diaphragm 6B, and the push rod 6C of the piston member 6 in the right direction. The spring receiving portion 6A pushes the diaphragm 9 and the push plate 10a of the push rod 10 disposed in the chamber 2a of the connection case 3 or the other case 2 in the right direction. Thus, the dust cover 11 is deformed to move the push rod guide 13 and the wedge 12 in the arrow B direction. The leading end 12a of the wedge 12 projects and moves in the right direction. This is transmitted to the wheel brake attached to the axle. Then, the sleeves 14 a and 14 a of the expander 14 in the brake shoe 15 are spread and a braking operation is performed by the action of the brake shoe 15.

Japanese Patent No. 2778963

The dust cover 11 in the conventional spring chamber A is made of, for example, an NBR material and has a flexible property that can be easily deformed, and has the shape and structure shown in FIG. The whole is composed of a double cylindrical body, and has an outer cylinder 11A and an inner cylinder 11B, both of which are integrally formed by an upper wall surface portion 11C. On the other hand, the base end of the inner cylinder 11B is provided with a protrusion 11a, and the protrusion 11a is set at an intermediate position of the push rod 10, specifically, at a position close to the distal end portion of the push rod 10. Fit and fix in the recess. On the other hand, the base end as the skirt portion of the outer cylinder 11A is provided with a protrusion 11b. The protrusion 11b is engaged with and fixed to the inner wall locking edge 2c of the other case 2. Then, the spring chamber A repeatedly operates, and each time the push rod 10 buckles the base point P when the dust cover 11 is greatly deformed during the full stroke from the fixed position as shown by the phantom line in FIG. If the number of times this state exceeds the specified durability number, a crack will occur and the base point P will break as shown in the virtual circle D in FIG. 5, for example, the maintenance will be overdue after the recommended replacement time specified in the instruction manual, When the dust cover 11 is cracked, there is a problem that outside air containing water, mud, water, etc. enter the spring chamber and rust the parts.

The structure of the dust cover in the spring brake chamber according to the present invention is intended to provide a dust cover that is not easily cracked and has excellent durability, and is constituted by the following configurations and means.

According to the first aspect of the present invention, there is provided a spring brake chamber including one case, the other case, and a connecting case connecting the two cases, and the spring receiving portion holding the power spring in the one case. And a piston member that interlocks with the spring receiving portion, and is arranged in a chamber in the other case, and is provided with a push rod that moves forward and backward by the operation of the diaphragm and controls braking / release of the brake. A dust cover which is a hollow cylindrical body and has a small-diameter cylindrical portion on the upper side, a large-diameter cylindrical portion on the lower side, and a mountain-shaped projection on the middle portion is fitted and fixed to the push rod. .

According to the second aspect of the present invention, there is provided a spring brake chamber including one case, the other case, and a connecting case connecting the two cases, and the spring receiving portion holding the power spring in the one case. And a piston member that interlocks with the spring receiving portion, and is arranged in a chamber in the other case, and is provided with a push rod that moves forward and backward by the operation of the diaphragm and controls braking / release of the brake. And a small-diameter cylindrical portion provided with a first locking projection that is fitted and fixed to the stop circumferential groove of the push rod in the upper opening, and has a substantially U-shaped cross section extending from the first locking projection. Engage and fix to the angled protrusion formed on the other slope from the folded portion and the inner wall locking edge formed on the inner bottom surface of the other case at the lower opening. With a dust cover formed by a second large diameter cylindrical portion having a locking projection, and set the length L ₂ that is fitted and fixed in the first hooking protrusion, the relationship of the full length L ₁ of the push rod It is characterized by the following formula.
Relational expression L ₂ ≧ 1/2 × L ₁

According to the third aspect of the present invention, there is provided a spring brake chamber including one case, the other case, and a connecting case connecting the two cases, and the spring receiving portion holding the power spring in the one case. And a piston member that interlocks with the spring receiving portion, and is arranged in a chamber in the other case, and is provided with a push rod that moves forward and backward by the operation of the diaphragm and controls braking / release of the brake. And a small-diameter cylindrical portion provided with a first locking projection that is fitted and fixed to the stop circumferential groove of the push rod in the upper opening, and has a substantially U-shaped cross section extending from the first locking projection. Engage and fix to the angled protrusion formed on the other slope from the folded portion and the inner wall locking edge formed on the inner bottom surface of the other case at the lower opening. With a made dust cover between the second large diameter cylindrical portion with a locking protrusion, the other hand,
The projection angle θ formed on the other slope is set to 75 ° to 120 °, and the relationship between the set length L ₂ for fitting / fixing the first locking projection and the total length L ₁ of the push rod is established by the following equation: It is characterized by doing.
Relational expression L ₂ ≧ 1/2 × L ₁

Since the structure of the dust cover in the spring brake chamber according to the present invention has the above-described configuration, the following effects can be obtained.

That is, according to the first aspect of the present invention, there is provided a spring brake chamber composed of one case, the other case, and a connecting case connecting the two cases, and the spring holding the power spring in the one case A structure of a spring brake chamber comprising a receiving part and a piston member interlocking with the spring receiving part, and a push rod which is disposed in a room inside the other case and advances / retreats by the operation of the diaphragm and which controls braking / releasing of the brake The dust cover, which is a hollow cylindrical body and has a small-diameter cylindrical portion on the upper side, a large-diameter cylindrical portion on the lower side, and a mountain-shaped projection on the middle portion, is fitted and fixed to the push rod. The structure of the dust cover in the spring brake chamber is provided.
With this configuration, the dust cover is formed of a hollow cylindrical body, and the angle protrusion is formed in the intermediate portion. Therefore, even if the push cover is repeatedly moved back and forth to deform the dust cover, the stress is applied to the dust cover. There is an effect of promoting the extension of the life of the dust cover without being cracked at all by being absorbed by the chevron.

According to the second aspect of the present invention, there is provided a spring brake chamber including one case, the other case, and a connecting case connecting the two cases, and the spring receiving portion holding the power spring in the one case. And a piston member that interlocks with the spring receiving portion, and is arranged in a chamber in the other case, and includes a push rod that moves forward and backward by the operation of the diaphragm and controls braking / release of the brake. And a small-diameter cylindrical portion provided with a first locking projection that is fitted and fixed to the stop circumferential groove of the push rod in the upper opening, and has a substantially U-shaped cross section extending from the first locking projection. Engage and fix to the angled protrusion formed on the other slope from the folded portion and the inner wall locking edge formed on the inner bottom surface of the other case at the lower opening. With a dust cover formed by a second large diameter cylindrical portion having a locking projection, and set the length L ₂ that is fitted and fixed in the first hooking protrusion, the relationship of the full length L ₁ of the push rod Provided is a dust cover structure in a spring brake chamber characterized by the following equation.
Relational expression L ₂ ≧ 1/2 × L ₁
With such a configuration, in addition to the effect of the invention of claim 1, the stroke amount of the dust cover is reduced, and the deformation amount of the dust cover is reduced without causing buckling, so that cracks do not occur. There is an effect that it is possible to provide a high-quality dust cover by reducing the replacement work of the dust cover.

According to the third aspect of the present invention, there is provided a spring brake chamber including one case, the other case, and a connecting case connecting the two cases, and the spring receiving portion holding the power spring in the one case. And a piston member that interlocks with the spring receiving portion, and is arranged in a chamber in the other case, and includes a push rod that moves forward and backward by the operation of the diaphragm and controls braking / release of the brake. And a small-diameter cylindrical portion provided with a first locking projection that is fitted and fixed to the stop circumferential groove of the push rod in the upper opening, and has a substantially U-shaped cross section extending from the first locking projection. Engage and fix to the angled protrusion formed on the other slope from the folded portion and the inner wall locking edge formed on the inner bottom surface of the other case at the lower opening. And a dust cover formed of a large-diameter cylindrical portion provided with a second locking projection, the projection angle θ of the other inclined surface is set to 75 ° to 120 °, and the first locking projection The structure of the dust cover in the spring brake chamber is characterized in that the relationship between the set length L2 to be fitted and fixed and the total length L1 of the push rod is established by the following equation.
Relational expression L2 ≧ 1/2 × L1
With such a configuration, in addition to the effects of the first and second aspects of the invention, the dust cover can be gently deformed by the forward and backward movement of the push rod, and the life can be extended to provide a high-quality dust cover. effective.

It is a vertical sectional view showing an embodiment in the structure of the dust cover in the spring brake chamber according to the present invention. It is a vertical expanded sectional view which shows the dust cover used for the spring brake chamber which concerns on this invention. It is the vertical sectional view which showed the example of the spring brake chamber in a prior art. It is the vertical expanded sectional view which showed the example of the dust cover used for the spring brake chamber in a prior art. It is an enlarged plan view which shows the state of the crack which arises in this dust cover when the dust cover used for the spring brake chamber in a prior art deform | transforms.

Next, an embodiment in the structure of the dust cover in the spring chamber according to the present invention will be described with reference to FIG.

In general, the spring chamber is used in a braking control system for large vehicles such as buses, trucks, and trailers, and the spring chamber E is shown in FIG. To explain this, 19 is one case, 20 is the other case, and both cases 19 and 20 are connected by a connecting case 21. The one case 19 has a chamber 19a, and a piston member 22 is arranged in the axial direction at the axial center. Inside the one case 19, a spring receiving portion 22A of a piston member 22 holding a power spring 23 is accommodated so as to be movable forward and backward in the axial direction. The piston member 22 includes a spring receiving portion 22A, a diaphragm 22B, a push rod 22C, and a spring 22D.

The piston member 22 includes a push plate 22a on the back surface of the diaphragm 22B, and a spring 22D is wound between the push plate 22a and one surface 21a of the connecting case 21 so as to be able to advance and retreat. Reference numerals 24 and 25 denote clamp rings, which fix the one case 19 and the connecting case 21 and the other case 20 and the connecting case 21 with diaphragms 22B and 26 interposed therebetween. The other case 20 has a chamber 20a, and a push rod 27 is disposed in the chamber 20a. The push rod 27 is fixed to a push plate 27a. The diaphragm 20 moves the push rod 27 to the right and moves the dust cover 28 and the wedge 29 to the right. The other case 20 is integrally formed with a cylindrical base 20b, and a push rod guide 30 is disposed in the cylindrical base 20b. The push rod guide 30 connects the push rod 27 on the one hand and the wedge 29 on the other hand. Further, the tip of the wedge 29 protruding from the cylindrical base 20b of the other case 20 intervenes in an expander (not shown). The expander connects a brake shoe (not shown) from above and below, and when compressed air is fed, the tip of the wedge 29 enters rightward. Then expand the expander sleeve and expand the brake shoe.

By the way, the dust cover 28 is made of, for example, an NBR material and has a structure shown in FIG. That is, the entire structure is a hollow cylindrical body, and the configuration is generally composed of a small-diameter cylindrical portion 28A on the upper side, a large-diameter cylindrical portion 28B on the lower side, and a chevron protrusion 28C on the intermediate portion. Since it comprised in this way, even if the push rod 27 repeated advancing / retreating operation | movement repeatedly, there existed an effect | action that stress was absorbed by the mountain-shaped projection part 28C and a crack did not arise at all. The small-diameter cylindrical portion 28A of the dust cover 28 is provided with a first locking projection 28a that fits in the locking circumferential groove 27b of the push rod 27 in its upper opening.該止Me circumferential groove 27b is set from the tip P at the push rod 27 in a substantially position of the length L ₂ of the half of the total length L _1, and set small stroke amount of time in deformation dust cover 28. The small-diameter cylindrical portion 28A extends from the first locking projection 28a in the left direction in FIG. 1 (upper end in FIG. 2) to form a folded portion 28b having a substantially U-shaped cross section. The folded portion 28b is formed in series on one slope 28e of the chevron 28C. The large-diameter cylindrical portion 28B of the dust cover 28 has a second locking projection 28c at its opening. The second locking projection 28c is engaged and fixed to an inner wall locking edge 20d formed on the inner bottom surface 20c of the other case 20. The second locking projection 28c is formed in a series from the outer peripheral surface 28d to the other inclined surface 28f of the angled projection 28C. Here, it is preferable that the projection angle θ formed by the one inclined surface 28e and the other inclined surface 28f of the mountain-shaped protrusion 28C is set to 75 ° to 120 °.

Next, the operation and the like will be described based on the embodiment of the structure of the dust cover in the spring brake chamber according to the present invention.
By depressing a brake pedal as a service brake, the command air pressure operates the relay valve from the dual brake valve, and the compressed air flows from the service brake port of the spring chamber E. Therefore, air pressure is applied to the front surface of the diaphragm 22B in the pressure chamber of the connection case 21, and the diaphragm 22B moves to the right. Then, the push plate 22a of the push rod 22 is moved rightward. The tip of the wedge 29 protrudes and moves in the right direction. This is transmitted to the wheel brake attached to the axle. Then, the expander sleeve in the brake shoe is expanded and the braking operation is performed by the action of the brake shoe.

On the other hand, when the parking brake lever is operated to the parking position, the compressed air is discharged from the chamber 19a at the spring brake port of the spring chamber E. The power spring 23 in the one case 19 is extended to move the spring receiving portion 22A of the piston member 22, the diaphragm 22B, and the push rod 22C to the right. The spring receiving portion 22A pushes the diaphragm 26 disposed in the chamber 20a of the connection case 21 and the push plate 27a of the push rod 27 in the right direction. Thus, the dust cover 28 is deformed to move the push rod guide 30 and the wedge 29 to the right. The tip of the wedge 29 protrudes and moves in the right direction. This is transmitted to the wheel brake attached to the axle. Then, the expander sleeve in the brake shoe is expanded and the braking operation is performed by the action of the brake shoe.

Next, the operation of the dust cover 28 will be described in detail.
When the driver operates the service brake or the parking brake, the diaphragm 22B, the push plate 22a, the diaphragm 26, and the push plate 27a are moved to the right and the push rod 27 is moved to the right as described above with reference to FIG. . Therefore, as shown in FIG. 2, the push rod 27 moves downward as seen from the drawing, and deforms the first locking projection 28a fitted and fixed in the retaining circumferential groove 27b of the push rod 27 to the position indicated by the phantom line. Since in fixed position to the push rod 27 of the first locking protrusion 28a at this time the dust cover 28 is set from the tip to the length L ₂ or Longer distance approximately half of the total length L ₁ of the push rod 27 The stroke amount when the dust cover 28 is deformed is set to be small.

Therefore the relationship between the total length _{L 1} of the first setting of the locking projection 28a length _{L 2} and the push rod 27 of the dust cover 28 from the distal end of the push rod 27, i.e., _{L 2} ≧ 1/2 × _{L 1} relationship The relationship in which the formula is satisfied was suitable. As described above, it has been found that the amount of deformation of the dust cover 28 is small and cracks are less likely to occur if the relational expression of the fixed position of the first locking projection 28a of the dust cover 28 in the push rod 27 is used.

On the other hand, the projection angle θ formed by one slope 28e and the other slope 28f of the mountain-shaped projection 28C of the dust cover 28 is set to 75 ° to 120 °, so that if the push rod 27 moves, the one slope 28e is shown in FIG. The dust cover 28 is gently deformed as shown by the phantom line shown in FIG. 6 and buckled to the chevron 28C and one inclined surface 28e or the other inclined surface 28f even when the push rod 27 is repeatedly moved repeatedly. Thus, there is no crack or breakage, and the life of the dust cover 28 can be extended.

The present invention causes cracks by fitting and fixing not only to dust covers in spring brake chambers applied to compressed air brake devices for vehicles, but also to shafts that perform large stroke piston movements such as air cylinders. A dust cover that is difficult and has excellent durability can be provided.

19 One case 19a Chamber 20 Other case 20a Chamber 20b Cylindrical base 20c Inner bottom surface 20d Inner wall locking edge 21 Connection case 21a Connection case one surface 22 Piston member 22A Spring receiving portion 22B Diaphragm 22C Push rod 22D Spring 22a Push plate 23 Power spring 24 Clamp ring 25 Clamp ring 26 Diaphragm 27 Push rod 27a Push plate 27b Stop peripheral groove 28 Dust cover 28A Small diameter cylindrical portion 28B Large diameter cylindrical portion 28C Angle projection 28a First locking projection 28b Folding portion 28c First 2 locking projection 28d outer peripheral surface 28e one slope 28f other slope 29 wedge 30 push rod guide

Claims (3)

A spring brake chamber comprising one case, the other case, and a connecting case connecting the two cases, a spring receiving part holding a power spring in the one case, and a piston member interlocking with the spring receiving part A spring brake chamber having a push rod that is disposed in a room in the other case and is advanced and retracted by a diaphragm operation to control braking / release of a brake. A dust cover structure in a spring brake chamber, characterized in that a dust cover having a small-diameter cylindrical portion, a large-diameter cylindrical portion below, and a mountain-shaped projection at an intermediate portion is fitted and fixed to the push rod. A spring brake chamber comprising one case, the other case, and a connecting case connecting the two cases, a spring receiving part holding a power spring in the one case, and a piston member interlocking with the spring receiving part A spring brake chamber having a push rod that is disposed in a room in the other case and that moves forward and backward by a diaphragm operation and controls braking / release of the brake. A small-diameter cylindrical portion provided with a first locking projection to be fitted and fixed in the groove, a folded portion extending from the first locking projection and having a substantially U-shaped cross-section, and from the folded portion to the other A large-diameter cylinder provided with a chevron-shaped projection formed on the slope and a second locking projection engaged with and fixed to an inner wall locking edge formed on the inner bottom surface of the other case in the lower opening Comprising a dust cover made of a section, and setting the length L ₂ that is fitted and fixed in the first hooking protrusion, spring brake chambers relationship of the full length L ₁ of the push rod, characterized in that established by: The structure of the dust cover.
Relational expression L ₂ ≧ 1/2 × L ₁ A spring brake chamber comprising one case, the other case, and a connecting case connecting the two cases, a spring receiving part holding a power spring in the one case, and a piston member interlocking with the spring receiving part A spring brake chamber having a push rod that is disposed in a room in the other case and that moves forward and backward by a diaphragm operation and controls braking / release of the brake. A small-diameter cylindrical portion provided with a first locking projection to be fitted and fixed in the groove, a folded portion extending from the first locking projection and having a substantially U-shaped cross-section, and from the folded portion to the other A large-diameter cylinder provided with a chevron-shaped projection formed on the slope and a second locking projection engaged with and fixed to an inner wall locking edge formed on the inner bottom surface of the other case in the lower opening Comprising a dust cover made of a part, the other hand, the set length L ₂ is projecting angle θ made by the other slope 75 ° to that set by 120 ° and is fitted and fixed in the first hooking protrusion, push structure in the dust cover to the spring brake chamber, characterized in that the relationship between the total length L ₁ of the rod is established by the following equation.
Relational expression L ₂ ≧ 1/2 × L ₁

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