In order to meet the explosion-proof requirements of hoists installed underground in coal mines, my country has produced the following forms of single-rope winding explosion-proof mine hoists: electrical explosion-proof mine hoists, hydraulic explosion-proof mine hoists, mechanical-hydraulic differential speed-regulating explosion-proof Mine hoist, etc.
①Electrical explosion-proof mine hoist
Electrical explosion-proof is mainly to change the electrical components, motors, and electronic controls to explosion-proof (it is reasonable that the mechanical parts such as brake shoes, hydraulic oil, etc. should also be explosion-proof). The electrical explosion-proof mine hoist is shown in Figure 11-12. The electrical explosion-proof mine hoist is relatively mature, and the speed regulation performance is stable, but the speed regulation is usually graded. The main disadvantages of metallurgical machinery are the complicated power distribution system, many resistance boxes, large heat generation, large underground chambers, and high underground infrastructure and installation costs.
②Hydraulic explosion-proof single rope winding type mine hoist
Except for electric explosion-proof mine hoists, hydraulic explosion-proof transmission forms are mainly adopted in China. The hydraulically driven explosion-proof mine hoist has superior speed regulation and starting performance, simple operation and compact structure. It is an ideal explosion-proof drive method for mine hoists. However, the application and development of hydraulic transmission hoists also depend on the specifications and manufacturing quality of high-power hydraulic pumps and hydraulic motors, as well as corresponding hydraulic components. Due to the slow development of hydraulic parts in my country, there has been a long time in the past. The lack of high-power and high-torque hydraulic motors and hydraulic pumps suitable for mine hoisting applications has also affected the development of hydraulic hoists in my country. For example, in the mid-to-late 20th century, when designing and applying hydraulic explosion-proof hoists, due to the small size, short life and high price of hydraulic pumps and motors produced in China at that time, the noise and heat generation of the hydraulic system were not well resolved. Affected the development of hydraulic hoists. In the future, all relevant units have also done a lot of work on improvements in noise, heat generation, and service life, and improvements and improvements have been made. my country only began to develop this type of explosion-proof mine hoist in the 1990s. The diameter of the drum is 1.2m (designed and produced by Hunan Zhuzhou Coal Mine Special Equipment Factory), 1.6m, 2m, and the current maximum is 2.5m.
1) Drive with a high-speed hydraulic motor through a reducer (single motor and multi-motor drive);
2) Direct drive with low-speed high-torque motor (also divided into single-motor and multi-motor drive).
③Explosion-proof mine hoist with differential transmission
The structure of the differential type includes: gate-controlled differential reducer differential, dual-motor differential speed regulation through differential reducer and pump-controlled reducer differential speed. The gate-controlled differential is to use the gate to control the differential speed of the differential reducer, so that when the hoisting motor is running at the rated speed, the hoisting drum can get different speeds lower than the rated speed of the motor. This kind of differential speed regulation has a simple structure, low price, high transmission efficiency, and convenient maintenance. However, when the brake is used to control the speed, the brake shoe and the brake disc generate more heat, and the brake force changes and the temperature changes greatly. If the friction coefficient changes, the speed regulation becomes unstable, and the friction pair wears quickly. The other is to use the combined output of two motors with different speeds through the differential, plus the combined output of the two motors with different rotations to obtain different speeds. This kind of structure is also very simple, the price is low, and the maintenance is convenient, but the speed regulation is graded, and the number of differential stages is also small. It is worth noting that the hydraulic pump-controlled speed-regulating explosion-proof hoist developed by the Luoyang Mining Machinery Research Institute. Metallurgical machinery is a kind of hoist with a differential speed-regulating control structure unique to our country. When it is running at a constant speed, it is the same as the general electric drive. It uses an explosion-proof motor to drive the hoist through a reducer. During acceleration and deceleration, it also uses the speed difference of the differential reducer to adjust the speed (this is the same as The differential speed regulation of the dispatching winch is the same). The main difference is: the adjustment of the differential speed is realized by controlling the flow of the hydraulic pump. Therefore, this type of transmission method has the characteristics of the direct transmission method of explosion-proof electric motor and the characteristics of the speed regulation method of hydraulic hoist. Its transmission efficiency is higher than that of hydraulic transmission explosion-proof hoist, hydraulic parts have long service life, low operating noise, low temperature rise, low price, and can realize stepless speed regulation. The main shortcomings of this form at present are: when there is no load and in a lifting process, the transition of differential speed regulation when the load changes positively or negatively needs to be improved.
In addition to the above-mentioned structural forms, other structural forms include: the use of control thyristors to change the voltage and speed of the AC motor stator voltage, which is mainly used for hoisting winches; and the use of hydraulic coupling oil filling to adjust The speed regulating form of hydraulic coupling is not mature yet and is limited to small winches. The most noteworthy is the AC variable frequency speed regulation. This scheme not only has low power consumption and high efficiency, but also has good speed regulation performance. The main problems at present are high prices and complex electrical systems, but it is one of the main development directions in the future.
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