KR19980702135A - Spring brake actuator with double ply pressure plate assembly - Google Patents

Abstract

A double ply pressure plate 36 is shown for use in a vehicle air brake system 10 such as a bus, truck, or the like. The two-ply pressure plate 36 has a diaphragm plate 92 which abuts the diaphragm 32 of the air braid system 10 and a support plate 98 which abuts the rear face of the diaphragm plate 92. It includes. The control rod 18 is welded to the support plate 98 and the diaphragm plate 92. The form of mechanical or metallurgical connection between the support plate 98 and the diaphragm plate 92 is formed between the mounting point of the rod 18 and the outer periphery of the smaller of the two plates.

Description

Spring brake actuator with double ply pressure plate assembly

Automotive air brake systems, such as buses, trucks, and the like, typically include brake shoes and drum assemblies that are actuated by actuator assemblies that are actuated by the selective application of fluids such as compressed air. Conventional air brake actuators have both an emergency or spring brake actuator which causes the action of the brake when pneumatic pressure is released and a service brake actuator which starts the brake under normal driving conditions by the application of compressed air. The emergency brake actuator includes a high compression spring that applies a brake when air is released. This is often referred to as a spring brake. Typically the spring brake actuator is arranged in line with the service brake actuator.

When the total air pressure is applied to the spring brake actuator, the air pressure acting against the diaphragm and the pressure plate compresses the spring. The spring brake actuator rod is integral with the pressure plate to be held in the retracted position by pneumatic or retracted by the return spring. When the brake pedal is pressed during normal drive operation, compressed air is introduced into the service brake actuator. The service brake actuator acts against the diaphragm, and the service brake pressure plate and the attachment push rod are extended so that the brake is proportional to the pneumatic pressure in the service brake actuator. It is applied with one force. In case of deliberate release of air from the spring brake actuator or loss of pneumatic pressure, the brake will be mechanically actuated by the force of the high compression spring acting on the spring brake actuator rod, which is then service brake. It acts on the push rod to apply the brakes. Examples of known double chamber spring brake assemblies are described in US Pat. No. 5,105,727 to Bowie, issued April 21, 1992, US Pat. No. 3,439,585 to Herrera, issued April 22, 1969, and 10, 1974. US Patent No. 3,842,716 to Swander Jr., issued May 22.

A typical service brake pressure plate assembly consists of a circular flat plate with an actuator rod welded to the center of one side of the plate. The rod is welded to the plate by conventional welding beads extending around the base of the rod. 6 shows an example of a known pressure plate assembly. This assembly 200 consists of a circular pressure plate 202 and an actuator rod 204 welded to one side of the pressure plate 202 by a circular welding bead 206. The actuator rod 204 is welded to the pressure plate 202 such that the longitudinal axis of the rod 204 coincides with the central axis of the circular pressure plate 202. Structurally, the largest rod experienced by the circular pressure plate 202 is experienced adjacent to the mounting point of the actuator rod 204. Less structural strength is needed near the perimeter of the circular pressure plate 202. Current pressure plates are formed from 1/4 inch thick steel and satisfactorily meet the structural requirements near the center of the plate. However, these plates far exceed the rods adjacent to each plate in normal operation. As a result, the thickness of the plate at the perimeter becomes excess weight.

It is desirable to maintain the structural integrity of the plate under high stress at the center while reducing the weight of the pressure plate.

The present invention relates to a spring brake actuator, and more particularly to a spring brake actuator having a two-ply pressure plate assembly.

1 is a cross-sectional view of a pneumatic brake acting assembly having a two-ply pressure plate according to the invention,

2 is a partial cross-sectional view of a first embodiment of a two-ply pressure plate according to the present invention for use of the pneumatic brake acting assembly of FIG.

3 is a bottom view of a two-ply pressure plate,

4 is a detailed cross-sectional view of the actuator rod and the pressure plate prior to welding the rod to the pressure plate;

5 is a sectional view of a second embodiment of a two-ply pressure plate according to the invention, and

6 is a side view of a conventional pressure plate assembly.

The spring brake actuator according to the present invention solves the problems of the prior art by including a two-ply pressure plate that resists shear forces and causes integral fixation between the actuator rod and the pressure plate.

The brake actuation mechanism according to the present invention is composed of a housing in which the first and second end walls that define the interior of the housing are opened with the opening disposed in the center of the second end wall. An elastomeric diaphragm is suspended in the housing and divides the housing into a first chamber and a second chamber. The pressure plate assembly is received in a second chamber. The plate assembly consists of a push rod adapted to connect to the brake by extending out of the housing through a centrally arranged opening. The pressure plate assembly is movable reciprocally in part in response to the introduction and discharge of the pressurized fluid into the first chamber. According to one embodiment of the invention, the pressure plate assembly consists of a first plate and a second plate. The second plate abuts the first plate in a face-to-face relationship with adjacent central portions. The push rod extends vertically from the first and second plates. The push rod has ends welded to the first and second plates.

In another embodiment of the invention, the pushrod is mounted to the center of one first plate and the first and second plates are fixed to each other by at least one connection located between the middle and the circumferential edges. It resists shear forces acting between the first and second plates.

Preferably, the connection between the central portions of the two plates consists of at least one uneven portion formed in the first and second plates to mechanically connect the two plates together. Alternatively, the intermediate connection of the first and second plates may be at least one spot weld.

The present invention relates to a method for manufacturing a pressure actuator assembly for a brake actuator, comprising the step of positioning the central portion of the conductive metal of the first plate member in a face-to-face relationship with the central portion of the conductive metal of the second plate member. Flux material lies in the recess in the proximal end of the conductive metal of the pushrod. The proximal end of the pushrod is located on the center of the second plate and surrounded by an insulating collar. When the first and second plates and push rods are in the compressed position, a large pulse of current is applied to the first and second plates and push rods so that the melting zone between the center of the plate and the push rods welds them together.

Referring to the drawings, and in particular with reference to FIG. 1, there is shown a cross-sectional view of a pneumatic brake acting unit 10 having a configuration well known in the art. The actuation unit 10 is composed of a service brake unit 12 mounted in a row on the spring brake or emergency brake unit 14. The service brake push rod 18 is provided with a U-shaped link 20 extending from the service brake 12 for reciprocating motion and adapted to be connected to a conventional brake (not shown) on a standard basis. The reciprocating motion of the push rod 18 by this action unit 10 causes the brakes to alternately act and release.

The service brake portion 12 is composed of a pair of facing cup-shaped housing portions 21, 22 having outward flange edges 25, 26 respectively. These housing parts 21, 22 are clamped together by clamps 27 at the flange edges to form the service brake inner chamber 30. The circumference of the elastomer diaphragm 32 is suspended between the inner edges 30 of the housings 21 and 22 between the edges 25 and 26. The service brake push rod 18 extends through the central hole 34 in the housing portion 21 into the service brake chamber 30 terminating in the two-ply pressure plate 36. The compression spring 40 extends between the two-ply pressure plate 36 and the inner surface of the housing portion 21. A spring seat 48 is disposed around the central opening 34 to receive the end of the compression spring 40 and hold it in position about the opening 34. The spring 40 presses the pressure plate 36 and the service brake push rod 18 to a fully retracted position as shown in FIG. Mounting studs 46 are provided in the housing portion 21 to mount the brake action unit 10 on a suitable bracket (not shown).

In order to operate the service brake, compressed air is introduced through the air service port 38 formed in the housing portion 22 and the two-ply pressure plate 36 and the diaphragm 32 are opposed to the compression force of the spring 40. Pressurizes to operate push rod 18. An exhaust opening 44 is provided in the housing portion 21 to allow rapid air exhaust from the inner chamber 30 when compressed air is introduced through the air service port 38.

The spring brake 14 consists of a pair of facing cup-shaped housing portions 51, 52 in which the edges are joined to define the inner chamber 53. The housing portion 51 is formed on the housing portion 52 and is provided with the outwardly circumferential flange edge 54 required inside the circumferential edge 56. The elastomeric diaphragm 58 is suspended in the spring brake chamber 53 and held at the circumference between the edges 54 and 56 of both housing portions 51 and 52. The portion of the chamber 53 between the diaphragm 58 and the housing portion 51 is filled with compressed air supplied through the air service port 59 in the housing portion 51 when the emergency brake is in the normal release position. To form an air chamber. The actuator rod 60 coinciding with the push rod 18 has one end extending through the central hole 64 formed in the end wall of the housing portion 51. This end of the actuator rod 60 terminates at the reaction plate 62 received in the central hole 63 of the end wall of the housing portion 22 of the service brake portion 12. The central hole 64 is provided with a bearing 66 having an annular recess to accommodate a pair of O-rings. This bearing 66 forms an airtight seal and a support surface for the actuator rod 60.

The other end of the actuator rod 60 terminates at a spring brake pressure plate 70 which extends through a centrally arranged hole 81 in the diaphragm 58 and engages the spring brake compression spring 72. The spring brake pressure plate 70 extends axially along the axis of the spring 72 and the flat portion 73 which engages one end of the spring 72. The tubular portion 74 is forcibly fitted on one end of the actuator rod 60 such that the spring brake pressure plate 70 and the rod 60 form an integral unit. The spring brake pressure plate 70 may be formed of aluminum casting.

In normal operation of the brake 10, the actuator rod 60 is compressed air retained in the portion of the chamber 53 defined by the diaphragm 58 and the housing portion 51 as shown in FIG. 1. You will be in the fully retracted position. When the compressed air is exhausted, the compression spring 72, whose one end engages with the outer end wall of the housing 52, has a spring brake pressure plate 70 in the direction of the brake push rod 18 of the service brake 12, and Pressing the rod 60 attached integrally. The housing part 22 of the service brake 12 and the housing part 51 of the spring brake 14 are formed of steel shells or integral aluminum castings attached to each other by circumferentially extending weld beads 76 or other suitable attachment means. Can be. The force of the spring 72 causes the actuator rod 60 to extend through the central opening 64 and the reaction plate 62 to apply the force to the two-ply pressure plate 36 and diaphragm 32 of the service brake. do. This action causes the service brake push rod 18 to act so that the brake is applied. When the brake is released, compressed air is once again introduced into the space between the housing portion 51 and the diaphragm 58. The force of compressed air against diaphragm 58 overcomes the compressive force of spring 72 and returns pressure plate 70 and rod 70 to the position shown in FIG.

Actuator rod 60 is a hollow tube or rod provided with central bore 61 to receive a brake release or a casing bolt 78. The bolt 78 is adapted to engage the end edge 80 of the tubular portion 74 of the spring brake pressure plate 70 to hold the spring 72 in the compressed position whenever desired. This bolt 78 can be used to manually release the spring brake or can be used to ensure that the compression spring 72 is fully compressed when the retaining function is performed on the brake assembly. This bolt 78 is loaded and engages a threaded fixing opening or nut 77 which is fixed by welding or staking to the end wall of the housing portion 52. The second nut or head 79 is fixedly attached to the threaded bolt so that the bolt can be rotated in the nut 77 by a general wrench or the like.

The two-ply pressure plate 36 according to the invention provides an equally strong fit between the push rod 18 and the plate 36 while reducing weight. As can be seen in FIGS. 3 to 5, the first embodiment of the pressure plate assembly 36 includes a diaphragm plate 92, a support plate 98 mounted on the diaphragm plate 92 and a diaphragm plate. And a service brake push rod 18 mounted on both the 92 and the support plate 98. The diaphragm plate 92 is composed of a front side 94, a rear side 96 and an arch or rolled outer circumferential edge 97. The support plate 98 is composed of a front face 100, a rear face 102 and a circumferential edge 103. It can be seen that the support plate 98 has a smaller diameter than the diaphragm plate 92.

Preferably, the diaphragm plate 92 and the support plate 98 are mounted adjacent to each other with the front face 100 and the rear face 96 facing each other and fixed to each other in a number of positions. The two plates are connected to each other via a plurality of uneven portions 106 formed on both plates in the middle between the edge 103 of the support plate 98 and the rod 18. This uneven portion has a diaphragm such that the protrusion 108 extends rearward from the rear face 102 of the support plate 98 and a corresponding recess 110 is formed on the front face 94 of the diaphragm plate 92. It can be formed by joining the female and male die which deforms the plate 92 and the support plate 98. The two plates were deformed such that the protrusions 111 formed on the rear face 96 of the diaphragm plate 92 were accommodated in the complementary recesses 112 formed on the bottom face of the support plate 98. In a preferred embodiment of the pressure plate assembly 36, the uneven portion 106 is sized such that the depth of the recess 110 and the height of the protrusion 108 are approximately one half the thickness of the diaphragm plate 92. It is.

As shown in FIG. 3, the uneven portion 106 is preferably arcuate and, when connected, forms a circle concentric with the periphery of the diaphragm plate 92. The uneven portion 106 serves to prevent the two plates from moving relative to each other by resisting the shear force acting between the two plates. Further, the uneven portion 106 is spaced radially outward from the push rod 18 to distribute the load over the entire body of the support plate 98. The interconnects of the uneven portions 106 of the plates 92 and 98 resist shear forces caused by deflection or deflection of the exterior of the diaphragm plate 92 relative to the support plate 98. The outside of the diaphragm plate must slide across the front surface 100 of the support plate 98 of the back side 96 of the diaphragm plate 92 to shear or deflect with respect to the support plate 98. The interconnection between the front and rear surfaces resulting from the uneven portion 106 prevents it from sliding and shearing. Thus, the assembly has the strength of the two plates closest to the mounting point of the pushrod 18 where strength is most needed. Preferably, the interconnection between the two plates is formed adjacent to the periphery of the small plate, in this case the support plate 98. However, the relative position of the interconnects is highly dependent on the shear force that will be exerted on the pressure plate assembly. By interconnecting the two plates to each other adjacent to the periphery of the smaller plate, the maximum resistance to shear forces is achieved as a result of the larger shear zones available at the furthest point of interconnection from the pushrod 18. .

The uneven portion 106 may act as a positioning portion on the backside 102 of the support plate 98 for the compression spring 40 of the service brake 12. It is important to keep the spring 40 centered around the longitudinal axis of the push rod. The uneven portion 106 holds the compression spring 40 in a specific direction with respect to the push rod 18 as a result of the abutting contact between the uneven portion 106 and the spring 40.

An alternative to the above-described upsets may be commercially known upsets as Tog-L-Lock ™ which is commercially available. Similar to the upsets described above, Tog-L-Lock ™ upsets cause deformation of one plate into one of the plates and mechanically interconnect these two plates.

The two plates 92, 98 are also connected to each other at the push rod 18. As can be seen in FIG. 2, the push rod 18, the diaphragm plate 92 and the support plate 98 are integrally welded to each other in a melting zone 14 composed of material from each of these separate elements. . Melting zone 114 results in integral welding or bonding of portions of pushrod 18, diaphragm plate 92 and support plate 98. This preferred welding method is a resistance welding method wherein the end portions 16 of the push rod 18 together with the portions of the support plate 98 and the diaphragm plate 92 are welded to each other to form an integral metallurgy between these three elements. To form a junction.

As can be seen in FIG. 4, prior to welding, the push rod 18 has a recess 18 formed at the end 116. Suitable flux material 120 is encased in recess 118. Flux 120 is conventional in resistance welding operations. After the flux 120 is positioned into the recess 118 of the control rod 18, the ceramic collar 124 is also positioned against the rear face 102 by abutting the rear face 102 of the support plate 98. It is housed on the rod 18 in a stretchable manner so as to surround the base of the rod 18. The support plate 98 is positioned against the diaphragm plate 92 with the central portions 126, 128 coaxial with the push rod 18 adjacent to each other. The collar 124 acts as a mold to maintain the desired shape of the plates 92 and 98 and the rods 18 in the dissolution zone 114. After all the elements are in place, the compressive force is applied between the push rod 18 and the diaphragm plate 92 and the support plate 98. Preferably, a compression force of 150 pounds is applied. After sufficient compressive force is applied, a large pulse of current passes through diaphragm plate 92, support plate 98 and control rod 18. As the current passes through these elements, the resistance to the current between the various elements appears as heat. The combination of the current of a large pulse, the pressure between the various elements and the abutment surfaces of these elements, causes the diaphragm plate 92, the support plate 98 and the push rod 18 to each other in the melting zone 14. Results in the dissolution of). After the melting zone is sufficiently cooled, the collar 124 is removed from the push rod 18 and the resulting product is integrally connected to each other at the points where the faces of the two plates are spaced apart from the push rod 18. The central part of the two plates is a two-ply pressure plate according to the invention, which is integrally welded to each other and to the push rod 18.

Figure 5 shows a second embodiment of a service brake pressure plate assembly according to the invention. In this embodiment, the pressure plate assembly 130 consists of a push rod 18, a support plate 98 and a diaphragm plate 92, which are preferably in the melting zone 114 by the above-described resistance welding operation. Weld in the center to each other. However, instead of mechanically interconnecting the surfaces 96, 100 by the concave and convex portions as illustrated in FIGS. 2 and 3, the surfaces 96, 100 are welded to each other by conventional spot welding operations. Preferably, a circular zigzag spot weld that surrounds the rod 18 secures the periphery of the two plates to each other. This spot welding 132 resists the sliding shear force applied on the two plates. For all embodiments, it can be seen that each ply of pressure plates can be formed from 10 standard thickness steels, resulting in significantly reduced weight from conventional pressure plates.

The two-ply pressure plate assembly according to the present invention provides a far superior advantage over conventional plate assemblies. Firstly, the dual plate assembly provides structural strength close to the pushrods of the assembly while also removing material close to the periphery of the plate that is not structurally necessary. Thus, the total weight of the pressure plate assembly is reduced without sacrificing any structural condition.

It can be seen from conventional testing that the force output curve of the brake can be improved by forming a lip or flange about the periphery of the pressure plate holding the diaphragm. The pressure plate assembly according to the invention can be formed from two steel foils replacing one thick steel piece. The flange or lip can be formed more easily and inexpensively on the outer circumference of the steel flakes than the thick steel pieces. For example, attempting to form a flange on a quarter inch steel piece is extremely difficult and expensive. However, such flanges can be easily rolled into 10 standard thickness steel plates. Therefore, an improved force output curve can be achieved for a brake comprising a two-ply pressure plate according to the present invention through a cheaper and easier manufacturing method than is known in the art.

Reasonable changes and modifications are possible within the scope of the above specification and drawings without departing from the scope of the invention.

Claims (21)

A housing having a first and a second end wall partitioning the interior of the housing and having a central opening at the second end wall, suspended in the housing and dividing the housing into a first chamber and a second chamber A pram, a pressure plate assembly housed in a second chamber, consisting of a push rod adapted to connect to the brake by extending out of the housing through a centrally arranged opening and partially inducing and introducing compressed fluid into the first chamber. In a brake actuation mechanism composed of said pressure plate assembly that is responsively movable reciprocally, said pressure plate assembly comprises: A first plate member having a peripheral edge, a central portion and a diameter portion; It is composed of a second plate member having a circumferential edge, a diameter portion smaller than the diameter portion of the central portion and the first plate, the second plate member abuts the first plate member in a face-to-face relationship with the adjacent center portion and the push rod is first Extending vertically from the first and second plate members, wherein the push rod has a proximal end adjacent to the central portion, wherein the central portion and the proximal end of the first and second plate members are integrally welded to adhere them to each other. The brake actuation mechanism characterized by the above-mentioned. 2. The brake actuation mechanism according to claim 1, wherein the first and second plate members are also fixed to each other by means of a connecting portion located intermediate between the central portion and the circumferential edge. 3. The brake actuation mechanism according to claim 2, wherein the connection portion comprises at least one spot welding portion between the first and second plate members. 3. The brake actuation mechanism of claim 2 further comprising a plurality of connections between the first and second plate members. 5. The brake actuation mechanism according to claim 4, wherein the connecting portions are intermittently spaced around the central portions of the first and second plate members in a circular pattern. 6. The brake action mechanism according to claim 5, wherein the connection portion is adjacent to an edge of the second plate member. The method of claim 1, wherein the first plate member is circular and has a first diameter portion, the second plate member is circular and has a second diameter portion, and the push rod is circular in cross section and has a third diameter portion, and A brake actuation mechanism, characterized in that the first diameter portion is larger than the second diameter portion and the second diameter portion is larger than the third diameter portion. 3. The brake actuation mechanism according to claim 2, wherein the connecting portion is composed of at least one uneven portion formed by deforming these members on the first and second plate members so that these members are hermetically connected to each other. 9. The brake actuation mechanism according to claim 8, wherein the at least one uneven portion is arcuate along a plane parallel to the plane of the second plate member. 10. The brake actuation mechanism according to claim 9, further comprising a plurality of irregularities which are intermittently interlaced around the central portions of the first and second plate members in a circular pattern. A housing having a first and a second end wall partitioning the interior of the housing and having a central opening at the second end wall, suspended in the housing and dividing the housing into a first chamber and a second chamber A pram, a pressure plate assembly housed in a second chamber, consisting of a push rod adapted to connect to the brake by extending out of the housing through a centrally arranged opening and partially inducing and introducing compressed fluid into the first chamber. In a brake actuation mechanism composed of said pressure plate assembly that is responsively movable reciprocally, said pressure plate assembly comprises: A first plate member having a peripheral edge, a central portion and a diameter portion; And A second plate member having a circumferential edge, a central portion and a diameter portion smaller than the diameter portion of the first plate, wherein the push rod is mounted on one of the center portions and extends vertically from the plate, wherein the first and first And the two plate members are secured to each other by at least one connecting portion located midway between the central portion and the circumferential edge to resist shear forces acting between the first and second plate members. 12. The brake actuation mechanism according to claim 11, wherein the at least one connecting portion is constituted by a spot welding portion between the first and second plate members. 12. The brake actuation mechanism according to claim 11, wherein the at least one connecting portion is composed of a plurality of spot welding portions between the first and second plates. 14. The brake actuation mechanism according to claim 13, wherein the spot welding portion is intermittently spaced around the center portions of the first and second plate members in a circular pattern. 15. The brake actuation mechanism according to claim 14, wherein the spot welding portion is adjacent to an edge of the second plate member. 12. The brake actuation mechanism according to claim 11, wherein the connecting portion is composed of at least one uneven portion formed by deforming these members on the first and second plate members so that these members are hermetically connected to each other. The brake actuation mechanism according to claim 16, wherein the at least one uneven portion is arcuate along a plane parallel to the plane of the second plate member. 17. The brake actuation mechanism according to claim 16, further comprising a plurality of irregularities that are intermittently staggered around the central portions of the first and second plate members in a circular pattern. In the pressure plate assembly for a brake actuator, A push rod having a proximal end; A first plate member having a peripheral edge, a central portion and a diameter portion; It is composed of a second plate member having a circumferential edge, a central portion and a diameter portion smaller than the diameter of the first plate member, the second plate member abuts against the first plate member in a face-to-face relationship with the adjacent central portions, and the push rod A pressure plate assembly which extends vertically from the first and second plate members, wherein the proximal end of the pushrod is adjacent to the central part, where the proximal end and the central part are integrally welded to adhere them to each other. In the pressure plate assembly for a brake actuator, A first plate member having a circumferential edge, a central portion and a diameter portion, and A second plate member having a circumferential edge, a central portion and a diameter portion smaller than the first diameter portion, wherein the push rod is mounted on at least one central portion and extends vertically from the plate, wherein the first and second plate members and the central portion are And a shear plate fixed to each other by at least one connection portion intermediate between the circumference and the periphery thereby resisting shear forces acting between the first and second plate members. In the method of making a pressure plate assembly for a brake actuator, Providing a metallic first plate member having a central portion and a diameter portion, Providing a metallic second plate member having a central portion and a diameter portion smaller than the first plate diameter portion, Positioning the central portion of the conductive metal of the first plate member in a face-to-face relationship with the central portion of the conductive metal of the second plate member; Placing the flux material in the recess in the conductive metallic proximal end of the push rod, Abutting the proximal end in the central portion of the second plate member and positioning a non-conductive collar around the push rod in the second plate member, Positioning the first and second plate members and the push rod in a compressed state, and Applying the current of the welding pulse to the first and second plate members and the push rod to dissolve the central portion of the plate members and the push rod to each other; Method characterized in that consisting of.