Braking system of coal mining machine

Abstract

The utility model provides a coal mining machine braking system which comprises a coal mining machine brake, a proximity switch and an isolation type safety barrier when an external programmable logic controller is provided with direct current. Wherein direct current on the external programmable logic controller is connected with the power supply end of the proximity switch through the isolation type safety barrier, and the signal output end of the proximity switch is connected to the external programmable logic controller. When the external programmable logic controller does not have direct current, the coal mining machine braking system comprises a coal mining machine brake, a proximity switch and an AC / DC converter. Wherein the AC side end of the AC / DC converter is connected with an external 110V AC power supply, the DC side of the AC / DC converter is connected with the power supply end of the proximity switch, and the output end of the proximity switch is connected with an external programmable logic controller. The braking system of the coal mining machine has the advantages that the anti-explosion function is achieved, the brake and the walking motor of the coal mining machine can be interlocked, damage to the brake and a transmission system of the coal mining machine is reduced, and the braking system can be widely applied to the field of mining.

Description

Technical Field

[0001] This utility model relates to braking technology, and in particular to a braking system for a coal mining machine. Background Technology

[0002] Chinese utility model patent number "ZL 202020974680.8" and invention title "A Hydraulic Multi-Disc Disc Brake with a Front Cover" discloses a front cover and a hydraulic multi-disc disc brake. The front cover is added to one side of the hydraulic multi-disc disc brake connected to the outer shaft. Correspondingly, the side of the hydraulic multi-disc disc brake away from the outer shaft serves as the rear end side of the hydraulic multi-disc disc brake with the front cover. This utility model solves problems such as complex installation, unreliable connection, inconvenient operation, and poor braking effect.

[0003] In practical applications, to meet the safety braking requirements of mechanical equipment, according to the operating specifications of coal mining machines, a parking brake must be installed when the inclination angle of the mining face is ≥15° to prevent the coal mining machine from slipping when stopped. The movement of the coal mining machine is achieved by the rotation of two travel motors within the traveling mechanism. Two brakes are installed at the end of the transmission system. When the operator issues a stop command through the coal mining machine's PLC, the hydraulic system pressure is zero, the brakes close, and the travel motors are de-energized. When the operator issues a start command through the coal mining machine's PLC, the hydraulic system pressure rises to the specified value, the brakes open, and the travel motors are energized. When the inclination angle of the mining face reaches 30° or more, the timing coordination between the energization of the travel motors and the opening of the brakes relies heavily on experience. Especially when the brakes are damaged and cannot open normally, the travel motors drag the unopened brakes, causing minor damage such as burnt-out brake friction pairs, or even severe damage to components of the traveling mechanism's traditional system. Therefore, developing a system that interlocks a hydraulic disc brake with a travel motor is an urgent problem that relevant technical personnel need to solve.

[0004] Therefore, it is evident that there is currently no coal mining machine brake with a proximity switch in the existing technology. Summary of the Invention

[0005] In view of this, the main objective of this utility model is to provide a coal mining machine braking system that interlocks the brake with the coal mining machine's traveling motor, thereby reducing damage to the brake and the coal mining machine.

[0006] To achieve the above objectives, the first technical solution proposed by this utility model is as follows:

[0007] A coal mining machine braking system, wherein, when an external programmable logic controller (PLC) is powered by 12V DC, the braking system includes: a coal mining machine brake (I) for controlling the braking or operation of the coal mining machine; a proximity switch (II) for sending a braking control signal generated when the internal mechanism of the coal mining machine brake (I) approaches a proximity switch (II) to the external PLC; and an isolated safety barrier (III) for transmitting the 12V DC power from the external PLC to the proximity switch (II); wherein,

[0008] The positive and negative terminals of the 12V DC power supply on the external programmable logic controller are connected to the positive and negative terminals of the power supply of the proximity switch (II) through the isolation safety barrier (III). The signal output terminal of the proximity switch (II) is connected to one input terminal of the external programmable logic controller.

[0009] In summary, in the coal mining machine braking system described in this utility model, when the coal mining machine is operating normally, the external programmable logic controller (PLC) controls the external hydraulic system of the coal mining machine brake to increase the hydraulic pressure to a specified value, the coal mining machine brake is released, and the internal mechanism of the coal mining brake enters the detection range of the proximity switch. The proximity switch sends a high-level braking control signal (1) to the external logic controller, and the external PLC controls the travel motor to be energized. When the coal mining machine stops normally, the external PLC controls the external hydraulic system of the coal mining machine brake to decrease the hydraulic pressure to zero, the coal mining machine brake begins to brake, the internal mechanism of the coal mining brake leaves the detection range of the proximity switch, the proximity switch sends a low-level braking control signal (0) to the external logic controller, and the external PLC controls the travel motor to be de-energized. This is the normal operating condition. Under normal operating conditions, the external PLC normally controls the operation and stop of the travel motor through the braking control signal output by the proximity switch. If the external hydraulic system malfunctions, for example, if the external hydraulic system pressure decreases, the internal mechanism of the coal mining machine brake will not be able to be pushed and approach the proximity switch, nor will it be able to enter the detection range of the proximity switch. In this case, the braking control signal sent by the proximity switch will be a low-level (0). This is the second operating condition. The third operating condition is when the coal mining brake is damaged, for example, due to seal failure. This prevents the internal mechanism of the coal mining brake from entering the detection range of the proximity switch, and the braking control signal sent by the proximity switch is also low (0). In the second and third operating conditions, the external programmable controller, based on the received braking control signal (0), controls the travel motor to not be powered on. In other words, the travel motor cannot start moving, preventing further damage to the coal mining machine brake and transmission system. In particular, when the inclination angle of the mining face is ≥15° or even reaches 30° or more, the protective effect of the coal mining machine braking system described in this utility model is even more significant.

[0010] To achieve the above objectives, the second technical solution proposed by this utility model is as follows:

[0011] A coal mining machine braking system, wherein, when the external programmable logic controller (PLC) does not have 12V DC power, the braking system includes: a coal mining machine brake (I) for controlling the braking or operation of the coal mining machine; a proximity switch (II) for sending a braking control signal generated when the internal mechanism of the coal mining machine brake (I) approaches a proximity switch (II) to the external PLC; and an AC / DC converter (IV) for converting 110V AC power to 12V DC power and transmitting the 12V DC power to the proximity switch (II); wherein,

[0012] The AC side of the AC / DC converter (Ⅳ) is connected to an external 110V AC power supply. The positive and negative terminals of the DC side of the AC / DC converter (Ⅳ) are connected to the positive and negative input terminals of the proximity switch (Ⅱ). The signal output terminal of the proximity switch (Ⅱ) is connected to one input terminal of an external programmable logic controller.

[0013] In summary, in the coal mining machine braking system described in this utility model, when the coal mining machine is operating normally, the external programmable logic controller (PLC) controls the external hydraulic system of the coal mining machine brake to increase the hydraulic pressure to a specified value, the coal mining machine brake is released, and the internal mechanism of the coal mining brake enters the detection range of the proximity switch. The proximity switch sends a high-level braking control signal (1) to the external logic controller, and the external PLC controls the travel motor to be energized. When the coal mining machine stops normally, the external PLC controls the external hydraulic system of the coal mining machine brake to decrease the hydraulic pressure to zero, the coal mining machine brake begins to brake, the internal mechanism of the coal mining brake leaves the detection range of the proximity switch, the proximity switch sends a low-level braking control signal (0) to the external logic controller, and the external PLC controls the travel motor to be de-energized. This is the normal operating condition. Under normal operating conditions, the external PLC normally controls the operation and stop of the travel motor through the braking control signal sent by the proximity switch. If the external hydraulic system malfunctions, for example, if the external hydraulic system pressure decreases, the internal mechanism of the coal mining machine brake will not be able to be pushed and approach the proximity switch, nor will it be able to enter the detection range of the proximity switch. In this case, the braking control signal sent by the proximity switch will be a low-level (0). This is the second operating condition. The third operating condition is when the coal mining brake is damaged, for example, due to seal failure. This prevents the internal mechanism of the coal mining brake from entering the detection range of the proximity switch, and the braking control signal sent by the proximity switch is also low (0). In the second and third operating conditions, the external programmable controller, based on the received braking control signal (0), controls the travel motor to not be powered on. In other words, the travel motor cannot start moving, preventing further damage to the coal mining machine brake and transmission system. In particular, when the inclination angle of the mining face is ≥15° or even reaches 30° or more, the protective effect of the coal mining machine braking system described in this utility model is even more significant. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the first component structure of the braking system for a coal mining machine described in this utility model.

[0015] Figure 2 This is a schematic diagram of the second component structure of the braking system for a coal mining machine described in this utility model.

[0016] Figure 3 This is a schematic diagram of the composition and structure of the coal mining machine brake described in this utility model.

[0017] Figure 4 This is a schematic diagram of the composition and structure of the AC / DC converter described in this utility model. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Figure 1 This is a schematic diagram of the first possible structural components of a coal mining machine braking system according to this utility model. Figure 1 As shown, the coal mining machine braking system of this utility model, when the external programmable logic controller (PLC) has a 12V DC power supply, includes: a coal mining machine brake I for controlling the braking or operation of the coal mining machine; a proximity switch II for sending a braking control signal generated when the internal mechanism of the coal mining machine brake I approaches the proximity switch II to the external programmable logic controller; and an isolated safety barrier III for transmitting the 12V DC power from the external programmable logic controller to the proximity switch II; wherein,

[0020] The positive and negative terminals of the 12V DC power supply on the external programmable logic controller are connected to the positive and negative terminals of the power supply of the proximity switch II via the isolation safety barrier III. The signal output terminal of the proximity switch II is connected to one input terminal of the external programmable logic controller.

[0021] In this invention, the proximity switch II is an inductive normally open proximity switch with a detection distance of 0.1 mm to 3 mm. "Normally open" means that the internal contacts of the proximity switch are normally open: when an external metal object approaches the proximity switch II and enters its detection distance, the contact closes, and the braking control signal sent by the proximity switch II is high level 1; when the external metal object does not enter the detection distance of the proximity switch II, the contact opens, and the braking control signal sent by the proximity switch II is low level 0.

[0022] In practical applications, the braking control signal output by the proximity switch II is intrinsically safe. The braking control signal itself has weak electrical energy and will not cause some flammable and explosive components in the mine to ignite and explode due to the absorption of external energy (such as electrical energy). Therefore, the braking control signal output by the proximity switch II can be directly transmitted to an external programmable logic controller without having to be transmitted through the isolation safety barrier (III).

[0023] In this invention, the proximity switch II operates under a 12V DC power supply. In practical applications, the proximity switch II can also operate under a 24V DC power supply, and the voltage level can be determined according to actual needs.

[0024] In practical applications, a mining machine brake I is installed on the outer shaft or output shaft of each of the two traveling motors of the coal mining machine. The starting, running, and stopping of the two traveling motors are all controlled by an external programmable logic controller (PLC). The control of the two traveling motors by the external PLC is existing technology and will not be elaborated here.

[0025] In practical applications, the 12V DC power supplied by the external programmable logic controller (PLC) is not intrinsically safe. Therefore, the first technical solution of the coal mining machine braking system described in this utility model also employs an isolated safety barrier.

[0026] In summary, when the coal mining machine is operating normally, the external programmable logic controller (PLC) controls the external hydraulic system of the coal mining machine brake to increase the hydraulic pressure to a specified value. The coal mining machine brake is released, and the internal mechanism of the brake enters the detection range of the proximity switch. The proximity switch sends a high-level braking control signal (1) to the external logic controller, which then powers on the travel motor. When the coal mining machine stops normally, the PLC controls the external hydraulic system of the coal mining machine brake to decrease the hydraulic pressure to zero. The coal mining machine brake begins to brake, and the internal mechanism of the brake leaves the detection range of the proximity switch. The proximity switch sends a low-level braking control signal (0) to the external logic controller, which then de-energizes the travel motor. This is the normal operating condition. Under this normal condition, the external PLC controls the operation and stop of the travel motor normally through the braking control signal sent by the proximity switch. If the external hydraulic system malfunctions, for example, if the external hydraulic system pressure decreases, the internal mechanism of the coal mining machine brake may not be pushed close to the proximity switch or enter its detection range. In this case, the braking control signal sent by the proximity switch will be low (0). This is the second operating condition. The third operating condition is when the coal mining brake is damaged, for example, due to seal failure. This prevents the internal mechanism of the coal mining brake from entering the detection range of the proximity switch, and the braking control signal sent by the proximity switch is also low (0). In the second and third operating conditions, the external programmable controller, based on the received braking control signal (0), controls the travel motor to not be powered on. In other words, the travel motor cannot start moving, preventing further damage to the coal mining machine brake and transmission system. In particular, the protective effect of the coal mining machine braking system described in this invention is even more significant when the inclination angle of the mining face is ≥15° or even reaches 30° or more.

[0027] Figure 2 This is a schematic diagram of the second component structure of the braking system for a coal mining machine described in this utility model. (See diagram below.) Figure 2 As shown, the coal mining machine braking system of this utility model, when the external programmable logic controller does not have 12V DC power, includes: a coal mining machine brake I for controlling the braking or operation of the coal mining machine; a proximity switch II for sending a braking control signal generated when the internal mechanism of the coal mining machine brake I approaches the proximity switch II to the external programmable logic controller; and an AC / DC converter IV for converting 110V AC power to 12V DC power and transmitting the 12V DC power to the proximity switch II; wherein,

[0028] The AC side of AC / DC converter IV is connected to an external 110V AC power supply. The positive and negative terminals of the DC side of AC / DC converter IV are connected to the positive and negative terminals of the power supply of proximity switch II, respectively. The signal output terminal of proximity switch (II) is connected to an input terminal of an external programmable logic controller.

[0029] In practical applications, the 110V AC power supply on the AC side of AC / DC converter IV is a non-safe power supply, while the 12V DC power supply on the DC side of AC / DC converter IV is an intrinsically safe power supply.

[0030] In this utility model, the coal mining machine brake I includes: a screw 1, a front end cover 2, a housing 3, a first combined sealing ring 4, a cylinder liner 5, a piston 6, a second combined sealing ring 7, a rear end cover 8, a plug 10, two sets of disc springs 11, a dust cover 12, a pressure plate 13, eight outer friction plates 14, and seven inner friction plates 15; wherein, the front end cover 2, the housing 3, the cylinder liner 5, and the rear end cover 8 form a housing, and at one radial edge of the housing, the screw 1 is used to fix the rear end cover 8, the cylinder liner 5, the housing 3, and the front end cover 2 in sequence; the seven inner friction plates 15, the eight outer friction plates 14, and the two sets of disc springs 11 are all annular;

[0031] The outer shell 3 is cylindrical in shape, the cylinder liner 5 is a barrel-shaped structure with a through hole at the bottom, and the piston 6 is installed inside the cylinder liner 5. The rear end cover 8 is fixedly installed on the outside of the cylinder liner 5 and the piston 6. The radius of the through hole at the bottom of the cylinder liner 5 is larger than the radius of the first slot hole.

[0032] Inside the outer casing 3, eight outer friction plates 14 and seven inner friction plates 15 are installed alternately and fixed to the inner wall of the outer casing 3 by splines. A pressure plate 13 is also installed between the last outer friction plate 14 and the bottom of the piston 6 and cylinder liner 5. The pressure plate 13 also has a through hole at its center, and the radius of the through hole of the pressure plate 13 is the same as the radius of the first slot.

[0033] An oil hole is also provided at the bottom of the cylinder liner 5, perpendicular to the direction of the cylinder liner 5. In practical applications, an oil plug is installed in the oil hole, and a dust cover 12 is installed on the outer end of the oil plug.

[0034] A front cover 2 is affixed to the side of the coal mining machine brake I connected to the outer shaft, and a first through hole is provided at the center of the front cover 2; a first slot is provided at the center of the piston 6 near the side end of the front cover 2, and the inner diameter of the first slot, the inner diameter of the inner friction plate 15, the inner diameter of the eight outer friction plates 14, and the inner diameter of the first through hole are all the same; a rear cover 8 is installed on the side of the coal mining machine brake I away from the outer shaft, and a second through hole is provided at the center of the rear cover 8, and a second slot is provided at the center of the piston 6 near the rear cover 8, and the first slot and the second slot are connected by a third through hole; a plug 10 is also installed at the bottom of the second slot and on the outside of the third through hole.

[0035] On the piston 6, and on the outside of the second slot, a first annular groove is provided; on the rear end cover 8, and on the inside of the rear end cover 8 and on the outside of the second through hole, a second annular groove with an annular boss inside is provided. The annular boss portion of the second annular groove corresponds to the first annular groove on the piston 6. The annular boss portion of the second annular groove and the first annular groove together form a cavity for installing two sets of disc springs 11; the piston body portion between the first annular groove and the second slot corresponds to the inner ring portion of the second annular groove of the rear end cover 8 except for the annular boss portion.

[0036] In practical applications, the inner diameter of the disc spring 11 is the same as the radius of the cylindrical protrusion at the center of the first ring groove, and the radius of the second slot is smaller than the radius of the cylindrical protrusion at the center of the first ring groove.

[0037] In practical applications, a first combination sealing ring 4 is installed in the gap between the bottom through hole side of the cylinder liner 5 and the piston 6, and a second combination sealing ring 7 is installed in the gap between the inner wall side of the middle part of the cylinder liner 5 and the piston 6.

[0038] In actual operation, the outer shaft or output shaft of the coal mining machine's traveling motor passes sequentially through the first through hole, the inner friction plate 15, and the outer friction plate 14, and extends into the first slot. One end of the proximity switch II passes sequentially through the second through hole and the second slot, and extends into the third through hole. The other end of the proximity switch II is a wire end, including three wires: two of the wires are connected to the positive and negative terminals of the DC power supply respectively through the isolation safety barrier III; the third wire serves as a braking control signal line and is connected to an input terminal of an external logic controller through the isolation safety barrier III.

[0039] In the two technical solutions of the above-mentioned coal mining machine braking control system, the internal mechanism of the coal mining machine brake I is close to the proximity switch II, specifically: the piston 6 of the coal mining machine brake I is close to the proximity switch II.

[0040] In practical applications, if the coal mining brake is damaged without a proximity switch installed, it needs to be manually released. In this case, by opening the rear cover 8, the outer friction plate can be manually separated from the inner friction plate through the third through-hole, thus releasing the coal mining brake. Even with a proximity switch installed, the coal mining brake will not show signs of damage, but the third through-hole still serves as a maintenance access point for the coal mining brake in special circumstances.

[0041] In summary, when the coal mining brake described in this utility model is working normally, under the action of the external programmable logic controller (PLC), when the hydraulic pressure of the external hydraulic system rises to the set hydraulic pressure, hydraulic oil enters the cylinder liner of the coal mining machine brake through the oil hole. The hydraulic oil pushes the piston backward, thereby compressing the disc spring and causing the outer and inner friction plates to separate. The coal mining machine brake then releases from the outer shaft of the travel motor. Simultaneously, the external PLC controls the travel motor to be energized, and the coal mining machine begins to move. Conversely, under the action of the external programmable logic controller (PLC), when the hydraulic pressure of the external hydraulic system drops to 0, the hydraulic oil in the cylinder liner returns to the external hydraulic system through the oil hole. The compressed disc spring is released, and the elastic force generated when the disc spring is released pushes the piston forward, thereby pressing the pressure plate. The pressure plate then presses the outer and inner friction plates together, and the friction force generated between the outer and inner friction plates brakes the outer shaft of the travel motor. Simultaneously, the external PLC controls the travel motor to be de-energized, and the coal mining machine cannot move due to being braked.

[0042] In this invention, the control of the hydraulic system by the external programmable logic controller is also existing technology, and will not be described in detail here.

[0043] In this invention, the AC / DC converter IV includes: a transformer T for stepping down 110V AC voltage to 12V AC; a bridge circuit for converting 12V AC to 12V DC; an RC filter for filtering the 12V DC output from the bridge circuit; and a Zener diode Dz for regulating the voltage output from the RC filter; wherein,

[0044] The bridge circuit consists of a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The anode of the first diode D1 is connected to the anode of the third diode D3, the cathode of the first diode D1 is connected to the anode of the second diode D2, the cathode of the third diode D3 is connected to the anode of the fourth diode D4, and the cathode of the second diode D2 is connected to the cathode of the fourth diode D4.

[0045] The connection terminals of the cathode of diode D1 and the anode of diode D2, and the connection terminals of the cathode of diode D3 and the anode of diode D4 are respectively connected to the two ends of the secondary side of transformer T. The connection terminal of the anode of diode D1 and the anode of diode D3 is connected to the second terminal of capacitor C in RC filter. The connection terminal of the cathode of diode D2 and the cathode of diode D4 is connected to the first terminal of capacitor C in RC filter. The first terminal of capacitor C is connected to one end of resistor R in RC filter. The other end of resistor R is connected to the cathode of Zener diode Dz. The anode of Zener diode Dz is connected to the second terminal of capacitor C.

[0046] In practical applications, transformer T, besides its voltage reduction function, also provides a certain degree of electromagnetic isolation. The stepped-down AC power then passes through a bridge circuit composed of four diodes for AC-to-DC conversion and RC filtering. In other words, the bridge circuit and RC filter also provide some electromagnetic isolation. This ensures that the DC power output from AC / DC converter IV is insufficient to cause an explosion in the mine; therefore, the DC power output from AC / DC converter IV is intrinsically safe. The 110V AC power supply, however, is for external use and is not required to be intrinsically safe; therefore, the 110V AC power supply is not intrinsically safe.

[0047] In summary, the above are merely preferred embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A shearer braking system, in the case of an external programmable logic controller with 12V DC, characterized in that, The braking system includes: a coal mining machine brake (I) for controlling the braking or operation of the coal mining machine; a proximity switch (II) for sending a braking control signal generated when the internal mechanism of the coal mining machine brake (I) approaches a proximity switch (II) to an external programmable logic controller; and an isolated safety barrier (III) for transmitting 12V DC power from the external programmable logic controller to the proximity switch (II); wherein, The positive and negative terminals of the 12V DC power supply on the external programmable logic controller are connected to the positive and negative terminals of the power supply of the proximity switch (II) through the isolation safety barrier (III). The signal output terminal of the proximity switch (II) is connected to one input terminal of the external programmable logic controller.

2. A shearer braking system, in the absence of a 12V DC supply to the external programmable logic controller, characterised in that, The braking system includes: a coal mining machine brake (I) for controlling the braking or operation of the coal mining machine; a proximity switch (II) for sending a braking control signal generated when the internal mechanism of the coal mining machine brake (I) approaches a proximity switch (II) to an external programmable logic controller; and an AC / DC converter (IV) for converting 110V AC power to 12V DC power and transmitting the 12V DC power to the proximity switch (II); wherein, The AC side of the AC / DC converter (Ⅳ) is connected to an external 110V AC power supply. The positive and negative terminals of the DC side of the AC / DC converter (Ⅳ) are connected to the positive and negative input terminals of the proximity switch (Ⅱ). The signal output terminal of the proximity switch (Ⅱ) is connected to one input terminal of an external programmable logic controller.

3. A shearer braking system according to claim 1 or 2 wherein, The coal mining machine brake (Ⅰ) includes: screw (1), front end cover (2), outer shell (3), first combined sealing ring (4), cylinder liner (5), piston (6), second combined sealing ring (7), rear end cover (8), plug (10), 2 sets of disc springs (11), dust cover (12), pressure plate (13), 8 outer friction plates (14), and 7 inner friction plates (15); wherein, the front end cover (2), outer shell (3), cylinder liner (5), and rear end cover (8) form a shell, and at the radial edge of the shell, the screw (1) is used to fix the rear end cover (8), cylinder liner (5), outer shell (3), and front end cover (2) in sequence; the 7 inner friction plates (15), 8 outer friction plates (14), and 2 sets of disc springs (11) are all annular; The outer shell (3) is cylindrical in shape, the cylinder liner (5) is a barrel-shaped structure with a through hole at the bottom, and the piston (6) is installed inside the cylinder liner (5). The rear end cover (8) is fixedly installed on the outside of the cylinder liner (5) and the piston (6); the radius of the through hole at the bottom of the cylinder liner (5) is greater than the radius of the first slot hole. Inside the outer casing (3), eight outer friction plates (14) and seven inner friction plates (15) are installed alternately and fixed to the inner wall of the outer casing (3) by splines. A pressure plate (13) is also installed between the last outer friction plate (14) and the bottom of the piston (6) and cylinder liner (5). The pressure plate (13) also has a through hole in the center, and the radius of the through hole of the pressure plate (13) is the same as the radius of the first slot. An oil hole is also provided at the bottom of the cylinder liner (5) and perpendicular to the direction of the cylinder liner (5); A front cover (2) is affixed to the side of the coal mining machine brake (I) connected to the outer shaft. A first through hole is provided at the center of the front cover (2). A first slot is provided at the center of the piston (6) near the side end of the front cover (2). The inner diameter of the first slot, the inner diameter of the inner friction plate (15), the inner diameter of the eight outer friction plates (14), and the inner diameter of the first through hole are all the same. A rear cover (8) is installed on the side of the coal mining machine brake (I) away from the outer shaft. A second through hole is provided at the center of the rear cover (8). A second slot is provided at the center of the piston (6) near the rear cover (8). The first slot and the second slot are connected by a third through hole. A plug (10) is also installed at the bottom of the second slot and outside the third through hole. On the piston (6), and outside the second slot, a first annular groove is provided; on the rear end cover (8), and inside the rear end cover (8) and outside the second through hole, a second annular groove with an annular boss is provided. The annular boss part of the second annular groove corresponds to the first annular groove on the piston (6). The annular boss part of the second annular groove and the first annular groove together form a cavity for installing two sets of disc springs (11); the piston body part between the first annular groove and the second slot corresponds to the inner ring part of the second annular groove of the rear end cover (8) except for the annular boss part. The inner diameter of the disc spring (11) is the same as the radius of the cylindrical protrusion at the center of the first ring groove, and the radius of the second slot is smaller than the radius of the cylindrical protrusion at the center of the first ring groove. The phrase "when the internal mechanism of the coal mining machine brake (I) approaches the proximity switch (II)" specifically refers to the piston (6) of the coal mining machine brake (I) approaching the proximity switch (II).

4. A shearer brake system as claimed in claim 3 wherein, The AC / DC converter (Ⅳ) includes: a transformer (T) for stepping down a (non-safe) 110V AC voltage to 12V AC; a bridge circuit for converting the 12V AC to an (intrinsically safe) 12V DC; an RC filter for filtering the (intrinsically safe) 12V DC output from the bridge; and a Zener diode (Dz) for regulating the voltage output from the RC filter; wherein, The bridge circuit consists of a first diode (D1), a second diode (D2), a third diode (D3), and a fourth diode (D4). The anode of the first diode (D1) is connected to the anode of the third diode (D3), the cathode of the first diode (D1) is connected to the anode of the second diode (D2), the cathode of the third diode (D3) is connected to the anode of the fourth diode (D4), and the cathode of the second diode (D2) is connected to the cathode of the fourth diode (D4). The cathode of the first diode (D1) is connected to the anode of the second diode (D2) and the cathode of the fourth diode (D4), and the anode of the first diode (D1) is connected to the anode of the third diode (D3) and the second end of the capacitor (C) in the RC filter; the cathode of the second diode (D2) is connected to the anode of the third diode (D3) and the first end of the capacitor (C) in the RC filter, and the first end of the capacitor (C) is connected to one end of the resistor (R) in the RC filter; the other end of the resistor (R) is connected to the cathode of the voltage stabilizing diode (Dz), and the anode of the voltage stabilizing diode (Dz) is connected to the second end of the capacitor (C).

5. A shearer brake system as claimed in claim 3 wherein, The oil hole is provided with an oil plug, and the outer end of the oil plug is provided with a dust cover (12).

6. A shearer brake system as claimed in claim 3 wherein, The gap between the bottom through hole side of the cylinder sleeve (5) and the piston (6) is provided with a first combined sealing ring (4), and the gap between the middle inner wall side of the cylinder sleeve (5) and the piston (6) is provided with two combined sealing rings (7).

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