Hydro-pneumatic sealing Since the production of torque-limiting fluid couplings in China in 1974, after more than 30 years of development, the annual output is now over 70,000 units, and the product varieties and application fields have developed greatly.
Limit-type fluid couplings are mainly used in large inertia equipment that does not require speed regulation and is difficult to start, such as ball mills, crushers, coal crushers, coal mills, mixers, tower cranes, scraper conveyors and belts. Equipment such as conveyors usually have a starting torque of 2 to 3.5 times the rated torque.
If the motor is improperly selected or the voltage fluctuates greatly, it will be difficult to start or even burn the motor.
The characteristic characteristics of the torque-type fluid coupling in the application are analyzed by dynamics. At the moment of load starting, the load starting torque on the motor shaft is M in the formula - the friction torque independent of the speed, which is the bearing and mechanical contact friction. The sum of the moment and the blast resistance torque is constant for the specific equipment - the load acceleration torque, the M acceleration torque is proportional to the moment of inertia J and the angular acceleration ε of the load system, or proportional to the mass of the system object m, the acceleration a, and The acceleration time t is inversely proportional, so the shorter the load acceleration time, the larger the acceleration torque M or M. When the motor is directly connected, the motor starts to constitute an impact load, and the acceleration time is extremely short, and the load starting torque is large and difficult to start. If the motor does not move the load, it will form a boring car and lengthen the starting current duration. In severe cases, the motor will be burnt. Adding a fluid coupling is a good way to solve the above problems.
1. Two-step start to reduce the load starting torque, improve the starting condition After adding the fluid coupling between the motor and the load, the original direct connection is added to the flexible hydraulic transmission, and the one-step start when the direct connection is made For the two-step starting of the motor and the load, the first step is to drive the hydraulic coupling pump to idle the start of the motor, n=0, M=0 and the soft start M and increase the speed quickly.
When M is started, the second step starts, the turbine drives the load to start and accelerates to the rated speed, and the startup is completed. The first step is the motor starting time, the second step is the load starting time, and the second step starting time is related to the load moment of inertia and the transmission system power condition.
The sum of the two-step starting times is the starting process time.
The hydraulic transmission makes the motor start and soft start at no load, which is beneficial to the motor starting and rapid speed increase, which improves the starting load capacity of the motor and shortens the duration of the starting current. The soft start of the load reduces the starting torque required for the load.
In this process, the one-liter motor of the torque and the lower load reduce the requirements on the motor. The small-size motor can meet the requirements, and the number or capacity of the motor frame can be reduced by one or two.
It can be seen from Figure 1 that the application of the fluid coupling improves the starting load capacity of the motor, and the load diagram of the small motor can start the original large motor. M China Hydraulic Pneumatic Seals Industry Association Hydraulic Branch / Yang Naiqiao Beijing lifting transport Mechanical Research Institute / Zou Tiehan brief comment on domestic torque-limiting fluid couplings Figure 1 Comparison of characteristics of large inertia equipment installed and not equipped with hydraulic couplings - load torque curve - large motor characteristic curve of hydraulic coupling -- Small motor characteristic curve with hydraulic coupling - external characteristic curve of hydraulic coupling 2. Reduced starting current and its duration Two-step starting of motor and load after adding hydraulic coupling, making motor The starting currents of the load are staggered from each other and are not superimposed. Moreover, due to the soft start, the starting speed is gradually increased, the torque is small, the current is small, and the motor speed is fast, so the starting current and its duration are reduced. Compared with the direct drive of the motor, there is obvious power saving effect as shown in Figure 2.
3. The ability to increase the starting load of the motor During the starting process, as the speed of the pump wheel increases, the pump wheel and turbine torque also increase. When M is shown in Figure 3, the turbine belt load starts running. It can be seen that the load is not directly driven by the starting torque M of the electric motor, but the starting torque of the turbine is used to start the load, so that the hydraulic transmission can improve the starting load of the electric motor.
The ability to reduce the load starting torque. The small-sized motor is selected to operate close to its rated working condition during steady-state operation, so the operating power factor is high, the efficiency is high, the loss of wind loss, iron loss, copper loss and the like are small. Therefore, energy saving factors have been included in the power selection.
2. Starting energy saving Due to the no-load start and soft start of the motor, the starting load capacity is improved, thus reducing the starting current value and its duration, reducing the starting power consumption and starting again compared to clicking the rigid transmission. Energy saving is shown in Figure 2.
3. The operation is energy-saving and reasonable selection, and the small-size motor is applied to make the motor run close to the rated working condition, which overcomes the under-loading condition of the big horse-drawn car, thus relatively improving the power factor and efficiency of the motor. After deducting the power loss of the hydraulic coupler by 3% to 4%, there is still energy saving effect.
In short, for large inertia equipment, the torque-type fluid coupling is applied, and the transmission energy-saving effect is obtained in the power selection, starting process and steady-state operation.
Structure and performance of torque-limiting fluid couplings All types of torque-type fluid couplings have the characteristics of improving transmission quality and saving energy.
From the following points, the characteristics of the fluid coupling to improve the transmission quality can be demonstrated.
1 can make the motor start and soft start empty, which is conducive to the motor speed.
2 The ability to increase the starting load of the motor utilizes the peak torque of the motor to start the load, overcoming the shortcomings of low starting torque of the asynchronous motor.
3Overload protection Even if the working machine is stuck, the power machine can still rotate with the pump wheel as usual, without overloading, stalling, and stalling, thus protecting the motor and the working machine from damage.
Fig.3 Combined working curve of motor hydraulic couplingFig.2 Energy-saving principle of applying hydraulic drive motor with no-load startingFig. 4. Reasonable matching can be applied to small-sized motor. The hydraulic drive makes the motor and load start in two steps and reduces the load starting torque. , the ability to increase the starting load of the motor, thus reducing the motor capacity, the small size motor can be used to meet the starting requirements of large inertia equipment. It can be seen from Fig. 3 that if the motor is directly connected, the starting torque M of the motor is less than the load starting torque and cannot be started; if the hydraulic transmission is applied, the starting torque M of the turbine is larger than the load torque M and can be started smoothly. ΔM=M is ​​the acceleration torque of the turbine. After starting, the turbine runs steady at the intersection of the M and M curves.
The torque-limiting hydraulic coupler's transmission energy-saving torque-type coupling is not regulated in the application, no speed regulation and energy saving, but it can drive energy saving. The transmission energy saving of the torque-limiting fluid coupling is shown in the following three aspects.
1. Selection and energy saving Because the hydraulic drive makes the motor start-up, soft start and two-step start, a small-sized motor can be selected to change the under-loading operation condition of the previous large-marathon trolley, which not only increases the motor starting load a motor- Hydraulic coupling combined working curve b fluid coupling - working machine combined working curve ΔM - acceleration torque hydraulic pneumatic seal 4 reduces starting current and its duration, reducing power consumption in starting conditions.
When more than 5 machines drive the same working device, the power can be balanced, and the starting time can be delayed, so that the starting currents of the motors are staggered and not superimposed, which greatly reduces the peak of the total starting current and reduces the impact on the power grid.
6 Reduce shock, isolate torsional vibration, protect equipment and transmission components, and extend equipment life.
7 It is easy to maintain and can be operated without maintenance for a long time.
Different types of torque-limiting fluid couplings also have their own structure, performance characteristics and advantages and disadvantages.
Static Pressure Discharge Type Limiting Torque Coupling Figure 4 shows the structure of the static pressure release coupling. The fluid coupling is vented by a pressure balance relationship between the outer edge of the working chamber and the side auxiliary chamber. The angular velocity ω= at the outer edge of the side auxiliary cavity ω=(ω2. When ω is reduced during overload, ω is lowered, so that the pressure at this point is lowered, and the working chamber is drained into the auxiliary cavity due to the high pressure of the working chamber, so that the transmission torque is lowered. The load is reduced, the turbine speed is increased, and the oil flows back into the working chamber. The fluid coupling has a simple structure, the reaction is insensitive when the load is abrupt, and the overload coefficient is large. The application area is small and the manufacturer has very few. The main application is Tower crane.
2. Dynamic Pressure Discharge Type Hydraulic Coupler Figure 5 shows the dynamic pressure discharge type hydraulic coupling. Its overload coefficient is T=2.0~2.5, the transmission power range is wide, the dynamic response is sensitive, and the load is abruptly 0.2s after the working chamber. The internal liquid flow forms a circulating flow state, which has a reverberation, and the overload protection performance is good, but the structure is complicated. It is often used in places where the protection power and working machine do not exceed the specified torque, and equipment that frequently starts and requires dynamic response, such as belt conveyor, scraper conveyor, bucket wheel stacker and reclaimer. The working medium for its application includes oil medium and water medium. The water medium is mainly used in underground coal mines.
Figure 4: Static pressure and discharge type hydraulic coupling structure diagram Most of the torque type couplings are rigidly connected with the turbine shaft as the output end and the input shaft of the reducer. The weight of the fluid coupling is affected by the reducer bearing. The bearing is subjected to shear, bending and torsion combined stress, and it is an alternating stress, which often causes the reducer to break the shaft. Because the reducer shaft is designed to withstand only the torque, the shear force and the additional bending moment are additionally applied by the weight of the fluid coupling. In order not to make the reducer bear the weight of the fluid coupling, some people put the fluid coupling upside down and put the output end as an input to install, so a new problem arises. Because the impeller type of the dynamic pressure and discharge type fluid coupling pump and the turbine are asymmetric, the inner radius of the impeller is not opposite, so that the flow coefficient of the starting liquid flow is increased, which cannot meet the working machine, especially the belt conveyor. Machine requirements. In recent years, some enterprises have increased the volume of the rear auxiliary cavity and lengthened the auxiliary cavity to meet the requirements of the start time of the belt conveyor, which is very popular among users. However, due to the increased weight and increased axial size, the probability and possibility of breaking the shaft of the reducer is increased.
There is also a structure that, when the auxiliary cavity is lengthened, the outer casing of the turbine end is expanded into the outer auxiliary cavity, which increases the liquid filling amount, makes the starting time longer, and can better meet the use requirements. However, due to the increased weight and size, the probability and possibility of breaking the shaft of the reducer is increased.
The above-mentioned application of the hydraulic coupling inverted, lengthening the auxiliary cavity, lengthening the auxiliary cavity and adding the outer auxiliary cavity is not a problem in every case, but theoretically, the probability of the problem is significantly increased.
The valve-controlled extension-filled fluid coupling is a branch of the dynamic pressure discharge type. It is equipped with 2 to 3 sets of normally open centrifugal rotary valves on the partition between the front and rear auxiliary chambers of the dynamic pressure discharge type. In the pump wheel is at rest or low rotation a structure diagram b general external characteristic curve Figure 5 dynamic pressure discharge hydraulic coupling 1. active half coupling and input sleeve 2. front auxiliary cavity 3. rear auxiliary cavity 4. pump Wheel 5. Oil plug 6. Fusible plug 7. Turbine 8. Turbine shaft output bushing Hydraulic and pneumatic seal speed when the rotary valve oil circuit is open, the oil circuit is closed at high speed. When the fluid coupling is started, the liquid in the working chamber can be quickly charged into the rear auxiliary chamber, which is beneficial to the start and soft start of the motor. As the speed of the motor rises with the pin of the pendulum to gradually close the oil path, the liquid in the rear auxiliary cavity flows into the working cavity through the communication hole, so that the turbine has a larger starting torque. The application of the rotary valve facilitates the ability of the motor to start at no load and increase the starting load of the motor. The valve-controlled extension-filled fluid coupling is mostly used in coal mine scraper conveyors, and the effect is good.
However, due to the complicated structure and high failure rate, production and application are decreasing.
3. The composite liquid-discharge type fluid coupling type torque-type coupling is limited by the liquid flow and liquid discharge. The hydraulic coupling which has both static pressure discharge and dynamic pressure discharge is called composite discharge force. The coupling is shown in Figure 6. This is a new product developed in China. The model number of YOX is currently only produced by two production plants. As the preferred accessory for the torque-type fluid coupling, it was included in the DTIIA Belt Conveyor Design Manual published in 2003.
1 Inner wheel drive mode, the input end is rigidly connected, and the weight of the fluid coupling is received by the motor bearing, thus avoiding the shaft breakage of the reducer.
2 When the brake wheel is installed, the axial dimension of the fluid coupling is not increased.
3 is most suitable for the three-point floating bearing drive unit as shown in Figure 7. If the drive unit uses a general dynamic pressure and pressure type force coupling, the axial direction is increased due to the increase of the brake wheel at the output end. The additional bending moment is increased, and the probability of the shaft breaking accident of the reducer is increased, and the composite draining type application has no such drawback.
Figure 6. Composite effluent fluid coupling structure 1. Pump wheel 2. Main shaft 3. Side auxiliary chamber 4. Housing 5. Working chamber 6. Rubber elastic block 7. Hub 8. Brake wheel 9. Turbine 4 water medium, Oil medium can be applied, which is convenient for common parts of coal mine underground and uphole equipment.
5 The overload factor is 0.8~0.2, which can fully meet the requirements of belt conveyors and other equipment.
6 The structure is simple and compact, and it has the smallest axial dimension and the lightest weight compared with other torque-limiting fluid couplings.
In summary, the YOX composite venting fluid coupling brings superior conditions to the structural design, installation, use and maintenance of the equipment mainframe, and is a good product to be recommended.
4. Blocking fluid couplings All kinds of fluid couplings need to have a difference in speed to transmit power, so there is speed and power loss, and the lock-type fluid coupling can effectively compensate for this defect. However, the current production and application of latching fluid couplings are few.
Figure 8 shows a structure of the lock-type fluid coupling. The centrifugal friction clutch lock-type fluid coupling is applied to the side auxiliary cavity of the static pressure discharge type fluid coupling on the belt conveyor. good. Due to the clutch, the latching fluid coupling does not transmit much power. In addition, no reversal occurs during operation. Once the reversal occurs, the turbine speed does not decrease, the friction clutch cannot be disengaged, and the function of the fluid coupling cannot be exerted.
The production and application of latching fluid couplings are few.
The composite venting fluid coupling is structurally different from the dynamic pressure venting type and the static pressure venting type. In addition to the performance of the general fluid coupling to improve the transmission quality and energy saving performance, it is important. It also has its own unique structural features.
Limit-type fluid couplings are mainly used in large inertia equipment that does not require speed regulation and is difficult to start, such as ball mills, crushers, coal crushers, coal mills, mixers, tower cranes, scraper conveyors and belts. Equipment such as conveyors usually have a starting torque of 2 to 3.5 times the rated torque.
If the motor is improperly selected or the voltage fluctuates greatly, it will be difficult to start or even burn the motor.
The characteristic characteristics of the torque-type fluid coupling in the application are analyzed by dynamics. At the moment of load starting, the load starting torque on the motor shaft is M in the formula - the friction torque independent of the speed, which is the bearing and mechanical contact friction. The sum of the moment and the blast resistance torque is constant for the specific equipment - the load acceleration torque, the M acceleration torque is proportional to the moment of inertia J and the angular acceleration ε of the load system, or proportional to the mass of the system object m, the acceleration a, and The acceleration time t is inversely proportional, so the shorter the load acceleration time, the larger the acceleration torque M or M. When the motor is directly connected, the motor starts to constitute an impact load, and the acceleration time is extremely short, and the load starting torque is large and difficult to start. If the motor does not move the load, it will form a boring car and lengthen the starting current duration. In severe cases, the motor will be burnt. Adding a fluid coupling is a good way to solve the above problems.
1. Two-step start to reduce the load starting torque, improve the starting condition After adding the fluid coupling between the motor and the load, the original direct connection is added to the flexible hydraulic transmission, and the one-step start when the direct connection is made For the two-step starting of the motor and the load, the first step is to drive the hydraulic coupling pump to idle the start of the motor, n=0, M=0 and the soft start M and increase the speed quickly.
When M is started, the second step starts, the turbine drives the load to start and accelerates to the rated speed, and the startup is completed. The first step is the motor starting time, the second step is the load starting time, and the second step starting time is related to the load moment of inertia and the transmission system power condition.
The sum of the two-step starting times is the starting process time.
The hydraulic transmission makes the motor start and soft start at no load, which is beneficial to the motor starting and rapid speed increase, which improves the starting load capacity of the motor and shortens the duration of the starting current. The soft start of the load reduces the starting torque required for the load.
In this process, the one-liter motor of the torque and the lower load reduce the requirements on the motor. The small-size motor can meet the requirements, and the number or capacity of the motor frame can be reduced by one or two.
It can be seen from Figure 1 that the application of the fluid coupling improves the starting load capacity of the motor, and the load diagram of the small motor can start the original large motor. M China Hydraulic Pneumatic Seals Industry Association Hydraulic Branch / Yang Naiqiao Beijing lifting transport Mechanical Research Institute / Zou Tiehan brief comment on domestic torque-limiting fluid couplings Figure 1 Comparison of characteristics of large inertia equipment installed and not equipped with hydraulic couplings - load torque curve - large motor characteristic curve of hydraulic coupling -- Small motor characteristic curve with hydraulic coupling - external characteristic curve of hydraulic coupling 2. Reduced starting current and its duration Two-step starting of motor and load after adding hydraulic coupling, making motor The starting currents of the load are staggered from each other and are not superimposed. Moreover, due to the soft start, the starting speed is gradually increased, the torque is small, the current is small, and the motor speed is fast, so the starting current and its duration are reduced. Compared with the direct drive of the motor, there is obvious power saving effect as shown in Figure 2.
3. The ability to increase the starting load of the motor During the starting process, as the speed of the pump wheel increases, the pump wheel and turbine torque also increase. When M is shown in Figure 3, the turbine belt load starts running. It can be seen that the load is not directly driven by the starting torque M of the electric motor, but the starting torque of the turbine is used to start the load, so that the hydraulic transmission can improve the starting load of the electric motor.
The ability to reduce the load starting torque. The small-sized motor is selected to operate close to its rated working condition during steady-state operation, so the operating power factor is high, the efficiency is high, the loss of wind loss, iron loss, copper loss and the like are small. Therefore, energy saving factors have been included in the power selection.
2. Starting energy saving Due to the no-load start and soft start of the motor, the starting load capacity is improved, thus reducing the starting current value and its duration, reducing the starting power consumption and starting again compared to clicking the rigid transmission. Energy saving is shown in Figure 2.
3. The operation is energy-saving and reasonable selection, and the small-size motor is applied to make the motor run close to the rated working condition, which overcomes the under-loading condition of the big horse-drawn car, thus relatively improving the power factor and efficiency of the motor. After deducting the power loss of the hydraulic coupler by 3% to 4%, there is still energy saving effect.
In short, for large inertia equipment, the torque-type fluid coupling is applied, and the transmission energy-saving effect is obtained in the power selection, starting process and steady-state operation.
Structure and performance of torque-limiting fluid couplings All types of torque-type fluid couplings have the characteristics of improving transmission quality and saving energy.
From the following points, the characteristics of the fluid coupling to improve the transmission quality can be demonstrated.
1 can make the motor start and soft start empty, which is conducive to the motor speed.
2 The ability to increase the starting load of the motor utilizes the peak torque of the motor to start the load, overcoming the shortcomings of low starting torque of the asynchronous motor.
3Overload protection Even if the working machine is stuck, the power machine can still rotate with the pump wheel as usual, without overloading, stalling, and stalling, thus protecting the motor and the working machine from damage.
Fig.3 Combined working curve of motor hydraulic couplingFig.2 Energy-saving principle of applying hydraulic drive motor with no-load startingFig. 4. Reasonable matching can be applied to small-sized motor. The hydraulic drive makes the motor and load start in two steps and reduces the load starting torque. , the ability to increase the starting load of the motor, thus reducing the motor capacity, the small size motor can be used to meet the starting requirements of large inertia equipment. It can be seen from Fig. 3 that if the motor is directly connected, the starting torque M of the motor is less than the load starting torque and cannot be started; if the hydraulic transmission is applied, the starting torque M of the turbine is larger than the load torque M and can be started smoothly. ΔM=M is ​​the acceleration torque of the turbine. After starting, the turbine runs steady at the intersection of the M and M curves.
The torque-limiting hydraulic coupler's transmission energy-saving torque-type coupling is not regulated in the application, no speed regulation and energy saving, but it can drive energy saving. The transmission energy saving of the torque-limiting fluid coupling is shown in the following three aspects.
1. Selection and energy saving Because the hydraulic drive makes the motor start-up, soft start and two-step start, a small-sized motor can be selected to change the under-loading operation condition of the previous large-marathon trolley, which not only increases the motor starting load a motor- Hydraulic coupling combined working curve b fluid coupling - working machine combined working curve ΔM - acceleration torque hydraulic pneumatic seal 4 reduces starting current and its duration, reducing power consumption in starting conditions.
When more than 5 machines drive the same working device, the power can be balanced, and the starting time can be delayed, so that the starting currents of the motors are staggered and not superimposed, which greatly reduces the peak of the total starting current and reduces the impact on the power grid.
6 Reduce shock, isolate torsional vibration, protect equipment and transmission components, and extend equipment life.
7 It is easy to maintain and can be operated without maintenance for a long time.
Different types of torque-limiting fluid couplings also have their own structure, performance characteristics and advantages and disadvantages.
Static Pressure Discharge Type Limiting Torque Coupling Figure 4 shows the structure of the static pressure release coupling. The fluid coupling is vented by a pressure balance relationship between the outer edge of the working chamber and the side auxiliary chamber. The angular velocity ω= at the outer edge of the side auxiliary cavity ω=(ω2. When ω is reduced during overload, ω is lowered, so that the pressure at this point is lowered, and the working chamber is drained into the auxiliary cavity due to the high pressure of the working chamber, so that the transmission torque is lowered. The load is reduced, the turbine speed is increased, and the oil flows back into the working chamber. The fluid coupling has a simple structure, the reaction is insensitive when the load is abrupt, and the overload coefficient is large. The application area is small and the manufacturer has very few. The main application is Tower crane.
2. Dynamic Pressure Discharge Type Hydraulic Coupler Figure 5 shows the dynamic pressure discharge type hydraulic coupling. Its overload coefficient is T=2.0~2.5, the transmission power range is wide, the dynamic response is sensitive, and the load is abruptly 0.2s after the working chamber. The internal liquid flow forms a circulating flow state, which has a reverberation, and the overload protection performance is good, but the structure is complicated. It is often used in places where the protection power and working machine do not exceed the specified torque, and equipment that frequently starts and requires dynamic response, such as belt conveyor, scraper conveyor, bucket wheel stacker and reclaimer. The working medium for its application includes oil medium and water medium. The water medium is mainly used in underground coal mines.
Figure 4: Static pressure and discharge type hydraulic coupling structure diagram Most of the torque type couplings are rigidly connected with the turbine shaft as the output end and the input shaft of the reducer. The weight of the fluid coupling is affected by the reducer bearing. The bearing is subjected to shear, bending and torsion combined stress, and it is an alternating stress, which often causes the reducer to break the shaft. Because the reducer shaft is designed to withstand only the torque, the shear force and the additional bending moment are additionally applied by the weight of the fluid coupling. In order not to make the reducer bear the weight of the fluid coupling, some people put the fluid coupling upside down and put the output end as an input to install, so a new problem arises. Because the impeller type of the dynamic pressure and discharge type fluid coupling pump and the turbine are asymmetric, the inner radius of the impeller is not opposite, so that the flow coefficient of the starting liquid flow is increased, which cannot meet the working machine, especially the belt conveyor. Machine requirements. In recent years, some enterprises have increased the volume of the rear auxiliary cavity and lengthened the auxiliary cavity to meet the requirements of the start time of the belt conveyor, which is very popular among users. However, due to the increased weight and increased axial size, the probability and possibility of breaking the shaft of the reducer is increased.
There is also a structure that, when the auxiliary cavity is lengthened, the outer casing of the turbine end is expanded into the outer auxiliary cavity, which increases the liquid filling amount, makes the starting time longer, and can better meet the use requirements. However, due to the increased weight and size, the probability and possibility of breaking the shaft of the reducer is increased.
The above-mentioned application of the hydraulic coupling inverted, lengthening the auxiliary cavity, lengthening the auxiliary cavity and adding the outer auxiliary cavity is not a problem in every case, but theoretically, the probability of the problem is significantly increased.
The valve-controlled extension-filled fluid coupling is a branch of the dynamic pressure discharge type. It is equipped with 2 to 3 sets of normally open centrifugal rotary valves on the partition between the front and rear auxiliary chambers of the dynamic pressure discharge type. In the pump wheel is at rest or low rotation a structure diagram b general external characteristic curve Figure 5 dynamic pressure discharge hydraulic coupling 1. active half coupling and input sleeve 2. front auxiliary cavity 3. rear auxiliary cavity 4. pump Wheel 5. Oil plug 6. Fusible plug 7. Turbine 8. Turbine shaft output bushing Hydraulic and pneumatic seal speed when the rotary valve oil circuit is open, the oil circuit is closed at high speed. When the fluid coupling is started, the liquid in the working chamber can be quickly charged into the rear auxiliary chamber, which is beneficial to the start and soft start of the motor. As the speed of the motor rises with the pin of the pendulum to gradually close the oil path, the liquid in the rear auxiliary cavity flows into the working cavity through the communication hole, so that the turbine has a larger starting torque. The application of the rotary valve facilitates the ability of the motor to start at no load and increase the starting load of the motor. The valve-controlled extension-filled fluid coupling is mostly used in coal mine scraper conveyors, and the effect is good.
However, due to the complicated structure and high failure rate, production and application are decreasing.
3. The composite liquid-discharge type fluid coupling type torque-type coupling is limited by the liquid flow and liquid discharge. The hydraulic coupling which has both static pressure discharge and dynamic pressure discharge is called composite discharge force. The coupling is shown in Figure 6. This is a new product developed in China. The model number of YOX is currently only produced by two production plants. As the preferred accessory for the torque-type fluid coupling, it was included in the DTIIA Belt Conveyor Design Manual published in 2003.
1 Inner wheel drive mode, the input end is rigidly connected, and the weight of the fluid coupling is received by the motor bearing, thus avoiding the shaft breakage of the reducer.
2 When the brake wheel is installed, the axial dimension of the fluid coupling is not increased.
3 is most suitable for the three-point floating bearing drive unit as shown in Figure 7. If the drive unit uses a general dynamic pressure and pressure type force coupling, the axial direction is increased due to the increase of the brake wheel at the output end. The additional bending moment is increased, and the probability of the shaft breaking accident of the reducer is increased, and the composite draining type application has no such drawback.
Figure 6. Composite effluent fluid coupling structure 1. Pump wheel 2. Main shaft 3. Side auxiliary chamber 4. Housing 5. Working chamber 6. Rubber elastic block 7. Hub 8. Brake wheel 9. Turbine 4 water medium, Oil medium can be applied, which is convenient for common parts of coal mine underground and uphole equipment.
5 The overload factor is 0.8~0.2, which can fully meet the requirements of belt conveyors and other equipment.
6 The structure is simple and compact, and it has the smallest axial dimension and the lightest weight compared with other torque-limiting fluid couplings.
In summary, the YOX composite venting fluid coupling brings superior conditions to the structural design, installation, use and maintenance of the equipment mainframe, and is a good product to be recommended.
4. Blocking fluid couplings All kinds of fluid couplings need to have a difference in speed to transmit power, so there is speed and power loss, and the lock-type fluid coupling can effectively compensate for this defect. However, the current production and application of latching fluid couplings are few.
Figure 8 shows a structure of the lock-type fluid coupling. The centrifugal friction clutch lock-type fluid coupling is applied to the side auxiliary cavity of the static pressure discharge type fluid coupling on the belt conveyor. good. Due to the clutch, the latching fluid coupling does not transmit much power. In addition, no reversal occurs during operation. Once the reversal occurs, the turbine speed does not decrease, the friction clutch cannot be disengaged, and the function of the fluid coupling cannot be exerted.
The production and application of latching fluid couplings are few.
The composite venting fluid coupling is structurally different from the dynamic pressure venting type and the static pressure venting type. In addition to the performance of the general fluid coupling to improve the transmission quality and energy saving performance, it is important. It also has its own unique structural features.
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