A drum brake that is not prone to overheating

Abstract

The present invention belongs to the field of truck brakes, and specifically is a drum brake that is not prone to overheating. The brake drum comprises a brake drum that rotates with the wheel, a cover plate that is fixed on a frame and on which a brake shoe is installed, and a water tank that is installed on a vehicle body. The brake drum is in a cylindrical shape, and an axial hole is opened at the center of an end plate of the brake drum. A heat-resistant rubber bag for accommodating cooling water is arranged on the outer surface of the side wall of the brake drum, and the heat-resistant rubber bag is in an annular groove shape. The edge of the heat-resistant rubber bag is sealed and connected to the side wall of the brake drum through a clamp. A water pipe is arranged on the end plate of the brake drum, and one end of the water pipe is connected to the inner cavity of the heat-resistant rubber bag, and the other end of at least one water pipe is connected to a water inlet pipe, and the other end of the remaining water pipe is connected to a water outlet pipe. A sleeve is arranged at the position of the wheel shaft, and the water inlet pipe and the water outlet pipe are respectively connected in series to the inner and outer pipelines of the sleeve. The drum brake of the present invention has good heat dissipation effect, is not prone to overheating, is safe to use, and has a good water-saving effect.

Description

Technical Field

[0001] The invention belongs to the field of truck brakes, in particular to a drum brake which is not prone to overheating. Background Art

[0002] At present, most heavy-duty transport vehicles use drum brakes. In drum brakes, the brake drum is a rotating element and the brake shoe is a fixed element. When braking, the friction plate on the brake shoe is pressed against the inner surface of the brake drum to generate friction on the brake drum, thereby achieving the braking effect. When a heavy-duty transport vehicle is driving on a slope, the brake is used very frequently, and sometimes even for a long time. The friction between the brake drum and the brake shoe generates a large amount of heat, most of which is transferred to the brake drum, causing the temperature of the brake drum to rise sharply to more than 300 degrees Celsius, or even to 600 degrees Celsius. At this time, the friction coefficient between the brake shoe and the brake drum will drop sharply, resulting in thermal decay, thereby affecting the braking effect. In severe cases, the braking ability of the drum brake will be completely lost, resulting in a traffic accident. In order to ensure the driving safety of heavy-duty transport vehicles, it is necessary to heat and cool the brake drum. At present, the simplest method is to use a water spray cooling device for the brake drum. The water spray cooling device usually includes a water tank, and the water tank is connected to the air reservoir by a pressure reducing valve, so that the water in the water tank can be sprayed on the brake drum through a hose to cool it. This heat dissipation method takes a short time and has a good heat dissipation effect, but there are some technical problems in actual use: 1. Directly spraying water on the high-temperature brake drum is very likely to cause the brake drum to be damaged due to sudden cooling and heating. Therefore, it is necessary to spray water on the brake drum when the vehicle is not braking, so the water consumption is relatively large. Usually, heavy-duty transport vehicles need to install water tanks weighing five to six hundred kilograms or even more than one thousand kilograms, which reduces the vehicle's payload; 2. Only a small part of the sprayed water evaporates, and most of the remaining water is directly sprinkled on the road surface and wasted. In many cases, the water directly freezes on the low-temperature road surface, inducing traffic accidents for other vehicles; 3. Since the volume of the water tank is limited, the water in the water tank will be exhausted after the vehicle travels a certain distance. If it is not discovered in time, or it is not convenient to replenish water in time, it is easy for the brake drum to lose its braking ability due to high temperature, which greatly threatens driving safety. Summary of the invention

[0003] The purpose of the present invention is to provide a drum brake that is not easy to overheat, has good heat dissipation effect, is safe to use, and has good water-saving effect. In order to achieve the above technical purpose, the technical solution adopted by the present invention is as follows: a drum brake that is not easy to overheat, including a brake drum that rotates with the wheel, a cover plate fixed on the frame and installed with brake shoes, and a water tank installed on the vehicle body, the brake drum is cylindrical, an axial hole is opened at the center of the brake drum end plate, and a heat-resistant rubber bag for accommodating cooling water is provided on the outer surface of the side wall of the brake drum. The heat-resistant rubber bag is in the shape of an annular groove, and the edge of the heat-resistant rubber bag is sealed and connected to the side wall of the brake drum through a clamp, and the central axis of the heat-resistant rubber bag overlaps with the rotation center of the brake drum. At least two symmetrical water pipes are provided on the end plate of the brake drum, one end of the water pipe is connected to the inner cavity of the heat-resistant rubber bag, the other end of at least one water pipe is connected to the water inlet pipe, and the other end of the remaining water pipe is connected to the water outlet pipe. The wheel shaft position is provided with a The water inlet pipe and the water outlet pipe are respectively connected in series to the inner and outer pipelines of the casing, the other end of the water inlet pipe is connected to the water outlet of the water tank, and the other end of the water outlet pipe is communicated with the water tank, and the water inlet pipe and the water outlet pipe are both connected in series with a one-way valve; a slide groove is arranged on the cover plate, and a slider with a roller shaft is installed on the slide groove, and a roller for extruding a heat-resistant rubber bag is installed on the roller shaft, and the roller is an eccentric wheel, and a reset spring is arranged between the slider and the slide groove to keep the roller away from the heat-resistant rubber bag under normal conditions, and the slider is connected to the two-way memory alloy pull rod on the brake shoe through a pull wire, one end of the two-way memory alloy pull rod is connected to the metal support on the back of the brake shoe, and the other end is connected to the pull wire, the two-way memory alloy pull rod is straightened when it is lower than 250℃, and is bent when it is higher than 250℃ and drives the pull wire to overcome the restoring force of the reset spring.

[0004] As a preferred embodiment, a partition is provided in the inner cavity of the water tank, the partition divides the water tank into a water inlet tank and a water outlet tank, and a partition hole connecting the water inlet tank and the water outlet tank is provided on the plate body of the partition; the water inlet pipe is connected to the water outlet tank, and the water outlet pipe is connected to the water inlet tank.

[0005] As a preferred solution, the water inlet tank is located on the windward side of the water tank, and heat dissipation fins are provided on the outer wall of the water inlet tank.

[0006] As a preferred solution, the connection position between the water inlet pipe and the water outlet tank is located at the lower end of the outer wall of the water storage tank, and the connection position between the water outlet pipe and the water inlet tank is located at the upper end of the outer wall of the water inlet tank.

[0007] As a preferred solution, the partition hole is located at the bottom of the partition.

[0008] As a preferred solution, the surface of the roller is coated with an anti-slip plastic layer.

[0009] As a preferred solution, the total distance the slider moves when the brake shoe swings and when the bidirectional memory alloy pull rod is bent is S1, the difference between the minimum distance between the center axis of the roller and the outer edge of the heat-resistant rubber bag under normal conditions and the distance between the short axis of the roller is S2, the difference between the minimum distance between the center axis of the roller and the outer edge of the brake drum inside the heat-resistant rubber bag under normal conditions and the distance between the long axis of the roller is S3, and the distance the slider moves when the bidirectional memory alloy pull rod is bent is S4, and the above distances satisfy the following conditions: S4 is greater than S2, and S1 is less than S3.

[0010] The advantages of the present invention due to the above design are: when a heavy-duty transport vehicle brakes while driving, the brake shoe rubs against the brake drum, converting the vehicle's kinetic energy into heat energy, a portion of the heat is transferred to the air through the brake drum, and more heat is transferred to the water in the heat-resistant rubber bag through the outer wall of the brake drum, thereby reducing the temperature of the brake drum. In addition, during the braking process, the brake shoe heats up and transfers the heat to the two-way memory alloy pull rod through the metal support on the back. The two-way memory alloy pull rod bends when it is higher than 250°C, driving the pull wire to overcome the restoring force of the reset spring, so that the slider drives the roller to move and squeeze the heat-resistant rubber bag, thereby causing the eccentric wheel to continuously squeeze and change the volume of the heat-resistant rubber bag. With the cooperation of the water inlet pipe and the water outlet pipe both of which are provided with one-way valves, the discharge of hot water and the supply of cold water in the heat-resistant rubber bag are realized, thereby ensuring that the water in the heat-resistant rubber bag can continuously cool the brake drum and avoid overheating of the drum brake.

[0011] In addition, after the hot water in the water outlet pipe flows back to the water inlet tank, the water inlet tank is located on the windward side of the water tank, and heat dissipation fins are provided on the outer wall of the water inlet tank, so the heat can be dissipated faster, and then re-enter the water outlet tank and the water inlet pipe, and be re-supplied to the heat-resistant rubber bag. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings; Figure 1 It is a structural schematic diagram of the drum brake of the present invention; Figure 2 It is another structural schematic diagram of the drum brake of the present invention; Figure 3 It is a structural schematic diagram of the drum brake of the present invention without the end plate; Figure 4 Another structural schematic diagram of the drum brake of the present invention without the end plate; Figure 5 It is a schematic diagram of the main structure of the drum brake of the present invention; Figure 6 It is a schematic diagram of the main structure of the drum brake of the present invention; Figure 7 It is a schematic structural diagram of a water inlet box and a water outlet box of the present invention.

[0013] The symbols of the main components are explained as follows: 1 brake drum; 3 shaft hole; 4 heat-resistant rubber bag; 5 water pipe; 6 water inlet pipe; 7 water outlet pipe; 9 one-way valve; 10 slide groove; 11 slider; 12 roller; 13 partition; 14 water inlet tank; 15 water outlet tank; 16 partition hole; 17 cooling ribs. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0015] Embodiment 1 A drum brake that is not prone to overheating, comprising a brake drum 1 that rotates with the wheel, a cover plate fixed to the frame and mounted with brake shoes, and a water tank 2 mounted on the vehicle body, the brake drum 1 is cylindrical, an axial hole 3 is opened at the center of the end plate of the brake drum 1, a heat-resistant rubber bag 4 for containing cooling water is arranged on the outer surface of the side wall of the brake drum 1, the heat-resistant rubber bag is in the shape of an annular groove, the edge of the heat-resistant rubber bag 4 is sealed and connected to the side wall of the brake drum 1 through a clamp, the central axis of the heat-resistant rubber bag 4 overlaps with the rotation center of the brake drum, at least two symmetrical water pipes 5 are arranged on the end plate of the brake drum, two of which are selected here, one end of the water pipe is connected to the inner cavity of the heat-resistant rubber bag, the other end of the other water pipe is connected to the water inlet pipe 6, and the other end of the remaining water pipe is connected to the water outlet pipe 7, a sleeve is arranged at the wheel shaft position, the water inlet pipe 6, The water outlet pipe 7 is respectively connected in series to the inner and outer pipelines of the sleeve, the other end of the water inlet pipe 6 is connected to the water outlet of the water tank 2, and the other end of the water outlet pipe 7 is communicated with the water tank 2. A one-way valve 9 is connected in series to both the water inlet pipe 6 and the water outlet pipe 7; a slide groove 10 is provided on the cover plate, and a slider 11 with a roller shaft installed on the slide groove 10, and a roller 12 for extruding a heat-resistant rubber bag is installed on the roller shaft, and the roller 12 is an eccentric wheel. A reset spring is provided between the slider 11 and the slide groove 10 to keep the roller away from the heat-resistant rubber bag 4 under normal conditions, and the slider is connected to the two-way memory alloy pull rod on the brake shoe through a pull wire, one end of the two-way memory alloy pull rod is connected to the metal support on the back of the brake shoe, and the other end is connected to the pull wire, the two-way memory alloy pull rod is straightened when it is lower than 250°C, and bends when it is higher than 250°C and drives the pull wire to overcome the restoring force of the reset spring.

[0016] Embodiment 2 According to the attached Figure 1 -Attached Figure 7As shown, a drum brake that is not prone to overheating includes a brake drum 1 that rotates with the wheel, a cover plate fixed on the frame and equipped with brake shoes, and a water tank 2 installed on the vehicle body. The brake drum 1 is cylindrical, and an axial hole 3 is opened at the center of the end plate of the brake drum 1. The outer surface of the side wall of the brake drum 1 is provided with a heat-resistant rubber bag 4 for containing cooling water. The heat-resistant rubber bag is in the shape of an annular groove, and the edge of the heat-resistant rubber bag 4 is sealed and connected to the side wall of the brake drum 1 through a hoop. The central axis of the heat-resistant rubber bag 4 overlaps with the rotation center of the brake drum. At least two symmetrical water pipes 5 are provided on the end plate of the brake drum, one end of the water pipe is connected to the inner cavity of the heat-resistant rubber bag, the other end of at least one water pipe is connected to a water inlet pipe 6, and the other end of the remaining water pipe is connected to a water outlet pipe 7. A sleeve is provided at the wheel shaft position. The water inlet pipe 6 and the water outlet pipe 7 are respectively connected in series on the inner and outer pipelines of the sleeve, the other end of the water inlet pipe 6 is connected to the water outlet of the water tank 2, and the other end of the water outlet pipe 7 is connected to the water tank 2. A one-way valve 9 is connected in series on both the water inlet pipe 6 and the water outlet pipe 7; a slide groove 10 is arranged on the cover plate, and a slider 11 with a roller shaft installed on the slide groove is provided, and a roller 12 for extruding a heat-resistant rubber bag is installed on the roller shaft, and the roller 12 is an eccentric wheel. A reset spring is arranged between the slider 11 and the slide groove 10 to keep the roller away from the heat-resistant rubber bag 4 under normal conditions, and the slider is connected to the two-way memory alloy pull rod on the brake shoe through a pull wire, one end of the two-way memory alloy pull rod is connected to the metal support on the back of the brake shoe, and the other end is connected to the pull wire, and the two-way memory alloy pull rod is straightened when it is lower than 250℃, and is bent when it is higher than 250℃ and drives the pull wire to overcome the restoring force of the reset spring.

[0017] A partition 13 is provided in the inner cavity of the water tank 2, and the partition 13 divides the water tank 2 into an inlet tank 14 and an outlet tank 15, and a partition hole 16 is provided on the plate body of the partition 13 to connect the inlet tank 14 and the outlet tank 15; the inlet pipe 6 is connected to the outlet tank 15, and the outlet pipe 7 is connected to the inlet tank 14. The inlet tank 14 is located on the windward side of the water tank 2, and a heat dissipation rib 17 is provided on the outer wall of the inlet tank 14. The connection position of the inlet pipe 6 and the outlet tank 15 is located at the lower end of the outer wall of the water storage tank 15, and the connection position of the outlet pipe 7 and the inlet tank 14 is located at the upper end of the outer wall of the inlet tank 14. The partition hole 16 is located at the bottom of the partition 13.

[0018] The difference between Example 2 and Example 1 is that the water tank provided in Example 1 is used for circulating water in the water inlet pipe and the water outlet pipe to cool the brake drum, while in Example 2, a partition is provided in the water tank and a partition hole is provided at the lower end of the partition to separate the partition into a water inlet tank and a water outlet tank, and heat dissipation ribs are provided on the outer wall of the water inlet tank, so that the high-temperature hot water that has just cooled the brake is first dissipated through the heat dissipation ribs during or after entering the water inlet tank, and then enters the water outlet tank through the partition hole, and then circulates into the heat-resistant rubber bag to cool the brake. The water inlet tank is arranged on the windward side, which is also conducive to the heat dissipation of the water inlet tank. The heat dissipation and cooling effect of Example 2 is better.

[0019] Embodiment 3 A drum brake that is not prone to overheating, comprising a brake drum 1 that rotates with the wheel, a cover plate fixed to the frame and mounted with brake shoes, and a water tank 2 mounted on the vehicle body, the brake drum 1 is cylindrical, an axial hole 3 is opened at the center of the end plate of the brake drum 1, a heat-resistant rubber bag 4 for containing cooling water is arranged on the outer surface of the side wall of the brake drum 1, the heat-resistant rubber bag is in the shape of an annular groove, the edge of the heat-resistant rubber bag 4 is sealed and connected to the side wall of the brake drum 1 through a clamp, the central axis of the heat-resistant rubber bag 4 overlaps with the rotation center of the brake drum, at least two symmetrical water pipes 5 are arranged on the end plate of the brake drum, one end of the water pipe is connected to the inner cavity of the heat-resistant rubber bag 4, the other end of at least one water pipe is connected to the water inlet pipe 6, and the other end of the remaining water pipe is connected to the water outlet pipe 7, a sleeve is arranged at the wheel shaft position, the water inlet pipe 6 and the water outlet pipe 7 are respectively connected in series on the inner and outer pipelines of the sleeve, the other end of the water inlet pipe 6 is connected to the water outlet of the water tank 2, and the other end of the water outlet pipe 7 is connected to the water tank 2. Both the water inlet pipe 6 and the water outlet pipe 7 are connected in series with a one-way valve 9; a slide groove 10 is arranged on the cover plate, and a slider 11 with a roller shaft installed on the slide groove is provided, and a roller 12 for extruding a heat-resistant rubber bag is installed on the roller shaft. The roller 12 is an eccentric wheel, and a reset spring is arranged between the slider 11 and the slide groove 10 to keep the roller away from the heat-resistant rubber bag 4 under normal conditions. The slider 11 is connected to the two-way memory alloy pull rod on the brake shoe through a pull wire, one end of the two-way memory alloy pull rod is connected to the metal support on the back of the brake shoe, and the other end is connected to the pull wire. The two-way memory alloy pull rod is straightened when it is lower than 250℃, and is bent when it is higher than 250℃ and drives the pull wire to overcome the restoring force of the reset spring.

[0020] A further technical solution is that a partition 13 is provided in the inner cavity of the water tank 2, the partition 13 divides the water tank 2 into a water inlet box 14 and a water outlet box 15, and a partition hole 16 is provided on the plate body of the partition 13 for connecting the water inlet box 14 and the water outlet box 15; the water inlet pipe 6 is connected to the water outlet box 15, and the water outlet pipe 7 is connected to the water inlet box 14.

[0021] A further technical solution is that the water inlet box 14 is located on the windward side of the water tank 2 , and heat dissipation ribs 17 are provided on the outer wall of the water inlet box 14 .

[0022] A further technical solution is that the connection position between the water inlet pipe 6 and the water outlet box 15 is located at the lower end of the outer wall of the water storage tank 15, and the connection position between the water outlet pipe 7 and the water inlet box 14 is located at the upper end of the outer wall of the water inlet box 14.

[0023] A further technical solution is that the partition hole 16 is located at the bottom of the partition 13 .

[0024] A further technical solution is that the surface of the roller 12 is coated with an anti-slip plastic layer.

[0025] A further technical solution is that the total distance the slider moves when the brake shoe swings and when the bidirectional memory alloy pull rod is bent is S1, the difference between the minimum distance between the center axis of the roller and the outer edge of the heat-resistant rubber bag under normal conditions and the distance between the short axis of the roller is S2, the difference between the minimum distance between the center axis of the roller and the outer edge of the brake drum inside the heat-resistant rubber bag under normal conditions and the distance between the long axis of the roller is S3, and the distance the slider moves when the bidirectional memory alloy pull rod is bent is S4, and the above distances satisfy the following conditions: S4 is greater than S2, and S1 is less than S3.

[0026] A further technical solution is that a branch pipe with a pressure relief valve is also provided on the outer pipeline of the sleeve.

[0027] The difference between Example 3 and Example 1 or Example 2 is that the roller in Example 2 is not coated with an anti-slip plastic layer, and the roller is in contact with the surface of the heat-resistant rubber bag 4 under normal conditions. The advantage of Example 3 is that the roller is set to be separated from the heat-resistant rubber bag 4 under normal conditions, and the bidirectional memory alloy pull rod is bent when it is higher than 250°C and drives the roller on the slider to squeeze the heat-resistant rubber bag 4 through the pull wire. When it is lower than 250°C, the bidirectional memory alloy pull rod is straightened. At this time, the roller is separated from the heat-resistant rubber bag, and a plastic layer is coated on the surface of the roller, which increases the surface friction. When the roller squeezes the heat-resistant rubber bag, the friction is increased, and the extrusion effect is good. In addition, when it is separated from the heat-resistant rubber bag under normal conditions, the heat in the heat-resistant rubber bag will not be transferred to the roller, thereby avoiding the roller from contacting the high-temperature heat-resistant rubber bag for a long time, thereby extending the service life.

[0028] The drum brake that is not prone to overheating designed by the present invention works as follows: when the transport vehicle brakes, the brake shoe rubs against the brake drum, and the heat is transferred to the water in the heat-resistant rubber bag through the outer wall of the brake drum, thereby reducing the temperature of the brake drum. In addition, during the braking process, the brake shoe heats up and transfers the heat to the two-way memory alloy pull rod through the metal support on the back. The two-way memory alloy pull rod bends when it is higher than 250°C, driving the pull wire to overcome the restoring force of the reset spring, so that the slider drives the roller to move and squeeze the heat-resistant rubber bag, thereby causing the eccentric wheel to continuously squeeze and change the volume of the heat-resistant rubber bag. Under the action of the gravity of the water tank and the cooperation of the water inlet pipe and the water outlet pipe both of which are provided with one-way valves, the discharge of hot water and the supply of cold water in the heat-resistant rubber bag are realized, thereby ensuring that the water in the heat-resistant rubber bag can continuously cool the brake drum and avoid overheating of the drum brake.

[0029] In addition, after the hot water in the water outlet pipe flows back to the water inlet tank, the water inlet tank is located on the windward side of the water tank, and heat dissipation fins are provided on the outer wall of the water inlet tank, so the heat can be dissipated faster, and then re-enter the water outlet tank and the water inlet pipe, and be re-supplied to the heat-resistant rubber bag.

[0030] The above is a detailed introduction to the drum brake that is not prone to overheating provided by the present invention. The description of the specific embodiment is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A drum brake which is not prone to overheating, comprising a brake drum (1) which rotates with the wheel, a cover plate which is fixed to the frame and on which the brake shoe is mounted, and a water tank (2) which is mounted on the vehicle body, wherein the brake drum (1) is cylindrical, and an axial hole (3) is provided at the center of the end plate of the brake drum (1), and the characteristics are as follows: The outer surface of the side wall of the brake drum (1) is provided with a heat-resistant rubber bag (4) for containing cooling water. The heat-resistant rubber bag (4) is in the shape of an annular groove. The edge of the heat-resistant rubber bag (4) is sealed and connected to the side wall of the brake drum (1) via a clamp. The central axis of the heat-resistant rubber bag (4) overlaps with the rotation center of the brake drum. At least two symmetrical water pipes (5) are provided on the end plate of the brake drum. One end of the water pipe is connected to the inner cavity of the heat-resistant rubber bag. The other end of at least one water pipe is connected to the water inlet pipe (6). The remaining water pipes are connected to the inner cavity of the heat-resistant rubber bag. The other end of the pipe is connected to a water outlet pipe (7); a sleeve is provided at the wheel shaft position; the water inlet pipe (6) and the water outlet pipe (7) are respectively connected in series to the inner and outer pipes of the sleeve; the other end of the water inlet pipe (6) is connected to the water outlet of the water tank (2); the other end of the water outlet pipe (7) is communicated with the water tank (2); and a one-way valve (9) is connected in series to the water inlet pipe (6) and the water outlet pipe (7); a slide groove (10) is provided on the cover plate; and a slider (11) on which the roller shaft is installed is provided on the slide groove. A roller (12) for extruding a heat-resistant rubber bag is mounted on the roller shaft, the roller (12) being an eccentric wheel, a return spring is arranged between the slider (11) and the slide groove (10) to keep the roller away from the heat-resistant rubber bag (4) in a normal state, the slider is connected to a bidirectional memory alloy pull rod on the brake shoe via a pull wire, one end of the bidirectional memory alloy pull rod is connected to a metal support on the back of the brake shoe, and the other end is connected to the pull wire, the bidirectional memory alloy pull rod is straightened when the temperature is below 250°C, and is bent and drives the pull rod to move when the temperature is above 250°C. The wire overcomes the restoring force of the return spring. During the braking process, the brake shoe heats up and transfers the heat to the two-way memory alloy pull rod through the metal support on the back. The two-way memory alloy pull rod bends when the temperature is higher than 250°C, driving the wire to overcome the restoring force of the return spring, so that the slider drives the roller to move and squeeze the heat-resistant rubber bag, so that the eccentric wheel continuously squeezes and changes the volume of the heat-resistant rubber bag. With the cooperation of the water inlet pipe and the water outlet pipe both of which are provided with one-way valves, the discharge of hot water and the supply of cold water in the heat-resistant rubber bag are realized; A partition (13) is provided in the inner cavity of the water tank (2), the partition dividing the water tank into a water inlet tank (14) and a water outlet tank (15), and a partition hole (16) for connecting the water inlet tank (14) and the water outlet tank (15) is provided on the plate body of the partition; the water inlet pipe (6) is connected to the water outlet tank (15), and the water outlet pipe (7) is connected to the water inlet tank (14); the water inlet tank (14) is located on the windward side of the water tank, and heat dissipation fins (17) are provided on the outer wall of the water inlet tank (14); The total distance that the slider moves when the brake shoe swings and when the two-way memory alloy pull rod is bent is S1, the difference between the minimum distance between the center axis of the roller and the outer edge of the heat-resistant rubber bag and the distance between the short axis of the roller under normal conditions is S2, the difference between the minimum distance between the center axis of the roller and the outer edge of the brake drum inside the heat-resistant rubber bag and the distance between the long axis of the roller under normal conditions is S3, and the distance that the slider moves when the two-way memory alloy pull rod is bent is S4, and the above distances satisfy the following conditions: S4 is greater than S2, and S1 is less than S3.

2. The drum brake that is not prone to overheating according to claim 1, characterized in that: The connection position between the water inlet pipe (6) and the water outlet box (15) is located at the lower end of the outer wall of the water outlet box (15), and the connection position between the water outlet pipe (7) and the water inlet box (14) is located at the upper end of the outer wall of the water inlet box (14).

3. The drum brake that is not prone to overheating according to claim 1, characterized in that: The partition hole (16) is located at the bottom of the partition (13).

4. The drum brake that is not prone to overheating according to claim 1, characterized in that: The surface of the roller is coated with an anti-skid plastic layer.

5. The drum brake that is not prone to overheating according to claim 1, characterized in that: A branch pipe with a pressure relief valve is also arranged on the outer pipeline of the sleeve.

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