LT6803B - A ridged brake shoe of a railroad vehicle - Google Patents

Abstract

The invention relates to the field of railroad transport, namely to brake shoes of railroad vehicles. The proposed ridged brake shoe of a railroad vehicle comprising a metal backing plate having fabrication holes on an outer surface thereof, the backing plate is attached on the friction element; at least three thermally conductive elements in the form of elongated protrusions are provided along an inner surface of the metal backing plate, the protrusions having side recesses, wherein the boundary ones from them are arranged biased from edges of the metal backing plate in a longitudinal direction, and at least one intermediate thermally conductive element is arranged between the boundary thermally conductive elements. The metal backing plate further comprises a metal ridge, where the proportion of the volume of the metal backing plate with the thermally conductive elements is 25-55% of the overall volume of the shoe.

Description

FIELD OF THE INVENTION

The invention relates to the field of railway transport, namely brake pads for railway vehicles.

State of the art

Brake pads are replaceable working parts that are part of the main part of the brake system. The quality of the brake pads affects the length of the braking distance, the increase in speed and operational safety. Brake pads shall have a specified friction coefficient independent of speed, high wear resistance and shall be stable under different climatic conditions.

Of course a brake pad for braking railway wheels. The brake pad consists of a support plate in the form of a curved strip and means for attaching the support plate to the brake head, the means being located at each end of the support plate. The brake pad further has brake pad liners that are attached to the support plate and has a brake surface for interaction with a pair of wheels of a railway vehicle (U.S. Pat. No. 6,581,732 (B1)).

The disadvantage of the known brake pad is the insufficient thermal stability due to the absence of a metal liner whose main purpose is to repel heat from the friction surface. In addition, the brake pads have many fasteners that do not form a barrier to heat dissipation, and they are also sources of corrosion generation at the joints between different surfaces.

Also known is a composite brake pad for use in railway transport, which comprises a support plate having a clamp and a curved strip-shaped brake surface with a friction element made of a first type of friction composite material covering the brake pad surface. The composite brake pad further comprises a second type of friction material which is made as a separate liner and is molded into the first type of friction composite material. The second type of friction material is completely embedded in the first type of friction composite. The first type of friction composites erodes due to friction with the wheel pair surface during normal braking, while the second type of friction materials have higher abrasive properties than the first type of friction composites. At least one element of friction material is associated with a support plate (U.S. Pat. No. 6,241,058 (B1)).

The disadvantage of the brake pad is the lack of heat repulsion from the contact area between the pad and the wheel elements. In addition, the pad does not have additional means for attaching the friction element to the support plate, which may cause the friction element to separate (break).

A brake pad is also known which has a cast iron support plate in which the friction liners are made of a carbon-carbon composite material. The brake pad support cast iron base plate is the structural base and the friction element of the brake pad work surface (patent UA 88410).

The disadvantage of the brake pad is that most of the friction surface consists of cast iron, which causes rapid wear of the steel wheel pores during braking and a defect in the formation of so-called rolled iron on them.

There is a known brake pad consisting of a steel support plate and an arched cast iron housing. The arch-shaped housing consists of a main part of the block housing, which has cylindrical inserts arranged in groups, and a profile part of the block housing, which has inserts in cross section. The pad has an additional metal support plate on which the cylindrical ribbed inserts of the main part of the pad body and the profiled part are arranged. The cylindrical inserts of the main part of the block body are made of a composite friction material with a coefficient of friction higher than the coefficient of friction of the base. The ribbed inserts of the profile part are made as profile elements and are embedded in the cross-section of the pad, which contacts the ribbed surface of the wheel and interacts with the side surface of the rail. The inserts are made of an anti-friction composite material with a coefficient of friction lower than the coefficient of friction of the base material and an abrasion lower than the material abrasion of the base material and the inserts installed in the main part of the pad body (patent RU 2494901).

The disadvantage of brake pads is that the use of metals with different chemical compositions (cast iron and steel) reduces corrosion resistance, and liners made of an anti-friction composite material that is resistant to abrasion can cause uneven wear of the pad along its width and displacement. in the brake system.

There is a known brake pad for a railway vehicle having a composite friction element attached to a support plate in the form of a metal curved strip, the surface of which has a central ridge with a hole for inserting a pin and side protrusions, as well as a means for mechanically fastening composite friction elements, strips and metal liners. . In one embodiment, the inserts are attached to the metal support plate by a threaded connection, while in another embodiment, the inserts are attached to the metal support plate by mechanical fastening, which is realized by notches cut in the metal support plate and reinforcing edges of the reinforcing plate. made in the form of at least one lateral surface of the inserts. The friction element has transverse grooves that are made on both sides of each insert so that they are bounded on one side by the lateral surfaces of the inserts (patent UA 115877).

A disadvantage of the known construction is that in one variant the friction element is attached to the metal support plate by a threaded connection, and in another variant the friction element is attached to the metal support plate by mechanical fastening in the form of notches cut in the metal support plate. is not reliable, especially in the case of emergency braking, and may result in detachment of the friction element from the metal support plate.

There is a known composite brake pad made of metal, in particular cast iron, for a composite brake block for railway vehicles, where the composite brake pad has a main plate-shaped body and a support surface on the inner side of the plastic composition of the composite brake block. The main body has at least one steel insert, preferably with plastic composition holders on the inner side of the main body. The steel insert does not have a rectangular cross-section along the entire length of the main body, but has a circular cross-section (application WO2011006635 (A1)).

The disadvantage of the known brake pad is that the determined percentage of the working surfaces of the liner and the friction elements is not sufficient to ensure the required heat repulsion from the friction zone. The pad is also characterized by a lack of structural elements that could contribute to the removal of products that occur during braking.

The closest prior art is a railway vehicle brake block consisting of a cast iron rear brake block and a friction material rigidly connected to the rear brake block. The back of the pad has a curved laminated base with an internal support surface for the laminate. The total surface of the brake block is formed largely of at least one outer surface of the friction material and, to a lesser extent, of the outer surface of the rear part of the at least one brake block. According to the invention, the base is formed without a support plate on the longitudinal sides and has a gill-shaped side wall on each transverse side. The friction material is arranged between the side plates. Each side plate has at least one break which extends from the upper surface of the side wall towards the support surface and divides the side wall into at least two parts. The edges of the side sections form part of the total braking surface (application WO2009036830 (A2)).

The disadvantages of the immediate solution are the rapid wear of the friction element during operation (plastic material), the friction liners have a high abrasion resistance, which reduces the frictional contact between the pad and the wheel, the mutual overlap coefficient, the coefficient of friction and thus the overall braking performance characteristics. Also, the side plates can be damaged during emergency braking because their connection to the rear wall of the block is cantilevered and its strength may be insufficient due to the small thickness.

The essence of the invention

The object of the invention is to increase the reliability and abrasion resistance of the pad, to increase the heat dissipation of the brake pads and to equalize the pad temperature along the working surface due to the high heat capacity and thermal conductivity of the metal support plate at a certain level of friction coefficient and minimum pair wear. attachment to a metal support plate, as well as to ensure more even wear along the shoe during its operation, to increase corrosion resistance due to a solid metal support plate with heat-conducting structural elements. Improving heat dissipation from the friction zone will significantly reduce the number of wheel pair defects that result from their overheating during braking.

The task was solved by providing a railway vehicle with a ribbed brake pad having a metal support plate with technological holes in the outer surface, the support plate being attached to a friction element made of a composite material. According to the present invention, at least three thermally conductive elements in the form of elongate protrusions are arranged along the inner surface of the metal support plate, the protrusions have lateral notches where their edges are offset from the edges of the metal support plate in the longitudinal direction, and at least one intermediate thermally conductive element is for edge heat-conducting elements, where the heat-conducting elements are made together with a metal support plate, the metal support plate still has a metal edge acting as an additional heat diffuser, and the volume ratio of the metal support plate to the heat-conducting elements is 25-55% of the total block volume, wherein the asbestos-free rubber-resin-based material is used as a friction element composite material.

The technical effect of this solution is the increased overall thermal conductivity of the brake pads and the equalization of the temperature field along the working surface of the pad due to the high heat capacity and thermal conductivity value of the metal support plate at the specified friction coefficient and minimum pair wear; more even wear over the entire length of the pad and reliable attachment of the friction element; increase in corrosion resistance due to the construction of heat-conducting elements, which are made together with a metal support plate; the absence of contact surfaces of different types (chemical composition) of metallic materials, which could lead to a corrosive electrochemical process, which is amplified by atmospheric phenomena (humidity, active gases in the air, etc.).

Thus, each of the thermally conductive elements has at least one notch dividing the thermally conductive elements into parts and thus forming thermally conductive sections arranged at the longitudinal edges of the pad working surface, and an intermediate thermally conductive element forming at least one thermally conductive section in the central part of the pad working surface. This ensures an even distribution of heat-conducting elements along the work surface of the pad and efficient heat dissipation during braking, as well as increasing the wear resistance of the brake pads.

In addition, the at least one intermediate thermally conductive element is arranged symmetrically with respect to the center of the longitudinal axis.

In addition, the thermally conductive elements have a cantilever connection to the rear part of the support plate and are of such a thickness as to prevent their damage during any braking mode.

In addition, the ribbed brake pad of a railway vehicle has 3 to 10 thermally conductive elements. When the number of thermally conductive elements is reduced to less than three, heat dissipation from the work surface is insufficient, leading to overheating of the pad, while increasing the number of thermally conductive elements to more than ten causes damage or rapid wear of the wheel pairs.

In addition, the thermally conductive elements are made with an angular slope with respect to the edge of the support plate, which is 0.2-8.0 °. As a result of this solution, heat from the work surface is evenly distributed over the entire area of the pad.

In addition, the friction material is attached to the surfaces of the heat-conducting elements of the support plate by pressing it in a dispersed state and vulcanizing under the influence of temperature and pressure. This allows the friction element to be securely attached to the support plate and prevents it from detaching during emergency braking.

In addition, an asbestos-free rubber-resin-based material with reinforcing fibers and impurities allows the surface hardness of the friction element to be achieved on a Brinell scale in the range of 3-35 HB, the coefficient of friction in a pair of steel wheels in the range of 0.06-0.30, values are given pads with a high coefficient of friction.

It has been found experimentally that, due to the use of asbestos-free rubber-resin-based materials containing reinforcing fibers and impurities, the optimal Brinell hardness values for low-friction pads should be in the range of 3-35 HB, while pads with a high coefficient of friction must be in the range between 1.2 and 10.0 HB. These limits allow to increase the abrasion resistance of the pad. The use of materials with hardness values below the limits set for each variant results in rapid wear of the work surface, while the use of materials with hardness values above the limits set for each variant can accelerate the wear of the wheel pair. In addition, it has been found experimentally that the optimal values of the coefficients of friction for asbestos-free rubber-resin-based materials with reinforcing fibers are as follows: for blocks with a low coefficient of friction, they are in the range of 0.06-0.30, while for blocks, with a high coefficient of friction, they range from 0.17 to 0.45. These limits are optimal because within these limits the coefficient of friction remains the most stable for a long time, and it also defines the optimal values of linear wear and increases the wear resistance.

In addition, the edge heat-conducting elements are arranged at the edges of the work surface or pulled from the edge in the longitudinal direction up to 150 mm. During the experiment, it was found that such an arrangement ensures the most efficient distribution of thermally conductive elements along the working surface compared to thermally conductive elements arranged between the edge elements. If the extreme heat conductors are installed more than 150 mm from the edge towards the center of the work surface, the heat conducting elements will accumulate and form sections that will cause uneven wear or even damage to the wheel pair.

In addition, the metal base plate of the pad has a U-shaped reinforcing insert mounted in the central part above the technological opening. Metal inserts also act as elements to compensate for vibration and impact loads during braking.

fig. shows a comparison of the temperature curve 1 of the working surface of a wheel using the pad of the present invention with the temperature curve 2 of analogous pads of a known prior art, in which the friction element is mechanically attached to a metal support plate.

Studies with ribbed pads applied to solid metal support plates have shown that the final wheel tread temperature using ribbed pads on solid metal support plates at an initial braking rate of 50 to 140 km / h is on average 30% lower. than conventional prior art pads used under the same conditions. The final working surface temperature of the wheel when braking from 160 km / h is 4% lower than when using pads with solid metal-based support plates. The ability to dissipate heat from the wheel work surface is much greater when ribbed pads are used on solid metal support plates. The use of the ribbed pads of the present invention significantly reduces the likelihood of defects on the wheelsets, as well as the incidence of ice build-up.

Brief description of the drawings in the figure

The invention disclosed herein will be more clearly understood from the following exemplified embodiment and the corresponding appended figures, in which:

fig. is a diagram showing a comparison of the working surface temperature of a wheel using a pad of the present invention with pads of the prior art.

fig. shows a general view from above of the metal support plate of the ribbed brake pad.

fig. shows a general bottom view of a ribbed brake pad metal support plate.

fig. is a side view of a ribbed brake pad metal support plate.

fig. is a section through Fig. 4. line A-A image.

fig. is a top view of the ribbed brake pad metal support plate.

fig. is a bottom view of the ribbed brake pad metal support plate.

The drawings illustrating the invention, as well as the specific embodiments of the invention, are only exemplary in nature and are in no way intended to limit the appended definition, but only to explain the essence of the invention.

Detailed description of the invention (information confirming the possibility of realization of the invention)

The ribbed brake pad of a railway vehicle consists of a metal support plate 3 with technological holes 4 in its outer surface and a composite friction element 5 made of an asbestos-free rubber-resin-based material attached to the inner surface of the metal support plate 3. Along the inner surface of the metal support plate 3 are arranged edge heat-conducting elements 6, pulled from the edges of the metal support plate 3 in the longitudinal direction, and intermediate heat-conducting elements 7, which are arranged between the edge heat-conducting elements 6. The heat-conducting elements 6, 7 are cast together with a metal support plate 3. The brake pad also has a metal edge 8 and a U-shaped reinforcing insert 9 arranged in the central part above the central technological opening 10. The friction element 5 is attached to the metal support plate 3 by pressing in a dispersed state and vulcanizing under temperature and pressure. .

The invention can be used in the construction of brake pads for certain types of railway vehicles, in particular locomotives. The brake pads consist of a metal support plate 3, which is made together with heat-conducting elements 6, 7 on the working surface. During braking, the pair of wheels comes into contact not only with the friction composite element 5, which is made of asbestos-rubber-resin-based material, but also with the heat-conducting elements 6, 7. Contact of the heat-conducting elements 6, 7 with the surface of the wheel pair enables the pad. perform a number of functions, the main one being the significantly higher heat repulsion from the friction surface of the pad and from the wheel pair, thereby reducing the wear of the wheel pair.

The invention provides stability to the frictional characteristics of the work surface throughout the service life of the brake pads, reduces wear on the wheel pairs and increases operational safety during emergency braking.

Claims (11)

DEFINITION OF THE INVENTION 1. A ribbed brake pad of a railway vehicle with a metal support plate with technological holes in the outer surface, the support plate being attached to a friction element made of a composite material, characterized in that at least three heat-conducting elements in the form of elongate protrusions are arranged longitudinally. the inner surface of the metal support plate, the protrusions have side notches where the edge protrusions are pulled from the edges of the metal support plate in the longitudinal direction and at least one intermediate thermally conductive element is arranged between the edge heat conducting elements, where the heat conductive elements are made together with the metal support plate, the metal support plate still has a metal edge as an additional heat diffuser, and the volume ratio of the metal support plate with heat-conducting elements is 25-55% of the total volume of the pad, and where the asbestos-free rubber-resin-based material, etc. woven as a composite friction element material. 2. A ribbed brake pad of a railway vehicle according to claim 1, characterized in that each edge thermally conductive element has at least one notch dividing the thermally conductive elements into parts, thus forming thermally conductive sections arranged at the longitudinal edges of the working surface of the pad, and the intermediate the thermally conductive element forms at least one thermally conductive section in the central part of the work surface of the pad. 3. A ribbed brake pad of a railway vehicle according to claim 1, characterized in that it has at least one intermediate heat conducting element arranged symmetrically with respect to the center of the longitudinal axis. 4. A ribbed brake pad for a railway vehicle according to claim 1, characterized in that the thermally conductive elements have a cantilever connection with the rear part of the support plate. 5. A railway vehicle ribbed brake pad according to claim 1, characterized in that it has from 3 to 10 thermally conductive elements. 6. A railway vehicle ribbed brake pad according to claim 1, characterized in that the thermally conductive elements are made with an angular slope towards the edge of the support plate, which is 0.2-8.0 °. 7. A ribbed brake pad for a railway vehicle according to claim 1, characterized in that the friction material is attached to the outer surfaces of the heat-conducting elements of the support plate by pressing it in a dispersed state and vulcanizing under temperature and pressure. 8. A ribbed brake pad for a railway vehicle according to claim 1, characterized in that the asbestos-free rubber-resin-based material containing reinforcing fibers and impurities imparts a Brinell scale hardness to the surface of the friction element between 3-35 HB and a coefficient of friction in the pair. with a steel wheel in the range of 0.06-0.30. 9. A railway vehicle ribbed brake pad according to claim 1, characterized in that the asbestos-free rubber-resin-based material containing reinforcing fibers and impurities enables the surface hardness of the friction element according to the Brinell scale in the range of 1.2-10.0 HB, and the coefficient of friction of the pad in a pair with a steel wheel ranges between 0.17 and 0.45. 10. A ribbed brake pad for a railway vehicle according to claim 1, characterized in that the extreme heat-conducting elements are arranged at the edges of the working surface and pulled from the edge in a longitudinal direction by a distance of up to 150 mm. 11. A ribbed brake pad for a railway vehicle according to claim 1, characterized in that the metal support plate has a U-shaped reinforcing insert arranged in the central part above the technological opening.